Talk about your power burp. The Department of Energy, Sandia National Labs, and a host of municipal utilities in the Midwest are in the midst of designing a compressed air generation plant in Iowa. The plant is expected to be operational by 2012 and produce 268 megawatts of power or 50 hours of power storage. That could enough to save a municipal utility $5 million a year. It works like this. Air compressors force air into underground caves. When power is needed, the air gets released to power a turbine, which generates electricity. The air compressors can run on fossil fuels or wind power. The technique uses about 50 percent of the natural gas that a normal natural gas power plant would use, so greenhouse gases would be cut there. Powering the compressors with wind turbines would of course generate even fewer greenhouse gas emissions. More importantly, the power generated from the turbines at night could run the compressors. Wind turbines tend to be somewhat active at night and utilities don't know what to do with that power since few people are awake to use it. Storing night energy in caves gives them an opportunity to generate cheaper power during peak times. VCs, by the way, are hot for storage. Industrial battery and flywheel companies like Deeya have received investments in recent months. Solar thermal plants are investing in molten salt facilities that can store heat. Two compressed air facilities exist: a 17-year-old facility in McIntosh, Alabama and a 30-year-old plant in Germany. Both of these are in salt domes. The Iowa facility will be in an aquifier. The DOE and Sandia are also inspecting sites in Ohio. So if it's so good, how come it's not more popular? Power was cheap until a few years ago. Thus, no one was really motivated to do this. Building a compressed air facility requires extensive geological surveys. One small, select leak and that playground built over the site is swirling around in the air like a balloon.