28 June 2013

Carbon-cutting steps like those Obama proposed could improve, and worsen, water woes

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By Thomas Sumner

As President Obama announced sweeping policies Tuesday aimed at curbing carbon emissions and combating climate change, water resources experts at a Washington, D.C. meeting across town from where Obama spoke discussed the entwined nature of water conservation and energy production.

“Saving greenhouse gas emissions saves water too,” said Robert Jackson of Duke University in Durham, N.C., as he and other panelists discussed retrofitting power plants that burn coal or other fossil fuels and turning to alternative energy sources. Jackson is Nicolas Chair of Global Environmental Change in Duke’s Nicholas School for the Environment.

The panelists noted that, according to the U.S.Geological Survey, in 2005 nearly half of the water removed from natural water sources in the United States went to thermoelectric power plants. These plants, including the coal-burning plants

Coal-burning power plants such as this one draw water from a river to cool off steam used to turn power-generating turbines. Photo by Martini DK / http://www.flickr.com/photos/martini_dk/

targeted by President Obama’s new initiatives, convert water into steam to turn massive turbines. In the process, most thermoelectric plants lose a small but significant amount of this cooling water–about 3 percent. When discharged, the heated water can harm the local environment. For each person in the United States about 100 gallons of water per year goes into energy production.

In some parts of the country, where water is becoming scarce, new technologies could allow power plants to use recirculated waste water or dry cooling techniques to produce electricity without the water and environmental costs, said Robin Newmark, director of the Strategic Analysis Center at the National Renewable Energy Laboratory in Golden, Colo., another panel speaker.

“A fairly significant number of plants could be converted with less than a 10 percent increase in the cost of electricity,” she said. “They would be essentially going from using fresh water to using none at all.”

Cutting water usage can, in turn, save energy, Newmark noted. For instance, in Southern California, electrically-powered pumps push water miles across the state, including over a 2,000 foot mountain, to thirsty communities

Newmark, Jackson, and others spoke in a session called Water-Energy Nexus, which took place at the 2013 AGU Science Policy Conference.

Alternative energy sources typically use less water than their conventional counterparts, Newmark said. In his speech Tuesday, Obama called for alternative energy production, such as wind turbines and solar panels, on public land.

Those sorts of technologies and energy conservation could help save precious water In areas of the United States already hit by drought and likely to face increasing dryness due to climate change. “Climate change may either exacerbate or benefit the different regions, but in general we’re seeing additional water being required in areas that don’t have a lot to spare today,” said Newmark. “A low-carbon future could also be a less water-intensive future.”

Yet, not all low-carbon options promote water thrift. Carbon-capture technologies that prevent greenhouse gasses from being released into the atmosphere from power plants consume energy and sometimes water, according to Jackson. Obama’s plan supports this technology by proposing that funding for overseas coal-burning power plants be limited to only those that include carbon capture.

“You can meet one goal, which in this case is to reduce carbon emissions, but there will be a water cost, there’s no question about that,” said Jackson. “But with most other things there isn’t that tradeoff. I don’t want to lose sight of the benefits we’re talking about that come from reducing emissions. We should not let the exceptions distract us.”

The panel’s two other speakers were Thomas Iseman, Deputy Assistant Secretary for Water and Science, U.S. Department of the Interior, Washington, D.C. and Richard White, Senior Policy Analyst. California Public Utilities Commission, San Francisco. Kristen Averyt, Director of Western Water Assessment at the Cooperative Institute for Research in Environmental Sciences in Boulder, Colo., moderated the panel.

Thomas Sumner is AGU’s science writing intern