Can Coal-Fired Plants be Re-Powered Today with Stored Energy from Wind and Solar?

by Davis Swan

There is a consensus in many countries that burning coal to generate electricity is something that needs to be phased out as quickly as possible. The Clean Power Plan in the U.S. has that as one of its most likely outcomes and there have been explicit commitments to retire coal-fired generation plants by governments all over the world.

When considering the options for replacing the electricity generated by coal-fired plants there are two characteristics of these plants that need to be considered. The first is that coal is the cheapest and most abundant non-renewable fuel available. The second is that coal-fired plants are very reliable – more reliable even than natural gas-fired plants because they can stockpile fuel on site so that they are not subject to pipeline congestion problems. And getting approval to build new pipelines is not easy these days.

One of the strategies for replacement of coal-fired generation is the development of more wind and solar power. This approach is not without its problems because of the inability to store energy from these sources which are often not available during peak demand times of the day. Matching the 24×365 reliability of coal-fired plants using renewables would be very challenging.

When you think about it the only thing wrong with coal-fired plants is the fact they burn coal to produce the steam used to drive turbines. If a renewable source of heat could be supplied to these plants they could continue providing reliable power and the negative aspects of burning coal would be eliminated.

In jurisdictions where renewable energy sources have been developed extensively the disconnect between electricity production and system load is starting to become problematic. For example, on many circuits on Oahu the amount of electricity generated by roof-top solar panels actually exceeds system demand mid-day some days. Although there is plenty of potential to expand solar power in Hawaii from a resource standpoint it will not be possible without the ability to time-shift production to match demand through the use of energy storage. As a result solar panel permits have been falling for the past two years.

In Denmark, where the nameplate capacity of wind turbines is approximately 1/3 of total generation capacity in the country, wind generation frequently exceeds domestic demand which requires the export of the excess to neighbouring countries. Obviously if all of Denmark’s neighbours also developed a similar amount of wind capacity there would be nowhere to export the electricity to. Texas and parts of the American Mid-West are facing similar issues.

So we are faced with two different problems;

  1. The need to stop burning coal to generate electricity
  2. The need to store excess electricity generated from wind and solar

Fortunately, there is a combination of field-proven technologies available today that can solve both problems. I will refer to this combination of technologies as “Thermelectric Power”.

Thermelectric Power provides a large rapid response load which can be used to stabilize the grid when there are variations in renewable energy generation. It also stores renewable energy by converting it to thermal energy.

The mechanism for storing the energy is molten salt – a mixture of 60 percent sodium nitrate and 40 percent potassium. Thermal Energy Storage (TES) systems using molten salt have been used for more than 10 years as a way to extend the hours that Concentrated Solar Power (CSP) plants can deliver electricity.

The initial research was done at the Sandia National Solar Thermal Test Facility in New Mexico. The first large-scale commercial application of the technology was at the 50 MW Andasol CSP in Spain which came on-line in March, 2009. The Solana CSP plant commissioned in the fall of 2013 in Arizona includes the largest TES facility deployed to date, able to produce 280 MW of electricity for up to 6 hours after sunset.

Excess wind or solar generated electricity can be used to heat the molten salt to a temperature of more than 1,000 degrees Fahrenheit using industrial electric heating elements. During peak demand periods the molten salt would be circulated through a heat exchanger to transform water into the steam required to power conventional steam turbines. The infrastructure to support the conversion of thermal to electrical energy by means of steam turbines exists at every coal-fired electrical generating station which allows the re-use of these very expensive components with only minimal modifications.

Both the heating of the molten salt and the use of molten salt to generate electricity using steam turbines are proven technologies that are deployed today. By integrating Thermelectric Power into an existing coal-fired generation station it would be possible to phase out the burning of coal as more and more wind or solar generation is developed. This approach would also maintain energy security because it would be possible to switch the power source back to coal for short periods of time to deal with extended periods of calm winds. This dual source approach minimizes both CO2 emissions as well as any risk of power failures on a grid where the primary sources of electricity are renewable.

The cost to implement molten salt storage at an existing coal-fired plant would be $250-$350/kwh. This is a fraction of the cost of utility scale battery storage. More importantly molten salt storage does not suffer degradation in capacity over time. The molten salt can be heated and cooled over and over again so that the service life of this technology is measured in decades.

Thermelectric Power could transform the more than 500 coal-fired generating stations in the U.S. into “green” energy sources. More than 10% of those plants are combined heat and power (CHP) plants on University and College campuses. Students and faculty have been actively protesting to stop the burning of coal at these plants for years.

As rate-payers, tax-payers, and advocates for a sustainable energy future we have a choice to make.

We can demand that coal plants be decommissioned and dismantled at a cost of billions of dollars. That choice would require the construction of natural gas-fired plants or nuclear plants with approximately the same generation capacity in order to handle peak loads in the evening when winds are calm – construction that would require more billions of dollars and would continue to emit vast amounts of CO2 annually.

Or we can demand that our coal plants be converted to Thermelectric Power which would dramatically reduce the amount of coal being burnt to generate electricity. Coal would only be used as a fuel when electricity generation from renewable sources was not available for extended periods of time. But the flip side of that is that coal could be used in that way to back up renewable generation. As a result we could develop as much wind and solar energy as we wanted without worrying about dealing with excess when demand is low and without worrying about destabilizing the grid.

A future fueled by renewable energy is possible using technology that is available today. We just need to want it enough to make it happen.

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

232 responses to “Can Coal-Fired Plants be Re-Powered Today with Stored Energy from Wind and Solar?

  1. Pingback: Can Coal-Fired Plants be Re-Powered Today with Stored Energy from Wind and Solar? | Enjeux énergies et environnement


    Tin selenide.

    Sounds promising.

    Does solar and wind work less efficiently in cold weather ?

  3. If it was cost effective they would have done it already. I suspect that the costs exceed the cost of coal power by such a wide margin that it isn’t going to be cost effective in the foreseeable future. And since we aren’t going to need to look beyond coal for the foreseeable future, let’s leave this expensive technology to the researchers and just get on with improving people’s lives by using the most plentiful and cost effective power available.

    • Mike

      “If it was cost effective they would have done it already.”

      Horse meet internal combustion engine. For the longest time, horses rode side by side with the ole car until someday there were no more horses.

      Even if you find the evidence for CAGW theory lacking, you can appreciate emerging energies such as molten sat reactors and tin selenide storage.

      Cleaner, cheaper, as reliable should be the long term goal no ?

    • “If it was cost effective they would have done it already.”

      Reminds me of the economist who refused to pick up a $20 bill off of the sidewalk because if it were real someone else would have done so already. I’m always skeptical about such schemes, but even I wouldn’t resort to your argument.

      • That’s your counterargument? Twenty dollar bill on the sidewalk. Let’s pretend that there is such an economist. Irrelevant. Power companies don’t leave $20 bills lying on the sidewalk. Especially when they are under pressure to get rid of coal. Mike Jonas is correct. If it made economic sense, it would be adopted.

    • Since a typical coal plant is about 35% efficient, that implies that thermal storage will have lower efficiency, maybe 30%. Who would want a battery that wastes 70% of the electricity? Doesn’t sound very sustainable.

      • Well spotted Jim. That is the key error in the reasoning here.

        Turning electricity into heat is one of the dumbest uses of electricity. Doing so in order to later covert it back into electricity is the dumbest thing on Earth.

      • Brent Wakefield

        But if you consider the source to be very cheap and renewable once infrastructure cost recouped the loss is irrelevant. It’s like saying we don’t want to use robots because they are less efficient at the job….but once robots are paid for there is negligible cost in the wasted work.

  4. Davis Swan,

    You say:

    “We can demand that coal plants be decommissioned and dismantled at a cost of billions of dollars……………………………
    Or we can demand that our coal plants be converted to Thermelectric Power which would dramatically reduce the amount of coal being burnt to generate electricity.”

    If this concept is as clearly economic and ready for use as you imply, we don’t have to “demand” it. The market should jump all over it.

    What’s holding it back?

    • “demand that our coal plants”

      The trick of the conman is to create urgency.
      To make you feel like “this” is an out of the ordinary circumstance.
      Scare you, take your money or something else you value.

      Clean, reliable and cheap power is a reasonable goal to attain.
      Molten salt nukes fine if they are self contained.
      Tin selenide storage options. Fine, if it costs out favorably.
      Coal, fine, if we burn it cleanly (low particulate and minimal damage in harvesting and wasste management).
      Oil, same …

      There are some reasonable agendas sleeping in the same bed with the conmen. They should find better bedfellows.

    • Mark – it is definitely more expensive to implement molten salt storage then to replace the coal-generated capacity with natural gas generation if the plant needs to run 24 hours a day. However, I think that between renewables and the existing non-coal fleet the converted plants (or any new natural gas plants for that matter) would only have to run perhaps 8-12 hours per day. In that scenario conversion looks quite attractive.

      Utilities are very conservative by nature and they are also very risk averse. Faced with having to close a coal-fired plant the cheapest and least risky alternative is a natural gas-fired plant. So if continued emission of CO2 (at a much lower rate than from burning coal) is not a concern and long term forecasts for natural gas prices are not a concern and pipeline capacity is not a concern and the stability of the grid as more renewables are added is not a concern then natural gas is the “obvious” choice for a utility. And that is the choice being made in most cases.

      Nobody has implemented this technology. It looks very low risk from my analysis but you never know until you actually give it a try.

  5. You say that the cost is $250-$350/kwh. But how long is that energy being stored? a day? Renewables have large seasonal variability in output. Is this technology able to deal with annual variability? How does it compare with pumped hydro storage?

    • Molten salt storage can last up to 7 days so it can handle daily variations in renewable generation but not seasonal. The only solution for seasonal storage that is practical today is hydrogen storage. See

      • Hydrogen storage is not practical. Not even close!

      • Why do you think that pumped hydro storage is impractical for long term storage?

      • Curious George

        You mention Andasol, which came online several years ago. I could not find any data for Andasol operations; for some reason they are not advertising the technology very efficiently. Could you please provide operational data for an existing solar-molten-salt plant?

      • Pumped hydro is a mature technology that has been used for decades. Existing pumped hydro facilities can be used to store any excess electrical power (or cheap power to be sold at a time when prices are higher).

        NIMBYs nixed a project at Storm King Mountain, along the Hudson River, that would have alleviated the Great NY City Blackout had it been built and it would have been ready for the Green Energy revolution, to store all that solar and wind power.

      • -1=e^iπ,

        The claim was that “The only solution for seasonal storage that is practical today is hydrogen storage”, not pumped hydro.

      • Huh? DS your own link says that hydrogen storage is 25% efficient.

        That effectively competes with nothing. Only nothing is less efficient than hydrogen storage. Since nothing is much cheaper, hydrogen storage must be attractively priced to find wide acceptance.

        Hydro storage may be 80+ percent efficient and competes with batteries for efficiency but has a lower cost than batteries and you don’t have to replace the pumped storage every five years.

        Claiming that hydrogen storage is an effective seasonal storage solution depends on your definition of effective and solution.

  6. Setting aside the completely ill conceived notion that coal plants need to be completely phased-out, the concept’s technical practicality is poor for a variety of reasons.

    Coal plants (or more accurately, the steam turbines) are designed to operate at around 1000 F and several thousand psig. The molten salt heat exchanger would need to replicate these conditions. The coal plant’s boiler is utterly useless.

    For a 1000 MWe coal plant, around 35,000 acres of solar collectors would be needed if the unit was in a desert area with lots of sunshine.

    Bottom line, the concept is technically and financially fatally flawed.

