Executive summary: Time domestic water pumps for periods of low electricity demand.
Problem: Wind energy has a large weakness that is difficult to overcome - energy is only generated when the wind is blowing. This is especially problematic when you need energy and the air is still. The common solution is to use other forms of energy on still days, but this generally results in burning coal, natural gas, oil, and other greenhouse gas creating resources.
One solution: A great way to make use of wind energy is by storing it when it's not needed and using it when it is. However, there are not many good ways of storing energy. Water energy storage is the most cost effective way to store energy. This consists of two lakes - one high on a mountain, one low in a valley. Water runs turbines when energy is needed, filling up the lower lake. When energy is not needed these turbines run in reverse, pumping water back up to the high lake.
The problems with this solution are that you need appropriate geography and it can be destructive to environments due to the rapidly changing lake levels. Also, although this is the most cost effective form of energy storage, it can still be quite expensive to build two manmade lakes.
My solution: Most towns and cities pump water up to water towers in order to provide domestic water at a constant pressure. Instead of pumping water to these water towers every time the level is low, pump water every time energy demand is low. This will effectively make domestic water storage into a distributed water energy storage system. Water towers don't currently know or care when energy is abundant or scarce - they turn on when water reaches a certain level. If we instead top off the tanks every slow-wind period, we're using unused energy to pump water and not using peak energy. A nice benefit of this system is that we don't need any additional construction - just a bit of control changes in water systems.-- Worldgineer, Dec 26 2007 Wikipedia says, "a water tower serves as a reservoir to help with water needs during peak usage times. The water level in the tower typically falls during the peak usage hours of the day, and then pumps fill it back up during the night."
HowStuffWorks says much the same, claiming that the tower's tank holds about a day's worth of water. It also points out that a frequently-running small pump is better than an occasional-use huge pump.
I'd say that the pumps probably run much of the time, with a leaning toward off-peak-demand-electricity being fairly obvious to the engineers. Working windpower into the equation isn't difficult, but probably won't naturally mesh with the daily cycle of a water tower. [ ]-- baconbrain, Dec 26 2007 Pumping water during off-peak hours when cost of energy is low is common practice in the water industry - for those towns that have adequate storage. Building water storage is expensive -- whether tanks or lakes -- so some cities have opted to accept higher pumping costs rather than make the large initial investment to build the needed storage.
Public water systems are huge consumers of electric energy and have for years been very aware of rising power costs. Forward-thinking water utilities have begun to adopt a wide range of alternative energy generation systems, including solar and wind power. Many drinking water utilities also operate wastewater treatment systems. The "solids" removed from the wastewater is treated in "digesters" which generate methane gas. That gas has been used in engine generators, microturbines, and even fuel cells. In some cases the digested “biosolids” is dried and also used as fuel.
Now, adding a wind generation system that is mounted ON or somehow incorporated into a water storage tank/tower would be interesting. Such tanks are almost always built on the highest point in the region they serve. I'm sure most would see significant wind...-- jdlaugh, Dec 26 2007 Why bother ? Drink beer inatead ...-- 8th of 7, Dec 26 2007 random, halfbakery