Intermittent grid storage

by Rud Istvan

From the utility grid perspective, a fundamental problem with wind and solar is intermittency.

In the US, wind has a median capacity factor of 31%. In California’s Mohave Desert, solar PV has a capacity factor of 23%. To make up the electricity supply difference during the rest of the time, grids must either add otherwise unnecessary backup generation, or flex base load generation (dropping below optimum output so the grid can accept the intermittent renewable input). At a minimum, flexing results in costly capital inefficiency. Otherwise unnecessary backup generation is even more costly.

The higher the renewable penetration, the greater this intermittency burden becomes. For Texas’ ERCOT grid with 10.6% wind, the additional costs are ~$19/MWh for generation plus ~$6.50/MWh for transmission. It is now so expensive in Germany (26% renewable generation) that its largest utility, RWE, took a €3.3 billion impairment charge 1Q2014. The second largest, E.ON, took a €4.5 billion impairment charge 4Q2014, and announced it was spinning its conventional generating assets off into an unprofitable separate company. E.ON will also be shutting Irsching 4 and 5, large efficient CCGT units completed in 2010 and 2011! Irsching simply is not viable without being compensated for the forced Energiewende flexing it endures, while selling its electricity against the subsidized renewables with which it is also forced to compete.

So renewables advocates hope for major advances in grid storage to offset wind and solar intermittency. This guest post surveys what might be possible in the future given what is presently known. The focus is on utility scale, but takes an irresistible detour through TESLA’s newly hyped residential Powerwall. Sandia has a more detailed (albeit somewhat dated and hopefully slanted) utility storage analysis than this post, for CE denizens interested in digging deeper.

There are in principle only five ways that generated electricity can be subsequently ‘stored’: potential energy (e.g. pumped hydro), kinetic energy (e.g. flywheels), electrostatic energy (capacitors), electrochemical energy (batteries), and chemical energy (e.g. water hydrolysis). Anyone inventing another is in line for an automatic Nobel Prize (probably two, physics or chemistry plus peace).

Pumped hydro storage (PHS)

Potential energy in the form of pumped hydro storage (PHS, essentially reversible hydroelectricity) is >99% of existing grid storage worldwide.The figure is from EPRI 2011. EPRI has not updated their overall grid storage analysis, but did estimate that ~140,000MW of PHS was installed by YE2014.

ES overview EPRIAll that a grid needs are upper and lower water ‘reservoirs’ in ‘hilly’ terrain, and reversible hydroturbogenerators. It is possible to excavate a lower reservoir deep underground, but at much higher cost. One such facility is proposed for Holland. O-PEC would be 1400MW x 6 hours for €1.8 billion, using a 1400m (!) hydrostatic head to minimize water and underground chamber volume.

PHSRound trip efficiency is high at over 80%, and facility life is long at much over 40 years. The LCOE depends on facility size, cost, and hydrostatic head, ranging from as low as ~$85/MWh (EIA) to as high as ~$150 to $200/MWh (Sandia). PHS has so far been used mainly for peak load shifting. Off peak base load is used to pump water into the upper reservoir, which then generates back into the lower during peak load. This allows a larger grid proportion of low cost base load generating at optimal output 24/7 than would otherwise be possible. Where grid/terrain possible, PHS can also support renewable intermittency as already done somewhat in southern Germany, Austria and Switzerland (the Alps).

PHS always pays on a grid system basis if suitable affordable terrain is available. Many places favorable for wind (low relief Iowa, Denmark, northern Germany) or solar (low relief Mohave Desert) are distinctly NOT favorable—even though PHS does not have to be co-located, just very strongly grid intertied.

Developed world grids have already taken most of the advantage they can of PHS. California is an odd exception.

Kinetic Energy Storage

Kinetic energy storage is also extensively used on the grid, in the form of synchronous condensers for reactive power compensation (aka volt amp reactive, VAR). These are essentially unpowered generators spinning on grid. Some old decommissioned coal generating plants repurpose the old generators as ‘new’ synchronous condensers. Rotors may weigh hundreds of tons and spin at up to 3600 rpm, but still only store enough kinetic energy to provide transient voltage/frequency regulation (VAR). Downtown Tokyo alone uses six Toshiba purpose built 200MVARs. The human figure illustrates the enormous size/mass of grid scale kinetic storage machines. They are still grossly insufficient for bulk intermittent renewable storage.Tokyo Toshiba VARBeacon Power enhanced kinetic energy density by using grid-coupled carbon fiber flywheels spinning at 16000 rpm (reaching Mach 2, requiring they spin in a vacuum). Beacon’s first (subsidized) 20MW x 0.25hour facility comprised 200 flywheels and cost $4800/MWh. Its purpose was frequency regulation (VAR), not bulk energy storage. This facility is the flywheel capacity in this post’s initial EPRI energy storage figure.

BEACONThat is far too little energy for bulk utility wind or solar intermittency. To back up a single 2MW wind turbine at 30% capacity factor would require ([1-0.3]*24 hours / 20MW/ 2MW * 0.25hour) 6.7 of the pictured facilities.

Electrostatic storage

Electrostatic storage in capacitors is ubiquitous. There are large capacitor banks for reactive power compensation (VAR) on all utility grids.

TRANSMISSION CAPSSuper capacitors have the highest energy density of any capacitor type, an order of magnitude more than the next best kind. Supercaps plus power electronics have created a rapidly growing new utility device class in the past decade, static compensators (statcoms). These substitute for smaller synchronous condensers; ABB’s statcoms come in sizes up to 30MVAR. Their advantage is no moving parts/maintenance. Like synchronous condensors and capacitors, statcoms store far too little energy for bulk wind and solar needs.

Electrochemical batteries

Electrochemical batteries presently have limited use on the grid. Rechargeable battery electricity is stored in some reversible electrochemical reaction. Familiar lead acid (PbA) electrochemistry is sponge lead/lead dioxide electrodes creating/removing lead sulfate, with sulfuric acid electrolyte conducting the needed sulfate ions. Which is also why deeply cycled PbA batteries have inherently short cycle life unsuited to utility storage. Cycling grows ever-larger and increasingly insoluble lead sulphate grains (sulfation), while the growing/shrinking lead sulfate in the electrodes eventually causes them to disintegrate from mechanical stress. Xtreme Power designed an industrial/utility PbA capable of 650 cycles to 80% discharge, which would last less than two years supporting solar. Xtreme delivered (to utilities) about 35MW at about $1000/MWh before going bankrupt. Xtreme is the PbA in the initial figure.

There are many reversible electrochemistries. Commercial ones include PbA, Nickel Metal Hydride (NMH, in most hybrid autos), lithium ion (LiIon, ubiquitous in portable electronics and electric vehicles), and sodium sulfur (NaS). There are several ‘experimental’ chemistries with one or more as yet unresolved issues. These include lower cost lead carbon (PbC, cycle life), lower cost and higher energy zinc air (cycle life, safety), lower cost and higher energy sodium ion (cycle life), higher energy lithium air (cycle life, safety), higher energy solid state LiIon (SSLiIon, cost, cycle life), and higher energy lithium sulfur (LiS, cycle life). Furthest along seem to be PbC, SSLiIon, and LiS (the links are illustrative, not exhaustive of all the entities working on these electrochemistries).

There is a lot of uninformed MSM reporting on battery progress, often based on hyped lab PR (most recently Harvard’s rhubarb battery, below). Electrochemistry has been known since Alessandro Volta’s 1799 stack of zinc, brine soaked paper separator, and copper twitched a frog’s leg. Sticking zinc and copper into a lemon still works—but not for any practical application. Many, many $billions have been spent on battery R&D over the past century. Progress remains a very slow slog. It is beyond unlikely that any fundamental electrochemical miracles remain unrevealed.

There are two basic battery design concepts. The familiar one (like PbA, NMH, and LiIon) stores electricity in the electrodes. This is not a problem for portable electronic tiny energy storage needs. It is a big problem for utility bulk storage requiring a lot of expensive electrode. A123 Systems delivered one 20MWh LiIon system (10 of the imaged containers) that cost (based on its federal loan guarantee) $17.1 million. This facility is the LiIon capacity in the initial figure.


Backing up a single ~$3.5 million 2MW wind turbine at 30% capacity factor would require 8.4 of these containers at a cost of ~$14.4 million. They would be purchased from NEC Energy Solutions; A123 went bankrupt. Its assets were sold to the Chinese at a $119 million loss to US taxpayers who gave A123 grants and loan guarantees. The Chinese sold the utility portion to NEC. NEC has a new order for 3 20MW installations for the PJM grid. Like Beacon’s flywheels, these are for frequency regulation, not bulk renewable energy storage. In that application (which does not deeply discharge the batteries), NEC says they last 20 years—still insufficient for wind or solar without replacement.

If energy density can be increased, then the amount of electrode per unit electricity can be decreased proportionately. LiIon’s theoretical limit is 1015 Wh/liter. The Panasonic cells Tesla uses (below) are about 620 Wh/L (cells, not the Powerwall battery at ~350 Wh/L with liquid cooling). Panasonic produces more advanced (and more expensive, shorter lived) smartphone cells that approach 800 Wh/L. There will undoubtedly be some further improvement in LiIon energy density, but nothing like what has already been achieved.

The main ‘electrode concept’ utility battery is NaS. Several hundred MW are already on grid, as the first figure shows. These operate at 350C (and must be kept at that temperature continuously), have a 15-year life (significantly longer than deeply discharged LiIon at ~10 years per Tesla), and have a round trip efficiency of 75%. They are used in special grid distribution situations, for example to support remote peak loads where a small peaker or a beefed up transmission line would be even more expensive than NaS. California’s PGE just installed a 4MW x 6hour NaS facility from Japan’s NGK. It cost $18 million.   NaSAt 30% capacity factor, about (16.8 hr *2MW/[4Mw x 6hr = 24MWh NaS] /0.75 efficiency) 1.9 of these facilities would be needed to back up a single 2MW wind turbine. NaS would cost $34 million to back up one $3.5 million turbine. And it would have to be replaced after 15 years to support the turbine’s ~25 year life. NaS is not commercially feasible for renewable bulk electricity storage.

The other class of battery design stores electricity in the electrolyte, and only uses smallish expensive electrodes to put it in and take it out as electrolyte is pumped through the electrodes. In such ‘redox flow’ batteries, the electrolyte can be stored in arbitrarily large tanks. This theoretically solves the grid scale electrode cost problem. And also part of the battery cycle life problem, since the electrolyte and/or electrodes can be separately replaced.

There are several redox flow chemistries in development. Some are expensive and corrosive, like the vanadium redox battery (VRB). The most recently hyped experimental system uses inexpensive organic quinones similar to those found in rhubarb. No word yet from Harvard on round trip efficiency, or how long their ‘breakthrough’ rhubarb flow battery might last.

One seemingly promising type (since a commercial unit exists) uses relatively (compared to vanadium) inexpensive iron/chromium, championed by 2008 California startup EnerVault. Their first ‘commercial’ flow battery (250kw x 4hour = 1MWh) was installed in 2014 to support a solar powered 250kw irrigation pump in Turlock, California. It has a round trip efficiency of 60%. To back up a single 2MW wind turbine at 30% capacity factor would require (16.8 hours *2MW/ 1MWh/0.6 efficiency) 56 of the pictured EnerVault facilities. Or requires tanks, electrodes, and pumps that are 56x bigger than pictured.

Flow StorageThe facility cost $9.5 million, $4.7 million from a US grant. EnerVault told EPRI and DoE (as part of the grant process) that it expected to be ~$350/kWh in volume production. Backing up a single $3.5million 2MW turbine might cost ‘only’ $12 million in the future. The useful lifetime is TBD; EnerVault says >20 years. But EnerVault also says the pumps last “thousands of hours” before needing replacement. That could mean yearly—and probably does. On April 14, 2015 EnerVault announced it was ‘restructuring’ (laying off most employees) and ‘seeking new owners’. Existing investors including Japan’s Mitsui, French oil company TOTAL, and 3M declined to put in more money. EnerVault has failed.

The foregoing examples illustrate the immensity of the utility bulk storage challenge. No foreseeable battery solution overcomes this enormous challenge.

Distributed grid storage

There has been much renewables discussion of ‘distributed’ grid storage. Put many smaller batteries at residential or commercial locations, in the hope that manufacturing volumes would provide cost economies of scale. Thus the MSM excitement Elon Musk created with his Tesla Gigafactory and the Powerwall. The 7kWh daily cycle unit (complementing rooftop PV) has a guaranteed 10 year life at 92% round trip efficiency for $3000, excluding installation and inverter.

Whether Powerwall makes any sense is a less exciting question, which Musk’s fawning MSM did not ask. Palo Alto’s approximate LCOE for rooftop PV is ~$0.155/kWh for a 5kWDC system before subsidies, according to Palo Alto itself. To charge a single Powerwall while still using the original PV as before, about (7kWh/5.4 ‘sun hours’ per NREL /0.92 efficiency) 1.4 kW of additional PV would have to be installed. Using Palo Alto’s ‘official’ estimate, that is an additional PV cost of about $8400 (including the inverter Tesla does not supply). Total cost $11,400 for one Powerwall is no problem—if you can afford to live in Palo Alto and install PV there in the first place. The city says its average home consumes about 1000 kWh/month or (1000/~30.5) 32.8kWh/day. A 6.4kW PV plus one Powerwall will not take an average Palo Alto home off grid—it is (32.8-12) 20.8kWh short. It would take 4 Powerwalls (plus their additional PV) to go off grid. Not enough dollars or roof to make that work.