    There is a a way to replace a coal plant with a technology that easily meets the proposed EPA CO2 reductions. Without getting into the technical weeds, the concept is a hybrid/nuclear plant that employs gasified coal. However, the cost of natural gas would need to be around $10/MMBTU for the hybrid-nuclear/Integtated Gasification Combined Cycle plant to compete. The hybrid-nuclear technology is patented and being developed by private industry.

    • Molten salt is used to generate electricity using steam turbines in at least 10 plants around the world. Whether the water in the boilers of a coal-fired plant is heated by an external flame or by a internal heat exchanger the result is the same. There is absolutely no technical issue in that regard.
      I am not suggesting that a particular solar collector be built to power these plants. It is a fact that renewable generation will exceed load often if it is fully developed. Denmark frequently has up to 1 GW of excess energy with a renewable capacity of less than 5 GW. Germany sometimes has 5 GW or more of excess generation. Without storage this electricity has to be exported or curtailed. Unless you believe that the development of wind and solar generation is going to stop soon then some way to deal with this intermittent energy has to be implemented. I am proposing one possible solution.

      • The boiler in a coal plant is designed for combustion. A molten salt heat exchanger is completely different heat transfer process.
        You are just flat out technically wrong.

      • Davis,
        “Whether the water in the boilers of a coal-fired plant is heated by an external flame or by a internal heat exchanger the result is the same. There is absolutely no technical issue in that regard.”

        Nope, you are way off technically here. Steam turbines for power plants are designed for specific steam temperatures and pressures as produced by their boilers. The turbine blade design and number is dramatically different even between nuclear and coal fired generators. The temperature of the steam in a nuclear plant is roughly half that of the coal plant.

        The liquid salt system by it very nature is a variable temperature system. As energy is drawn from the salt, it’s temperature drops. That is not merely a problem of reduced efficiency with reduced steam temperature. Lower temperatures allow condensation in the lower pressure stages of the turbine. That condensation acts like the water in hydraulic metal cutting systems. It gradually etches the blade surfaces away.

        As for using the plants for peaking generation, steam plants are not appropriate for start/stop operation. Their components must be heated up slowly. It is not unusual for a coal plant to take over a day to come up to full load capacity from a cold start. Real world power plants are and must be much, much more complex than the simple fire/boiler/turbine/condenser sketches typically used to describe them. That complexity is needed to achieve the high efficiency necessary for commercial generation.

        Additionally, issues abound for scaling up the heat exchanger design to the gigawatt range of the coal power plants they they are intended to replace. Consider the consequences of a leak in the heat exchanger tubes introducing the salt mixture into the steam system. Turbines, pipes, and pumps in coal plants are not designed to deal with that kind of contamination and corrosion potential.

        So, building a proof on concept salt based power plant is far from the reality of converting a current production coal fired plant to operate on salt.

      • Well, keller and Gary have done put the ole quietus on this story. Perhaps the lack of technical feasibility explains why power companies aren’t jumping on the molten salt bandwagon.

      • “You are just flat out technically wrong.”

        Yes, that seems to be the case. But, you offer also a price estimate on a totally wrong technical solution. It’s not serious.

    • Right now the Henry Hub spot price for natural gas is around $2 per MMBTU. Are any of these hybrid plants running now?

  7. Davis Swan,

    There is a consensus in many countries that burning coal to generate electricity is something that needs to be phased out as quickly as possible.

    There is not such consensus, except among the climate cultists.

    The real consensus, among ~99% of the world population, is that we need energy at least costs. While coal is cheapest, that’s what we want.

    If you want cheap energy to replace coal, the obvious answer is nuclear. The energy is stored in the fuel until needed, just like it is in fossil fuels. No or little energy storage is needed. Nuclear is the least cost way by far to reduce emissions from electricity generation. Why are you trying to find anything but the obvious solution?

    • “Nuclear is the least cost way by far to reduce emissions from electricity generation”

      Smart insider money seems to agree with you, but they are 5 years out from a molten salt reactor pilot build and 10 years to replication. All seems reasonable if we don’t hold ourselves ransom to undependable solar and undependable and destructive wind.

      Paleoclimate trendwatchers think the odds are higher that we get much colder by 2020. Looks like fossils will be essential during any transition to nuke.

      Of course none of the above has anything to do with yet to be proven CAGW. We are at the high side of the long term natural temp pattern. Ultimate irony is that we are likely worrying about the opposite of what we should be concerned about.

    • This survey from a year ago ( found that 55% of Americans wanted less reliance on coal while 21% wanted more reliance on coal. The Canadian province of Ontario has stopped burning coal to generate electricity and the new government in Alberta has pledged to head in the same direction. New Zealand is phasing out coal ( The UK has also made a commitment to retire all coal-fired plants ( The Sierra Club’s Beyond Coal campaign has resulted in the closure of more than 100 U.S coal-fired plants in the last 5 years ( ). There are many other examples from around the world. I think it is hard to argue that there is not a consensus to stop burning coal.

      • Davis Swan,

        Inless you are not aware of it, USA is not the whole world and not weven representative of the whole world. Furthermore, ask the question in such a way as to make it clear what the costs is, and the proportion of those who support higher electricity prices, less jobs, lower standards of living declines to only the far Lefft Greenies.

      • @ Peter Lang – Wow I had no idea NZ, UK and Canada were part of the US.

      • There are many other examples from around the world. I think it is hard to argue that there is not a consensus to stop burning coal.

        55% is more than half but far from consensus and it is based on believing the alarmist media that keeps preaching climate model output and keeps ignoring actual data.

        Around the world, coal use is increasing. Even Germany is building new coal plants. Their wind and solar don’t work as well as coal.

        Actual data will win this debate, sooner or later, and the world will know that this new pope in Rome is no smarter that the pope in Galileo’s time.

        There are those in the alarmist camp today who would like to burn some of us skeptics on the stake, or at least put us in jail.

        In history, more cases of consensus were found to be false than cases that still hold up today. Consensus is generally found false after the generation dies, because people do carry consensus to the grave.

        I agree with Peter Lang, the real consensus, among ~99% of the world population, is that we need energy at least costs. The alarmists tell us we must lower our standard of living to keep the earth from warming and the oceans from rising, but not even Al Gore or Bill Gates have given up their standard of living.

        Low cost, abundant, energy is what everyone needs and should have. So far, coal has done that better than anything else.

  8. Davis Swan,

    The cost to implement molten salt storage at an existing coal-fired plant would be $250-$350/kwh.


    What does that cost include?. Is it the full. cost of electricity, including grid costs and generation with equivalent availability and capacity factor that a coal plant can achieve (e.g. 85% which is the figures used in many LCOE calculations).

    • This is an estimate of the capital cost of implementing the technology. The operating costs would be dependent upon many factors such as grid transit fees, the cost of off-peak electricity, etc. Those costs would impact any storage technology such as batteries, flywheels, etc. Personally I believe that there should be much more financial support for energy storage – waiving grid access fees, introducing a Feed-In-Tariff, paying for ancilliary services or grid balancing (as they do in Germany). The estimate is based upon an analysis that I have done incorporating input from the leading molten salt storage companies.

      • First, it cannot be an estimate of the capital cost because you give unties of kWh, not kW. So, it is clearly a cost of energy or energy storage capacity. You haven’t explained which.

        Second, what is the source of the estimate/ Where is the design and basis of estimate documented?

        You need to compare the estimated system cost for your system of wind plus solar plus coal plus energy storage plus additional grid costs with the cost of nuclear to meet the same requirements. You haven’t shown that.

        My guess (from EIA estimates of power plant capital and operating costs ) is the capital cost would be in the order of 3 to 5 times the cost of new advanced coal plants and 2 to 3 times the cost of nuclear plants to mee the same requirements. The LCOE would be very high too; the only saving is a some coal. Fixed O&M and are much higher per MWh and Variable O&M are higher too because the cost of cycling thermal plants ic very high.

        You really should do these analyses yourself before posting if you expect to be taken seriously.

      • Peter you said “Inless you are not aware of it, USA is not the whole world” – do you really think that my post deserves a sarcastic response?

        Peter you said “it cannot be an estimate of the capital cost because you give unties of kWh, not kW” – capital costs for storage are always given in cost per kWh – for example see
        I have run many simulations of LCOE, ROI, IRR, etc. for different configurations of molten salt storage. As I already replied there are many factors most of which would apply to any energy storage system. I believe that molten salt conversion of coal-fired plants achieves many positive benefits for a reasonable cost. Not the lowest cost which is natural gas if the plant can be guaranteed to run at a high capacity factor. This is no longer a good assumption and you will note that recently constructed, highly efficient natural gas fired plants in German are being closed because they are running at low capacity factors due to renewables (

      • do you really think that my post deserves a sarcastic response?

        Wall actually, that’s all your response to my comment warrants. Instead of responding directly to the point I made, you made an irrelevant comment quoting junk statistics from surveys in developed countries; the surveys ask a loaded questions to get the result they want. they did not properly explain the consequences for each option. So the surveys are irrelevant.

        To refute my statement you need to show that more than 7.3 million people would vote for much higher energy costs, lower standard of living, less jobs and all the other consequences of imposing higher energy costs on a country.

      • PL:What’s the use of arguing about costs of a technology that does not work?

  9. I would expect that engineers in Germany would be considering this.
    They have a lot of coal plants and are building more. Anyway, it’s a very interesting concept.

  10. What is the loss in efficiency due to this procedure compared to just placing wind turbine electricity straight onto the grid.

    • There is a very significant loss of total energy with the molten salt scheme – up to 70% loss depending upon the efficiency of the steam generator. That is horrible I admit but if the wind generation is truly surplus – that is to say in excess of existing system load, then it would have to be curtailed which results in 100% loss.

      • “That is horrible I admit but if the wind generation is truly surplus – that is to say in excess of existing system load, then it would have to be curtailed which results in 100% loss.”

        Thanks for the answer.

        It would also be good to get an expected cost in terms of kilowatt-hours. I suppose, however, that this is independent of the efficiency, since as you say, the power is free.

  11. This idea is so ridiculous it is unbelievable. You should estimate the capital cost (or all components, including grid) cost of electricity, CO2 emission, cost per tonne CO2 avoided before posting ideas like this. You haven’t provided a link to the design or the cost estimate. I am amazed Judith posted it.

    • I have had this concept reviewed by the Energy and Environmental Research Center and they did not find it to be “ridiculous”. There are numerous challenges relating to grid transit fees, cost of input electricity, etc. which would apply to any energy storage system. I think it follows that if the capital costs be kwh are 1/3 or 1/4 of any battery technology then this proposal is reasonable compared to any utility scale battery energy storage.

      • You make many claims but none are supported. And you clearly haven’t done a proper cost analysis. The cost of this is very much higher than nuclear and you haven’t even done a comparison. Its a disgrace. But it’s typical of what the RE advocates do all the time.

        Please post your basis of cost estimates for capital cost. LCOE, and CO2 abatement cost for your idea and show properly comparable figures for the coal and nuclear alternatives.

      • While I do think Peter Lang is being unnecessarily impolite, I do share some of his concerns. It would have been preferable if the post had more information about estimates of the cost, the methodology used, duration of storage, feasibility, etc.

      • -1=e^iπ,

        Fair point. I just find it extremely frustrating to see this sort of complete nonsense still being posted. The problem is that so many people don’t have sufficient background to do reality checks for themselves. So they believe it.

    • I agree, as a former PE in a power-plant, this “idea” is absurd.

  12. Davis Swan,

    I’d normally let it go, but someone with such fine taste in surnames shouldn’t have howlers like 24x7x365 in his work. 24×7 is OK; I guess you could throw in a x52 if you really wanted. I think it’d be better to drop it altogether; it’s redundant.

    But yes, there may well be more future in molten salt energy storage than there is in batteries.

