Salt Energy Meets Solar Energy
Using molten salt to store solar energy, researchers hope to implement large-scale solar power generation, with a single tower capable of producing up to 500 megawatts of peak power.
SolarReserve is a new company created by a partnership between the US Renewables Group and aerospace parts maker Hamilton Sundstrand Corp., a subsidiary of United Technologies Corp. (United Tech also owns the tech company Rocketdyne, which supplies the electrical power systems on the International Space Station.)
SolarReserve is aimed at tackling a different challenge, though one just as ambitious as space - storing energy in the form of heat in molten salt. The company plans to build solar power towers filled with a mixture of sodium and potassium nitrate salts. The technology, known as solar thermal, is different from photovoltaic solar cells: solar thermal has an efficiency of up to 40%, whereas solar cells' average commercial efficiency is only about 22%.
During the day, the solar thermal towers would gather enough sunlight to melt the salts, which are stored until more energy is needed. Then, the molten salt could be used to heat water that operates a steam turbine, which generates electric power. Eventually, SolarReserve would sell the power systems to utility companies.
A single tower would be able to produce up to 500 megawatts of power per year, which would meet the needs of about 250,000 households - a decent-sized city.
The researchers say that using molten salt for energy storage is advantageous over using water as in a conventional hydroelectric plant, since it is more predictable than water reserves and can release energy on demand.
SolarReserve plans to have its first solar plant complete by the end of 2010. Hopefully, it will be in time to meet the solar energy goals of several Southwestern US states in the next one to two decades.