It's common sense that at any point in time, some wind arms are making very little or no electricity, while others, nearby, are cranking at peak output as a weather front passes or storm brews. In theory, linking wind farms together might well result in a stable average output, once enough wind farms are installed in a region. TreeHugger's Jeremy gave this some coverage:- last year, incorporating some cool graphics.
The question is, how large the area, and how many wind power linkages are needed, to hit that sweet spot where base load stability equivalence is reached? After how much investment does such a network begin to be cost effective?
Before we get to geography and the number of utilities involved, some analogies might help frame the concept.
Weather analogy:- Just as an climate can be thought of as the average of all weather, nearby, and grid interlinked, wind farms produce a collective output that physically averages the forces of nature: 'gusty and turbulent winds reach Kansas City today, reaching St. Louis by early tomorrow morning."
WWW analogy:- The global average number of persons "on-line" at any instant remains high, regardless of multiple time zones and cultural practices, because all nations are physically linked. If the world had separate internets, one for each continent, for example, information flows would be substantially bumpier through the passage of day to night, and so on. Cristina Archer and Mark Jacobson, authors of a recent paper about this, published in the American Meteorological Society's Journal of Applied Meteorology and Climatology, came up with the Hamster Analogy.
It's a bit like having a bunch of hamsters generating your power, each in a separate cage with a treadmill. At any given time, some hamsters will be sleeping or eating and some will be running on their treadmill. If you have only one hamster, the treadmill is either turning or it isn't, so the power's either on or off. With two hamsters, the odds are better that one will be on a treadmill at any given point in time, and your chances of running, say, your blender, go up. Get enough hamsters together, and the odds are pretty good that at least a few will always be on the treadmill, cranking out the kilowatts.
The combined output of all the hamsters will vary, depending on how many are on treadmills at any one time, but there will be a certain level of power that is always being generated, even as different hamsters hop on or off their individual treadmills. That's the reliable baseload power.
The connected wind farms would operate the same way.
The researchers found that nearly a third to a half of yearly-averaged wind power from 10 or more interconnected wind farms can be used as reliable baseload electric power.
A full copy of the paper is available from Standford University, here (pdf file).
If the hamster analogy has your brain fired up enough to think about the entire renewable power menagerie at once, have a look at this related post on the Energy Blog.
Via::Stanford News Service, "Study finds that linked wind farms can result in reliable power" Image credit::Cristina Archer and Mark Jacobson, Figure:- "Hours And Energy Output - 11 Stations" from the paper "Supplying Baseload Power and Reducing Transmission Requirements by Interconnecting Wind Farms."