  13. I’m not an engineer, nor thoroughly conversant with power plant economics, but scanning over this, it seems as if a much more efficient use of a molten salt stage at a coal plant would be to preheat the water in an existing plant to simply reduce the amount of fuel required for the boiler. I understand some power plants are already using solar water heaters upstream of the boiler in order to accomplish this.

    This would still add grid level storage to capture peak solar or wind, stabilizing the grid, reduce fuel use at the plant, and likely not require re-engineering the boilers or turbines as Davis Swan’s plan likely does.

    • That is an implementation decision that would be made after a thorough engineering study. My first reaction is that your suggestion is sound and could very well be the right approach. As you say, there was the plant in Colorado that used that approach.

      • Mr. Swan,

        It is a good idea to consider and at least should lead to creative thinking that may lead to other innovations. Given that the available supply of coal in the US far excedes the useful life of plants and the engineering concerns raised in above comments, we shouldn’t be giving up on coal. The toxic aspects of burning coal can be controlled fairly easy and I would expect a significant backlash against the misapplication of the overly broad EPA charter in placing constaints on GHG’s, which can’t be attributed to direct impacts on regional weather. Even the indirect effects through the well mixed global atmosphere can’t be shown to affect regional weather and health on a meaningful level.

  14. 1 Modernise coal for more wealth. Coal must never be wasted either by being left in the ground or burnt in old clunkers. You are not driving a forty year old Ford Falcon for very good reasons.

    2 With that wealth, experiment where private business won’t, but in the full consciousness that you are now punting, not investing.

    3 Do not mainstream what is experimental. If Stored Energy is looking good, do it somewhere, not everywhere.

    4 Do not buy into the world’s pipeline wars and sea lane wars and territorial wars more than you have to. (So coal and nukes!)

    5 Use coal wealth and coal power to, for example, run humans back and forth quickly in proper rail networks which do not increase or clash with traffic. Bugger cycleways where they just don’t fit despite all aspiration (I’m a cyclist). Coal is wealth, cars are freedom.

    6 As Cato the Elder said: The Climatariat must be destroyed. (Well, he was actually talking about something else, but you catch my drift…)

  15. I am a 40+ year power engineer and pre-heating water with say solar energy is insignificant and of no particular value in the overall thermodynamic cycle. Ditto for augmenting steam production. The cost versus benefit is pretty poor. Emission impacts are in the “bug-dust” category.

    Also the idea of backing off a thermal plant invariably drives up the cost of running the plant. Costs must be distributed over fewer production hours. Economics 101.

    Coal boilers are designed for combustion processes. Heat transfer using molten salt is vastly different.

    The proposed concept will not work.

    • As you say, it wont work.

      Cycling coal plants costs in the order of $100,000 on average for each stop and start. That’s due to the life shortening of the equipment caused by the thermal stresses caused by the cooling and heating.

    • I appreciate your comment and your experience. If you could provide a brief description of the difference between a coal-fired plan and the steam generation implemented at the Solana plant in Arizona I would appreciate it.

      • Sure. Solana max temp is 390C, pushing two small Siemans steam turbines net 125MWe each. Molten salt storage is only 6 hours, accomplished by a train of 6 two tank MSS systems (hot/cold, each of the 12 tanks ~122 feet in diameter and about 60 feet high (each tank 2.9 million gallons), total 135,000 tons of 60% sodium, 40% potassium nitrate). Footprint for 24 hours of storage far too large, and temperature too cold, for reconfiguring an old coal unit. Average of 40 year old US units is 116MW, about like new Solana. 24 hours storage would require 48 Solana tanks. Averge US old subcritical steam temperature is ~ 550C, not 390C. Square peg in round hole problems. Devil is in the engineering details.

      • I am a current power plant PE, Operations and Engineering. In addition to what ristvan has stated, even if a new turbine was procured with the needed design inlet pressure, as someone previously pointed out, the inlet pressure would be constantly dropping as the molten salt cooled. It is no small engineering challenge to create a turbine that can deal with these inlet conditions. Condensation will damage turbine blades, this can be mitigated somewhat by use of moisture extraction in the interstage turbine blades, but it can’t be fixed. This turbine would require frequent maintenance and be inefficient.

        Without a lot more engineering and economic detail, I would judge this to be impractical.

      • +1 very clearly put

    • Davis Swan,

      If you could provide a brief description of the difference between a coal-fired plan and the steam generation implemented at the Solana plant in Arizona I would appreciate it.

      It seems like you are asking me to do your research for you. I am certainly not interested in doing that. There are far more important high level issues to deal with without getting diverted into down in the weeds issues like the one you’ve asked for.

      Once you answer my question about the basis of your estimates, I might be more inclined to consider there is some value in taking you seriously. At the moment I don’t think you are capable of doing such analyses. My simple capital cost estimate below shows how ridiculous your idea is. And there is no point in playing the usual game of pointing out inaccuracies in the assumptions and inputs; what you need to do is do a better, more detailed, analysis and justify your figures.

      • Davis Swan. The Solana plant was built by Abnegoa which has just filed for bankruptcy. Evidently, Solana does not work well enough for the company to survive.

      • DHR. And with $1.6 billion in loan guarantees and subsidies, selling electricity at $0.16/kwh wholesale when the local blended retail rate is $0.11. Only reason $2 billion was wasted is the state was stupid enough to mandate that 15% of its generation must be renewable by 2020.

  16. Extract from: The Difficulties Of Powering The Modern World With Renewables

    Energy Storage

    This is the obvious solution; store intermittent renewable energy during periods of surplus generation and release it during deficit periods. But the only existing technology that can do this at the scale necessary is pumped hydro, and as discussed at length in previous posts here, here and here the amount of pumped hydro storage needed is enormous. At only moderate levels of solar & wind penetration the UK would need several terawatt-hours of storage, maybe as much as a hundred times the capacity of its existing pumped hydro plants, while Europe and the US would need tens of TWh each and the world proportionately more. There is no realistic prospect of bringing this much new pumped hydro – or even conventional hydro, which can also function in an energy-storage mode – into service in the foreseeable future even if enough suitable hydro sites could be found.

    The alternative is battery (or flywheel, or compressed air, or thermal) storage. These technologies are so far from deployment on the multi-terawatt-hour scale that they can be discounted. (According to Wikipedia total world battery + CAES + flywheel + thermal storage capacity still amounts to only about 12GWh, enough to fill global electricity demand for all of fifteen seconds.)”

  17. Let’s do a quick and dirty calculation of the unit capital cost ($/kW) for three options to supply power at 90% capacity factor and 90% availability using EIA plant costs (2102$) :

    1. Nuclear = $5,530
    2. Coal = $2,934
    3. Coal + wind + PV + storage = $14,308
    • Coal = $2,934
    • Wind = $2,213
    • PV = $3,873
    • Storage = $5,208

    The capacity of wind, solar and storage in option 3 would have to be optimised. The optimised capacity of these may be more or less than the capacity of coal. I’ve simply assumed 1 unit of capacity for each technology for this ball park analysis. In this case the capacity factor of wind and solar might be around 30% and 60% provided by coal. So the emissions savings would be less than 1/3 (because intermittent renewables are less than 100% effective at reducing emissions; e.g. about 50% effective at about 20% penetration of intermittent renewables).

    I’ve used the capital cost per kW of pumped hydro for storage because it is the only figure I have to hand and we know it is by far the cheapest energy storage methodology (currently providing 99.4%) of electricity storage globally. However, what is most important is the energy storage capacity. The energy storage capacity would need to around 1/3 of annual electricity if the intermittent renewables provided 50% of annual electricity generation.

  18. Davis Swan,

    I’d urge you to read these:

    The Renewables Future a Summary of Findings

    The Difficulties Of Powering The Modern World With Renewables

    • Peter – thanks for these links. I think you posted from euanmearns before. These are and excellent source for understanding many issues surrunding tenewables.

  19. We need to get federal funding to test these ideas. Or can we talk Google into putting up $20 million a year so we can have conceptual engineering & cost and schedule estimates?

  20. I think this is brilliant.

    The UK is retiring coal plants with the aim of replacing them by a mix of wind, gas and nuclear. Nuclear is stalled by cost and the opposition of the Green Blob. Gas is intended to fill the gaps in wind, but presently the UK government despite creating a capacity market (new form of subsidy) to encourage intermittent gas finds new gas is not being built. So there is an urgent need for dispatchable but intermittent supply.

    Your proposal seems to meet this. One would need several such conversions and they should meet the condition that MWh stored > time to start boiler and switch to coal for wind lulls are often long – days not hours.

    The only issue that troubles me is the speed at which a switched off coal station could start up. Could it get goping as fast as a CCGT? An OCGT (one station recently built in UK, I believe)

    • A good technical paper on increasing the flexibility of coal-fired pants can be found here.

      Before considering a Thermelectric conversion a detailed engineering study of the specific coal-fired plant would be required in order to assess the optimal approach and to determine whether or not the whole exercise was worthwhile. Implementing flexibility measures would be part of that effort.

      • Thanks for the link. So you would want “hot” start in your proposed system. This makes Charles-The-Moderator’s proposal look better, co-firing a base-load coal station with molten salt.

        Unfortunately for the UK that is not consistent with removing coal altogether (which the UK government is politically committed to). There are two other problems.

        The first is that we don’t have much excess renewable generation in the UK and it is not clear that we will build enough renewables for this to be a problem.

        The second is the subsidy structure. The Coire Glas pumped storage scheme has stalled because it is not counted as renewable, so it is not clear that funding would be available to change to thermoelectric-coal co-firing.

      • ==> “…the flexibility of coal-fired pants…”

        Regardless of what you think about the advisability of renewables, you have to admire the flexibility of coal-fired pants!

      • Joshua – maybe that is the origin of the term “pants on fire” – was way too late when I wrote that post!

  21. Here’s another ball park estimate using your cost of energy storage capacity, and the results from this analysis for UK:
    Estimating Storage Requirements At High Levels of Wind Penetration

    To generate a constant 25 GW of power with wind power in UK in February 2013 would require 150 to 200 GW of wind power and 1200 GWh of energy storage. The capital cost would be (using EIA estimates, :

    25 GW wind power @ $2213/kW = $55 billion
    1200 GWh storage @ $300/kWh = $396 billion
    total = $451 billion for 25 GW constant supply in February 2013 in UK

    That’s $18,000/kW. Compare this with:
    1. Nuclear = $5,530/kW
    2. Coal = $2,934/kW

    I admit I do not understand your design or your proposal – i.e. how much electricity would be generated by wind, solar, coal and from storage. Without those numbers it’s hard to do any more detail calculations than the rough reality checks I’ve done here.

    However, the important ;point is I’s urge you to post your analyses to back up you assertions or withdraw this post until you have.

    I think the reality checks I’ve posted here are sufficient to show that the idea is ridiculous.

    I’d also urge you to read the posts I’ve linked here and above. The provide a good model for you for doing your analyses and explaining them.

  22. Peter you obviously do not believe that a sustainable energy future based upon renewables is possible. I am familiar with Roger Andrews’s postings and I have expressed exactly the same concerns about intermittency and unreliability that he discusses. I also believe that nuclear power is a good option and that Germany’s intention to shut down its nuclear fleet is a mistake. So we agree on many points. However, even if I believed that the continued development of renewables was foolish I think it is going to go ahead anyway. Public opinion and public policy in many, many countries regarding the threat of climate change is not weakening significantly. We’ll see what comes out of Paris but I doubt that it will be a weakened attack on CO2 (justified or not).

    And despite what Roger has written I think the development of renewables can proceed a very long way yet. To backfill wind when calm conditions are encountered (like Roger’s April doldroms) we can just use the existing non-renewable fleet. More wear and tear on the equipment, higher costs, and lower capacity factors for everyone – that’s for certain. But the system would survive and the only problem would be that it costs more money. As an example Germany has implemented a “grid stability” market which is growing quite rapidly and is really just a capacity market. As long as rate-payers and tax-payers can be made fearful enough about climate change the added costs will be sold to the public as the only way to save the planet.

