http://www.news.com/Storing-sun-and-wind-power/2100-13840_3-6221396.htmlWhen the sun sets or the wind dies down, renewable energy sources get a lot less reliable.
That's why large-scale electricity storage technologies are being pursued by a number of energy technology companies. Although none of these technologies are commonplace, they could fill a niche in the booming solar and wind industries and make renewable energy more economically compelling.
One company with a novel approach is Massachusetts-based start-up General Compression, which is building a wind turbine that compresses air and stores it underground in caves or other geological structures. The compressed air is drawn when needed and expanded to drive electricity generators.
A document on General Compression's Web site last month that has since been removed indicated it was looking for $30 million this fall to finance its expansion.
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