On Thu, 14 Jun 2007, Patrick Giagnocavo wrote:
Vegetable oil can degrade much faster than diesel.
What you really want is a large pond at the top of a hill, and another large pond at the bottom of the same hill.
When utility prices are low, pump the water to the upper pond. When power is needed, have your installed hydropower setup allow water to flow through the turbine from the upper pond to the lower pond.
In a city, a very large tank located at the top of the building and an equally large one in the bottom with a pipe between the two, should suffice. Remember that the "head" or height difference is a large factor in determining how much power a hydro setup can generate. I just wanted to give a little bit more perspective on above: 1 liter of diesel fuel contains approx 10000WH.
1 liter of water pumped 100 meters up has a potential energy of .272WH It takes a *lot* of water to provide a measurable difference for a datacenter of any significant size... -alex