    I am also not as pessimistic about the future of energy storage as you and Roger are. There are a few large battery projects underway and eventually these will drop in cost and become reliable enough to be useful (I say that having recently written a pretty negative post about batteries I do also believe that the molten salt concept could be viable under the right conditions and another concept that I have put forward is something I call “unpumped storage”. I don’t think any of these are the magic bullet but in combination they will have an impact, slowly reducing our dependence upon non-renewable sources.

    I respect your right to have an opinion but on most of the issues related to renewables I think we will have to agree to disagree.

    • Davis Swan,

      Peter you obviously do not believe that a sustainable energy future based upon renewables is possible.

      Correct. I don’t see evidence that renewables can provide a large proportion of global energy demand, now or in the future. And neither you nor anyone else has been able to demonstrate it can. Like most renewable energy advocates, you dodge doing the relevant analyses and cost estimates. You have not provided any evidence they can be economically competitive. You dodge that important issue.

      However, even if I believed that the continued development of renewables was foolish I think it is going to go ahead anyway.

      Your belief is not a rational argument. It’s based on nothing. It’s wishful thinking. Nuclear was accelerating and reached 18% of electricity supply by about 1980. It’s now back to 11%. That’s because it fell out of favour with the public, and the anti-nukes caused the costs to ratchet up by a factor of about eight. Renewables are already far too expensive and non-hydro renewables are at only about 3% of global electricity supply.

      Are you aware that the EROEI of renewables plus storage is insufficient to support modern society and reproduce themselves. So they are not sustainable. There is no persuasive evidence that the past growth rates will continue to high proportions of global electricity supply. And, meanwhile, advocating for them as you are doing is delaying progress. In fact recent evidence is the growth rate has stalled already.

      Every year UNEP publishes a chart of annual global investment in renewable energy, the lion’s share of which (92% in 2014) goes to wind and solar. Here’s the latest version:


      To backfill wind when calm conditions are encountered (like Roger’s April doldroms) we can just use the existing non-renewable fleet.

      Davis, you have to cost the whole system on a life cycle cost basis. You can’t just keep making baseless statements like this.

      What is your background? Are you an engineer? How much experience do you have in energy projects?

      But the system would survive and the only problem would be that it costs more money.

      A totally baseless comment. Wishful thinking. Demonstrates negligible understanding.

      There are a few large battery projects underway and eventually these will drop in cost and become reliable enough to be useful

      What’s the relevance of silly statements like this. Just meaningless adjectives and no quantification. Do you have any idea how much energy storage would be required to back up for wind power? Have you ever crunched the numbers?

      I respect your right to have an opinion but on most of the issues related to renewables I think we will have to agree to disagree.

      That’s a cop out. I’ve done the numbers, you haven’t. So have many other people and many authoritative bodies. I’ve given you many links. Your comments suggest you have not read them or don’t understand them.

      You are clearly wrong but apparently not prepared to admit it. I suggest you should withdraw this post.

      • “Peter you obviously do not believe that a sustainable energy future based upon renewables is possible.”

        It’s possible, just has a very large price tag.

      • -1

        “It’s possible, just has a very large price tag.”

        Indeed. The investment money (top tier and investment houses) seems addicted to the certainty of new power. My business will pass the cost onto my customers. My customers will want higher salaries to pay for the higher priced goods. More dollars will have to be printed. Definitely inflationary.

        What happens if a country such as China/Russia say no thank you, we will burn coal and gas ? Their cost of fucntioning is less than the other yahoos who saddle themselves with expensive energy. Do they become country non grata ? Sanctions ? War ?

        What if they go along to get along.

        Is the net result a giant wave of international inflation ?

        :::: trying to look beyond the craziness to brass tacks … it will all seem so silly once the natural patterns of climate kick us back to cold ::::

      • You are being a little harsh, Peter. He doesn’t need to withdraw the post. A simple “What TF was I thinking?” will do.

    • -1=e^iπ

      “Peter you obviously do not believe that a sustainable energy future based upon renewables is possible.”

      It’s possible, just has a very large price tag.

      I disagree. It’s not possible for many reasons. But here’s one for starters:

      • “I disagree. It’s not possible for many reasons. But here’s one for starters:”

        Nonsense. Humans lived with low CO2 footprints for millennia. All we need to do is live in poverty and reduce life expectancy back to 30. A renewable future is very possible.

      • All we need to do is live in poverty and reduce life expectancy back to 30. A renewable future is very possible.

        True. PLUS reduce global population by 90%

      • -1

        Odds are

        1. Hillary gets elected and the US shuts down more and more fossil power.
        2. Solar and winds pop up everywhere.
        3. The consumer pays 25 to 50% more.
        4. The Appalachian coal country secures massive welfare programs.
        5. Those that live in CO2 nonattainment industrial zones get class actions checks.
        6. Massive inflation kicks in.
        7. The rest of the developed world drinks the koolaid.

        So what happens if the IPCC predictors continue to be wrong and instead it gets crazy cold ? How fast can the developed countries turn around and start burning fossils again ?

        What is the lag time between “oh hell we were wrong” and back to fossils again ??

      • “So what happens if the IPCC predictors continue to be wrong and instead it gets crazy cold ? How fast can the developed countries turn around and start burning fossils again ?
        What is the lag time between “oh hell we were wrong” and back to fossils again ??”

        Well, to quote Max Plank:
        “A scientific truth does not triumph by convincing its opponents and making them see the light, but rather because its opponents eventually die and a new generation grows up that is familiar with it.”

        Given that most young people in developed countries are arguably being fed a lot of propaganda, we might have to wait for millennials to die out, or at least be outnumbered by younger generations. So maybe the late part of this century might see a return.

        Until then, the religious conviction of the true believers in climate change being the end of the world will remain strong.

  23. What is the estimated life-cycle for the pipes and other equipment exposed to high-temperature molten salts? Do we have any long-term experience or is everything less than 10 years old?

  24. Peter – by the way – you wouldn’t happen to be the President of Dunedin Energy Systems – developer of small scale nuclear systems?

  25. Davis Swan,
    Since I cannot find any numbers in your article I cannot check for myself, but have you kept in mind that the efficiency of a (coal-)boiler/steam-turbine/condenser is below 50%?
    Half of the energy that is put in the water/steam (at a final temperature of approx. 600 deg C.) by the boiler or by the molten salt is not transformed into kinetic energy (going to the generator to generate electricity from it) but is cooled away in the condenser at a temperature level of approx. 30 deg. C. Obviously this energy is no longer able to perform work and generate electricity, but still usable for heating purposes for instance.

    So, you will only be able to recover half of the electricity you put in the molten salt. Is this taken into account?

  26. coal fired plants, China is building one a week, how is that ‘all governments world wide are phasing them out’?

  27. My ball park calculation above using Davis Swan’s estimated cost per kWh of storage capacity and EIA’s cost of wind power is
    1. wind + solar + storage = $18,000/kW.

    Compare this with
    2. Nuclear = $5,530/kW
    3. Coal = $2,934/kW

    But that’s with just 40 hours of energy storage (at full power). You’d probably need 2000 to 4000 hours of storage and 8x over build of wind farms to manage seasonal variations in wind power.

    The cost of this scheme is so ridiculous it’s unbelievable the Davis Swan is still defending it.

  28. As an energy expert, I read this piece (and all the responses) with great interest.

    I’d say that several responders gave it the appropriate rating: wildly speculative.

    From the get-go this piece is about politics, not science (or engineering). This business that there is a “consensus” that we “must get rid of coal ASAP” is a horrifically bad basis to build an energy policy on.

    Consider where did any “consensus” came about — from lobbyists who influenced the media, who (in turn) have propagandized the public.

    That wind energy is “clean, free and green” is pure marketing pablum, and totally false. Yet this is what the public has been innundated with. These people know full well that the public (and their representatives) are technically challenged regarding energy matters, so they make absurd claims with impunity.

    To say that we then have to accede to this self-serving fabricated propaganda is preposterous.

    Instead of blindly accepting the lobbyist concocted “All of the Above” energy policy, we should be advocating “All of the Sensible.”

    “Sensible” would be defined as alternative energy soutions that are a Net Societal Benefit.

    A Net Societal Benefit would be determined from a scientific assessment of proposed technologies (like this), where a technical, economic and environmental evaluation is done.

    So, Mr. Swan, if you believe you have that scientific proof, then please post it forthwith.

    At that point we can compare your results with other options (e.g. switching the coal facilities to gas).


    john droz, jr.

  29. I am skeptical of this scheme for several reasons, but here is reason #1. This looks to me a lot like Ivanpah with the solar collectors being remote and subject to lower collection efficiency (PV and wind vs mirrors), transmission losses, and conversion losses before arriving at the molten salt stage.

    To date it appears that Ivanpah operates at lower than expected efficiency in part due to a larger than anticipated need for fossil fuel to maintain the minimum temperature in the storage area at times when solar power is not up to the task. This scheme would seem to have the same issue unless large amounts of surplus power are available at all times. More high temperature storage can minimize this problem but as storage is increased costs go up and losses increase.

    At best this looks like a sink for zero value surplus electricity with the benefit of gaining a small amount of usable power in the process. Perhaps it is worthy of some research funds in order to obtain some real numbers as to capital and operating costs vs output. Ready for prime time? Doubtful.

    The need for such a scheme, not to mention the extra grid costs to make it work, highlights the kinds of extra costs incurred with high penetration rates of intermittent energy sources.

    • Let me suggest the kind of simple time-shifting which is likely more efficient and cheaper than the system proposed here:

      At residences install an additional electric hot water tank prior to the existing tank/on-demand heater. Use a controller to turn on the heat elements when the pre-heat water is below a certain temperature and the cost of electric power is below a certain price. The cost/KwH would need to be quite low to beat natural gas but in certain areas this might be possible at certain times of day.

    • Sciguy

      Ivanpah was given the OK to use more natural gas to keep the boilers up as denoted here:

      …..”AQ-34 The combined fuel use from the auxiliary boiler and the nighttime preservation boiler shall not exceed 525 328 MMSCF of natural gas in any calendar year; combined fuel use is the sum total of natural gas combusted from Boilers …..”

      Parker Wells gave a presentation recently noting a cost estimate for the CSP facility at Ivanpah. His presentation focused on how some advances in energy storage could improve the dispatch ability of the project.

      By now the PPA contract(s) put in place to ensure the project would be built are likely available for review- the details were confidential when the project was approved at the CPUC

      It appears the operators of Ivanpah have been able to operate the facility to optimize delivery of power at super peak times as CPUC Commissioner Florio recently noted that the Average kWh price of RE, taking into account Time of Delivery (TOD) factors, reached as high as $.20 kWh. Page 3 of the link below notes the drop in large scale RE projects to $.05 kWh.

      • Here is the bottom line on centralized thermal storage (TES) vs a simple system as I proposed.

        1. In both cases, electricity is generated and transmitted …. so its a wash.

        2. With centralized thermal storage the electricity flows from transmission lines directly to the TES facility while for the home system it must also traverse the distribution system…. very sight advantage to TES.

        3. There will be similar losses converting electricity to heat in both systems for a wash (actually, the home owner might be able to use a heat pump for a much higher conversion efficiency). The home owner now has hot water ready for use, less storage losses incurred before use.

        4. Upon demand and after storage losses (very high temperature delta), the TES system will convert heat to steam and steam to mechanical power and mechanical power to electricity. This process is MAYBE 50% efficient.

