Focus on Energy

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Panels gather the sun's rays for concentrating solar thermal energy.
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Juice from Concentrate, a report on concentrating solar thermal energy, comes from the Resources Institute.
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Solar tubes heat water for this house.

Washington, D.C. – Concentrating solar thermal (CST), a renewable energy technology that can provide electricity around-the-clock, has the potential to replace traditional fossil fuel-based power sources and become a central part of the U.S. power supply.

“Now, while Congress works on climate and energy legislation, is a good time to focus on CST and what is needed to fully realize the potential of this attractive renewable energy option,” says Britt Staley, the lead author of a new report by the World Resources Institute. “State and federal support for developing renewable energy sources and increased federal oversight of the transmission grid are needed.”

The authors of Juice from Concentrate argue that CST is different from many renewable energy technologies that provide power intermittently. When combined with thermal storage, CST can generate electricity on demand, not just when the sun is shining. It can also be integrated with other kinds of backup power.

Electricity from other renewable sources can be stored in batteries, but these are inefficient and expensive. CST power can be stored as heat in tanks – like coffee in a thermos – and used to produce electricity when needed. CST’s ability to provide electricity on demand and around-the-clock could enable utilities to meet baseload power instead of relying on coal-fired power plants.

If CST displaced new coal plants built in the United States today until 2030, carbon dioxide emissions could be reduced by 5 billion tons cumulatively – offsetting the annual emissions from electricity consumption of 35 million homes over that period.

“Even though there are 9,000 megawatts on the drawing board worldwide, several barriers exist to solar thermal power development,” Staley says. “Up-front investment for CST is high compared to that associated with coal plants. Federal and state policy support can help bring down costs over time to make CST competitive with coal.”

For instance, a 30 percent Investment Tax Credit for CST projects constructed before 2017 has helped spur investment in the United States. Generous feed-in-tariffs have supported development in Spain, where electric utilities are obligated to purchase solar thermal power at a fixed, above-wholesale price for the electricity.

Water usage is another barrier highlighted in the report. One CST plant uses roughly the same amount of water per kilowatt hour of output as a coal plant. This can create a problem in arid regions, such as the Southwest United States, where solar conditions are favorable, but water resources are scarce.

“Alternative cooling systems are available and can reduce water requirements, but these systems can increase project costs,” Staley says. “Creating investment incentives for plants to incorporate these technologies will be important to the long-term sustainability of CST.”

Truly taking advantage of CST’s potential will mean building a more complete infrastructure to bring power from sunny deserts to urban centers. The authors suggest that greater federal oversight of the electricity grid and improved coordination between grid operators are necessary.

World Resources Institute is an environmental think tank that goes beyond research to find practical ways to protect the earth and improve people’s lives. The organization’s mission is to move human society to live in ways that protect Earth’s environment and its capacity to provide for the needs and aspirations of current and future generations. WRI was launched June 3, 1982, as a center for policy research and analysis addressed to global resource and environmental issues.

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