Molten Salt Reserves (Holy Grail?) Lure Solar Producers

August 10, 2010-

While writing the market update story for the Sept/Oct issue of Renewable Energy World North America, I kept hearing things like:

"Whoever can figure out ways to store the sunlight is going to win. Storage is the game-changer technology." -Buck Martinez, senior director of solar development, Florida Power & Light

Because solar is so flighty (sadly, the sun always goes down at night, unless you're in the Arctic Circle at the right time of year), energy can only be produced during peak hours -- when the sun is shining its glorious beams.

But leave it to a rocket scientist to change that. Terry Murphy studied rocket propulsion at Purdue University, then landed a job at Rocketdyne. During his time there, he studied the Space Station's onboard power system that tracks the sun, manages consumption and stores energy. Now, he is translating his knowledge of the sun by developing a solar power tower technology for SolarReserve, a startup company formed by US Renewables Group, the renewable energy private equity firm. This technology promises to prolong the use of solar energy into the evening hours.

"Murphy says a solar power tower built in the American southwest could dispatch about 500 MWh annually. A 200 MW facility could have a cap ex roughly between $3,000 to $4,000 a kW, installed. That equates to an overall project investment of $600 to $700 million." -Renewable Energy World

It's no wonder this solar thermal development has been coined “the holy grail of renewable energy” by The New York Times. Molten salt reserves store solar power by focusing thousands of mirrors on millions of gallons of liquefied salt. SolarReserve’s technology uses ground-mounted heliostats, heat-concentrating towers, high operating temperatures and storage mechanisms to reflect sunlight. Heliostats reflect sunlight to receivers atop 553-foot towers. There the sunlight transfers heat to molten salt, warming the sodium and potassium mixture to 1,050 degrees Fahrenheit. It is then transferred to a storage tank where it loses no more than 1 degree a day.

“We have the ability to shift power generation. It doesn’t stop when the sun goes down,” Tom Georgis, vice president of development, told me in a phone interview.

So far, SolarReserve has been in a testing stage, but developments are underway for the solar market to determine if this technology will prove to be the holy grail.

SolarReserve's largest projects are:

1) The development of a 150-MW solar farm in the Sonoran Desert east of Palm Springs. The Rice Solar Energy Project will store seven hours’ worth of the sun’s energy and is anticipated to go online in October 2013.

2) A 100-MW solar energy project near the town of Tonopah, Nev., which will break ground at the end of 2010. In January, SolarReserve served a contract with Nevada largest utility, NV Energy, for this project, which marks the first time a U.S. utility has contracted for solar power tower technology utilizing molten salt storage. Potentially, this could be the first commercial installation that will be able to avoid intermittency problems like cloud cover, as well as the ability to provide power after the sun goes down.

Will SolarReserve be able to break through the barriers of nightfall, cloud cover, and such? For the next couple of years, the solar industry will be waiting in expectation to see the results of these two projects. Until then, the holy grail of solar continues to stay just out of reach.