From Inderscience Publishers , something sure to make greens go “See, I told you!”, except for that little fatal mistake at the end. Read on.

Wind turbine payback

US researchers have carried out an environmental lifecycle assessment of 2-megawatt wind turbines mooted for a large wind farm in the US Pacific Northwest. Writing in the International Journal of Sustainable Manufacturing, they conclude that in terms of cumulative energy payback, or the time to produce the amount of energy required of production and installation, a wind turbine with a working life of 20 years will offer a net benefit within five to eight months of being brought online.

Wind turbines are frequently touted as the answer to sustainable electricity production especially if coupled to high-capacity storage for times when the wind speed is either side of their working range. They offer a power source that has essentially zero carbon emissions.

Coupled lifecycle cost and environmental assessment in terms of energy use and emissions of manufacturing, installation, maintenance and turbine end-of-life processing seems to be limited in the discussions for and against these devices. “All forms of energy generation require the conversion of natural resource inputs, which are attendant with environmental impacts and costs that must be quantified to make appropriate energy system development decisions,” explain Karl Haapala and Preedanood Prempreeda of Oregon State University, in Corvallis.

The pair has carried out a life cycle assessment (LCA) of 2MW wind turbines in order to identify the net environmental impact of the production and use of such devices for electricity production. An LCA takes into account sourcing of key raw materials (steel, copper, fiberglass, plastics, concrete, and other materials), transport, manufacturing, installation of the turbine, ongoing maintenance through its anticipated two decades of useful life and, finally, the impacts of recycling and disposal at end-of-life.

Their analysis shows that the vast majority of predicted environmental impacts would be caused by materials production and manufacturing processes. However, the payback for the associated energy use is within about 6 months, the team found. It is likely that even in a worst case scenario, lifetime energy requirements for each turbine will be subsumed by the first year of active use. Thus, for the 19 subsequent years, each turbine will, in effect, power over 500 households without consuming electricity generated using conventional energy sources.

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Haapala, K.R. and Prempreeda, P. (2014) ‘Comparative life cycle assessment of 2.0 MW wind turbines’, Int. J. Sustainable Manufacturing, Vol. 3, No. 2, pp.170-185.

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The mistake, or some might call it an inconvenient oversight:

Thus, for the 19 subsequent years, each turbine will, in effect, power over 500 households without consuming electricity generated using conventional energy sources.

The problem here is the assumption that a wind turbine is the equivalent of a conventional coal or nuclear power plant. It isn’t, and as we know wind is not a constant thing:

“My biggest fear is if you see 20 percent wind on your system, and then it comes off at a time period where you don’t have resources to replace it — that’s going to, could, result in a blackout situation,” he says.

If there was not a backup power source that could be controlled 24/7/365 for those 500 homes, they would be in the dark when the wind falls below minimum levels needed to operate the wind turbine.

For example, a popular wind Turbine, the Vesas V90-2.0 2 megawatt turbine says in the technical specifications:

4 meters per second is equal to 8.9 miles per hour. By my own observation, I can say there are quite a number of days where wind is lower than that at ground level and even at tower height. Today for example, there is quite a number of areas with low or no wind in the United States. The blues are the low wind speed colors.

Source: http://earth.nullschool.net/#2014/03/26/0900Z/wind/surface/level/equirectangular=-96.36,44.28,879

As we have seen before, when power is needed most, we can’t always count on the wind to blow at a level that will keep a wind turbine producing, requiring another power source to back it up. Thus, it is a blatant fallacy to claim:

…each turbine will, in effect, power over 500 households without consuming electricity generated using conventional energy sources.

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