Utility companies, in an effort to provide more carbon-free power, have learned to diversify their power-power generating facilities. Instead of the power grid being supplied by a single source, many different sources come together to provide power for the whole grid. Solar power is one of these sources, but has a flaw, that is, when the sun doesn’t shine, no power is generated.
A photovoltaic [PV] plant’s solar panels produce clean carbon-free power as long as the sun is shining, but as soon as sun goes down, instant power loss. In order to get around this, power companies have to resort to power generators running fossil fuels, including oil, gas, even coal. Concentrating Solar Power [CSP] plants have the same problem, but thermal energy storage [TES] can be added to the system to smooth out variations during the day, as well as lasting a few hours into the night, reducing the amount of fossil fuels required.
While the addition of TES to CSP plants adds significant value, it has been difficult to quantify this and make it an attractive option for the utilities. Green energy is nice, but it all comes down to the bottom line, or production costs, for a utility company. Researchers at the US Department of Energy’s [DOE] National Renewable Energy Laboratory [NREL] recently completed a study that confirms TES benefits, ecologically and economically.
Using Energy Exemplar’s PLEXOS simulation model, the NREL researchers compared variations of a gas-turbine and solar power plant, using PV, CSP, and CSP w/ TES technologies. A CSP plant with a six-hour TES system keeps variations in solar output to a minimum, as well as lasting part way into the night, which “adds $35.80/MWh to capacity and operation value of the utility, compared to PV alone, and even higher extra value when compared to CSP without storage,” according to Mark Mehos, NREL manager of the CSP program.