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The Wind Crop

From the various places I go to learn about how wind energy works, it seems to be accepted that the maximum amount of wind power that can be generated at any moment on a square kilometer of land is 1 Megawatt. For reference, that is about enough power to power up somewhere between 750 and 1,000 homes. Let’s assume away any environmental problem with windmills involving the use of rare earths, large amounts of cement and metals and emissions required for construction, their limited lifetime, requirements for backup generation, impact on wildlife, impact on wind patterns (after all, remember the First Law of Thermodynamics), etc. and just look at its scaleability (we’ve done these calculations here before).

The U.S. Energy Information Agency reports that the U.S. collectively uses about 3.7 trillion Megawatt-Hours of electricity over the course of a year – which in a perfect world would require, with 24-7 unimpeded generation capacity, an installed capacity of over 400,000 megawatts. In reality we need much more than this.

OK, so given the best case scenario for wind, how many acres of the U.S. would have to be planted in wind farms in order to power the U.S. solely with wind? This is of course a straw-manish idea, no one is proposing to go all wind, but the thought experiment does help give a sense of the scale we are talking about. Optimistically, wind can generate 8,760 Megawatt-Hours of electricity per year on a square kilometer – scaling this up to be able to produce electricity for the entire country’s demands would require 104 million acres to be planted in windmills.

How big is that?

This year, the USDA estimates that  about 90 million acres will be planted in corn, about 85 million acres planted in soybeans, and 56 million acres in wheat. In other words, we’d need more acres planted in windmills than we would need for the entire corn crop in the United States, most of which is not of course dedicated to feeding people (about half of this goes toward biofuels, it wold be interesting to add this acreage to the windmill acreage and all of the other acreage needs that arise due to refusals to allow more GMO crops, promotion of organic methods, etc.).

Ignoring Alaska, the wind crop would be the third largest state in the Union behind only Texas and barely behind California. An alternative way to compare this crop size is that it would take up about 5.5% of the total land area of the continental United States. How much land is used, collectively, by cities? 3 percent. Imagine doubling the amount of cities that are currently in America, and instead of loading them with skyscrapers, bars, museums and schools, we just lined the city blocks with windmills. It would certainly look cool.


2 Responses to “The Wind Crop”

  1. sherlock says:

    I also remember a few years ago, Denmark, the most “wind-using” nation (something like 20% of their electricity needs), hadn’t actually shut down a fossil fuel plant. This is because of wind power’s inherent unpredictability and the need for backup energy sources when there is low wind. However, you can’t just start up a fossil fuel plant whenever you want. It typically takes a few days to start up a plant. They have to be constantly running (and burning fuel) to be able to immediately take over during time periods of low wind.

    • wintercow20 says:

      And one reason they are able to even have as much as 20% is that they can sell excess wind to other countries since during periods of peak generation the country actually can’t use (or store) all of that generation.

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