        5. The TES system will hand its electrical output to a transmission system, then a distribution system, and then on to the customer premises, delivering about 40-45% of the electrical power which would have been received by the customer in step 2.

        So by virtue of an efficiency of 40-45%, the power delivered by this high-tech system will cost the homeowner about 2-2.5 times as much per KwH plus the additional capital and operating expenses. As a homeowner, I think I would want a chance to have the cheap power if a trivial bit of tech would allow me to use it effectively.

        As a reliable sink, I would also trust a mechanism spread over many thousands of homes over one huge sink.

  30. I’ll bet electrolysis and fuel cell oxidation of sodium oxide would turn out to be cheaper and more efficient (cost as well as energy) than thermal storage. Sodium metal would be far easier and safer to store than compressed hydrogen, the temperatures would be similar, and the oxygen produced from electrolysis could be (short-term) used with carbon-capture technology. (CO2 capture is much easier with oxygen/CO2 fired combustion than air-fired.)

    As for re-using coal plants, IMO the best option would be to convert them to CCGT. I don’t know if the existing boilers could be used, and I’ll admit pipeline congestion problems would probably necessitate building new gas storage on-site. But the result would be a bigger power plant, capable of being switched to fossil-neutral gas when it becomes available.

  31. Molten salt just delays the problem.

    Usable wind generally blows about 20% of the time. We can do a quick back of the envelope calculation and say…gee..if we could just time shift from the 4 or 5 hours per day when the wind is blowing to the peak 4 hours of the day all would be well.

    The wind blowing 20% of the time is as likely to be all day Monday…then no wind until Friday as it is a few hours a day.

    Time shifting a few days as opposed to hours is an order of magnitude larger storage problem.

    Then we have the ultimate problem…a large high pressure system over much of the continental US in January…no wind…very little sunshine and massive demand for power lasting more then a week to heat our homes and businesses.

    If we believe CO2 is truly a problem…then we are going to have to stop heating our homes/businesses with oil/coal/natural gas.

    In the US peak electricity consumption is normally the summer…but winter demand is not far behind(In Texas it’s about even now)…when we all change to heat pumps for heat then winter demand will far outstrip summer demand. Solar panels/wind turbines are useless in winter cold snaps.

    Not having enough power in the summer more most people means being uncomfortable…not having power in the winter means freezing to death.

    • Indeed Harry, here on the East Coast the summer heat waves are due to Bermuda highs where the wind stops for a week or more, hence the ozone exceedences. But the engineering question: how could we handle this with renewables, remains. In fact it gets very interesting.

  32. This is fun stuff! Putting on my engineering hat and hiding my policy hat, the issue of storage is clearly the renewable gorilla. Plus the war on coal is certainly shutting down a lot of plants. My idea has always been to dismantle them and rebuild them in poorer countries who need the juice. Engineering estimates suggest that this can be done quite cheaply.

    My concern is that “moltifying” an existing coal fire plant might well be more expensive than building a new molten salt storage plant. You are really only using the turbines, plus some steam handling gear, all of which is around 40 years old, or more. It might be better to build new plants, near the renewable generators. But then new plants need to be permitted in ways that existing plants do not.

    In fact it is the independent renewables generating companies that might build them. Storage may well get very valuable in the days they says to come.

    • Like cash for clunkers, but without destroying productive capital.

      Unbelievable that we destroyed engines that we could have simply sold overseas.

  33. Is this the same technology — concentrating solar — that is zapping birds in Nevada? or California?

  34. Matthew R Marler

    We can demand that coal plants be decommissioned and dismantled at a cost of billions of dollars.

    Or we can demand that our coal plants be converted to Thermelectric Power which would dramatically reduce the amount of coal being burnt to generate electricity.

    It is worth repeating that those are not the only alternatives. Of the alternatives that have been described in these and other venues, they are pretty poor, and ought to be resisted.

    • >Or we can demand that “SOME OF” our coal plants be converted to Thermoelectric Power which would dramatically reduce the amount of coal being burnt to generate electricity.

      Best case this is a solution for a subset of Coal Plants. It will be limited to those where the life of the existing infrastructure works cost effectively with the projected new additions. Coal plants can last a long time, but will the remaining life cycles of components compliment the expected/estimated life cycle of the molten salts and solar collection? Many coal plant locations will not have suitable land available as they were built years ago for considerations like water, and coal delivery. It’s good to go for the low hanging fruit and find some success before advocating for an overarching solution.

      • True enough, although every coal fired power plant has a coal yard, which is where the molten salt energy storage facility can go. As an engineering concept this is pretty interesting, because renewables need massive storage under decarbonization. As a policy not so much.

  35. “The mechanism for storing the energy is molten salt – a mixture of 60 percent sodium nitrate and 40 percent potassium. ”

    It is interesting to note that if one considers the natural concentration of radioactive potassium-40 (K-40), any reasonably sized ‘thermelectric’ generator as described here (and existing ones) would be out of the radioprotection limits imposed to nuclear power stations.
    There would be literally several Sieverts of K-40 with no proper nuclear containment… , in case of a breach of the hot salt storage container the radioactive K-40 would be released in the environment… a fact which by itself shows how ridiculously low the limits for nuclear power stations are… which is the real reason why nuclear is so expensive.

  36. Seems like a good idea even if the plants continue to burn coal. Just stick giant water heater elements in the tanks with tank temperature a negative feedback to the coal feed

  37. This has got very ugly

    There looks to be a few climate criminals arguing the case for coal on this very blog…

    We have come to something when the climatariat seek to directly harass dissenters to the party line. I am sure JImd, Jch and others will be along soon to condemn these tactics. Any time now. Any time…


    • I think demonizing your opponents is unfortunate but it happens with almost all contentious political issues. For example, I have seen many “skeptics” demonize scientists by calling them corrupt. So yes no one should resort to these type of tactics to win an argument or political fight. But I don’t think there is a lot that can be done about it.

      • > … demonize scientists by calling them corrupt

        Undoubtedly, some are. Steve McIntyres’ recent article on Jagadish Shukla is of interest

        But mostly it is the rot of moral vanity, of noble cause corruption, that causes the angst

        Davis Swan’s article here drips of noble cause wishes, unfettered by any experience of, or expectation of, real practical accountability. dougbadgero above, 8:33pm, skewered this by commenting on the obvious (to me) issue of the cooling rate of molten salt affecting inlet pressures. Given that wind gusts are unpredictable in their appearance and longevity, this issue drops the Swan notion into the Marianis Trench

      • Joseph,

        I see no reason why scientists should be immune to corruption. However, the greater problem would seem to be Warmists pretending to be scientists. These pretenders – primarily second raters – are either fools or frauds. Fools for believing non scientific rubbish due to ignorance, or frauds for knowing Warmism to be nonsense, but promoting it anyway – for obvious reasons.

        Arguments are irrelevant. It matters not what one thinks. As Feynman pointed out, the elegance of one’s theory accounts for nought, if unsupported by experiment.

        You have no experimental support for the madness that is Warmism. No matter how much you fight, argue, or contend, the facts do not change. Good luck anyway!


      • Joseph “I think demonizing your opponents is unfortunate but it happens with almost all contentious political issues.”
        Should have stopped right there instead of continuing on to demonize your opponents.
        Might have believed you meant it.

      • You haven’t seen call climate scientists corrupt and the science fraudulent?. How is that not demonizing your opponents?

      • When climate scientists ARE corrupt and the science IS fraudulent. Do you think calling an ISIS member a terrorist is demonizing? Is calling a scam artist a criminal demonizing? In any case, history will record it all in the end, no matter how much some try to rewrite it.

  38. All this sounds great … but there is always a catch. Before we can turn to solar and wind, power generation needs to be at least close to the cost per KWh of generating electricity with coal. Allowing the excess “grid energy” to be “stored in molten salt” then becomes more or less “free”. I’ve read that windmills have a shorter lifetime than coal-fired plants (25 years instead of 30) and the larger the windmill the greater the likelihood of bearing failure – and the increased cost of ongoing maintenance. Have the authors done the cost/benefit analysis?

  39. One version of a renewable energy source is hydroelectricity. However, if one looks at the area flooded by the James Bay project in Canada, for example, one sees numbers in the range of 11,000square kilometers. Area is the price of energy collection schemes. Has anyone actually calculated the sheer area that one would have to cover in solar cells in terms of square miles or kilometers if one wanted to replace coal powered plants? I took a quick shot at it from the point of electrical requirements alone in Canada, a country of a mere 33million and the area was phenomenal.

  40. This proposal is ignorant. It ignores basic facts of chemistry, physics, engineering, and economics; some of which have been pointed out by other commenters.

    “”The mechanism for storing the energy is molten salt, a mixture of 60 percent sodium nitrate and 40 percent potassium. Thermal Energy Storage (TES) systems using molten salt have been used for more than 10 years as a way to extend the hours that Concentrated Solar Power (CSP) plants can deliver electricity.”

    The nitrate salt based TES systems used in CSP plants operate at about 300 C. That is completely incompatible with the 600 C used in modern coal fired plants, or even the rather lower temperatures used in older plants.

    “Excess wind or solar generated electricity can be used to heat the molten salt to a temperature of more than 1,000 degrees Fahrenheit using industrial electric heating elements.”

    Not if you are using nitrate salts. They decompose (explosively, I think) at about 400 C (700 F).

    “The cost to implement molten salt storage at an existing coal-fired plant would be $250-$350/kwh. This is a fraction of the cost of utility scale battery storage.”

    Maybe half the cost of batteries. And that is way too high for more than a few hours of storage. That would be enough to accomplish diurnal time shifting, but would be at least an order of magnitude too small to account for wind and solar variations associated with weather systems.

    The best round-trip efficiency you would get from this scheme would be about 45%; that is the efficiency of a modern coal fired plant. That would more than double the cost of electricity, even if the storage were free. If you are converting an old plant, you will get whatever lower efficiency that plant was designed for.

    And then there is the fact that most coal fired plants do not have turbines that were designed to be rapidly ramped, so they can’t be used effectively for load following.

    • Mr. Swan needs to wave a white flag, on this one. Let’s move on.

      • Remember, the breakthrough will come from some wild idea. Kudos to this Swan for thinking, kudos for responding in comments, and yet more kudos for not getting abusive.

        I’ll have to quit if discussions continue this civilly.

      • Kim,

        There is no end to these sorts of crazy ideas. They get the attention and people believe there is hope for renewables despite the relevant facts. But the RE advocates ignore the relevant facts. They don’t want to know about them. Davis Swan is a classic example. He doesn’t want to know about the relevant facts. This nonsense has been going on for 50 years. It’s time that people who have some understanding and who can do reality checks call them out.

      • Be consoled that reality checks are a survival advantage.

      • Peter: “There is no end to these sorts of crazy ideas”.

        Nor should there be. It’s not as if any harm is done, if the idea is preposterous it will never see the light of day. This forum should be a place for vetting ideas. Ideas may lead to progress Most of us don’t have your knowledge and background and some of us are interested in renewable technology. I’ve read many pieces on renewables and the possibilities of new technology. Thanks to you I am better able to discern whether or not they are practical. I am grateful that JC is showing posts on renewables so I can learn more about it. Perhaps Mr. Swan is mistaken about some of what he says but he may have some contribution nevertheless.

      • Ordvic,

        Fair comment. I am just frustrated because thei ssame sort of emiotionally and ideologically driven nonsense has been going fdor 30 years. It’s massively retarding progress because people spend most of their time reading cr@p and not focusing on genuine, cost effective solutions.

    • Are the skeptics of Swan’s idea saying that they can think of no way to engineer and repurpose the coal-plant turbines for this solar application, so you might as well scrap them? What is the bottom-line message here? I don’t know much about engineering, but surely there are things you can do to make those turbines work or make that steam suitable to them. Perhaps the critics have not thought this through enough yet with an eye to what positive use you can make of this infrastructure.

