Concentrating solar-thermal power plants will remain in low demand in the U.S. for the foreseeable future as companies such as SolarReserve LLC develop new plants overseas, according to industry analysts.
One of the factors: Hydraulic fracturing.
“The U.S. is a different market than the rest of the world because we have a whole lot of cheap natural gas from fracking,” SolarReserve CEO Kevin Smith told Bloomberg Environment.
Despite that outlook, the Energy Department is promoting research on this type of solar power, which uses mirrors that focus solar energy on a tower, heating liquids to make electricity from steam. The department announced $86 million in funding for concentrating solar research and development since September, including $24 million announced April 17.
Today’s U.S. market heavily favors solar photovoltaics—the kind of technology featured in rooftop solar panels.
Most large solar-thermal development will occur overseas where the plants more effectively compete with power plants using natural gas and other fuels, Mark Mehos, National Renewable Energy Laboratory thermal systems group manager, told Bloomberg Environment.
New concentrating solar power, or CSP, plants are being developed in South Africa, the Middle East, Chile and Australia, where natural gas is scarce and expensive. About 6 percent of U.S. solar power comes from solar thermal plants, according to the U.S. Energy Information Administration.
The global concentrating solar power market is expected to grow by 12.7 percent by 2025, Scott Sklar, president of the Stella Group Ltd., a clean energy policy firm, told Bloomberg Environment.
But growth will be a “tough slog” for solar-thermal in the U.S., John Rogers, a senior energy analyst at the Union of Concerned Scientists, told Bloomberg Environment.
“It has a tough road ahead if you just look at the incredible cost reductions that PV has achieved,” he said. “It’s not clear how CSP gets those cost reductions.”
Concentrating solar-thermal power plants use thousands of mirrors called heliostats that focus solar energy on a central tower containing water or molten salt, heating the liquid and turning an electric turbine with steam.
In some plants, the liquid stores the sun’s energy as heat, enabling the plant to generate electricity steadily all night or whenever it is needed and serving a similar purpose as a natural gas power plant.
Storage Less Cost-Effective
“Photovoltaic prices are very low,” Smith said. “We don’t see any more CSP [concentrating solar power] projects built unless they have substantial energy storage.”
Solar power plants using photovoltaic panels need to use large batteries to store the electricity generated with the panels so the power can be used when needed, or when the sun isn’t shining. But batteries that provide power for many hours at at time are expensive today.
“CSP—it can run for a long period of time, approaching a baseload plant,” Mehos said. “You can build a big battery, but it becomes less cost-effective above six or eight hours.”
Storage to Drive Market
The need for energy storage to provide a steady stream of renewable energy onto the electric power grid will drive new solar-thermal development in the long term, especially in South Africa, Chile, China. and Australia, Smith said.
SolarReserve, which operates one solar-thermal plant in Nevada, is developing new solar-thermal power plants in South Africa and Australia.
“There’s a lot more demand for storage in international markets,” Smith said. “The U.S. might be a few years away before we see a resurgence.”
Advancements in solar-thermal technology will likely focus on new materials that can store solar energy at higher temperatures and generate electricity for longer periods of time, he said.
Rogers said Energy Department investments in solar-thermal research are important so cost reductions can be found.
NREL is researching new ways to use molten salt, carbon dioxide, and other gases to store solar energy more efficiently, Mehos said.