Being a little bit Palo Alto/Tesla green comes at a large cost. The 10-year, 0.065 discount rate LCOE of single Powerwall is $0.118/kWh. To that must be added the LCOE of the extra charging PV, adjusted for Powerwall efficiency. According to Palo Alto, that is (~0.155/0.92) $0.168/kWh, for total Powerwall LCOE of $0.286/kWh. The residential cost of electricity in California (March 2015) averaged ~$0.17/kWh. Powerwall is a bad deal, costing almost twice what California’s residential grid electricity does. (Tesla cars are a similarly bad deal.)

Chemical storage

Chemical energy storage involves electricity reversibly converted into simple chemical energy (some fuel). Two chemistries have been seriously proposed: hydrogen and methane.


Hydrogen can certainly be hydrolyzed from water. And the necessary electricity can certainly come from intermittent renewables. The most efficient way to convert hydrogen back to electricity at grid scale would be a PEM fuel cell or an SOFC. The math can be done using Ballard’s 1MW PEM, since a few have actually been sold as demos. Ignore the technical difficulties of bulk hydrogen storage, which the following methane alternative ‘solves’.

The theoretical efficiency of hydrolysis is ~88%. About 4% of commercial hydrogen is made this way today, with real efficiencies of ~75%. EERE says PEM fuel cells can be 60% efficient. But that is also theoretical. Ballard’s real 1 MW ClearGen® is 40±2% efficient, with a lifetime of ~15 years (similar to NaS). The round trip efficiency of a hydrogen electricity storage system would be about (0.75 * 0.4) 30%. For a utility, that is awful.

The electricity to be stored comes mainly from otherwise flexed base load generation, with chemical storage buffering renewable intermittency no different than PHS buffers peaks. The energy cost alone would be about ($57/MWh baseload / 0.3 efficiency) $190/MWh. Ballard’s ClearGen® costs about $10 million/MW (including inverter, transformer, and installation).That calculates a capital LCOE of about $114/MWh. Adding hydrolysis and H2 storage, the system LCOE is >>$304/MWh. It is simply not commercially viable–by nearly an order of magnitude. Before solving the hydrogen storage problem.


Or, hydrogen from electrolysis could be reacted with CO2 over nickel catalysts to produce methane. Methanation is significantly exothermic, although up to half of the resulting ~20% ‘waste’ heat could be reused (e.g. heating input feedstock, since the catalysis works between 200C and 550C). A number of lab scale reactors plus at least one pilot facility have been built, with methane yields from ~70% for one pass to ~95% for three. Solves the hydrogen storage problem. The resulting synthetic methane can be stored and used like natural gas from any other source (e.g. in flexible CCGT with 58-61% efficiency). Input CO2 could theoretically be obtained from fossil fuel carbon capture (without sequestration), a process with 20-30% parasitic energy loads.

Methane round trip energy efficiency would be about 0.75 (hydrolysis) * 0.95 (catalysis yield) * 0.9 (net [half] methanation exothermic loss) * 0.8 (minimum CC parasitic load) * 0.6 (flexed CCGT) or ~31%— no better than hydrogen alone, after all the chemical complications. Methane storage avoids the technical hydrogen storage challenge, but at the expense of much additional chemical plant capital, operations, and maintenance cost. It worsens the chemical storage economics.


Most renewables advocates don’t appreciate the scope and scale of electricity grids, the difficulties intermittency creates, and the technical/ commercial inadequacies of electricity storage technologies other than PHS.

Utilities already utilize four out of five forms of energy storage wherever they make sense. Potential energy is ubiquitous pumped storage. Kinetic energy is ubiquitous synchronous condensers. Electrostatic energy is ubiquitous capacitors and statcoms. Conventional electrochemical batteries are not practical except in special situations, and probably never will be. Flow batteries may improve on conventional batteries somewhat, but are still far from feasible for large-scale bulk wind and solar storage needs. Chemical storage is even worse than batteries because of its inherently greater thermodynamic inefficiency.

It is very unlikely that any grid storage solution (other than PHS where feasible) could ever practically cover the intermittency of high penetration utility scale wind and solar. Utility voices (like RWE and E.ON) charged with making electricity grids work seamlessly and reliably despite ever increasing renewable intermittency burdens are only starting to be heard. Those voices are very negative. It may not be until some grid goes dark because of intermittency (as increasingly uneconomic flexed conventional generation is shut in Germany and UK) that the general public will understand. Germany, UK, and California seem determined to run this unfortunate experiment for the rest of us. One or more appear likely to succeed soon in experimentally proving the grid instability ‘blackout’ hypothesis. The question is mainly when, not if.

Acknowledgements.  APlanningEngineer provided many helpful comments on earlier drafts.

JC note:  As with all guest posts, keep your comments relevant and civil.




261 responses to “Intermittent grid storage

  1. Batteries are sometimes seen as the holy grail in the clean energy challenge. . There’s a false belief that with “good” batteries every thing will fall into place for intermittent renewable resources. Rud explains why developing “good” batteries is challenging and good solutions overwhelmingly are not likely on the horizon. Not much in the history of batteries would suggest that the concerns Rud identifies will be bypassed any time soon. The other piece is that although good cheap batteries would help make intermittent resources more useful other hurdles would still remain.

    For independent operation of stand alone generation/storage “sizing” will be a major problem. Extra wire, transformers and such to support loads through peak usage periods impose some cost burdens but not near what would be required for an independent generation-storage system. So independent service will require either huge costs, considerable inconvenient load shifting, leaning on the grid or some combination of these factors. When you see optimistic forecasts you have to ask what’s being assumed in those regards-it’s likely not service as usual.

    For storage it’s important to know what the losses are (you always lose some power when you store it, and for some time frames and technologies it can be large), at what rate energy can be stored, how much can be stored,what rate it can be withdrawn at and how its capability may decline with use. Batteries may look better if the whole story is not known and if associated costs (like AC conversion) are left out.

    • One side note-as/if storage becomes cheaper it will lessen the delta between peak and off peak prices. Early adopters counting on long term value from that arbitrage may see it wiped out as cheaper or more storage opportunities emerge and reduce the delta. The idea that widespread adoption of home batteries will allow numerous residents to buy low and sell high contains the seeds of its own destruction.

    • The best solution is pumped power, even if it’s remote. That’s going to require high voltage transmission lines.

  2. Reblogged this on and commented:
    An excellent review. It shows why the most practical variable renewable electricity backup is a fossil fuel spinning reserve and why the real costs of solar and wind will be a lot higher than advertised.

  3. How would you class compressed air? Personally, I’m somewhat skeptical of the numbers offered, but it’s often suggested as the “cheapest” option.

    • The compressed air plants work with a combustion (gas) turbine to store energy. The combo works similar to hydro (but while flexible is not as flexible as hydro). They generally store at night hopefully when prices are (there is excess power) and contribute to the peak. I would rate the U.S. application in Alabama as a good test, proving the concept, providing a useful plant -but in the end ignoring “research” benefits the local system would have been better served spending that same money on combustion turbines alone. But had the area seen excess power at night or huge cost differentials that assessment would change.

  4. Pingback: Intermittent grid storage | Enjeux énergies et environnement

  5. David L. Hagen
    • I chose not to discuss even though the two extant facilities capacity are in the EPRI figure. There are two reasons. First, efficiency. Worse than PHS, since the heat of compression is lost, and gas turbines are less efficient than hydro turbines since water is incompressible. As a result, nothing has been built since the first two experiments (Germany 1978, Alabama 1991). Second, geology. Both CAES facilities use solution mined salt cavities. These are by definition sealed pressure tight. It was speculated that depleted natural gas fields might also serve as pressure tanks. PGE got a $25million DOE grant plus a matching CPUC grant to look at 120 depleted gas fields in California, the idea being to build a 300MW x 10 hour CAES facility. 117 of the fields turned out to be plainly unsuited. Geology would leak under pressure. The most promising field, King Island in San Joachim County was permitted for pressure testing by the EPA late in 2014. No word yet from PGE on results. If pressure tight, PGE still has to estimate round trip efficiency, since there will be additional ‘frictional’ energy losses in this porous sandstone formation. In my view, just another ARRA08 boondogle.

    • Compressed air is being considered or perhaps already tested for wave/tidal power. There is also thermal storage, as used with concentrated solar, where you heat up a fluid to hundreds of degrees that can be used later to drive a steam turbine.

      • JD, yes. Molten salt thermal is a PRE generation storage option. Had it in the post. And in fhe previous post on CSP. Both PE and JC suggested taking out here for simplicity. What part of generated electricity did you not understand? I even italicized the emphasis on generated electricity. Fail.

      • It can be used post generation too. Imagine the electricity from a wind farm being used to heat up such a fluid instead. Anyway, CSP is just the leading example, and is already in use. Worth mentioning, because thermal storage has proven viable.

      • Jim D,

        Even better, store the heat in compressed CO2. It is settled science that CO2 traps, stores, and accumulates heat. By compressing the CO2, it will hold even more, and by not releasing any heat, an infinite amount can be stored. This can then be utilised at will, days, weeks or years later.

        Completely silly, isn’t it? About as silly as storing heat in the atmosphere, or oceans, to be released later!

        Some people will believe anything.

      • David Springer

        “What part of generated electricity did you not understand? I even italicized the emphasis on generated electricity. Fail.”

        What part of an electrical heating element don’t you understand? Fail

        Snarky. Double fail.

  6. rogercaiazza

    Thank you for an excellent summary that answered many questions I have had about storage.

  7. I will repeat my prediction that I think the future is the grid will move to a WAN->LAN-Node architecture. It’s in the DNA of the technology and the future was preordained decades ago. Rud and aplanningengineer are always looking for the weak spots in the renewable energy story and I appreciate that but I have notice aplanningengineer has become more jaded and cynical since his first post. I wish you had spent at least a little time looking in to demand response and load shifting. Since you avoided it completely I will assume you also omitted other favorable aspects of energy storage management to fit your agenda.
    On a happier note Peabody Energy (#1 US coal company) is down 25% this morning trading for $1.6x a share. Can’t wait to see the bill for having the tax payer step in and clean up the environmental disaster they are about to dump on us. You really have to feel sorry for all those employees left without pensions and healthcare. Blame natural gas for causing this catastrophe.

    • JackSmith – I appreciate your comments. I may be sounding too cynical. I tend to be a “balancer” when I think things are out of whack. The hype I’ve seen on Telsa recently is excessive. On the other hand “some” of the obstacles I point out, undoubtedly will prove not to be major, but some may. Load shifting is a good topic for a future post. There are benefits but limits there as well, back in the 90s it was all about improving load factor and flattening the load shape and trying to incentivize that, but we found thatcheap peaking CTs changed the economics quite a bit.

      • Thank you, I completely agree on the Tesla hype. The load shifting and demand response issue won’t really have much of an impact until there are enough connected ‘smart’ appliances deployed. I remember back in the early part of the GWB regime there was an attempt by the DoE to set much higher SEER ratings on HVAC systems. In the end the targets were rolled back to something like 5% over the compliance period. According to the DoE this push back from the HVAC industry will result in an extra demand on the grid equivalent to several hundred large power plants over the next 30 years. Short term thinking over long term benefits. I guess that’s why the highest efficiency HVAC and smart appliances are designed in Japan/Korea and Europe.
        One more comment about grid reliability. Since I installed a UPS for my computer 2 years ago I have logged at least 30 grid ‘irregularities’ ranging from out of phase sine waves, voltage spikes to over 140 VAC and 7-8 short blackouts (<3 seconds). None of these problems had any thing to do with renewable energy on the grid and everything to do with managing the existing local grid. Based on my experience the Tesla battery (or something on the order of 10-30 KWh would at least isolate me from damaging service interruptions.

      • @jacksmith4tx – The “smart appliance” solution may work in some locales, but not well here in Arizona. One appliance, the air conditioner, is *required* to work, at very high power utilization, for a long time during a summer day.

        Back in the day, “energy controllers” were popular, and I had one. We were billed on the peak hour of each month, in kWh for that hour. My controller was smart enough to allow me to set the value I would allow for that hour. I ended up removing it, because it simply was not practical to limit that by even 1kWh.

        If homes were extremely well insulated, that might change some, but the mean temperature is often over 90, so you would still be running the A/C, but maybe just at a lower average, or at different hours. That’s *a lot* of insulation. I did the calcs for my house, and then I had two independent engineers do it. All of us concluded that the economic payoff for improving insulation was over a dozen years. It would be less on new construction, of course.

      • Hi John,
        Have you considered the following;
        Install a smart electric timer on your water heater. When your old WH dies switch to a on-demand in-line water heater. I’m looking at this
        Switch to zoned heating and cooling. It slashed my electricity use by 40% with a 4 year payback.
        Go 100% LED lighting – You can buy LEDs that are cheaper than CFL right now.
        Induction cooking – fast, precise, cool running, greatest thing since the microwave.

        I was honored as Texas Biggest Energy Saver by ERCOT for 2012 and 2013 so my ideas have been road tested.