      • Jimmy

        Some skeptics aren’t convinced it’s a good idea to retrofit (to unreliable alternatives) coal fired power plants (CFPP) until the data is conclusive that the change in climate is not just part of a natural variability. Indeed, it would be best to be prepared to be wrong in the event that it gets cold.

        A wiser approach would be to offer up a pilot or two that demonstrates the proof of concept.

        Still wiser is to assure ourselves that alternatives such as MSR (nuke) reactors are capable of mass production in a timely manner as a replacement to fossil fuels before we send CFPPs to the scrapyard.

  41. Curious George

    Coal is the root of all evil. Also a great opportunity. I’ll drive the value of coal stocks to zero. Then I’ll buy the mines for nothing. Finally, I’ll show that CO2 is actually beneficial, and reopen the mines to much fanfare and a joy of trade unions, creating thousands of jobs.

    That’s how a redistribution of wealth works.

    • So you’d redistribute the wealth into your own pocket? By Jove, I think you’ve found the secret to Al Gore’s success!

  42. Heat the salt with waste heat from running supercomputers. You might as well get come use out of the electricity before it becomes heat.

    You’d need a hibernate mode in the computers, of course.

    • Curious George

      A sensible proposal. All that is missing is a concentrator of a thermal energy – when you get 2 gallons of water 200 degrees hot, make it into 1 gallon 400 degrees hot, and 1 gallon 0 degrees hot. That would benefit everybody (except fans of thermodynamics). That’s where Bill Gates’s money should go.

      • You can do that. Use a heat pump. Remember to capture the waste heat from the compressor (why they put home heat pump compressors outdoors is a mystery).

        All the electric powergoes into heat. Just get use of it first.

      • Curious George

        Now we are getting somewhere. Supercomputers are cooled by heat pumps, which can be designed to molt salts instead of dissipating heat in cooling towers.

      • “why they put home heat pump compressors outdoors is a mystery.”

        Partly because it’s cheaper to heat most homes then cool them. But mostly because the outdoors is a vastly larger heat sink then a house.

      • You’d keep the same coils outdoors but the compressor indoors, thus capturing its waste heat too.

        You’re right about cooling season, though.

        Also heat pumps waste energy to melting condensation ice, at least mine did in the season it lasted long ago.

    • Good idea – those computers generate a lot of waste heat running climate models.

  43. Why not pump water up in a reservoir? Hydroelectric is upscalable.

  44. You get only about 50% of the input electricity back with this system. (Thermal efficiency of the process is 67%. Then there are some turbine and pumping losses.)

  45. Svend Ferdinandsen

    If you read danish this blog is excellent by Henrik Stiesdal.
    A prominent person in Siemens windpower group.
    He suggests thermal storage in sand or the like, but heated with a compressor, making some 25% more heat than the electricity to drive the compressor. (A sort of heat pump).

    • Seemed interesting, so I took a look. Discovered I don’t read Danish. Except, I assume “vind” means wind. Same as in India.

      • Don, google will translate. The upshot is that the article says wind can be a huge part of the energy mix if you have enough cheap storage. But of course we already know that.

  46. Are there transmission costs, can energy be delivered to these plants as easily as it can be supplied from?

    • On a networked system. load will stress the system differently than a generation source. It all depends on how it works with the other loads and resources on the system. For more details see

    • Maybe I can state it a little differently. This is the kind of question that does not have a yes/no kind of response. The power grid is a distribution system delivering power from large sources to smaller, dispersed loads. While the power lines connections to power plants could easily carry power into the plant, the overall grid system is build, for obvious cost reasons, to split power plant energy into multiple smaller paths. Any change in the direction of electric power flow would likely require upgrade of some paths. Electric transmission utilities constantly battle public utility and government agencies for permission to upgrade their systems. It can take decades to receive approval for a transmission line addition or even upgrade.

      Adding new power plants to the grid is a non-trivial (and expensive) process. The engineering challenge in dealing with new and variable large source and loads not something we can dismiss as trivial.

    • SA, yes, but Swan’s scenerio assumes a level of wind and solar that would require massive upgrade anyway, so probably not a big increase over that assumption.

  47. One of the issues I have to learn to deal with is being able to concisely explain what using ammonia as an energy currency and fuel is about and the opportunities that exist.

    Please take a quick look at the attached very well written four page Prologue by Jim Esch, Proceedings of the IEEE Contributing Editor, to the most thorough examination on the subject found in “The Dual-Fuel Strategy: An Energy Transition Plan.” (Digital Object Identifier 10.1109/JPROC.2013.2245039)

    The Dual Fuel Strategy: An energy Transition plan, by CalPoly Tech prof. William Ahlgren, is part of a very detailed three part submission made to the California Energy Commission in, William Ahlgren Comments: Plan to completely decarbonize the electric power sector, which contains the Prologue and three other reports:

    1. W. L. Ahlgren, “The Dual-Fuel Strategy: An Energy Transition Plan.” Proceedings of the IEEE 100, 3001-3052 (2012).

    2. W. L. Ahlgren, “Fuel Power Density.” Journal of Pressure Vessel Technology 134, 054504 (2012).

    3. W. L. Ahlgren, “Planning for Hundred-fold Increase in Global Ammonia Production.” Ammonia Plant Safety and Related Facilities, Vol. 54, pp. 81-90 (American Institute of Chemical Engineers, 2013).
    I did not attache the 6.458 Gigabyte pdf of the complete submission with the Prologue and three reports, but it can be downloaded here:

    PROLOG by JIM ESCH, Proceedings of the IEEE Contributing Editor, IEEE 100, 2998-3000 (2012), An introduction to The Dual-Fuel Strategy: An Energy Transition Plan – by CalPoly Tech Prof. William AhlgrenIEEE 100, 3001-3052 (2012),

    Global extractable petroleum reserves have entered a phase of depletion, causing increasingly unstable oil supply and price. Other fossil sources, coal and natural gas, remain relatively abundant but their continued use carries the threat of accelerating global warming. The time has arrived when fossil fuel sources need to be replaced with renewable (and perhaps nuclear) sources of energy.

    One reality must be faced: electric energy will not serve as a total replacement for fuels. Fuels are an efficient means for transporting and storing energy, and they are compatible with existing energy infrastructure, an immediate advantage that will leverage the transition to renewable fuels. This paper advocates a dual-fuel strategy for that transition.

    The fuels proposed are nitrogen based (ammonia) and carbon based (methanol). They are complementary: ammonia is carbon free but relatively toxic, requiring care in handling, while methanol is more easily handled but contains carbon. The energy density of ammonia and methanol is half that of current-day fossil fuels, yet it is sufficient to meet 95% of the world’s fuel requirements. The remaining 5% can be met with high-energy density methanol derivatives. Alternatives to ammonia and methanol exist, including blends rather than pure compounds. The dual-fuel pair that ultimately emerges might be different from ammonia and methanol; but it is likely that one member of the pair will be nitrogen based and the other carbon based.

    Liquid fossil fuels come solely from petroleum. Liquid renewable fuels, by contrast, can be derived from any energy source: renewable, nuclear, or fossil. This source neutrality translates to agile production that provides an essential competitive advantage: low-cost nonsustainable fossil sources can be employed in the early stages of the transition to sustainable nonfossil sources.

    Converting natural gas to liquid renewable fuel will be pivotal in the early stages, providing a low-cost alternative to oil-derived fuels. Low-cost and stable supply of these alternatives is essential to trigger a virtuous cycle of market feedback. As markets grow and mature, increasing demand for liquid renewable fuels will stimulate technology innovation that will enable competitive production from renewable or nuclear sources.

    Successfully moving from fossil to renewable and perhaps nuclear sources will require institutional as well as technological innovation. Producers, distributors, and consumers must join in a broad, mutually supportive alliance for market and technology development. In the paper, the alliance is named the Dual-Fuel Exchange. This institution will help trigger a virtuous cycle of market feedback leading to rapid transition from fossil to sustainable sources.

    During the transition, most CO2 generation will be centralized at large fuel production plants located near gas and coal fields. Concentration of CO2 generation in a few large sources will enable profitable carbon capture sequestration and sale, which has the potential to reduce global carbon emissions by as much as 90% early in the transition perhaps as early as 2030.

    The dual-fuel strategy makes a distinction between energy source, vector, and infrastructure, based on an understanding of the energy supply chain as a series of processes: extraction, conversion, refinement, transport, storage, and end use. There are three energy sources: fossil, renewable, and nuclear.

    An energy vector is anything that carries energy and can be traded (monetized). Currently, the only viable vectors are fuels and electricity. Fuels (chemical energy vectors) dominate energy trade because they are the best way to transport and store energy. Electricity is a power vector that can be transported on transmission lines, but must then be converted to another form for storage. The energy infrastructure is the matrix of built environment that enables energy trade.

    This paper proposes and argues for a dual-fuel strategy to make the transition from fossil-fuel-based economics to more sustainable alternate energy sources.

    The dual-fuel strategy proposes to derive renewable fuels from fossil sources at first, as part of a transition plan. Fuels are deeply entrenched in the infrastructure; sources are easier to change. Once established, renewable fuels can be kept as energy vectors while changing the energy sources from which they are produced. The biggest challenge to any energy transition strategy is economic inertia, the tendency of a political–economic system to resist change, in this case the change away from fossil fuels and sources. To overcome this inertia, renewable sources must supply competitive fuel energy vectors that can be traded using the existing infrastructure.

    Our legacy infrastructure for energy distribution and use is a system of pipelines, tankers, refineries, distribution systems, and conversion devices developed primarily for oil derived liquid fuels. This infrastructure must continue to be utilized as we convert from fossil to renewable fuels. Fossil fuels are entrenched in the system due to Catch 22: conversion devices for alternative fuels are not available, so there is no incentive to produce alternative fuels, so there is no incentive to develop new conversion devices. This is a vicious cycle; to defeat it, a countervailing virtuous cycle is needed.

    The way forward begins with niche trigger markets where renewable fuels have a low barrier to adoption and a distinct competitive edge. Five near-term markets that could comprise the leading edge in the transition to a dual-fuel future are: 1) marine propulsion for ammonia and methanol tankers; 2) ammonia-powered railway locomotives; 3) methanol-powered local-use road vehicle fleets; 4) small-to-mid-size integrated power systems or energy hubs; and 5) base-load electric power and other industrial plants with boilers and furnaces.

    In these markets, renewable fuels must be available with more stable supply and at a lower cost than oil derived competitors. The combination of low-cost and stable supply is the trigger that initiates positive market feedback a virtuous cycle that brings about rapid change. Plentiful natural gas is the opportunity we can exploit to make this happen. Natural gas should be viewed as an energy source to be converted to liquid fuels which are energy vectors.

    Today natural gas is used as both source and vector, but its competitive advantage vis-a`-vis oil is enhanced if it is converted to liquid fuels. This is especially true of stranded natural gas reserves those not easily accessible to pipeline transport.

    Renewable fuels are made from air and water. The leading substances that can serve as energy vectors are hydrogen, ammonia, and methanol. Hydrogen is a gas; ammonia and methanol are liquids. N2 is 2000 times more plentiful in air than CO2, thus the air capture of CO2 will be more costly than N2, favoring nitrogen-based liquid renewable fuel. Ammonia is the low-cost chemical energy vector of the future, with methanol playing a complementary role in specific uses where higher cost is justified.

    For some applications, e.g., residential heating and cooking, methanol will be further converted to dimethyl ether (DME) to take advantage of its higher vapor pressure and compatibility with conversion equipment designed for propane. In other applications, e.g., long-haul aviation, a higher energy density fuel is required. Then, methanol can be converted to iso-butanol, n-dodecane, or other higher alcohols or gasoline-like mixtures of alkanes and cycloalkanes.

