by Judith Curry
Producing energy uses water, and providing freshwater uses energy. Both these processes face growing limits and problems. In most power plants, water cools the steam that spins the electricity-generating turbines. Refining transportation fuels requires water, as does producing fuels—for example, mining coal, extracting petroleum, or growing crops for biofuels. Using water in our homes and businesses requires getting it there, treating it, heating it, and more.
The Union for Concerned Scientists has produced a new article:
The 10 things are:
- Keeping the U.S. power on each day requires more water than 140 New York Cities.
- In the southeastern U.S., power plants account for two-thirds of all withdrawals of freshwater
- Water discharged from a coal or nuclear plant is hotter–by an avrage of 17F in summer–than when it entered the plant.
- Water troubles can shut down power plants
- Clea energy can mean low carbon and low water — or not.
- Powering your car with ethanol may use dozens of gallons of water per mile.
- California uses 19% of its electricity and 32% of its natural gas for water
- Water supply conflicts are growing across the U.S.
- As climate changes, so does the water cycle.
- We have many tools at hand.
Read the whole paper, it isn’t long. From the last point We have many tools at hand:
No-water energy: Using technologies such as wind and photovoltaics means doing away entirely with water use for electricity production. Reducing the need for generating the electric- ity or transportation fuels in the first place—through more-efficient ap- pliances, buildings, and vehicles, for example—not only saves money and reduces heat-trapping gases and other pollutants, but also eliminates the corresponding water use.
Low-water energy: Shifting old coal or nuclear plants using once-through cooling to more-water-efficient closed- loop cooling technologies would increase water consumption, potentially even doubling it, but would reduce water withdrawals by two orders of magnitude. Dry- and hybrid cooling options help address water consumption. Such technologies could be particularly important in water- constrained regions. Such cooling technologies would, however, reduce power plant efficiency and increase their costs—and, in the case of fossil- fuel-fired plants, do nothing to reduce emissions of heat-trapping gases.
Several steps can be taken to reduce the water demand of some renewable energy options. CSP plants, for example, which are ideally sited in some of the country’s sunniest—and driest—locations, are increasingly turning to dry cooling, despite the higher costs. For biofuels, minimizing reliance on irrigation and switching to low-water perennial crops—or even to waste from cities, farms, and forests—could make it possible to lower the water requirements of biofuel production and reduce heat- trapping emissions.
Given the many connections be- tween energy and water, the choices we make in the near future about how we produce and use energy will determine not only the extent to which we mitigate the worst impacts of climate change, but also how resilient our energy system is to the variability of our water resources and the many competing demands for it. Smart choices now will mean lower risks, greater energy security, and strong environmental and economic benefits.
Freshwater Use by U.S. Power Plants: Electricity’s Thirst for a Precious Resource (Union of Concerned Scientists)
Estimating Freshwater Needs to Meet 2025 Electricity Generating Capacity Forecasts (U.S. Department of Energy)
JC Comment: The energy-water nexus seems to me to be an under appreciated policy issue, that is of looming importance in many regions, both in developed and developing regions. In most regions, population increase and economic development are arguably placing greater pressure on water resources for energy than climate change (natural and/or anthropogenic).