    • “I will repeat my prediction that I think the future is the grid will move to a WAN->LAN-Node architecture.”
      Advantages: Lower transmission costs and more Resilience. Unfortunately the best bet of PHS is the opposite of small and local. Given the road we seem to be on, it seems to me the wisest place to put money is PHS. If Greens want to put their money somewhere and do something, they can form an organization and build a facility. The entity could be a non-profit I suppose but subject to further investigation, or a Green for profit corporation, partnership or possibly a co-op. PHS seems to be no-regrets. We assume the problem is intermittentcy. The most straight forward way to address that is PHS. PHS becomes more profitable the worse the intermittentcy becomes. It is a product someone wants to buy. PHS is the bet that things will get worse. Istvan and PE, we have river bluffs in Minnesota. I suppose 150 meters is not too uncommon. What about Winter? It’s assumed the river is the lower basin.

      • What about the land use and environmental objections?

      • I don’t think sucking up every available drop of surface water to boil and pump it is a rational choice and you have grossly underestimated the knock on effects (and costs) of PHS.

        According to the USGS as of 2010:
        Total withdrawals for thermoelectric power accounted for 45 percent of total water withdrawals, 38 percent of total freshwater withdrawals, and 51 percent of fresh surface-water withdrawals for all uses.

        PHS of course has a place in the grid but don’t over sell it.

      • Rivers as the lower reservoir are environmentally problematic unless in a reservoir behind a dam (water flow fluctuation). Like TVA Raccoon Mountain. Winters are no problem. And 150 meter bluffs work– you just need to store more water volume, since the potential energy is just mass times gravitational potential. Google the Ludington Michigan PHS for an example where the hydrostatic head is fairly low and winter is no problem. Many images available. The big issue in Minnesota would be land acquisition costs along the river.

        Yes, PHS is no regrets. That is why grids everywhere use it when they can. Except in nutty California. The Eagle Crest PHS was provisionally federally permitted back in 2005. 1.3 GW x 18.5 hours. Another Raccoon Mountain. Upper and lower reservours both long since abandoned existing open pit Kaiser Steel iron ore mines from WW2. All that is needed is the connecting tunnel, turbogenerators, and water. Less than ten miles from an existing high voltage transmission corridor. NO environmental impact. Yet the 2013 CPUC storage mandate was carefully crafted to expressly EXCLUDE this option. Dirty political details on why (EnerVault and the like lobbying) in essay California Dreaming in ebook Blowing Smoke, foreword by Judith.

      • Even though it’s the best option its really hard to justify the costs of pumped hydro storage. Its very hard to find places where it can be built and work economically.

        Arbitrage exists because their are limited storage options. When storage is common the price differential shrinks. If you are optimistic about other storage technologies (batteries) it makes it harder still to justify a PHS facility. Why build something that will last years beyond a 30 year planning horizon which is justified by its ability to do arbitrage long term if some other technology is going to allow a high degree of generating/load shifting such that you can’t recoup the investment price through arbitrage.

        My call would be to exploit PHS where you can, recognizing those options will be limited because there are not likely to be competitive options thay will emerge in the mid to Longer terms. I don’t know how someone that is overall gung-ho on storage in general as a solution to intermittent resources, can call for significantly more PHS at this time. Why build PHS if cheap effective batteries are in the horizon in 15 to 20 years?

      • “What about the land use and environmental objections?”
        In Minnesota, most rural land is farmed for crops. Which can add silt to the rivers. They pay to take near river and stream land out of production to clean up the rivers. Larger river stretches such as Lake Pepin would be pretty minimally effected I think.

      • It’s my opinion the grid is headed for a break. The problems of green production are going to increase. The spread between peak and off peak is going to widen. We can roll out one thing that has an average success rate that doesn’t involve more fossil fuel use. We know how to make it make work, and while it may not be optimal, with vision and political sustain, it can’t be as bad as what we’ve seen lately. I see a current and future demand for batteries, and we have one thing that works. Perhaps we can look at it this way. Can we kill solar and wind? No. Can we stop their advance? No. Now what? For the now, for the next 5 years we need to stabilize the grid. I suppose it’s a fix. The least worst option. Some may have suggested we should be in favor of something.

      • @aplanningengineer…

        Let’s suppose the reservoir issue is dealt with separately, how much would non-reversible Francis turbines with motors, generators, and clutches, for a full-time spinning reserve, cost. Say, per megawatt, assuming terawatt volumes?

        I have a couple ideas how the reservoir issue might be dealt with, but I’d like to know what my boundary conditions would be.

      • AK-I don’t know of any recent estimates for the info you requested (nor a way to get breakdowns from old estimates), but I will agree with your point. That is if you put aside all reservoir cost issues-the hardware for the pumped storage unit would not be prohibitive in itself. However most locations would require a big budget for the civil engineering required.

        TVA completed Racoon Mountain in1974 for $300 M for 1.6 GW. Rocky Mountain not too far away in Georgia cost $1.6 billion in 1995 for just over 1GW. Different locations and different challenges, but I’m not sure and not a civil, but strong cost escalation over time attributable to reservoir related costs appears likely,

      • @aplanningengineer…

        TVA completed Racoon Mountain in1974 for $300 M for 1.6 GW. Rocky Mountain not too far away in Georgia cost $1.6 billion in 1995 for just over 1GW. Different locations and different challenges, […]

        But that’s all thinking inside the box. What if we think outside the box? I know people trying to plan for utilities want mature technology, but what if we project some innovative possibilities beyond the point where they’ve become mature?

        The biggest problem I see is that people who do projections for utility-type projects don’t like to make even hypothetical assumptions regarding how immature technology might be used once it’s mature. The issue I have with that it that while you can’t be certain the projected technological solution will work, you can’t be certain it won’t.

        For instance, suppose you have access to mature technology for excluding the pressure at an ocean depth of 500-700 meters (AFAIK roughly optimum for Francis turbines). Suppose you can have access to as much empty space as you need at that depth for $2.00/cubic meter?

        Without worrying about how that would be accomplished, could pumped hydro be made cost-effective with that mature technology available? If $2.00/cubic meter is too much, how much lower would it have to go? Or, could it be made to work with a higher cost, say $2.50 or $3.00/cubic meter?

        If so, then the question of how to achieve that technological maturity, and its cost* (and ancillary benefits) at a societal level, becomes much more important, especially to anybody looking for ways to solve the fossil carbon problem without (significantly) impacting energy prices or global life-style improvements.

        * By “its cost” I’m referring to the cost to society of subsidizing the rapid development and maturation of the appropriate technologies.

      • AK – there are boxes and then bigger boxes still. I play a little outside some boxes. Some wild ideas may become home runs. It’s good that some people pay attention to them and nurture their developement. But they need to have some demonstrated credibility before they get touted more broadly.

        I would say take 10 immature technologies, maybe each with a one n ten chance of being a game changer. We can’t bet on all 10 or pick the winner. From where I am the siesta strategy is to wait and see what proves out. Me as a planner suggesting a wait and see look, is not meant to say researchers and innovators should not work on those out of the box areas, just that my planning (with some hedging maybe) should mostly wait.

      • Siesta strategy – that was a spell check assisted typo for best strategy, but maybe that should tell me something. I hope I am not employing a siesta strategy.

    • My scam detector is ringing.

      I suspect that local grids will be greenie Trojan horses. Neighbors on the wrong side of the ballot will find themselves paying high energy prices to well-connected local grid “non-profits” or greenie businesses. Some people will make a killing but most will be hurt. Many of these little monopoly fiefdoms will be selling power from “sustainable sources”, of course. No doubt the FUD will be all about neighborhood or local control or some other similar nonsense. It will be about power, but not the kind you get from the electrical outlet.

      Run bunny, run, the wolf is gonna get you, one by one …

    • David Springer



    • I’ve been to the mines in Wyoming.

      Open pit mining in Wyoming isn’t the same as mountain top removal. Scrape off a few meters of top soil…dig out the coal seem…put the top soil back…the resulting land is a few meters lower then before. Without a ‘before/after’ elevation map it’s hard to tell what has been reclaimed.

      Of course those aren’t the mines that are the ‘poster children’ of environmentalists.

  8. I’d suggest taking storing energy by speeding up and slowing down earth rotation.

    Talk about spinning reserves. Weight is no problem.

    There’s a simple way (this is a test of whether somebody understands how gyroscopes work), a horizontal gyroscope at the north pole. The torque is applied or received from the differential rotation of the earth and the gyroscope.

    Even without any input, we have enough earth rotation to last hundreds of years.

    And of course the gyroscope doesn’t have to be at the north pole.

  9. There are just not enough elements between Helium and Lithium, or between Fluorine and Neon, for a new battery breakthrough. Thanks for an excellent, sobering post!!

    • Good grief! Somebody can read the periodic table! ;-)

      This has been my point about electrolytic storage limits for quite some time. Unfortunately, most wishful thinkers don’t understand the basics of electrolytic storage cells.

      One wonders how to remedy that shortfalll in their technical education because once you tell them that it can’t be done, they refuse to try to learn why it is so.

  10. Too many people that think solar and wind are THE answer have given little or no thought on the need for back up; I suspect we all know lots of people like that. I ask them how do you run a hospital or steel mill on intermittent renewables.
    We may not really need more STEM workers, but we certainly need a more informed public when it comes to technology and public policy.

  11. More gorilla marketing to pump the TSLA stock price.

    • Norway the oil tycoon and Holland, Russia’s oil and gas tap. So funny.

      • Oil is therefore regarded as a vital national resource and is the backbone of the Norwegian economy, though just like in the UK, its best years are in the past. Production levels have been dropping since the turn of the century, peaking at 3.5m barrels per day in 2001 to less than 1.9m in 2014.

      • Why yes, you don’t see Norwegians wearing cowboy hats and chewing on cee-gars. They’ve shown you can be loved by the ABC, Fairfax, Guardian, HuffPo etc for your green aspirations…even as you pump that good black and get filthy rich from it. They’re gushed over for their “moving tree-felling ceremonies” and, hombre, can those Norwegians dam rivers! Their toxic waste is removed from the books by a deal with Sweden, who, of course, say their incinerators are the greenest and best. (What’s not state-of-the-art and green up that way, right?) Norway’s whale kill…oh, why go on? It’s all for those natural blondes and their sovereign wealth fund – not for snips ‘n snails ‘n puppy dog tails.

        I’m not objecting to anything Norway does, by the way. In fact, I’m envious of their luvvie appeal. You can’t buy the kind of PR they get from an adoring media who would savage Tony Abbott if he so much as bumped into a tree or tripped on a cane toad.

        And the Netherlands, grimy Russian service station to the world, are not far behind Norway in green appeal. How do they do it? Quick, show us more pics of bicycles thronging the streets of quaint old Amsterdam!

        There are both money and love in fossil fuels if, like Sir Les Patterson used to say, you know how to work those journos. Merkel is able to present her nation’s brown coal surge as an urgent “anti-nuclear” measure. It’s working! Angela is still their honey! When is stupendously resource-rich Australia – which can’t even afford to run a smelter – going to learn from these green Euro-sophisticates? Maybe we need a new slogan on our national crest, a quote from Ethel Merman about what’s really the greatest business of all.

      • Now THAT is too funny mosomoso! All true. Hollywood put angel’s wings on Obama and here we are.

      – Opportunities for Norway

    • How’s that scheme of storing energy going in Norway?

      How will they scale to accept around 80GW peak unwanted renewables from just Germany? (Reached earlier this year.) Will they have enough storage capacity to fill in the lulls in renewables; which can go on for 9 to 14 days when there is insignificant wind and short days with cloud cover make PV a joke? The storage capacity would be in the vicinity of 17million MWh.

      Not that there is currently, nor is there likely to be, sufficient “renewable” generating capacity to fill such storage before those lulls. The “overbuild” capacity requirement is more than 6 to take advantage of what little wind/solar is available between total lulls. i.e. you have to build at least 6 times as much nameplate capacity.

      The connections to Norway and the storage pumps would have to handle peaks in excess of 300 GW. Renewables are then no longer cheap; certainly far from affordable for any industry that wishes to be competitive against those not strangled by renewables and unafraid of nuclear power.

  12. This excellent post ties in with the previous, related posts to provide a much-needed slap to the head for “alternative” energy proponents. It may be useful to compile this series into a single reference source for public policy makers (or at for least their staffers).

    From a longer viewpoint (perhaps MUCH longer), there are potential technologies (e.g., superconducting materials; manufactured materials utilizing nano-scale manipulation) that could address some of the significant issues in electricty generation, storage and distribution. But for rational policies today and tomorrow, these informative posts should be required reading.

  13. Pingback: 1 – Intermittent [power] grid storage | Offer Your

  14. Roger Andrews has a number of excellent posts over at Energy Matters about the problems with grid-scale energy storage. Pumped hydro is about the only thing that comes close, but even that has no hope. What’s worse is the fact that the lifespan of wind turbines is half of what is claimed.

    • Yes. I linked to their Holland FLES post.

    • Pumped hydro. The question is, “where are you gonna put all that water?”

      I don’t think people are going to accept flooding any mountain valleys. Those days are behind us, nimby and all that.

      • That objection is one reason there is not more PHS. The alternative going underground option ‘only’ costs 5x more than both reservoirs on the surface. But Holland is caught between a flat land and a high grid renewables hard place. Hence its O-PEC trial balloon. North Germany and Denmark want to export intermittency to Norwegian hydro. From what I can see, the Norwegians are delighted to put it tomtheir sourthern neighbors, as their oil fields are in permanent decline.
        Perhaps Holland will spend aka ‘waste’ the money for this project. But Holland sits on Europe’s largest nat gas field, Groenigen. Flexible CCGT would be so much more sensible for that country, but for EU CAGW nightmares.
        The foolishness is starting to have real consequences. Reality will bite, hard.