    Four processes can be used to produce renewable fuels: photochemical, thermochemical, electrochemical, and petrochemical. Petrochemical conversion is not sustainable, but it is vital as the trigger mechanism leading to sustainable systems.

    Hydrogen is attractive as a renewable fuel due to its simplicity, relatively high electrochemical conversion efficiencies, and benign environmental impact. The problem with hydrogen, however, is that it is a gas, not compatible with the legacy energy infrastructure. Hydrogen is more difficult to compress and liquefy than natural gas, which itself is only marginally competitive with liquid fuels. Ammonia and methanol are more competitive than hydrogen because they are liquids: they can be stored, distributed, and converted in engines and combustors requiring only relatively modest modification from those currently in use.

    Ammonia can meet about 80% of all fuel needs, those in which professional handlers would be required to have the training and equipment to use it safely. The remaining 20% of fuel requirements could be covered by the more easily handled fuel methanol or a derivative. When produced from natural gas, neither ammonia nor methanol is carbon neutral, but both are potentially carbon neutral energy vectors. The strategy is to create a market environment that can realize this potential by stimulating development of renewable energy sources. The same market environment opens the possibility of near-term reduction in greenhouse gases by enabling carbon capture at large centralized sources.

    The transition from fossil to sustainable energy is a two-step process: first replace fossil with renewable fuels, then replace the energy sources used to produce those fuels. The competitive advantages driving the transition are threefold: legacy compatibility; agile production; and risk mitigation. For the strategy to take hold, the renewable fuels at first must be derived from gas or coal sources to produce them at a competitive cost versus oil-derived fuels.

    This is accomplished by standard petrochemical processes in wide use today. Once markets are established, competing electrochemical, photochemical, and thermochemical conversion processes will emerge in response to expanding demand for renewable liquid fuels. The end result will be an efficient, flexible market that can produce a stable energy supply at low cost.

    The paper highlights the attractiveness of high-efficiency interconversion between electric power and liquid renewable fuels. Electrochemical energy converters batteries, fuel cells, and electrolyzers will play a central role in the future global energy system. For purposes of trade, chemical storage as fuel is inherently preferable to chemical storage in batteries.

    It would therefore be a mistake to abandon fuel in favor of batteries. Although efficient low-cost electrochemical interconversion (electricity-to-fuel and fuel-to electricity) is challenging, it is not impossible. If achieved, it would have a transformative effect on society, with dramatic impact on the global economy. Approaches to efficiency improvement include high-temperature electrochemical conversion based on proton-conducting solid electrolytes.

    Direct photochemical and thermochemical conversion processes are acknowledged as viable alternatives to electrochemical conversion. Biofuels produced from algae or other energy crops are one path to photochemical conversion, but probably not the lowest cost path; artificial photosynthesis of precursors (such as synthesis gas) to ammonia and methanol production seems more promising.

    Nonfuel storage will continue to be an important adjunct to the electric power vector. Today the most cost effective means are pumped hydroelectric storage and compressed air energy storage. Utility-scale battery storage is under development. Improving the round trip efficiency of electrochemical fuel converters would give the competitive advantage to this storage mode, however, due to the greater utility (and hence value) of fuel. Even at lower efficiency in the conversion process, higher overall efficiency in the energy chain may be achieved by fuel-based

    Energy transmission and distribution as fuel instead of as electric power enables distributed trigeneration: combined cooling heat and power. When electric power is generated near the end use, low-grade heat produced as a byproduct can be used, rather than wasted. Renewable fuels can have several possible manifestations, including carbon-free substances, carbon-containing substances, and mixtures (blended fuels). The range of possibilities is briefly reviewed in this paper.

    Ammonia is the leading example, after hydrogen, of a carbon-free fuel. It reacts with oxygen to form nitrogen and water vapor. It has relatively low vapor pressure and is easy to transport and store. Its principal drawback is high relative toxicity, yet it can be handled safely with proper training and equipment. A vast worldwide ammonia infrastructure already exists. Existing natural gas pipelines can be converted to ammonia using the same right-of-way or perhaps even the same pipeline.

    Steam generation for electric base-load power and industrial process heat can be supplied by ammonia combustion with minimal modification to existing facilities, since only the burners of furnaces need modification. Ammonia can power any engine or combustor currently run on fossil fuels, and it can also be used in fuel cells. Ammonia can be used either directly or indirectly; indirect use entails passing ammonia through a reformer, a device that converts ammonia to nitrogen and hydrogen.

    Ammonia has significant environmental and safety advantages. Fire and explosion risk is low. The risk of spills is serious, but less so than petroleum spills. The release of ammonia into the environment is naturally remediated within a relatively short time. While short-term consequences are serious, there is no long-term environmental damage from an ammonia spill. Ammonia is immune to accidental ignition. The transportation of ammonia in pipelines is advantageous compared to electric transmission over high-voltage lines; there is reduced environmental and view-shed impact, higher transmission efficiency, and potentially higher overall system efficiency.

    It is also more efficient and less costly than natural gas and hydrogen transmission because ammonia pipelines can operate at lower pressure and less energy is needed to run pumps and compressors. Ammonia transport by sea is superior to CNG or LNG for bringing stranded natural gas to market. Using ammonia for electric power generation enables zero-carbon emissions at the generating plants. Carbon capture would be shifted from the generating plant to the gas or coal fields that are the source for the ammonia, where it can be integrated more efficiently.

    The hazards associated with ammonia and methanol must be considered in relative terms. No fuel is perfectly safe. Methanol is less toxic than gasoline. It is relatively easily processed by organisms, thus the impact of a spill is less than that of a comparable crude oil or gasoline or diesel fuel spill. The environmental impact of methanol exhaust emissions is less than those of gasoline and diesel fuel. Ammonia is more problematic. Nitrification is an issue, and the toxicity of ammonia to aquatic organisms is real. These negative effects must be evaluated by comparison to those of fossil fuel use.

    A common misconception is that ammonia combustion must be accompanied by excessive NOx emission. In fact, just the opposite is true: ammonia is used in contemporary combustion processes to minimize NOx emission, and through combustion engineering the NOx generated by burning ammonia can be less than that of other fuels.

    Although ammonia’s toxicity is a drawback, it is compensated by significant advantages. We must weigh the pros and cons of ammonia and methanol against those of other fuels, recognizing that there is no perfect fuel.

    The dual-fuel strategy provides a hedge against the risks of unstable oil supply and global warming. The transition to a dual-fuel economy can be accomplished within a few decades. It enables an order of magnitude reduction in global carbon emissions early on, perhaps as much as an order of magnitude by 2030, and ultimately zero net carbon at completion, perhaps as early as 2050. The dual-fuel strategy is a feasible plan to create a sustainable post petroleum global economy.

    • Curious George

      Brave, bold, and brilliant. Ditch your car and get a green one, running on a highly toxic and corrosive substance. Never mind that you only get a half of mileage; it will suffice for 95% of your needs.

  48. Gas turbines spin up quickly. Coal boilers not so, there is a long period for bringing the boiler to operating temperature, therefore the match to immediate demand with gas is much better. Also it is not clear that the turbines for coal (or gas) are a good match to CSP. Might be best to have separate systems.

  49. Takes about 8-10 hours for a coal fired plant to start generating electricity at capacity, and a few hours before you get 30% mostly because considerable energy is needed to heat the boiler up to operating temperature

    • Yes, but that is not how you load follow with a coal plant. You never reduce power below the point where it has considerable capability to ramp back up again. It is easier to go from 30% to 60% than from 0% to 30%. Same goes for nuclear.

    • Eli,
      Not quite. A major problem requiring the slow startup is dealing with is heat differential in components. Large steam power plants have large components. Rapid heating causes temperature differences across even solid metal objects. While a single rapid heat up might not be a particularly bad problem, frequent temperature cycling allows cracks to develop and grow in equipment that will be operating a very high temperatures and pressures. Heat up must be slow enough to allow thermal soak on components. These steam plants are intended for 30 to 50 years of operation. Minimizing stresses on equipment is critical for that life span.

      Even if thermal stresses were not a problem, there would be a concern for cold traps. That is areas of the steam system that might not be cool enough to reduce the temperature of the steam to a point where water droplets and condensation can occur. That, of course, can allow slugs of water to be forced at high velocity through the steam system. That is a situation that is good to avoid.

      • Oops: sentence should read: “That is areas of the steam system that MIGHT BE cool enough to reduce the temperature of the steam to a point where water droplets and condensation can occur.” (fingers and brain on different wavelengths)

  50. Warmist holiday wishes to all and to ending dhimmitude in Western academia and its forced conversions of scientific skeptics to the pagan god of the global warming alarmists.

  51. Here’s another equally loony idea – clearly never checked with engineers with the qualifications and expertise to provide advice.

    • Peter Lang,

      From your link –

      “As with all new, unproven technologies, we can not predict exactly what problems we might encounter. But some ideas are presented here.”

      Yes. Well. One might just as well buy up a load of old railroad wagons, a load of track, fill the wagons with rock, and use surplus power to tow them up a suitable hill, and create as much potential energy as desired.

      Letting the wagons descend releases the energy, which can be used to power all sorts of things when the sun don’t shine, and the wind don’t blow.

      Old technology, but tried and true. Recycles rolling stock and track no longer fit for high speed use. How hard could it be? Not hard, just fairly pointless given present coal, oil, gas, and nuclear reserves.

      Ideas? Unlike backsides, most people have more than one. A backside is more essential than an idea – you can survive without an idea!

      The Warmists live in denial of reality.


    • Wow. Rock – 500m high. Hefty Hydraulic Pressure, Batman!

      Don’t want to be anywhere near that thing when it goes FRAAAAAACK!!!!

  52. Davis Swan,

    Could you please tell the readers a short bio about your relevant background? Are you an engineer? How much experience do you have in energy projects?

    • Peter – neither my background or my proposal are of any real interest to you so I don’t know why you ask. I have read some of your articles and it is very clear that no amount of analysis or economic justification will influence your thinking in any way. If National research organizations are unable to sway you I certainly have no chance and will not spend a lot of time trying.

      I have degrees in Geography and Geophysics and I have been involved with energy policy development and research for more than 30 years since the time I was the energy critic for the official opposition in the province of Alberta, Canada. I worked for more than 20 years in the oil & gas industry as a geophysicist and later as an Information Technology professional. I have had articles published in three peer-reviewed scientific journals on statistical topics.

      I worked for the company that commercialized horizontal drilling in the oil and gas industry – a technology that was, at the time, considered absolutely crazy by everyone in the oil patch. In fact, our President was able to purchase a large heavy oil field for $1 from Gulf Oil because Gulf was absolutely convinced the technology would not work. Less than 5 years later Gulf Oil offered to buy back the field (by purchasing our company) for $500 million.

      No energy storage proposal is economically competitive at the present time. However, there are two reasons I put forward this proposal;

      1) I believe that the development of renewables will continue for many years because politics and public opinion support it – the economic factors are not the determining factor. The majority of opinion seems to be that this is a war against the destruction of our ecosystem and in a war the cost does not matter.

      2) I believe that burning coal to generate electricity is negative because of the CO2 and the particulate pollution in the form of mercury, arsenic and other contaminants in the coal.

      In many of my statements I use the word believe because I cannot forsee the future with certainty. Perhaps renewables will fail. Perhaps clean coal will become a reality or some carbon capture technology will emerge. I do not dismiss any of those possibilities but I do not believe that they are the most probable outcomes.

