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Thursday, November 14, 2013

US Government Loans For Solar Storage

The US government is investing heavily in solar storage (the pot to catch that soup). Here we summarize recent additions to the solar thermal storage market.

All five of the major solar thermal projects—including Solana and Ivanpah—that are scheduled to come on line in 2013 and 2014 were awarded loans through the U.S. Department of Energy's Loan Guarantee Program. Solana received a federal loan guarantee for $1.45 billion of the approximately $2 billion cost of the project, according to the parent company, Abengoa. BrightSource Energy reports a $1.6 billion federal loan guarantee on the approximately $2.2 billion Ivanpah project.

Solana stores some of the sun's energy as heat, using a molten salt as the thermal medium. The molten salt is stored in the round tanks, seen at the bottom center of this overhead image of Solana. This storage capability sets the plant apart from photovoltaic or wind technologies, which are dependent on the immediate availability of the sun or wind. With storage, Solana can operate while clouds pass overhead, providing a predictable supply of power to the grid. It can continue to produce electricity for up to six hours after the prime hours of sunlight have passed. This flexibility is particularly important as demand for electricity often peaks in the early evening. Storage technology was critically important in the development of Solana's 30-year power purchase agreement with Arizona Public Service (the largest utility in Arizona), which will buy all of Solana's output.

Both parabolic trough and power tower technologies can be integrated with varying levels of thermal storage. For example, the Crescent Dunes solar thermal power tower plant near Tonopah, Nevada that is expected to come on line by the end of 2013 will include 10 hours of thermal energy storage.