The Solana plant will be able to meet winter heating and lighting needs by putting electricity on the grid early in the morning—before the sun is shining—and help satisfy summer cooling demand by producing power after sundown. The plant, which can power up to 70,000 houses, has signed a 30-year agreement to sell electricity to utility company Arizona Public Service.
Mark Mehos, a solar program manager for the National Renewable Energy Lab in Golden, Colo., said such molten salt storage systems add about 20% to the construction cost of solar plants but more than make up for it by boosting a plant's flexibility and productivity.
Electricity from solar plants is expensive, especially at a time when natural-gas prices have plunged, making gas-generated electricity cheap by comparison. Utilities, which are under state mandates to buy more clean power, say solar power may look more economical in the future if fossil fuel prices rise or if a tax is imposed on carbon emissions by power plants.