That’s according to new research from the National Renewable Energy Laboratory (NREL), which today released a new report, “Analysis of Concentrating Solar Power with Thermal Energy Storage in a California 33% Renewable Scenario”. The report discusses how concentrated solar power (CSP) projects like the Ivanpah Solar Electric Generating System—which doesn’t have storage or the Crescent Dunes Solar Energy Plant—which does have storage, can add additional value by using thermal storage. The report compared and contrasted CSP with thermal storage to three other types of electric generating systems.
Ultimately the report found that CSP with thermal storage added significant value compared to other energy sources. It put the overall operational value of CSP at between $80 per megawatt hour to about $135 per megawatt hour. That’s compared to baseload value of about $60 per megawatt hour.
The study was limited to California and considered it within the context of the California renewable energy portfolio standard, which requires utilities in the state to source 33 percent of their electricity from renewables by 2020, and within the electric grid managed by the California Independent System Operator (CAISO).
"We created a baseline scenario, then added four types of generators, a baseload generator with constant output, a photovoltaic system, a CSP plant providing dispatchable energy—or power that can be turned on or off on demand—and another CSP plant providing both energy and operating reserves," said NREL Senior Analyst Paul Denholm, who co-authored the report with Yih-Huei Wan, Marissa Hummon, and Mark Mehos, manager of NREL's CSP Program. To model the scenarios the researchers used the PLEXOS model.
One of the reasons the CSP system with thermal storage is able to add such value is because it requires no fuel and can operate as a constant—or baseload— generator, much like a natural gas or coal-fired power plant. As such it doesn’t require additional fuel, doesn’t require extra energy to ramp up and can provide more or less energy as needed, which photovoltaics can’t do on their own and CSP can be adapted to. "CSP plants switched on during periods of highest consumer demand for electricity resulted in very high capacity value. And the difference in value in CSP plants with and without thermal energy storage depends greatly on the amount of other variable-generation renewable energy sources on the grid, such as wind and photovoltaics," said Mehos.
The research also found that CSP with storage can add even more value if allowed to provide reserve power, which includes frequently operating at less than its full load. “Which would be a substantial change in operational practice,” NREL said.
Other studies have projected similar benefits with CSP with storage. But NREL offers a more objective, science- and engineer-based evaluation that could help raise potential financiers’ interest in supporting CSP projects.