Storing solar power in the form of molten salt. SolarReserve says it can do it, and it's landed a project with NV Energy to prove it.

The Santa Monica, Calif.-based startup announced Tuesday that it has signed a 25-year power purchase agreement with the Nevada utility to buy power from a 100-megawatt solar-thermal plant to be built near the town of Tonopah, Nev.

SolarReserve, which last year raised $140 million in a Series B round let by Citi's Sustainable Development Investments and Good Energies, said it intends to start construction next year, though the Nevada Public Utilities Commission still needs to sign off on the deal.

Central to SolarReserve's plans is the molten salt energy storage system it has licensed from United Technologies. Like many solar-thermal systems, SolarReserve uses a field of mirrors, or heliostats, to focus the sun's heat on a tower to heat a liquid to power a turbine.

In SolarReserve's case, that liquid is a molten salt that is then pumped into a closed-loop system to generate steam to power a turbine. It's the same technology tested out by the Department of Energy in the landmark Barstow, Calif. solar thermal pilot project known as Solar Two back in the 1990s.

SolarReserve also hopes to build a 150-megawatt solar thermal and molten salt storage project east of Palm Springs, Calif., and has a longer-range goal of building up to 5 gigawatts of plants in the coming years.