I heard a really good talk about lifecycle analysis (LCA) yesterday that took wind energy as an example, and examined the overall ecological footprint associated with an individual large turbine. On average, about 7.8 megawatt-hours of energy goes into extracting the materials, forging the pieces, transporting, assembling and installing the device, maintaining it through its lifetime, and then dismantling and recycling it when it is no longer useful. However, it will produce, on average, 157.8 megawatt-hours of electricity in the course of its 20-year lifespan, a return of a bit more than 20 to 1.
Although there are additional considerations in the form of land use and ecological impact to birds and bats that complicate matters, wind remains attractive overall from an LCA perspective. Concerns about land use, it seems to me, need to take into consideration that turbines can be deployed in pasture land, orchards, etc. And while it’s true that birds are occasionally killed, they’re many thousands of times more likely to die at the hands of cats, automobiles, and plate-glass windows.
From a cost perspective, mid-sized approaches on the order of a few hundred kilowatts that may be appropriate for corporate campuses, factories, schools, and so forth pay themselves off in a period of three to eight years, depending on incentives, the prevailing rates for electricity from the local utility, and wind characteristics.