New energy storage projects make solar power more viable

New York Times : As renewable energy sources continue to be developed, efficient ways to store that energy are being sought. In fact, some states are beginning to require that utility companies install storage. Because using batteries is too expensive, some companies are looking to store the energy as heat, a method that is less efficient but cheaper. Two new solar projects in two of the US’s sunniest states, California and Arizona, look promising. Solana, which cost $2 billion and is already up and running, covers three square miles of desert 50 miles southwest of Phoenix. And the Ivanpah project in California should be functioning by the end of the month. Both use a series of mirrors and black painted pipes and tanks to focus and store the Sun’s energy. Thermal storage is not just about storing heat, however. A New Jersey–based company, called Calmac, uses off-peak electricity to make ice, which is then used to run air conditioners.