      • Can’t argue with that.

      • The Netherlands will cut gas production at Groningen, the largest gas field in western Europe, by about a quarter over the next three years, the Economics Ministry said on Friday, bowing to public concerns over earth tremors in the area.
        The decision to cut production will mean lower revenues for the government at a time when it is already struggling to meet the European Union’s budget deficit targets, even after years of austerity measures.
        “The studies showed that there are risks and consequences, including earthquakes,” of the gas extraction in Groningen, Prime Minister Mark Rutte told reporters at his weekly press conference before the details were announced.
        “They not only cause material damage but also serious emotional damage. The cabinet understands that people are worried.”

      • Further reduction of Dutch natural gas production: The end of an era?

  15. Pingback: 1 – Intermittent [power] grid storage | Exploding Ads

  16. JimD is an enthusiast for green energy AND for battery storage in recognition of some of their shortcomings. It will be interesting to hear his take on this


    • Yes, home distributed storage just needs battery prices to come down, and there is a trend. Also intermittent energy can be backed up with other green energy like biomass burning (or even perhaps BECCS). Using natural gas as a backup rather than primary power also makes it last longer while cutting emission rates. Nuclear is an option in some countries. It is not storage or nothing with renewables. It is cleaner backups first and then storage, as it develops over the next few decades, which will eventually preclude the need for backups. There are a couple of distinct technological stages towards decarbonization. It won’t happen tomorrow, but it can happen gradually.

      • other green energy like biomass burning

        I do like your sense of humor.

      • catweazle666

        “home distributed storage just needs battery prices to come down”

        It doesn’t matter how much battery prices come down, there is no way on Earth that batteries by their very nature are ever going to be remotely environmentally friendly.

        Funny how you lot never admit that.

  17. Thank you for a good essay.

  18. Now you’re getting on to my specialist subject Judith :)

    There doesn’t seem to have been any mention of Isentropic’s “pumped heat” storage thus far? This from the other side of the Atlantic Ocean in 2012:

    • Jim, I debated adding Isentropic’s ‘pile of rocks’ reversible heat pump idea, ‘PHES’. Decided not to for two reasons. First, there are very serious criticisms of the claimed 75% round trip efficiency on thermodynamic grounds. Some even argue Isentropic is a Maxwell’s Demon. Second, in June 2012 they got £14million in project funding plus equity from the UK ETI to build a 1.5MW x4 hour demonstration project for Western Power Distribution in the Midlands at Totton. As of July, 2015, there is nothing. Leads me to suspect the theoretical criticisms are valid, and that Isentropic is another EtoGas (methane storage). Just does not work in the real world.

      • If you don’t much care for “hot rocks” then how about going to the opposite extreme with “liquid air”? Also from 2012:

        Cryogenic liquids are widely used in industry already, but their adoption as an energy vector is only just beginning. A number of British organisations, research teams and Universities are already developing ways to use liquefied air (or liquid nitrogen, its major constituent) as a zero emission energy storage medium and transport fuel.

      • Curious George

        Jim – why do your links contain no numbers?

      • Work out the thermodynamics, then get back. Like aluminum, liquid air is ‘known’ as another form of electricity, considering how much is used to make it. There was a nutty Indiana entrepreneur who proposed using some aluminum something compound to generate hydrogen from water plus the compound to power emergency generator/cars with fuel cells, then recycle the resulting residue aluminum oxide. Turns out the chemistry works but the RTE is less than 10%. He did present his business plan to U. Chicago B-school with me in the audience.
        As bad an idea as SkyMine for CO2 sequestration, an example in my ebook The Arts of Truth which got $25mil IIRC of DOE demo funding!

      • Did you follow George’s excellent example and click through links until you got to the numbers?

        If so what did they reveal? Another Maxwell’s demon?

  19. Okay, so before subsidies, Elon Musk’s Powerwall works out to about 2X the cost of Calif. electricity rates. However, do you get a different result with the math that the Greeks are using?

  20. Someone needs to write a factual Elizabeth Kolbert (New Yorker) style series of articles about green power/alternative energy.

  21. Reading about the shortcomings and costs of green energy makes me wonder how we could answer this question;

    “is aiming for 350ppm of co2 – through the use of green energy in order to combat ill defined climate change- compatible with the health and well being of 7 billion humans?’


      • Justinwonder

        I am afraid our ruling elite do not agree with you and will be spending great amounts of our money to prove they are right. Sounds a bit like the elites touching belief in the euro as a worthwhile currency despite all the evidence to the contrary.


      • Tonyb,

        The Brits are smart to be out of the Euro. The Greeks are willing to spend every last bit of the German’s savings. I predicted long ago Greece would be out of the Euro – it just ain’t going to work. I’m surprised they have lasted as long as they have. I suppose that is testimony to good politician ‘s ability to kick the can down the road until they are out of office, but I am not sure. As that great leader, M. Thatcher, once said, ” the problem with socialism is that eventually you run out of other people’s money.”

        I think the referendum is a way for Tsipros to duck responsibility – let the foolish people choose their own flavor of economic suicide. No matter which way they go, they are toasted.

    • What the ruling elite thinks is important is right in front us. Check the latest US defense budget and we are adding $350 billion to modernize and expand our nuclear weapon systems – also not compatible with the health and well being of 7 billion humans (and most of the rest of the biosphere).

      • National defense is one of the few things the federal government is supposed to be responsible for. Instead, the Feds have their fingers in a million pies. – much to the dismay of all those pies.

        I like defense, we pay ourselves to defend ourselves. What’s not to like?
        I suppose we don’t really need all that defense, we could just go on vacation to a beach in Tunisia, visit the World Trade Center and take some photos, take the subway in England. It’s all good … Nothing to lose your head about.

      • Our defense budget is bloated because we are told we must defend American “interests” rather than America.

      • I like defense, we pay ourselves to defend ourselves. What’s not to like?

        To the larger extent, we tax ourselves to defend various foreigners from still other foreigners.

      • Opluso,

        All in our best interest. The last time we tried to sit one out, WWII, it didn’t work out too well. It is better to put the fire out early. Besides, if we aren’t the global cop, then who is?

        Remember the broken windows theory of law enforcement, when evil doers see a lack of order they see an opportunity to misbehave.

    • The trends in population and per capita CO2 point to 700 ppm and still rising fast in 2100. Something has to change, whether it is temperature and sea level, or energy sources. The status quo is not an option.

    “CMU/MIT study finds large-scale battery manufacturing will do little to reduce unit costs past a 200-300 MWh annual production level”

    Interesting article. The implication is that we have to go to new technologies to get significant battery cost reductions.

    As to the actual cost – Musk claims his $250/kWH utility batteries will drop significantly in price. $100 per kwh is the Musk claimed target cost.
    Taking a 3 MW wind turbine
    Efficiency 25%
    30% backup requirement
    $100 / KWH battery cost
    5000 cycle lifetime (13.7 years) degrades to 80% of capacity.

    Assuming we have to back up 30% of renewable output.

    3 MW wind generator produces 750 KW, or 18.000 MWH per day.

    18 * 0.30 = 5.4 MWH of batteries or $5,400,000.

    5400 KWH*365*13.7 = 270 million KWH from the pack but the average will only be 90% so 234 million kWH.

    That is about 25¢ per kWH assuming 100% utilization of the battery pack every day. It is fine for Germany at 36¢ per kWH. A bit pricey for the US at 12¢.

    Given the pollution caused by battery production there is something in the economics that I am missing.

    Of course if the renewable advocates continue to screw up the power grid we could end up paying 24¢ per kWH and batteries would appear to be a good investment.

    The problem with greens is their solutions only make sense if they allowed to mess with, and cripple or make more costly, the current system which was cheap and working fine before they came along..

    • Oh, more point – the battery pack needed to use 100% of the 25-30% of the nameplate energy produced by the windmill costs a little more than the windmill.

      3 MW windmills can be had for $4 million, the battery pack at a Musk hopeful future 60% reduced price is $5.4 million.

      So non-dispatchable power costs over twice a much under very optimistic assumptions to back up to where it can be used dispatchably.

    • Elon Musk knows what P. T. Barnum knew – there’s a sucker born every minute. Elon Musk works Washington and Washington works for him. Like the old bank robber replied, when asked why he robbed banks, ” because that’s where they keep the money.”

      • The cost to move 30% of the energy from non-dispatchable renewables to a more ideal time is significantly greater than the cost of the renewable energy sources themselves. It really doesn’t make sense to have more than about 18% of capacity be renewables.

        There just isn’t any way to rationalize putting significantly more renewable energy on the grid than we have today. We can check off “done” in the renewables column and start looking at real energy sources for new power plant deployment.

    • Ah, but in that deep cycle use Tesla says they will last 10 years (IMO already hype. Reality says 8). So, to service a ~25 year life windmill, they have to be replaced at last twice. My post was limited to simple times a facility for one windmill. It did not take into account either lifetime or degradation during storage lifetime. My ‘ridiculous’ point can be made without referrencing the true storage nuances you correctly point out. Regards.


        The interesting thing is LFP batteries have a maximum recommended temperature of 40°C so especially in California the batteries may have to be located underground or be air conditioned.

        There are a number of issues with lithium batteries. The lifetime numbers are based on 80% DOD (requires 25% more batteries). The roundtrip efficiency claimed by Tesla is 92%. This means that for every 100 W delivered to the batteries only 92 W is returned. 8.7% of power supplied to the batteries is discarded. A realistic lifetime of 10 years or less would just be icing on the cake.

        Since there was an err in the original calculation the effort will be revisited.

        So assuming:
        1. 30% backup of actual output (2 1/3 hours at nameplate output)
        2. 25% actual output of rated output.
        3. 80% DOD (depth of discharge).
        4. Average capacity 90% of rated capacity (when it hits 80% they are replaced.
        5. 10 year lifetime.

        Initial capacity: 6750 kWh/day
        Nominal capacity (80%): 5400 kWh/day
        Average capacity used (80%*90%):4860 kWh/day
        Initial cost (Musk phantom price): $675000 (much less than the windmill)
        Effective cost per delivered kWh (assuming incoming electricity is free): 3.8¢.
        Actual cost is 3.8¢ + 1.087% of the cost of turbine energy per kWh.

        The good news (after correcting a math error in the original calculation) is that battery backup – if you can get them at Musk’s future cost instead of $250 /kWh, is that attaching battery backup to capture badly timed renewable power would make economic sense in most situations.

        At the current $250+ per kWh battery systems cost almost much per delivered kWh as the average US power cost (it is probably a pointless exercise).

        On another topic.

        The availability of windmills is sort of interesting. There seems to be a lot of infant mortality.

  23. To rely on intermittent power, needs both a surplus of generators, as they have to deliver the mean energy, and then you need large reservoirs.
    A 2 MWpeak windmill with 30% factor can only supply an average of 0.6MW.
    The difference then have to be stored/delivered and dependent on the statistics of the wind, the storage might be vast. Alternatively you build more generator capacity, and use it only fully part of the time.
    If it was not for the fixation on CO2, in most cases it would be cheaper to back up with conventional. Eg. how much conventional can you build for the price of an adequate storage? A conventional plant store the energy in unused fuel.

  24. Two minor errata just noticed. Both the Beacon and Xtreme cited costs should be $/kWh, obviously not $/MWh as in the text.

  25. Wow! Great essay – more like a reference manual than a post. I’m bookmarking this for future reference.

    Btw, I read an interesting book about batteries that showered A123 with praise and described the Chevy Dolt as the Second Coming. They missed by a wide margin. Things fall apart, I guess. I suppose you’ll soon hear from the indignant desert birds.

    The thing about green energy solutions, including wind, solar, and batteries, is that no amount of rational discourse makes any difference. At one end of the phalanx you have the green business interests and donation and gov grant dependent NGO no gos. At the other end you have the Gaia gospel believers for whom any info at all only reinforces their beliefs. Following behind are the useful you know what’s, all led by the banner carrying politicians and their chroniclers (MSM). It would be amusing if it weren’t such an expensive pita for us.

    Once again, great post and keep up the good work.

  26. Besides these shortcomings I think solar and wind will eventually have to be abandonded due to how much land usage that has to be used. Solar may still have a place for personal use.

  27. Tom Murphy has made sums to show the scale of e national-sized battery for wind and solar:
    quote: “Putting the pieces together, our national battery occupies a volume of 4.4 billion cubic meters, equivalent to a cube 1.6 km (one mile) on a side. The size in itself is not a problem: we’d naturally break up the battery and distribute it around the country. This battery would demand 5 trillion kg (5 billion tons) of lead.”

  28. First, grid interconnects along long distances serve the same purpose for intermittency as energy storage

    Second, where there is no grid (e.g. developing countries especially in the countryside) all this is irrelevant.

    • ER, you need to bone up on your AC electrical engineering. You know, complex numbers, the square root of minus one, and all that related nasty math stuff that describes completely little details like VAR on transmission lines. You have just proven your probable ignorance thereof.
      Got pictures of viable grid energy storage options other than PHS? If so, please enlighten us unwashed illiterate climate skeptic heathens with them.

      • > You have just proven your probable ignorance thereof.

        I don’t always prove the existence of God, but when I do, I backtrack to its probable existence.

