Wind PowerJul 23rd, 2008 | By Jonathan Golob | Category: Energy, Featured Articles, Lead Article
The strip of States from Texas to North Dakota had to be useful for something–beyond nuclear warhead storage, cows, and a rapt audience for Fox News. The middle strip of country blows. Literally. Some of the most consistent winds in the world blow across these States. For wind power, consistency is everything.
A modern windmill is pretty fantastic. Blades half as long as a football field slowly rotate around a hub to generate an astonishing three megawatts of electricity. Over a year, that’s about as potent as twelve-thousand barrels of oil.
All windmills get their energy from slowing down the wind a bit, capturing energy as rotational force. To generate much energy, you need many windmills distributed regularly where the wind blows. Almost all of the investment and cost is upfront–during the manufacturing, placement and wiring up of the mills. This is the opposite of a coal-fired plant, where most of the lifetime costs are buying up fuel to run the plant. Once you’ve built and placed your wind farm, so long as there is wind, you’re basically generating electricity for free.
This actually amplifies the uncertainty of investing in wind power. Building a coal power plant costs less (per megawatt) upfront. And the plant will reliably produce a certain amount of energy, so long as you buy coal. If you can’t count on the wind blowing steadily for decades, the much higher starting costs seem scarier and scarier.
Where you build your wind farm really matters. You want some place close to where people want to buy energy and where the wind is totally consistent, where it blows the same speed every day. Here’s where technological advances are really helping: Climate models and detailed records going back decades help us pinpoint where the winds are the best, along with where we think the wind will be the best in the future.
Wind’s energy comes from differences in pressure. Sunlight hits the atmosphere, heating it. Then its gas molecules (mostly nitrogen and oxygen) get jittery from that solar energy, bouncing around more and increasing the local pressure. They start to move en masse, seeking lower pressure points in the atmosphere. Gravity from the sun, the moon, and the earth all tug, deflecting their course. The molecules of gas in the atmosphere also feel the planet turning beneath them. All of this together makes up the wind.
The rub is, all of the pollutants we’ve added to the atmosphere are changing how the atmosphere interacts with sunlight in relatively unpredictable ways. (This is global warming or climate change.) So, where the wind blows now might not be where the wind will blow in a few decades. Our continued belching of greenhouse gases makes building a wind farm riskier, and therefore less attractive, than building a fossil fuel plant.
For now, we could use better transmission lines to connect Midwestern wind farms with major American cities. And we can improve our wind prediction tech–including new systems that account for climate change–to take some of the risk out. But boy, talk about your screwy logic. The things prompting our desire for alternative energy–climate change, pollutants–are what make wind power, by itself, an unlikely candidate to replace fossil fuels as our major energy source.
(For more, here’s a comprehensive technical report on wind power.)