CleanTech investing has an entry on a company that has technology to store wind power as compressed air stored in underground tanks. Cutely named General Compression (warning: web site home page auto-starts Flash with audio, a huge web marketing no-no) has their attempt to solve the big battery problem: storing energy from sources that are not consistent like wind.
The big problem with technologies like wind and solar has been developing storage so output is steady during lulls or darkness. Fossil fuels have held their grip because they are very stable storage media for energy. General Compression aims to store wind energy as compressed air underground then use it to turn turbines when needed. The only problem I have with this is: If we’re going to dig big holes, why not tap into geo-thermal, an unlimited and constant source?