NREL Reports on Value of CSP with Thermal Energy Storage

A new report, Enabling Greater Penetration of Solar Power via the Use of CSP with Thermal Energy Storage, published by the National Renewable Energy Laboratory says concentrating solar power (CSP) plants with thermal energy storage (TES) can dispatch power even during periods of high demand or reduced solar output. This flexibility could boost the use of other types of renewable energy, such as solar photovoltaic (PV)or wind power, that are generated intermittently, the report notes.

Authors Paul Denholm and Mark Mehos describe how CSP systems with TES address the challenges anticipated as greater levels of variable resources, such as PV and wind, are integrated into the Western Interconnect, the major power grid that extends from western Canada, south to Baja California in Mexico, and eastward over the Rocky Mountains to the Great Plains.

There are two major challenges to economically integrating such variable and uncertain resources into the grid. One is the mismatch between when the sun shines, or the wind blows, and when there is a demand for energy. To address this obstacle, CSP with TES can shift energy production to periods of high demand or reduced solar or wind output.

A second challenge is the limited flexibility of conventional generators, such as fossil-fueled power plants, to accommodate variable generation resources, like PV and wind. In this case, CSP with TES can provide substantial grid flexibility by rapidly changing output, via higher ramp rates, in response to the highly variable net load created by high penetration of solar and wind generation.

The report describes how NREL examined the degree to which CSP may complement PV by performing a set of simulations in the U.S. Southwest. The results indicate the general potential of CSP with TES to enable greater use of solar generation, including additional PV.

The authors state that the preliminary analysis performed in their work will require more advanced grid simulations to verify the actual ability of CSP to act as an enabling technology for other variable generation sources. An important next step will include complete production simulations, using utility-grade software, which consider three things: the realistic performance of the generation fleet, transmission constraints, and actual CSP operation.