The following post I made over a year ago. I realized there was a problem with it some months ago and I Googled my name and that old post comes up so I decided it was time I come back and correct it. A few people caught the problem with the idea - lousy efficiency. It seemed logical at the time air blowing one way for storage and then back the other way when you want to use it wouldn't have a problem with losses. In fact as I say in my first post it is already being done here and in Germany and is being proposed somewhere in Iowa. With two places already doing it and the decision to go forth in another, I figured the kinks had been worked out and there certainly wouldn't be an efficiency problem whereby only about 25% of the original power stored would be recoverable, but this is indeed the case. It is interesting to read through these posts to see how engineers come up with ideas and through a kind of vetting process whether in the end it flies or it doesn't. This one is definitely shot down! Another idea that might work is being submitted, that of using existing dams to expand their use to include energy storage and it is included here beginning on the second page. Another person came up with the idea and I expanded on it. Consider it. Read and decide what you think about that idea and determine for yourself if you think it is feasible. I believe it is! Here is an opportunity to prove me wrong on a major idea - Twice! And now, the following is the first post where I step all over myself with a really terrible idea:
It's already being done in Germany in one place in the United States, 40 miles north of Mobile Alabama. One of the concerns about wind mills is what happens when there is no wind. Another is which is the best way to store energy for when that happens? The answer is pumping compressed air into deep underground mines. We have abandoned mines all over our country, many of them located near big cities that will need dependable reliable electrical power 24/7. These mines stretch for miles underground and can hold enough compressed air at pressures equal to energy stored in Hoover Dam's Lake Mead. Like the wind doesn't always blow, it doesn't always rain water into Lake Mead either. Some days it rains, some days it doesn't. Some days the wind blows, some days it doesn't. When the wind is good, the compressor pumps pump air into the mines which should be most of the time. Maybe it would be weeks or months before the energy stored in the mines would be depleted because of lack of winds. The wind mills supplying power could be a thousand or miles away, the power sent to the mines in the form of HVDC which is how you want to send power those long distances. Just like Hoover Dam's turbine generators run from water under high pressure, compressed air would run turbine generators located at the mines. Many people use compressed air to power nail guns and air hammers. This system I'm talking about would work the same way. We easily think of energy stored behind dams that we call hydro electric, we need to think now of turbo-electric.