Hello,

We noticed you're browsing in private or incognito mode.

To continue reading this article, please exit incognito mode or log in.

Not a subscriber? Subscribe now for unlimited access to online articles.

Graphiti

Water Power

Decisions about future energy sources will need to factor in water consumption as well as greenhouse-gas emissions.

Slideshow:

In the United States, energy production will account for almost 90 percent of the projected increase in consumption of freshwater between 2005 and 2030, according to Argonne National Laboratory. Power plants that use nuclear fission or fossil fuels, such as coal and natural gas, consume billions of gallons of water per day for cooling. Fossil-fuel plants that use carbon-capture technologies to cut carbon dioxide emissions consume even more water than conventional ones. As for renewable energy sources, they pre­sent a mixed water-use picture. While wind power and photovoltaic solar power use little water, solar thermal power—one of the fastest-growing renewable sectors—uses a great deal. Biofuels from non­irrigated sources, such as switchgrass, use relatively little water, but ethanol made from irrigated corn is hugely water-intensive. In the chart at right, we compare recent estimates of average lifetime water consumption and greenhouse-gas emissions for various electricity sources and transportation fuels. Note the water-use range of irrigated corn ethanol. The water consumption associated with E85, a blend of 85 percent ethanol and 15 percent gasoline, ranges from 20 to nearly 1,000 gallons per 100,000 BTU, depending on agricultural practices.

Information graphic by Tommy McCall and Mike Orcutt

Sources: Energy Policy; Environmental Science & Technology; Argonne National Lab; Congressional Research Service; National Energy Technology Laboratory; Carey King

“Geothermal” refers to flash-steam-powered plants and is given in grams of carbon dioxide (gCO2) per 100,000 BTU. All other figures are given in gCO2 equivalents per 100,000 BTU.

“BTU” refers to British Thermal Units; “CCS” refers to carbon capture and storage technologies; “IGCC” refers to integrated gasification combined cycle.

One gallon of gasoline is equal to 114,500 BTU.

The water intensity of sugarcane is an estimate for São Paulo, Brazil, where the crop is not irrigated. The water intensity of ethanol from switchgrass is an estimate based on a relatively small amount of data.

The figure given for greenhouse-gas emissions associated with compressed natural gas used in transportation assumes that the natural gas is extracted and used in the United States.

More from Sustainable Energy

Can we sustainably provide food, water, and energy to a growing population during a climate crisis?

Want more award-winning journalism? Subscribe to MIT Technology Review.
  • Print + All Access Digital {! insider.prices.print_digital !}* Best Value

    {! insider.display.menuOptionsLabel !}

    The best of MIT Technology Review in print and online, plus unlimited access to our online archive, an ad-free web experience, discounts to MIT Technology Review events, and The Download delivered to your email in-box each weekday.

    See details+

    12-month subscription

    Unlimited access to all our daily online news and feature stories

    6 bi-monthly issues of print + digital magazine

    10% discount to MIT Technology Review events

    Access to entire PDF magazine archive dating back to 1899

    Ad-free website experience

    The Download: newsletter delivery each weekday to your inbox

    The MIT Technology Review App

  • All Access Digital {! insider.prices.digital !}*

    {! insider.display.menuOptionsLabel !}

    The digital magazine, plus unlimited site access, our online archive, and The Download delivered to your email in-box each weekday.

    See details+

    12-month subscription

    Unlimited access to all our daily online news and feature stories

    Digital magazine (6 bi-monthly issues)

    Access to entire PDF magazine archive dating back to 1899

    The Download: newsletter delivery each weekday to your inbox

  • Print Subscription {! insider.prices.print_only !}*

    {! insider.display.menuOptionsLabel !}

    Six print issues per year plus The Download delivered to your email in-box each weekday.

    See details+

    12-month subscription

    Print magazine (6 bi-monthly issues)

    The Download: newsletter delivery each weekday to your inbox

/3
You've read of three free articles this month. for unlimited online access. You've read of three free articles this month. for unlimited online access. This is your last free article this month. for unlimited online access. You've read all your free articles this month. for unlimited online access. You've read of three free articles this month. for more, or for unlimited online access. for two more free articles, or for unlimited online access.