      • Willard, I dunno about God. But I do know about Maxwell’s equations unifying electricty and magnetism. Else you would not be reading this reply. So, can you physically reply, no matter the reply message? If yes, you have already lost your apparent specious arguement.

      • The latest news from those cunning Germans:

        Siemens has been awarded an order for a high-voltage direct current (HVDC) transmission system to connect the British and Belgian national grids via subsea cable.

      • Knowledge of Maxwell equations doesn’t seem to immunize against basic inferential inaccuracies, Sir Rud.

        The Maxwell equations are not powerful enough to circumvent Eli’s point that putting Africa on grid is not a trivial task.

      • Ruddy darling, Perhaps, just sayin perhaps, you should have followed the first link, you know, the one here before haring off on a wild bunny chase. If you had you would have read about how network interconnects can take the place of local power storage not store power

        The point of these interconnects is to balance load between a variety of green and greenish generation methods. The French link, of course, can network in the nuclear plants in France, the Norway links take advantage of pumped water storage and other hydro capabilities. Spain, in addition to rain has a lot of wind on the plain which it already covers a significant fraction of its electrical needs from. Ireland has potential excess wind generating capacity and there are plans for new tidal electric generation in France. Although not shown here, Sahara solar could easily be linked to Europe by the same technology. A hidden implication is that as long as a number of countries continue to develop nuclear political decisions to forego may not have much of an effect on the continental scale, with the developers selling power to the others. If this is the case we may see many such links between Japan and Asia

        Now Eli is sorry that you were confused. On the other hand, given your act, Eli cannot claim to be surprised. Amused, well yeah, always amused.


      • Perhaps the (allegedly!) illegal fossil fuel subsidies on this side of the pond have something to do with that?

        On 4 December [2014], Tempus Energy lodged a legal challenge in the General Court of the European Union, applying for annulment of the European Commission’s State aid approval of the UK government’s capacity market policy design.

    • Eli Rabbett,

      You quoted –

      “Although not shown here, Sahara solar could easily be linked to Europe by the same technology.”

      How hard could it be? All you would need is some Sahara solar. Then all you would need would be some wire. And then some customers, to pay for all the non existent electricity, coming out of the end of the non existent wires!

      As to your comment about irrelevancy, maybe you might consider how relevant your comments are.

      “The point of these interconnects is to balance load between a variety of green and greenish generation methods. ” seems to be a bit of PR to diminish the deficiencies in “green and greenish generation plans”.

      Relevance to intermittent grid storage? How about contributing something a little more relevant than suggesting providing additional non existent solar power connected to a non existent grid, to take up the slack when demand exceeds “green and greenish” power supplies, including solar power.

      Rudd has provided a good post. It would be nice if detractors like yourself could actually provide some facts, rather than Warmist diversionary tactics, and general frenzied hand waving.

      Fossil fuels are free. Turning them into electricity, and getting it to your power outlet in useable form, is not. Even more costly are free fuels like sunlight and wind.

      You remind of the guy who said “If I had some ham, I could make you a ham sandwich, if I had some bread”.

      • > Fossil fuels are free.

        As in “free speech” or in “free beer”?

      • Willard,

        I know you are only pretending to be stupid. Your point is?

      • Your “fossil fuel are free” is an empty slogan, MikeF. Last time I checked, the gas stations where I lived did not advertised any free fossil fuel. The best they do is a few cents less per liter. They offer better deals on their coffees, if you can call them coffees.

        Don’t get me started on the other meaning of free.

      • Don Monfort

        Fossil fuels are free for the taking, willy one. Just like the wind and solar rays. However, it costs money to make useful power out of all that stuff. Can you tell us why people are still overwhelmingly choosing to purchase power produced from fossil fuels, wee willy? I will help you. It’s closer to being free than the greenie alternatives. And the pause is killing the cause.

      • Fossil fuels are a continuing expense for mining, refining, transporting, combusting, etc. None of these costs attach to solar or wind. The costs of renewables are pretty much capital costs.


      • > Fossil fuels are free for the taking

        People are free, Don Don. Not suff like fossil fuels.

        Also, most of the times you need to ask first:

        Fossil fuels are not as unexpensive as one may think:

        In this paper we extend the Hotelling model by including both stock externalities and non-polluting backstop technology. These extensions change several of the most basic properties of optimal exhaustible resource use. We show that the extraction path may have an inverted U-shape form, implying that consumer price first decreases and then increases. Rather than there being a clear-cut difference between exhaustible resource and backstop consumption, these two energy forms may be consumed simultaneously. Optimal energy consumption may also start with backstop consumption and evolve to a regime of simultaneous use. None of these properties is possible in an exhaustible resource model without stock externalities.

      • Fossil fuels are not as unexpensive as one may think

        They are until activists start making up numbers to add to the cost, funny how it always makes them more expensive than the horribly expensive alternatives.

      • Don Monfort

        Fossil fuels rule! Sales of little greenie cars, already moribund, fall some more. Word from Motown:

        Somebody tell little prof. rabetticus halpernicus that when you add up the costs to produce the end product, fossil generally costs less than the greenie alternatives. Otherwise, we would all be on the greenie stuff like stink on dookey. Take an econ 101 class, wabbette. Do they teach that inconvenient stuff at Howard, these days?

      • > when you add up the costs to produce the end product, fossil generally costs less than the greenie alternatives.

        That depends upon how you define “cost,” Don Don:

        [S]ome energy costs are not included in consumer utility or gas bills, nor are they paid for by the companies that produce or sell the energy. These include human health problems caused by air pollution from the burning of coal and oil; damage to land from coal mining and to miners from black lung disease; environmental degradation caused by global warming, acid rain, and water pollution; and national security costs, such as protecting foreign sources of oil.

        Since such costs are indirect and difficult to determine, they have traditionally remained external to the energy pricing system, and are thus often referred to as externalities. And since the producers and the users of energy do not pay for these costs, society as a whole must pay for them. But this pricing system masks the true costs of fossil fuels and results in damage to human health, the environment, and the economy.


        The “Fossil fuels are free” slogan is not unlike the troglodytes’ prediction of the beginning of the end of Obamacare:

      • Don Monfort

        Silly willy, I know what costs are. While you have been running your mouth, I have been running businesses. Get out in the real world, willy.

      • You’re not running a business right now, Don Don, unless we’re counting your protection services as one.

        Were you into water or waste management, by any chance?

      • Don Monfort

        I am running a business. Your snide speculation on what businesses I have been in would be offensive, if they and you weren’t so lame and inconsequential. Stop with the irrelevant BS, willy.

    • Eli:
      Interconnects substitute for batteries. Yes at a cost:
      “…the $1.5 million-per-mile cost of a high-voltage line.”
      I suppose those that build interconnects need to assume the supplier will continue to do that for at least 30 years. If wind power eventually turns out to be a turkey the costs of the transmission lines may not be recovered.

    • Not true. Several times a year the whole of Western Europe lies under a high pressure system resulting in less than 3 Bft in the whole area for a week or longer. That means no wind energy. For all countries to solve this with interconnect would mean a fully connected long distance network of DC interconnectors, each several 10’s of GW. That would cost even more than batteries and it would be awful to live under.

      • The HVAC/DC cables that are mentioned do exist in Europe between various countries. They contribute about 1% of load shifting between UK/Holland, UK/France, Holland/Norway, Danmark/Norway, UK/Ireland. Germany is trying to get connection to a large offshore windpark, BARD, using HVDC interconnects. After 3 years, the windmills are still running on their diesel generators to prevent their bearings to set for ever. (Google BARD, preferable in German language). In other words, coping with very high power HVDC interconnects is not as easy as plugging the charger into your iPhone.

    • Steven Mosher


      It sounds like you need some good luck to make storage a reality.

      two points

      1. Rud did NOT discuss energy in africa or other Gridless places
      So you are OFF TOPIC
      2. You need to demonstrate a solution that works for places with a grid.

      Both sides have issues where they believe we will get lucky

      here is a clue. We have a better chance at lucking out with ECS than we do with lucking out and finding some cheap storage solution.

      • > So you are OFF TOPIC

        Actually, it puts the first sentence of Sir Rud’s conclusion:

        Most renewables advocates don’t appreciate the scope and scale of electricity grids, the difficulties intermittency creates, and the technical/ commercial inadequacies of electricity storage technologies other than PHS.

        into some kind of perspective.


        > We have a better chance at lucking out with ECS than we do with lucking out and finding some cheap storage solution.

        I’d like an engineer-level formal derivation of that claim, pretty please with sugar on it.

      • There is and will be no single solution. As far as the grid issue goes, getting the grid big and smart enough goes a fair way to solving the problems attached to renewable intermittency.

        A commenter up above asked about putting a cable btw Europe and Africa. Given that such cables exist over much longer distances than through the Straits of Gibralter, that should not be a problem. The issue, of course is political Concentrated solar power is growing pretty fast (over 3B MW now), a lot in Spain.

        One of the bridging solutions are gas turbines (GT) which have relatively low capital and operating costs relative to coal these days and esp with GT combined cycle systems can reach efficiencies of > 50%. GTs can be spun up and down quickly enough to cover for fallout from other sources which coal, oil and nuclear cannot.

        And yes, Eli is sure that in 30 years we will have workable fusion power and CO2 storage.

      • @eli

        The question is not ‘can you lay a cable across the Straits of Gibraltar’. Sure you can. It’s only about 9 miles. We already have cables between UK and France (minimum 25 miles)


        Can you lay a useful cable between those parts of Africa where the electricity can be generated and those parts of Europe where the power is used.

        In geographic terms that’s more like from the south of Algeria to the Rhine Valley..about 2000 miles.

        Which is a very different proposition. You can consider it as similar to laying a cable form El Paso, NM, to NYC, NY. It’s a long long way, and I doubt much useful lekky would pop out the far end. And if powered by solar, it’ll do nothing for those dark January nights when European demand is at its highest.

  29. Solar activity as a climate change contributor
    The authorised newly ‘redesigned’ historic Sunspot numbers

    ‘Amplification’ of 140%, 167% or even 190% of the old values has been introduced.

    • We actually have direct measurements of solar forcing over the last few solar cycles. From valley to peak the change in the solar constant is about 0.5 W/m2 and the change in the number of sunspots is about 200.

      That the number of sunspots increased in the re-evaluation only says that the constant of proportionality between the number of sunspots, and the solar constant is smaller than we thought

      • With the exception of the fact that re-evaluation factor is not constant throughout. Approximately: 166% up to 1850s, 190% following decade, back to 166% to 1946 , 141% to 1980s, then ‘all sorts’ from 130% -170% to the present day..

      • Professor ‘Rabett’
        As an academic you are well aware that the any data correction is ‘motivated’ by getting the ‘truer’ (or is it more true) illustration of the past events.

      • There goes the Little Ice Age

      • Professor ‘Rabett’
        You spoke in haste
        As you can see from the graph

        Inclination from two linear trends shows that in the new data solar activity rose faster (by whole of 7%) since 1700 to the present day than previously assumed based on the old data (0.0986/0.0921= 107%) .
        The LIA was ended by the steady rise in the solar output since 1700.

  30. Many thanks to Rud for this update on on incompatibility of wind and solar sourced electric power with the requirement of a stable electricity supply once the installed capacity of these sources exceeds the ability of the grid to ramp up and down. This has been well understood by engineers for a good while.

    Sad to sad, but entirely predictable, this truth will only get through to the media and political class when the grid somewhere crashes big time as Rud forecasts. I don’t know enough about Canada but Germany and Britain are prime candidates for such failures. Denmark would be as well but for being tied into Scandinavian hydro power.

    So the sooner the failure happens, and let’s hope the failure is massive, the sooner we will get a rethink on installing more wind turbines, themselves a threat to health, bird life, a complete eyesore and of dubious ability to reduce CO2 emissions.

  31. Land hungry gobblers of landscape, operating
    one third of the time for a trickle of energy,
    requiring one of those $14.4 million a pop
    back-up power ancillory units or ramping up
    fossil fuel back-up, what’s not to like, eh
    greenies … and doesn’t it save lots of CO2?

    ‘Between the idea
    And the reality…
    Falls the shadow.’
    H/t The hollow men.

    • Highest regards to you down under from me up over. Farmers unite!

      • Antipodean regards ter you and thx, Rud Istvan, fer yr
        highly informative contributions @ CE,

      • That was a good post. Thanks to you and to PE.

        You know, Elon Musk and the media put me in mind of the old French song, Parlez-moi D’Amour. The chick knows the guy is just making up all his mushy love-talk, but insists on hearing every single word of it. Then she wants to hear it all again.

        Parlez-moi de Tesla!

      • Moso, I have invasive multiflora rose, garlic herb, and Chinese honeysuckle on my farm (not to mention wild hemp (marijuana) planted per the USG in WW2 as a really bad erosion control and rope idea). All brought by original European settlers, all degrading my woodlots and pastures. We keep it all under control using ‘chemical warfare’ in the crop fields, but sadly not otherwise. Same as you may have with non-native bamboo. Farmers all struggle the same ways, but in our own ways. Highest regards.

    • Not to worry. There are hundreds of square miles of ruined land left behind by greedy coal miners who never intended to clean up after they dug up all that carbon. I use to think bankers and politicians were scum of the earth but these coal barons are even worse.

      Want to insult a AGW skeptic? Tell them their opinion is worth less that a share of Peabody Coal stock.

      • Thanks for that baseless babble, jack.

