It reads: “A two-megawatt windmill is made up of 260 tons of steel that required 300 tons of iron ore and 170 tons of coking coal, all mined, transported and produced by hydrocarbons. A windmill could spin until it falls apart and never generate such energy as was invested in building it.”
It credits the quote to “Thomas Homer-Dixon, Carbon Shift”.
Wind turbines produce clean and renewable energy. They are an important alternative to fossil fuels like coal that contribute to climate change.
In South Africa, the five largest renewable energy projects are all wind farms, which together contribute 645.71 MW to the electricity grid.
Wind turbines have to be in windy places
In February 2019 Full Fact rated the quote as incorrect, saying it was “based on a selective quotation”.
It was taken from an essay by earth scientist David Hughes, published in the 2009 anthology Carbon Shift, edited by Thomas Homer-Dixon.
In the essay Hughes argues that wind turbines must be placed in the right location, with lots of wind, if they are to produce their full amount of energy.
The original passage from the essay (with the selective quote in italics) reads: “The concept of net energy must also be applied to renewable sources of energy, such as windmills and photovoltaics. A two-megawatt windmill contains 260 tonnes of steel requiring 170 tonnes of coking coal and 300 tonnes of iron ore, all mined, transported and produced by hydrocarbons. The question is: how long must a windmill generate energy before it creates more energy than it took to build it? At a good wind site, the energy payback day could be in three years or less; in a poor location, energy payback may be never. That is, a windmill could spin until it falls apart and never generate as much energy as was invested in building it.”
So Hughes said a wind turbine placed in poor conditions might not generate enough energy to pay back what it took to make the turbine, but in a good wind site it could pay back the energy in under three years.
“Studies show turbines pay their energy cost back quickly,” Full Fact says.
Thomas Homer-Dixon responds
After seeing many versions of the quote on social media, Homer-Dixon responded in 2018 with a blog post labelling it “fraudulent”.
“I didn’t write the text, the text itself is selectively quoted, and the argument it makes, taken in isolation, is meaningless,” he wrote.
“This text is selectively excerpted from a chapter written by David Hughes in Carbon Shift (2009), a book I co-edited.”
He concludes: “So, 1) I didn’t write the text, 2) the text itself is selectively quoted, and 3) the argument it makes, taken in isolation, is meaningless. Three strikes.”
The truth of the turbine
It is “extraordinary that so many wind turbines would be bought and paid for by the industry if they actually consumed more energy than they produce”, says a 2018 article by Stephen Hanley on Planetsave.
Of course some energy is consumed in building a wind turbine and the pylon that supports it, Hanley says. But “the typical wind turbine will generate enough electricity to offset the energy consumed to create it in about 7.5 months or less”.
The 2014 study Comparative life cycle assessment of 2.0 MW wind turbines examines the life cycle and environmental impact of two 2.0 MW wind turbines.
It analysed the energy payback based on the sum of energy demand and the energy produced by the wind turbines over 20 years. It found that the energy payback period for the two turbine models were “found to be 5.2 and 6.4 months, respectively”.
A 2010 analysis found that in 50 separate studies, “the average wind turbine, over the course of its operational life, generated 20 times more energy than it took to produce”.
This was “favourable” in comparison to fossil fuels, and nuclear and solar power. – Taryn Willows
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