      My proposal does not make any economic sense unless you believe that renewable energy will at times become practically worthless – sun at mid-day and wind when there are strong winds across large areas. And I do not pretend to know the details about complications that might emerge from converting a coal-fired plant to use molten salt. Perhaps a different thermal storage material would have to be used to raise temperatures to that currently prevalent in the plant. Perhaps the turbine would have to be modified.

      What I do know is that re-powering these coal-fired plants would avoid the cost of decommissioning them and would re-use much of the physical plant, the grid connections, and the operations expertise of the staff saving local jobs. There are tangible benefits to all of that.

      • Mr Swan

        Thanks for that respectfully written post.

        Do you and your organization account for the potential of a coming cold climate in your recommendations for managing existing coal plants ?

        Much like the example you gave concerning horizontal drilling and your organization’s ability to see what was unseen, has anyone presented the opportunities that coal plants present if the climate becomes colder ?


      • Curious George

        “No energy storage proposal is economically competitive at the present time.” I agree, the technology – including molten salts that you analyze – is not viable yet. In the long run, storing energy as heat is subject to heavy losses. Getting energy back from heat is highly inefficient.

        No one has yet provided operational data for Andasol. I am glad that the government was able to recuperate the losses from Solyndra on your oil field.

      • – CCGT can be fast start – 20 minutes or less, so can cope with the variability of renewables more readily. By contrast coal station generation takes quite a while to get going, but whether this is primarily because of the coal burning aspect or the power generation I do not know.

      • Don’t quite know what happened to the partial post above!

        “I believe that the development of renewables will continue for many years because politics and public opinion support it – the economic factors are not the determining factor. The majority of opinion seems to be that this is a war against the destruction of our ecosystem and in a war the cost does not matter.”

        Cost does matter, but the strategy of western nations is to subsidise a promising energy source for a while until it reaches mass market status and can stand on its own two economic feet. This is what happened to nuclear initially and wind and solar PV are no exceptions. The good news is that the strategy works and the unsubsidised costs are coming down year on year, leading to grid parity in places already with more to come.

        “My proposal does not make any economic sense unless you believe that renewable energy will at times become practically worthless [e.g.] sun at mid-day and wind when there are strong winds across large areas. ”

        In the 2050 timeframe the predictions are that solar PV power in the daytime could be as low as 1.5 US cents / kWh. In this scenario you would certainly overconfigure it by a factor of two or three, and there must be many times when the incremental cost drops to zero because of huge oversupply. Wind probably won’t be quite as cheap, but still cheap enough to be well overconfigured, as this still avoids the higher costs of some extra storage.

        The standard proposal for handling the excess is “power to gas” from electrolysing water, rather than your suggestion (though your analysis and lateral thinking is always welcome). That’s because CCGT has a lot of advantages over coal :

        – CCGT can be fast start – 20 minutes or less in some cases, so can cope with the variability of renewables more readily. By contrast coal station generation takes quite a while to get going, but whether this is primarily because of the coal burning or the power generation I do not know.
        – hydrogen or methane can be stored indefinitely
        – the existing natural gas grids already store a few days of gas (equating to many days of electricity as most gas is used for heating).
        – the gas grids already exist as a method of delivering renewable gas from where it is produced to the existing CCGT generating stations.
        – if you don’t need all the gas produced for generating power (and you probably don’t) then feeding it into the gas grid allows it to be used in some worthwhile way without much further thought.

      • Assuming the climate continues to “change” in the desired direction and not colder. Reminds me of housing prices that always go up.

    • “And I do not pretend to know the details about complications that might emerge from converting a coal-fired plant to use molten salt.”

      A lot of knowledgeable commenters have enumerated and explained the complications to you. Doesn’t seems to have had any effect .

      • Don

        I haven’t really been following the discussion closely and there seems to be a lot of claims and counter claims. However, whether we like it or not , the Paris shindig illustrates the truth of much of Davis’ comment here;

        ” I believe that the development of renewables will continue for many years because politics and public opinion support it – the economic factors are not the determining factor. The majority of opinion seems to be that this is a war against the destruction of our ecosystem and in a war the cost does not matter.”

        We might think that over reliance on renewables is mad, or that nuclear is a better bet, and may also disagree that public opinion supports renewables , however those who make the decisions-our respective govts-have drunk so much of the green blobade, and were so anti nuclear in the past, that Davis’ point about the politics is bang on the money. It might be OUR money, but it is bang on it and I don’t see the tide changing soon.


      • Tony, coal fired power plants are not going to be converted to molten salt whatevers. This post is about as useless as that McLellan Oscillator BS. I know not what course others might take, but I am moving on. This one has ceased to be amusing.

      • The ecosystems love increasing CO2 and hate the pale shadows of solar panels, and the lethal vorpals and nerve rending moans of the windmills.

  53. very few numbers here…
    show us one working, calculate the actual costs.

  54. Re heating the salt solution, on the old perpetual power idea, Could the steam generated by the power stations be diverted back/along the input to heat the water/salt up pre use?
    Or is this already done?
    Seems a shame to send the heat directly to space.

    • There are a number of CHP (combined heat and power) schemes which involve producing power and heat from fossil fuelled generating stations. You get as much electricity out of the heat as you can, then the residual “low temperature” heat is pumped to heat houses and offices, for which it is plenty hot enough. Because you are avoiding having to burn yet more fossil fuel to heat the buildings you get quite a high theoretical efficiency.

  55. Converting well organized energy [electricity] into disorganized energy [heat] and then back again always comes with a hefty loss.

    People have been studying this since the beginnings of the Industrial Revolution. In the meantime we understand pretty well what the limits of our capabilities are.

    On the positive side though, this idea is considerably saner than the one about pulling molecules of CO2 out of the atmosphere and turning them into fuel – which has similar issues with the fundamental laws of the universe.

    carry on.

  56. Berényi Péter

    We can demand that coal plants be decommissioned and dismantled at a cost of billions of dollars. […] Or we can demand that our coal plants be converted to Thermelectric Power

    Why demand? Molten salt can be heated either by electric heaters or by burning coal. As soon as you can make electricity cheaper than coal, it’s done, you do not have to b>demand anything. Now, can you?

  57. It’s time for a meaningful rapprochement between public-funded academia and public benefit. When commenting on the change in his political philosophy — given that capitalism simple out-innovated other economic systems and without robbing the liberty of others — stated, “I am no longer a socialist, but I still am a Marxist.”

  58. Can anyone tell me how quickly a coal-powered plant can ramp up to production for an idle state? This applied to the use of any other heat source being used on an intermittent basis to produce steam. When the intermittent source is not available, wind, solar, melted salt….can the plant ramp up on coal quickly enough to avoid interruptions to the grid?

    Obviously, there is some foreknowledge in the melted salt scheme — one can predict when incoming energy is not sufficient to keep the melted salt hot enough to do the trick….can the coal-powered side of the plant ramp up and take the load? How much of an overlap (representing inefficiencies) would this mean?

    Can solar or wind be used directly to heat or pre-heat water for the coal-side, thus saving fuel and burning less coal?

    • > Can anyone tell me how quickly a coal-powered plant can ramp up to production for an idle state?

      That depends on the actual state of idleness. Do you mean from a stone-cold, black start; a state where the boilers are being fired but electrical output from the turbines is being grounded; somewhere in between ?

      Cold, black start – about 72 hours, if the boilers are already descaled (cleaned). If descaling is necessary, perhaps up to a week

      Boilers being fired – about 10 hours (there are plants I have seen where much practice has of necessity reduced this to about 4 hours)

      Other “states of idleness” – anywhere between 10 and 72 hours

      I should also point out that coal-fired plants do not normally stockpile their raw fuel for longer than about 3 months due to the very real risk of piles internally heating and spontaneously combusting. The whole stockpile chain from mine to ship to wharf to power plant is acutely mindful of this issue. Ccontinuous, live stockpile management is a high-end parameter

      • Reply to ianl8888 ==> Thank you. Very informative.

        Can you give us then, a quicky evaluation of the feasibility (under different scenarios) of the proposal to the scheme presewnted to use wind/solar energy –> melted salt –> steam as a augmentation of existing coal powered plants?

  59. Davis,

    Interesting idea, but there is one problem you have not mentioned.

    Firstly, by using pure heating elements you reduce the maximum thermodynamic efficiency. If you really intend to operate at 1000 degrees C then the loss is only a few tens of percents, but at lower temperatures it is much more. A heat pump is much more efficient than a heating element at the lower temperatures.

    The maximum theoretical efficiency of heating the salt to 1000 degrees C (= 1273 K) for your proposal is 1.0, but for a heat pump you get extra heat from an external low-temperature source (assumed below to be at 0 degrees C (= 373 K)), so you can get an efficiency of
    1273 / (1273 – 273) = 1273 / 1000 = 1.273. This doesn’t break any laws of thermodynamics because 1 / 1.273 of the energy put in is also the maximum theoretical work you can get out of a heat engine, so the two compensate.

    The more standard plan to re-use existing fossil fuel generation is “power to gas”. You use the surplus electricity to electrolyse water, then store the hydrogen. Later you can generate in the renewable gap period using CCGT equipment run with the stored hydrogen with about 44% total efficiency. If your CCGT equipment can’t hack hydrogen then you convert it to CH4 methane but the efficiency comes down to around 38%. Still not bad though.

    The big advantage is that the gas does not degrade with time, and you can store it in quantities as large as you like to power the really long gaps. Most countries already have a gas grid incorporating a few days of storage which could be used to do this.

  60. This is a good solution if you don’t have a stable high pressure with no wind sitting over you for months in winter. I doubt it would work in Siberia.

    But as it would work in the USA, why not put it up on a list of potential cost-effective transition technologies for the period 2020 – 2050+ in America?

  61. Brian G Valentine

    “Can Coal-Fired Plants be Re-Powered Today with Stored Energy from Wind and Solar?”

    Of course they can, however we need more medical marijuana to make this a “reality”

  62. Weather dependent technologies like wind and solar have little or no part to play in supplying cheap low-emissions electricity. This study analyses the case for the Great Britain electricity grid: . Figure 14 shows the CO2 emissions savings and the total system cost per year by adding 5 GW increments of each technology. Hydro (I available, but it isn’t) and nuclear would be the most effective at reducing emissions. Hydro would be the cheapest if it was available. Adding nuclear is by far the cheapest way to achieve large emissions savings. Wind, marine, CCS and pumped hydro are all very expensive and ineffective. The worst of all is to close old nuclear plants; doing so would increase emissions and costs. Their life should be extended if possible.

    Pumped hydro is extremely costly and ineffective. Any other type of energy storage would be far more costly.

    The least cost option to achieve the same emissions intensity as France, i.e. 40 g/kWh, is with 31 GW of nuclear – see this comment for more on this:

  63. Pingback: Weekly Climate and Energy News Roundup #209 | Watts Up With That?

  64. Davis Swan:
    Seems there are good reasons to do this. A coal and renewables hybrid. Hanging onto coal while acting as a battery. I imagine it’s hard to put a price on grid stability. Supply points of the grid are assumed to currently have optimal locations. That’s where I’d put the batteries. Grid architecture would be in place as well to some extent. I think the efficiency numbers might be better than some think. Electricity is converted to heat. With insulation, I don’t see it being lost. A heat exchanger isn’t going to lose much. I see losses with the steam turbines, same as there currently are, say 70%.

    Now this is interesting, coal suffers this same loss. How much coal will not be burned, dug up or shipped?

    Another use that is probably more efficient is those large steam heating systems used by some universities some with their own windmills. They now contribute to grid stability by heating molten salt during the heating season, and the rest of time helping to load level. As far as the economics go, how much does one pay to get rid of the intermittentcy and grid stability problems of renewables? And when will we ever actually pay for that? While pumped hydro storage is more efficient, no one wants to pay for it or have it in there back yard or pay for the transmission lines most likely needed.