      • Yeah I’m having fun watching the pain and suffering of the owners and investors. But it’s really not funny at all is it? These coal companies will have the last laugh when their former employees will be left without pensions and healthcare. It won’t be funny when the EPA is gutted by the right wing just as these same companies dump their toxic wastelands on the public. But hey life’s not fair so I don’t expect any of these crooks will ever face justice – that’s only in the movies.

        To everyone else you might want to check out Mr. Robot.
        Do you think it was just a coincidence that Trump Enterprise LLC just had their systems hacked? The dark net is watching us.

    • Mosomoso,

      I checked out the Tesla this past weekend while (whilst) killing some time in Houston. I have to admit it’s sexy, but not for my money.

      I have been reading the Quadrant online lately and it is reigniting my love affair with things Australian from years ago.

      • Mark, no harm in looking – though I thought Austin was the town to indulge that sort of curiosity. Being a bit of a hippie with only a weak right-wing gene, I could be a huge sucker for something like a Tesla. I’m sure that’s why God keeps me in somewhat reduced circumstances.

        I’m now driving a Toyota 4Runner to improve my cred around here. (I used to get about in an old Peugeot and use a Mac. Couldn’t convince a soul I wasn’t green and left. Still hard.)

  32. Another great summary, Rud.

  33. What about storing intermediate products like “cold” or “heat”? While it seems one would want air conditioners running at times when the sun is shining, perhaps one could create a big at home vat of super cold liquids, and tap into that for off-peak cooling. That might help offset vicissitudes in wind production. And, it can help with hot days when there isn’t enough energy in any event.

    • Yeah, I left out potential energy storage in the form of a large thermal potential energy gradient. Isentropic. See rational above. I choose not to propogate pure BS. Where is the funded demo plant?

      • Well, i suppose you aren’t going to give me two nobel peace prizes, even though you said if someone could come up with one more way =)

        This was really a modest thought I’m curious about, and was wondering whether it had any merit, is all.

        Your response to my note indicates you are focused on putting electric energy in, and getting electric energy out: you think about electricity as the fundamental unit of exchange. My air-conditioning thought was why does electricity need to be the fundamental unit of exchange? What is really desired is to provide flexibility for when energy is required. Storing ultra cold energy in a material with a high specific heat could help provide flexibility on when energy for a specific purpose is consumed (cooling), though it could only ever after be used for one purpose: producing cooling locally. Statistics are what they are, but I read that 12.5% of at home energy is in cooling, and I suspect with many corporations it’s much more.

        While electricity isn’t often used for heating, I’ve had similar thoughts about how to store summer heat for use in winter heating. I’ve even run some experiments, though ran into some issues with wave guides.

      • I’ve decided this is a BS answer. The question should not be “How do I solve this problem the way I want to,” but “How do I solve the problem.”

        You set a high bar for yourself, failed, and failed again by being rude over your own failure.

        You have shown that you do not want to solve the problem except in the manner you want to solve it, which is within your own understanding, and have rejected, out of hand other solutions because you haven’t thought of them/have no intimacy with them.

        Another way of thinking is that these solutions are dangerous, because they diminish your value.

    • Perhaps Rud is unaware of the “Power of Ice”?

      • David Springer


      • Rud is aware. During my first read through of an earlier draft, I wondered if the thermal options should be included for completeness, but I saw Rud wanted to focus on electrical generation to storage to electrical generation. A more expansive focus would have some benefits but disadvantages as well. That’s an authors choice, and others are free to present alternative perspectives, but I don’t think you can fault the author for his chosen focus.

      • Let me get this straight. Rud is aware of a variety of potential methods for “grid scale” energy storage that involve heating and/or cooling low cost materials like air, water and stone, yet he chooses not to mention any of them in his overview of the field?

        I don’t know if you have taken George’s eminently sound advice yet, but if not please take a gander at this:

        As you can no doubt readily appreciate I have contacts inside a variety of UK DNOs. I’ll ring around tomorrow, but they may of course all tell me “mum’s the word”.

      • Jim Hunt – I don’t know what to make of your link. The article refers to a self imposed twelve hour time limit to restore power???? Such a thing is near unimaginable here and the system you describe is vastly different than anything I’ve encountered in the U.S. Having power flow on the grid between customers that originates from customers requires considerable expensive protection. What’s described sounds like a shoestring budget operation. What it proposed would need a lot more than batteries (you have to convert battery power to AC and the protecting equipment). Perhaps the system would be improved by the measure advocated, but it would not be easy.

      • APE – The UK regulator imposes an outage time limit (possibly 16 hours?) after which the DNO (using UK terminology) gets fined. WPD choose to try and avoid breaching that limit!

        Lots of people around here already have grid-tie inverters to go with their rooftop solar PV. Is that what you’re getting at?

      • Jim

        I live very close to the village you linked to. Basically the grid is full and can’t cope with any more renewables. The announcement was made around a year after your article


      • I’m well aware of that Tony. In fact I predicted it in front of the Teignbridge District Council planning committee in Newton Abbot, in a series of objections to large scale solar PV “farms” in the area.

      • Jim

        Did you see the article by David Rose on the little Haldon solar farm?


      • Tony – I did, but to be frank I don’t much care for Mr. Rose’s coverage of such issues. It seems to me that he has “an agenda”!

        I objected to that one too, but it never went before the committee. I’m astonished that a major planning decision can be “delegated” to a mere planning officer unless the local councillor chooses to “call in” the application. I did speak to the gentleman concerned, but his mind was made up it seems.

      • Jim Hunt – I am surprised that allowing an outage of anywhere near that limit is acceptable. Sometimes a conflagration of events will lead to a long outage, but we take every reasonable precaution to limit outage times (no fines needed). Are you assuming they would run car batteries through their roof top inverter system? If that’s something being done somewhere in the world, I’d appreciate a link to it. Do the rooftop inverters provide the sine wave on their own or do they use the grid as part of their commutation. I think most need power. See this link.

      • APE – I can only assume you haven’t got around to browsing the V2G blog yet? Or seen the Tesla Energy hype? Li-ion is “flavour of the month”, not lead/acid. Maybe start here and then click lots of links?

        The inverters certainly implement “anti-islanding” here in the UK. Given the way our National Grid currently works some sort of “community microgrid” would be needed for your own static and/or EV batteries to power your neighbours house.

      • I meant to reference this link instead of the above.

      • Jim Hunt – I’ve looked at you links, but they don’t really tell me much. I’m not sure of your points and I asked you the questions about your system to see if I was misunderstanding it or if you were unaware of how it operated, because it seems to operate in a way which justifies the concerns I described which started this conversation. It’s going to be a complicated expensive effort to change equipment and put in new for your micro grid and it would likely be more sensible just to run an alternate feeder from the grid (add some switching equipment) to provide some redundancy for backup.

      • APE – Sure. There’s any number of ways that things might be “rewired” to try out the concept. However “Microgrid” involves less typing than your suggestion and has a bit of a “buzz” surrounding it at the moment, here in the UK at least. Perhaps the best place to experiment would be a completely new build? No old kit to rip out!

      • Micro grid to me seems to be a word that allows people’s imaginations to run wild with all kind of benefits and perhaps even magical properties without confronting any of the challenges and limitations it would impose as well as the benefits that would be lost if we abondon the the bulk system approach. Connected AC systems must operate in synchronism, so you just can’t higgely piggely connect “independent” micro grids. Do you want independent micro grids? A key to making renewables more successful is exploiting the uncertainty of intermittents and load with the diversity available through wider area exchanges. The grid provides backup if their are outage problems and support and stability during disturbances. Economic power exchanges between areas allow huge financial benefits. MRO in the U.S. Sends excess capacity in the summer south and the Esposito direction in the winter. You will need some CT plants at least and the bulk grid allows them to be located where their are less air quality concerns.

        Some areas are likely well suits for diversity of resources ifor a small or regional microgrid. But many areas are not-they will be big losers if an interconnects grid is supplants by microgrids.

        Generic writings on what microgrids might do in the future which don’t address the tradeoffs, don’t give hope and don’t point the way or explain things any more than an old episode of the Jetsons might.

      • APE,
        I find myself in agreement with you about the trade offs of macro vs. micro grids. I don’t want to loose access to the main grid even if I could justify the cost of a battery system (which I can’t at current prices). But I would like to see more residential PV systems equipped with small 5-10 KWh batteries in the future for two reasons:
        1) To provide isolation from intermittent grid fluctuations. Like many Americans I already have multiple electrically powered networks in my home – Cable boxes, WiFi, Bluetooth, GPS, VOIP module, even my in-home wireless handsets use a separate 2.5GHz frequency network. My point is it is a major hassle when the main grid has a hiccup and over the years it has cost me hundreds of dollars in damaged equipment not to mention the too frequent ritual of reprogramming clocks, alarm systems and a host of microprocessor controlled devices.
        2) To smooth the power load when I switch on heavy loads like hot water heaters, ovens and dryers or when clouds cause PV system to fluctuate wildly. I have a very granular view of my electrical system via an eGauge energy monitoring system ( so when I see my water heater come on automatically while I’m already pulling a 7-8 KW load with my dryer or oven it makes me cringe because I know that’s pulls the voltage down on every house tied to my local transformer. The use of instantaneous battery power on a PV system is like an accumulator in a hydraulic fluid system and makes all the system components perform better and last longer.

        * The above list of networked devices in my home has reinforced my belief that the future is will be more and more networks. The IWatch and the explosion of wearable/implantable devices are just now extending the reach of networks to our bodies. As I said before I think our destiny is already embedded in the DNA of our digital technology and in some ways we are just waiting to see what it has in store for us, like it or not.

      • Jack Smith – my experience and understanding may not be universal to all areas and situations but here’s what colors my perspective. Ocasinally the bulk grid causes problems

      • Wife is driving and hit a bump and the above got sent too soon. Anyway Jack I’m not sure I’m describing your situation, but mostly those kind of problems are from a bad distribution system (not the bulk grid – but maybe a combo of two). Yes a good microgrid would fix those problems, but so might a good distribution system. I would expect a bad microgrid could give you problems as well, so to me it seems an issue of quality of service and microgrid or not is not a critical problem.

      • Good answer. When you mentioned improving the resilience on the main grid I am reminded of the law of diminishing returns. The current grid is about 99% stable but the cost of that final 1% will be so high that you will have a hard time selling the idea to a PUC and investors – it won’t happen. So like it or not I don’t ever expect the grid to reach 100% stability so the burden is on us to augment our own electrical supply if truly uninterruptible electricity is important.

      • My power is pretty stable, I’ve have a couple glitches over the last say 2 years, and 4 or 5 outages over the last 7 years where all but one was from thunderstorms, and that one they were working on the power lines up the road.

      • Jack Smith – could your problem be readily addressed for $100 to $400 with a UPS. uninterruptible power supply

      • APE,
        I mentioned before on this blog I have had a UPS for years. My reason was because I lost a computer power supply and graphics card ($250) due to some kind of power spike on the grid. I spent the bucks to get a mid to high end unit and one of it’s features is it connects via USB to my computer and provides me with a detailed log of all ‘events’. This (plus my eGauge) is why I know the number and nature of the power fluctuations on my local grid. We have all lived with these ‘defects’ our entire life but thanks to state of the art backup systems you can buy today we can finally have some appreciation for the complexity and cost of really reliable electricity.

  34. Rud

    Thanks for this fantastic post! By doing a comprehensive survey you have gone a long way toward bringing some sanity to this whole intermittent power debate. You did miss one distributed storage option, however, which I shall call the “high iron” approach.

    Visualize a large tripod above each residence in California, each supporting a large pulley. The 20 KWH of required daily reserve would be stored in the form of a large iron ball suspended from the pulley by steel cable. Excess PV capacity would power an electric winch and raise the ball during daylight hours.

    Now lets talk scale. Assuming 100 percent efficiency, one kilowatt powering the winch would be able to raise 100Kg of iron one meter per second. Thus 20 KWH could raise 2,000Kg to a height of 3,600 meters, or 72,000 Kg to 100 meters. So given a round-trip efficiency of about 80 percent, each home would simply need to hang an iron ball weighing about 80,000 Kg about 100 meters overhead. Every evening, with family tucked safely inside, the iron ball would descend slowly toward the roof, drive the winch in generation mode, and release all of that “free” energy. What could possibly go wrong with that?

    Sleep well California!

    • Punny and funny, Sciguy. I admit did not cover it. A clean miss. Whatever.

    • sciguy54,

      Can I buy one for my car? What range would I get? Does it come in pretty colours?

      Sounds like a winner to me!

    • We Californians already have the Sword of Damocles hanging over our heads! :)

    • 80,000 Kg” of iron would take up about 10 cubic meters. Make that a 100 meter (330 foot) deep hole, a 1.5 meters (5 ft) in diameter. Your iron weight would be maybe 8 meters (25 ft) long. Easy to take a perfectly plausible idea and turn it into silliness by being silly.

      Of course, whether it would be cost effective…

      • As a kid I was an engineer’s aide on a large data center construction project. Footings consisted of 4 and 5 foot diameter holes drilled down through clay to bedrock and I was tasked with certifying that the bottom of each hole was clean before concrete was poured. Climbing down the rebar cages 15 feet or so with whisk and dustpan in hand was spooky enough, I can’t imagine looking up 330 feet!

        You would need to add the cost of a concrete or steel liner to maintain “holiness”. In the southeastern US we would call this kind of hole a water well, so you would also need to add about 10% more volume to the iron ball to compensate for buoyancy.

