Did you know? 100,000 gallons of water required to produce 1 Mwh!

Last Updated On

We may collect a share of sales from items linked to on this page. Learn more.

A new report says American businesses and policymakers are not fully realizing that huge water demands are a major hidden cost that cannot be overlooked.

Synapse Energy Economics has released a report, prepared for the non-profit organizations: Civil Society Institute (CSI) and the Environmental Working Group (EWG).

The report is titled “The Hidden Costs of Electricity: Comparing the Hidden Costs of Power Generation Fuels”. It examined the six fuels used to generate electricity — biomass, coal, nuclear, natural gas, solar (photovoltaic and concentrating solar power), and wind (both onshore and offshore). They were analyzed in the following categories: water impacts, climate change impacts, air pollution impacts, planning and cost risk, subsidies and tax incentives, land impacts, and other impacts.

Some examples of the water-related findings are below:

  • Nuclear power has critical cooling requirements that require huge amounts of water. Roughly 62 percent of U.S. nuclear plants have closed-loop cooling systems. Reactors with closed-loop systems withdraw between 700-1,100 gallons of water per megawatt hour (MWh) and lose most of that water to evaporation.
  • In addition to fouling streams and drinking water through mining and coal-ash dump sites, coal-fired power relies heavily on closed-loop cooling systems which withdraw between 500 and 600 gallons of water per MWh and lose most of this via evaporation. Withdrawals for open-looped cooled coal-fired power plants are between 20,000-50,000 gallons per MWh. Most of the water is returned, but at a higher temperature and lower quality.
  • Under a so-called “Clean Energy Standard,” biomass would become a much larger source of U.S. electricity generation; however, biomass also requires vast amounts of water. The report notes that a typical 50 megawatt (MW) biomass plant could withdraw roughly 242 million gallons of water per year and lose most of this. Adding 10 of these plants in a region would use 2.42 billion gallons of water per year.
Green Home Ideas: Smart Technology that Won’t Break the Bank

Grant Smith is a senior energy analyst with the Civil Society Institute. He says many institutions are overlooking the strain that new projects will have on our already scarce water sources:

“The government and energy industries are literally flying blind as they plan for continued reliance on coal, natural gas, nuclear power and industrial biomass to meet our energy needs. Each of these is water intensive and leads to pollution of water, which is increasingly scarce and in competition for other uses such as agriculture and other commercial uses. The drought intensifies the urgency and the imperative that political leaders in both parties hit the pause button on the headlong rush to support nuclear power and fossil fuel use.”

Meanwhile, Seth Sheldon is a lead water/energy analyst. He criticizes the U.S. government for its response:

“In 2005 the Congress mandated a federal water/energy roadmap. Nearly eight years later, that roadmap has not been produced and either through bureaucratic inertia or fear of hard political questions, the questions are not even being asked, much less their solutions explored. At a time of significant water scarcity and increasing threats to water quality, we can ill afford to ignore this central question about the future of our energy choices.”

Other water-related data highlighted in the report includes the following:

  • The full picture for nuclear power water use may be even more dramatic. Estimates of lifecycle water use for three European reactors range from 2,600 to 6,900 gallons per MWh, not including cooling water use.
  • Coalbed methane recovery of natural gas depletes ground water: one estimate puts total groundwater removed between 1997 and 2006 at an astounding 172 billion gallons.
  • Estimates of the lifecycle water withdrawals from wind projects, including both onshore and offshore projects, range from just 55 to 85 gallons per MWh.
Fresh Water: An Invaluable Resource

The full report is available online at: CivilSocietyInstitute.org

Madison E. Rowe Avatar

3 thoughts on “Did you know? 100,000 gallons of water required to produce 1 Mwh!”

  1. It’s annoying that they don’t seem to provide any apples-to-apples comparisons here. For instance, what does it mean to compare per watt-hour use to annual use?

    And where does 100,000 gallons come into it? I don’t see that figure anywhere in the article.

    • Typical central powerplants like coal or nuclear generate around one gigawatthour. There is 168 hours in one week or 8500 hours in one year. Then you mulitply it by 1000 if you base it on mwh instead of gwh for each powerplant. you get 8,500,000 “hours” a year based on mwh. the powerplant may be down 10% of the time so you get maybe 7,700,000 “hours” in mwhs.
      and you mulitply 7,700,000 to each amount of gallons used to produce one mwh as you know it is about 1000 gallons per mwh in average generally. then you comes to 7,7 billion gallons .. if you want acrefeet for water then you divide by 42,000 gallon in each acrefeet of water. you get how many acrefeet? use your calcuator.. A typical water reservoir has 100,000 acrefeet up to a milllion acrefeet for huge ones .

  2. Mr. Fraser,

    The best thing to do is to go to the report. Table 5. Water Impacts on page 8 describes water use for each technology. The 100,000 gallons per megawatt hour figure stems from a study which calculated that when water use for biomass from dedicated energy crops (switch grass, for instance) is included with what a biomass-powered power plant withdrawals, it may be as high as 100,000 gallons per megawatt hour. I heard a presentation by a professor at Purdue University a few years ago in which he said that if we ramped up biomass and biofuels production for energy use envisioned by the Obama Administration at the time, we’d have to use the equivalent amount of water in Lake Superior every year to grow the crops.

    To calculate the amount of water used say by a 1,000 megawatt nuclear plant, you would multiply 365 by 24 to get then number of hours in a year. Multiply that by 85% – the amount of time such a plant would run during the year. Then you would multiply 1,000 by that number to get the number of megawatt hours the plant would generate in a year. Finally, you would multiply that number by the number of gallons per megawatt hour the plant withdrawals. Open-loop cooling systems with withdrawal far more water than closed-loop systems. But closed-loop systems use (consume or lose through evaporation) far more water than open-loop systems.

    You can also calculate the water withdrawals for electric generating technologies by going to the Energy Information Administration web site to see how many megawatt hours they generate in a year and multiply that by the gallons per megawatt hour.

    Civil Society also commissioned another study by Synapse (Beyond Business as Usual 2011) that describes overall water withdrawals and consumption by the electric power sector.


What do you think? Leave a comment!