        Almost anything is possible. Practical is a much smaller subset.

      • You would need to add the cost of a concrete or steel liner to maintain “holiness”.

        Ancient civilizations used brick or ashlar (stone blocks). My guess is you could usually use pressed fill from the hole, stuck together with a small amount of epoxy. Cast into blocks, stuck together with more epoxy. That would save on transport costs.

        […] you would also need to add about 10% more volume to the iron ball to compensate for buoyancy.

        Or seal the hole and add a sump pump.

        Almost anything is possible. Practical is a much smaller subset.

        Oh, I’d say it’s practical enough. (Assuming learning curve and economies of scale.) Just not cost-effective compared to the alternatives.

      • Its interesting that they use traction engines rather than cogged. They will be limited to about 3% grade and the engines will weigh about 4 times as much as the draw bar pull. The steeper the grade the heavier the locomotives must be in relation to the pulled load.

        I have ridden the Vitznau-Rigi cogged line among others. More compact and lighter hardware but very specialized vs modifying more standard equipment.,

        You would need to allow for a large overrun field at the bottom of the line in case of a runaway accident. Don’t place anything expensive directly below lower terminus.

      • wrong place for this… sorry!

    • Sciguy, Here’s the prototype!

      • 6 of those would do nicely!

      • Mike Flynn

        You load sixteen tons,
        And what do you get,
        Another day older,
        And deeper in debt.
        St. Peter, don’t you call me,
        ’cause I can’t go,
        I owe my soul,
        to the company store!

        – Merle Travis – re Kentucky coal mining.

        Solution to grid shortfall?

        Build a bigger grid, with reserve capacity. Nobody likes wasted capacity, but we throw away useable food, cars, electronic equipment, and waste time, money, and effort, pursuing all sorts of ultimately useless or pointless pursuits.

        It’s usually better to have it and not need it, than need it and not have it!

        In any case, what could be greener than converting fossilised plant matter back into the CO2 and H2O from whence it came? What can be wrong with re greening the Earth? Nothing that I can see, but I’m pretty dumb.

      • Health and safety issue:

        There’s no sign to indicate that one should bend knees when lifting. ;-)

  35. There are in principle only five ways that generated electricity can be subsequently ‘stored’: potential energy (e.g. pumped hydro), kinetic energy (e.g. flywheels), electrostatic energy (capacitors), electrochemical energy (batteries), and chemical energy (e.g. water hydrolysis).

    It might also be used in applications where intermittent power can be used directly — eg drilling, refrigeration, irrigation for farms, . . .

    • There are a number of applications where power is needed but isn’t continuously required.

      Well, windmills on the great plains were used for irrigation. As long as enough water is pumped you really don’t care when it is pumped. But as is typical of these applications – there isn’t a requirement to be connected to the grid.

      But there have to be some industrial users who would move their power consumption if the peak to off-hours differential was high enough.

      Perhaps first we should look at why we are doing this. Society used to emphasize convenience… The “low impactors” want to make life less convenient and more expensive for somewhat dubious reasons.

      Grid changes should cut costs and/or increase reliability while providing “on demand” power..

      Renewable energy is a step backward.

      • Renewable energy is a step backward.

        Don’t agree entirely. The grid gives a control problem of matching generation with demand. Intermittent sources can be added to “batteries” (eg pumped water storage) to ease controls of supply, but similar actions could be applied to demand (eg irrigation, municipal water storage, ethanol manufacturing, . . .). While the control problem becomes more complicated, adding applications that can absorb excess power to perform useful work might be useful in grid management.

      • I’m not against renewables. I’m against renewables right now.

        Fossil fuel is going to get more expensive. Some renewable technologies will get cheaper, more efficient, and cleaner to build in the future.

        There is no reason to deploy expensive white elephant renewables now. Why pay a premium for less practical expensive early adopter renewables now to avoid burning cheap fossil fuel?

        Burn cheap fossil fuel now and deploy practical cheap clean renewables to replace it later. Let the economics drive the decision. The substantial renewable subsidies is a good indication deploying now isn’t the smart choice.

  36. well may be you miss another way, to make users store energy for instance heat, as long people use electricity to heat something of course.

  37. Peter Lang

    Rud Istvan,

    Excellent post. Thanks you.

    Judith, think you for posting this. It’s excellent and informative. I think it is rally valuable to be publishing articles lie this and Planning Engineer’s posts. This is the sort of information that climate scientists and CAGW believers – and all those who advocate for technologies that have very low probability of having any significant impact on GHG emissions – need to encourage them to challenge their beliefs and the dogma spread by these people.

    I’s urge you to start applying the uncertainty monster to the probability that renewable energy is likely to provide much of global electricity in the future.

    Planning Engineer (and others), thank you for your comments too.

  38. Peter Lang

    Rud Istvan,

    If energy density can be increased, then the amount of electrode per unit electricity can be decreased proportionately.

    For comparison with the energy density figures you quoted in your article, could you tell the energy density of nuclear fuel in Wh/L (after conversion to electricity)?

    NaS would cost $34 million to back up one $3.5 million turbine. And it would have to be replaced after 15 years to support the turbine’s ~25 year life.

    That’s and interesting, easy to remember, figure. The battery would cost about ten times the cost of the wind turbine.

    Could you add a table to your post to summarise the LCOE for wind energy with the various energy storage technologies you’ve discussed – and so the figures are meaningfully comparable – e.g. $/MWh for systems that produce reliable, dispatchable power.

  39. stevefitzpatrick

    It is clear that storage is only practical if it is pumped hydro. But there may be a better alternative: high efficiency natural gas powered piston engines with exhaust heat recovery. These engines can come in sizes of 10 megawatts (or more), have >50% thermal efficiency, can run efficiently over a reasonable throttle range, with >95% availability, and lifetimes of > 60,000 hours before overhaul. Banks in parallel provide a power plant that scales smoothly over a huge power range (0-250 MW). The plant is relatively inexpensive (~$1.1 million per MW capacity). Linked with wind power, this type of generation plant would satisfy some passionate green desires at low capital and operating cost, so long as natural gas is available at relatively low cost. Fully loaded cost (fuel, capital, maintenance, operation) can be under $0.05 per KWH.

    • rogercaiazza

      Sadly the “passionate” greens would whine that this would “enable” fracking gas use and likely not support even something as practical as this.

    • Consider that displacement is effectively storage given a smart distribution network. Hydro is a simple example, hydro in Norway levels the load from wind and solar in Denmark and elsewhere because the two countries networks are tied together.

      • Consider that displacement is effectively storage given a smart distribution network. Hydro is a simple example, hydro in Norway levels the load from wind and solar in Denmark and elsewhere because the two countries networks are tied together.

        Yeah but the length of the extension cord isn’t all that long, and therefore the loss can be accounted for, but that isn’t a cable across both ponds to get 24 hours sunlight, so while the “energy” is “free”, the infrastructure, especially for the power density is horribly expensive, and then don’t forget the environmental damage done, the roasted, and fileted critters, and why isn’t the EPA fining the heck out of the blender owners for chopping up endangered species?
        Now, I think most are fine with fossil chemistry for another 30 years, which is interesting as I forecast we needed to be off dino juice by 2050.

      • There is a serious proposal out there for a undersea HV power cable btw Iceland and the UK, and from there on to Europe. Also daisy chain.

      • No, displacement is not storage on a smart distribution network. Grid connection of intermittent sources to conventional load-following sources (like hydro, coal, or gas power plants) consumes the capacity of those sources to throttle to meet the cumulative demand.

        Eventually, you consume all of this capacity, and all of the safety margin in the new network to meet the requirements of non-load following sources, and this requires yet more extremely expensive equipment (such as grid tied energy storage) to manage the network.

        Sure, we can engineer to meet the requirements and maintain some semblance of stability on the network, but when you look at the sheer amount of equipment required to meet these requirements, and the massive prohibitive cost to the user (several times what you’re paying now for electricity) of using excessive intermittent renewable energy, it doesn’t make a lot of sense.

        You green folks should listen to Hansen on this one. If you want to get off carbon, sunshine and windmills won’t get you there. You need nuclear.

  40. Super capacitors have the highest energy density of any capacitor type, an order of magnitude more than the next best kind. Supercaps plus power electronics have created a rapidly growing new utility device class in the past decade, static compensators (statcoms). These substitute for smaller synchronous condensers; ABB’s statcoms come in sizes up to 30MVAR. Their advantage is no moving parts/maintenance.

    Has anyone seen a electrolytic capacitor blow up? There’s a lot of energy stored in them, and they hold a fraction of the energy that’s stored in supercaps, And I like the idea of capactors being used instead of batteries, like in a car (actually I think they use them in F1 now).

  41. Why not freight trains on hills? Railroad technology is well tested and proven. A 1000m train can weigh 12,000 tons. Take it 20km up a 5% slope and you have 120000 MJ potential = 33,3 MWH. (math okay?) Several trains could run on the same track. If the trains move very slow you could make them even heavier. Fill them with something nobody wants like slag from a steelmill. Put it somewhere dry, sunny or windy – the great divide? maybe near a bauxite deposit?

    Anybody see serious problems with this?

    • Its interesting that they use traction engines rather than cogged. They will be limited to about 3% grade and the engines will weigh about 4 times as much as the draw bar pull. The steeper the grade the heavier the locomotives must be in relation to the pulled load.

      I have ridden the Vitznau-Rigi cogged line among others. More compact and lighter hardware but very specialized vs modifying more standard equipment.,

      You would need to allow for a large overrun field at the bottom of the line in case of a runaway accident. Don’t place anything expensive directly below lower terminus.

      • sciguy,
        That’s a good point, but cogs are certainly expensive.
        Vitznau-Rigi also looks very lightweight .

        I suppose dragging a very heavy load uphill would require a whole different catagory of cog.

      • Mike Flynn


        I was thinking more of an motor at the top of the hill, and a cable (made of unobtanium, for strength – only joking!)

        Given low initial cost, and suitable terrain, it seems possibly practical for niche use. For example, running an AC electric welder of around 7.5 kW for 5 or 10 minutes may be beyond the usual domestic battery backup capacity. 100 tonnes with a vertical drop of even 10 meters stores a fair bit of energy, which can be utilised at very high rates. Something like a very, very, large capacitor.

        I’m lucky. At the flick of a switch, I’ve got access to about 10 kW. Love mains power.

    • rogercaiazza

      I can think of some problems:
      • Railroads don’t like steep grades and a quick scan of the steepest grades on 56 historic US railroads (Trains Magazine special edition of railroad maps) showed that 5% grade is steeper than most, if not all, grades available on those railroads.
      • Curves affect the impacts of grade and those impacts work against your proposal
      • Railroad track is expensive and your plan would clog up a track making it difficult to operate other trains. Building a dedicated track, particularly where grades are steepest could be prohibitively expensive.
      • In the US most track is not-electrified and diesel-electric locomotives are used. How would you get the power to and from the train?

      • rogercaiazza, I mean building a track for this purpose only, not going anywhere, no tunnels or bridges.

    • Suppose weather causes all the cars to be at the bottom with further demand expected in the next 6 hours. Diesel electric locomotives now return some cars to the top.

    • KenW:

      Although I don’t favor your concept, you might look into connecting trains on both sides of the hill — similar to counterweight in elevator configurations. Add electric generators to capture energy from wheel motion and braking mechanisms (as with electric cars). And forget the slag for dead weight. Pump water instead.

      Or just build a natural gas turbine generator, instead.

  42. Rud, PE,

    Just supposing, you lived somewhere in the boondocks; nice scenery, cheap land, but a depressed economy.

    If you had a really cheap and reliable supply of electricity you might attract industry and jobs, and, if you had a big investor you could build yourself a renewables plant and storage facility for that purpose.

    Assuming the investor wants a decent return on his money; can you think of any circumstances which would make economic sense now or in the near future? (in lieu of a government handout I mean) What would be your best bet?

    • Ken-I think low cost energy is a great way to attract businesses to a depressed area. I don’t see the link between renewables and low cost. While you can argue “free energy” the infrastructure is huge.

      Some think having clean energy will attract business. I’ve seen the belief touted but never the results. In particular I remember being in Ohio a ways back and reading the editorials promoting their renewable portfolio standards as a way to encourage more business. At the time and since my take was that every increment your energy goes up the less competitive you are for new business (especially if energy intensive).

      If/when/where federal/national policy’s allow someone to go to an area not saddled with past energy blunders and construct a low cost system with say natural gas (assuming frcracking remains an option) then such an area might see a turnaround,

      • thanks for the answer AP,

        “I don’t see the link between renewables and low cost.”

        It’s a hypothetical. I’m just assuming that’s what we want to do.
        Is it even remotely possible?

      • Ken W, the cost of renewables, hydro, wind and solar is all (pretty much) capital costs. The costs of fossil fuels are operating costs, exploration, extraction, transportation, refining, etc. Capital costs are relatively low

        As the fall in the cost of solar voltaic shows, it is more likely that renewables will get cheaper than fossil fuels

      • catweazle666

        Eli Rabett : “As the fall in the cost of solar voltaic shows, it is more likely that renewables will get cheaper than fossil fuels”

        Congratulations on spectacularly missing the point – an noble effort even by your exalted standards.

      • Eli: “Ken W, the cost of renewables, hydro, wind and solar is all (pretty much) capital costs. ”

        Hydro, yes. If you’re using wind and solar to meet an actual increase in demand, you will need to spend capital on load-following generation or grid-tied energy storage to meet demand due to the intermittent nature of their generation. What you wrote was not accurate.

      • Ken – overwhelmingly most places and applications (industrial for sure) renewables cost more (needed back up makes it worse). If you assume that prices continue to drop-maybe renewables will be superior. (If the system is saddled with older costlier less efficient older renewable resources that will make it harder to have the lowest prices.). Some assume a continued linear drop in costs, which could get you there. Others (me included) suspect you will reach a point where the decrease in cost starts to flatten out such that it happens at a much lower rate and slows down over time. (Ie. Prices don’t linearly approach zero, but rather some other higher minimum cost.)

      • Planningengineer,

        Some on this blog claim that the cost of solar is dropping exponentially. I believe them, so I’m going to wait until it goes to zero. Anyone who doesn’t believe that is a calculus denier!

        I do wonder about the cost of labor…perhaps that goes to zero also…hmmm…I better go back and look at those deltas and epsilons again….

      • Some on this blog claim that the cost of solar is dropping exponentially. I believe them, so I’m going to wait until it goes to zero. Anyone who doesn’t believe that is a calculus denier!

        Obviously you failed calculus. An exponential price drop will never reach zero. It’s asymptotic. Do you know what that means?

        I do wonder about the cost of labor…perhaps that goes to zero also…

        The Singularity and Socialism: Marx, Mises, Complexity Theory, Techno-Optimism and the Way to the Age of Abundance I haven’t read it, and I’m virtually certain I would define “socialism” differently than Townsend. There’s an interview with him here.

      • That calculus thing is good news. There is a park a couple miles fand a 5 minute drive from my house. Earlier this year it took me about 30 minutes to run there. Through exercise and practice my running time decreased to 25 minutes,and lately I just got to 20 minutes. Driving time has not decreased at all and looks like congestion if it gets worse may add a minute or two (I forecast a 40% increase). By next year it should be a lot faster to run there. Then I might start running to work and save a lot of gas.

      • I walk to work, sometimes even in my pajamas. Takes me under a minute most days, unless the cat walks with me.

  43. catweazle666

    Thank you for an excellent, well-informed and researched piece, Rud.

    As an added bonus, it has drawn a fine clutch of the ascientific Green knuckledraggers out from under their bridges, with their claims for fairy dust and unicorn flatulence or whatever fantasy energy storage medium they found on a crackpot internet site or were informed about by a bloke in the pub.

    There’s just no telling some people.

  44. Beta Blocker

    Summer is here, and it is once again time to push for using the state of California and the states of the US Northeast as experiments in testing the proposition that the renewables, wind and solar, can handle 80% of our electricity requirements at total lifecycle costs which are equivalent to what coal and nuclear can deliver.

    Governor Jerry Brown has issued an executive order to all of California’s state agencies that they must consider climate change in every regulatory action they take and in every planning decision they make. At the national level, President Obama has announced a goal of cutting America’s carbon emissions 28% by 2025 and 80% by 2050.

    In the state of California, a golden opportunity is presenting itself for renewable energy advocates to block any further construction of fossil fuel power generation facilities; and to force all of California’s government agencies to take those regulatory and planning measures which will strongly encourage a significant reduction in California’s total energy demand.

    There is no reason why the governors of the Northeastern states couldn’t issue similar executive orders with the goal of achieving similar results.

    If what the renewable energy advocates are saying about total lifecycle costs for wind and solar is true, and if this experiment were to be seriously pursued, then by 2025, California’s and the US Northeast’s GHG emissions should be significantly lower than they are today, with unit electricity costs being only slightly higher than what they are today.

    On the other hand, if electricity costs in those two regions end up being significantly higher than today’s costs, a wealth of evidence will have been generated which explains in precise objective terms why the original cost projections weren’t accurate.

    Just do it and see what happens.

  45. Rud,

    Excellent post. You mention five ways to store electrical energy. Though I have never see it outside of a lab, there was early work on electromagnetic storage (inductors) at superconducting temperatures. A lot of headaches, which is why you do not see them. A complement to capacitors, and a tribute to Faraday.

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  47. markopanama

    Excellent post. You have quantified what has been bothering me about renewables for some time, the storage problem. Yours is be a very valuable contribution to the discussion.

    I am reminded of the old maxim, when you are up to your ass in alligators, it is easy to forget that your initial intention was to clear the swamp. The original premise of AGW was that CO2 is destabilizing the climate and its use must be curtailed in order to stop or reverse the destabilization. So what does that imply in terms of realistic energy technology and policy?

    First, I am convinced that even if you believe in the premise (and belief is a term that has no standing is science), incrementalism will never deliver the promised results. Why not?

    The most obvious point is that as solar/wind eats into fossil fuel (FF) markets and FF demand drops, the price also drops. Given the trillions of sunk investment in FF distribution infrastructure, end user equipment, generation capacity, extraction capacity and leases, in a pricing dogfight, renewables lose big time. Witness the effects of fracking. Next, the FF industry earns carbon credits for “taking” CO2 from power plants to use instead of water for fracking and radically increase the efficiency of extraction without the environmental concerns. Game over, renewables.

    But the real elephant in the room is storage (or in my case,16 African males suspended from poles 100 meters over my property, slowly descending while turning clockwork generators to keep my Netflix running during the long night… If the humans of 100,000 years ago, huddled around fires in caves, retreating ahead of the advancing glaciers could see us now…)

    Back to the topic, if incrementalism isn’t going to deliver, then we need to look to revolution. Where should we be looking?

    The obvious answer, which your article drives home, is energy density and distributability:

    Solar/wind is diffuse, unpredictable and hard to store. And we are trying to store the primary energy, from which useful power is extracted. Not so with FF, which are “free” in the sense that we did not have to generate the power to create them, then extract it later. Renewables have a double-cost.

    FF is the highest chemical energy density we have for practical fuels, easy to ship from here to there, and can be turned on or off at a moments notice. Cars, power plants, boats, airplanes can all use it equally. If the supply is disrupted for a day or two, no biggie, there is plenty in the distributed storage system.

    Nuclear in all its forms is by far the highest energy density and the lowest cost to extract for usable energy – but it fails in the distributability measure – at least so far. Point failures are devastating, witness Fukushima, Chernobyl etc.

    So where do we look? Massive fusion reactors?

    Tom Watson, head of IBM, coming from a history of mechanical calculators, famously opined that the world market for electronic computers would be 3 or 4 at the most. If massive $100 billion fusion reactors are the future, then Tom would be right. But it would fail as a revolution.

    When Robert Noyce and Gordon Moore invented the integrated circuit, the real information revolution was born.

    Moore later observed that computer power doubles every 18 months, meaning a 500X increase in ten years. Noyce observed that to be a real revolution, an advance needed to be 10X better than what went before. How will that happen in energy?

    Nobody at this point knows for sure. But renewables would have to reach a 10X reduction in price vs FF to really make a dent.

    If fusion suddenly became practical, we might see a progression not unlike the computer, with the first models installed in large scale grid systems, then ten years later migrating to the community and in another ten years, powering our cars.

    Or not. Moore/Noyce and Nicolaus Otto were small shops, not in the employ of the dominant corporations or governments of the time. Maybe the crazy Italian has really figured out LENR? Or not.

    High energy density, safety and distributability.

    One thing is for sure – when the revolution comes, no one will miss it. Around the world, countries, their governments and individual people will instantly say – oh yea, gimme some of that! Just like cell phones and automobiles.

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  50. Molten Salt Reactors offer true 24/7 emission free energy. The Weather needs to wake up as China is walking away with the Oak Ridge National Labs MSR design. China’s is on a multi-billion crash ten year program relaunching the successful Test MSR fro the 1960s.

    MSRs can’t blow up, melt down or make weapons. They don’t use water, are low pressure and don’t need expensive pressure domes, triple redundancy cooling and power sources. The failure mode is freezing solid. They should cost 30-40% the cost of PWRs to build and in 50% of the time or much less.

    Yearly 10,000 tons of the super fuel thorium is tossed away process Rare Earth Elements, enough to power the planet without additional mining. One reactor uses the same amount of concrete and still as one Wind Turbine.

    They are so inherently safe, they can be placed upon every municipal water treatment facility for the highly distributed grid, giving each city $.03 KWh energy cost lowering the city’s cost of services and protecting its population for grid failures from Weather, EMP attacks or Carrington Events.

  51. There are two other ways to store energy although neither of them is really possible at the present time, they are theoretically possible.

    Magnetic: Using the energy stored in an inductor energized with DC current. For this to work the wire would have to be a superconductor. Recovery of the energy would probably require a flyback circuit and a capacitor.

    Relativistic: By accelerating particles close to the speed of light, their mass is increased an arbitrarily large amount and a large amount of energy can be stored in them, not just 1/2*m*v^2. The energy could then be recovered by using the particles to directly generate electricity.

    Both of these are so far out that they are almost science fiction so there is no way to estimate if they would be economically practical.

  52. Not a huge issue, but your capacity factor for California solar is too low. Mid-20s to low 30s are common with new utility-scale plants. For example, Alpine Solar, a 66MW plant in the Antelope Valley region of the desert, recorded capacity factors of 29.4 in 2013 and 28.9 percent in 2014. Elsewhere in the state, California Valley Solar Ranch, a 249.8MW plant, recorded a capacity factor of 31.3 percent in its first full calendar year of operation, 2014. Data obtained through the U.S. EIA’s Electricity Data Browser (

  53. Every 1MW nameplate install of Solar/wind needs several MW of gas-fired backup to be bought, installed & fueled unpredictably. The myth that solar/wind “eat into FF” is just that.

    What does, as the industry long has known, eat into FF is nuclear power, with its power density 1,000,000 times that of FF and its reliability and capacity over 90%. Real environmentalists care about these facts.

    As other countries advance nuclear development, the US begins to fall behind in what will be a huge international market.

    China National Nuclear Power Manufacturing recently went IPO in Shanghai. They were looking to raise a modest number of $millions.
    They raised over $280B.

    At an academic dinner two Octobers ago, their head of international marketing simply said: “We intend to dominate world nuclear power markets”.

    Dr. A. Cannara
    650 400 3071

  54. Huh. One of the major players in developing utility-scale energy storage is not mentioned here: Aquion. And Aquion uses nontoxic, fully recyclable materials in stackable (hence scaleable) modules, unlike most other batteries, so they are a totally clean way to store energy. They are mentioned in many articles; here is the website:

  55. p.s.: Aquion just won a major award: the Innovation Award for the Energy Storage Industry, for their nontoxic utility-scale battery design, so they really should have been mentioned in this article; why leave out something recognized for its importance and innovative design?

    • PPS – As Rud would already know if he’d bothered to click through a link or two of mine.

      Whilst he does mention “sodium” as being “experimental”, he doesn’t seem to have heard of General Electric either:

      • Right, there has been a breakthrough (finally!) in utility-scale and micro grid-scale energy storage, and it is a total game-changer for renewable energy. Total: now we really can go 100% renewable with electricity supplies. Also important to note, as you say, that these are in production and have been installed. The moment is at hand (finally). It is a shame to see this article miss the most important fact about in this issue. This is no secret: it is all over the utility industry news. I hope Rud reads the news articles and our links about it, and offers an update/retraction on this blog at least.

      • How many battery breakthroughs we have already had according to research and company announcements?

        I agree that the news is promising, but it takes still some time to see, what the ultimate value of sodium batteries is.

  56. Pekka, NO these are not research and company announcements only. As I mentioned, read utility news magazines and other outlets.

    You can hardly go wrong to say that to “see the ultimate value of sodium batteries” for sure will take time, of course, but there is no reason to doubt the impact that is possible with the current technology. The testing has been done, those are not in the development stage, they are being produced and installed.

    p.s.: Just to show you: here is Aquion’s “How to Buy” page:

    • The ultimate question is not, whether a new technology (like sodium batteries in this case) is competitive in certain markets against other present technologies. A real breakthrough in battery technology requires more than that, it must succeed in creating new markets on a large scale. We are not that far yet.

      • As for answering what you call the “ultimate question” you may be right. But I was addressing Rud Istvan’s post, in which he says the question is this: ” This guest post surveys what might be possible in the future given what is presently known.”
        That is the question I was discussing. And I wanted to make sure people knew something really really important that Rud’s post didn’t take note of, so that they weren’t misled by this post on intermittent storage. I think anyone would agree that Aquion’s batteries, already tested, in production, installed, and available for purchase at various scales, including utility-scale, are relevant to Rud’s question, and change the perception one has of the future of intermittent storage.

  57. Renewables is like trying to power your car with a wind sail. There are no alternatives to the efficiency of the old petrol auto, not even electric except if you have a petrol engine driving a generator powered motor. The motor replaces the drive train and could be put on each wheel.

    I think the current 2 best contenders is Liquid Fluoride Thorium Reactor and the PRISM reactor. Both are proven designs and are being built in the UK, Russia and China. But here we are still fooling with a centuries old power. Don’t get me wrong but the best form of solar harnessing is passive while wind is limited. And I think there are much better wind designs then those prop jobs.

    Anyhow the 4th gen reactors make the Fukushima designs look like 50s clunkers and they are very much safer from meltdown.

    But one never knows when a breakthrough in energy technology will occur but I doubt it will be in renewables as the fuel is no where near the density of nuclear fuel and only about 1% of fossil.

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