Sunday, 25 August 2019

Just how energy efficient are wind turbines?

Wind farms are being erected all over the world and a recent study from the University of Sussex and Aarhus University has shown that Europe has the capacity to produce more than 100 times the amount of energy it currently produces through onshore wind farms.
In an analysis of all suitable sites for onshore wind farms, the new study reveals that Europe has the potential to supply enough energy for the whole world until 2050. Peter Enevoldsen, assistant professor in the Center for Energy Technologies at Aarhus University, Denmark said “...but even without accounting for developments in wind turbine technology in the upcoming decades, onshore wind power is the cheapest mature source of renewable energy, and utilizing the different wind regions in Europe is the key to meet the demand for a 100% renewable and fully decarbonized energy system.”
The study estimates that more than 11 million additional wind turbines could be theoretically installed over almost 5 million square kilometres of suitable terrain generating 497 EJ of power which would adequately meet the expected global energy demand in 2050 of 430 EJ.
Maybe the land is available, but the materials needed to construct all these wind turbines by 2050 would certainly not be, as I highlighted in the posting Is Zero Carbon by 2050 attainable? Wind power gives many the impression of getting something for nothing, but of course that is not the case. Construction of a wind turbine requires a great deal of raw material and energy and there is also an environmental factor, not least involving the construction of the concrete foundation, as the cement industry is one of the world's greatest emitters of CO2.
Which leads me to my eponymous question- just how energy efficient are wind turbines?  The figure below, from the World Bank, shows how much raw material is needed to manufacture just one 3 MW turbine.
I would like to know if anyone has performed a complete life-cycle energy analysis on a wind turbine of this size? How much energy is used from initial mining to final decommissioning and what is the estimate of net energy produced during the life of a turbine? I think the results might be surprising, as mining, processing and extraction of rare earth elements alone are known to be particularly energy intensive.
If anyone has information on such a LCA please let me know. If little has been done, then wouldn't this be a great student project?
Twitter @barrywills


  1. Coal fired power stations also need mined metals. The generators driven by steam use as much copper, rare earths and a lot more steel and concrete than a wind turbine. How much concrete in a cooling tower? Then there's the fly ash, and tailings ponds, the acid mine drainage issues at the coal mine, the haulage trucks quaffing diesel etc. A one sided look at the inputs to wind turbines isn't enough. It really should be a comparison of the total energy footprint of all alternatives.
    Patrick Jay, Director at Adroit Process Equipment Pty Ltd, Australia

    1. Agreed Patrick. We could argue that much energy is also needed to build nuclear power stations, but then the energy produced by the subsequent nuclear reactions would easily offset this input. I would think that the net energy in a coal-fired power station would also be large enough to justify the input. My question is what is the net energy produced by a wind turbine over its life time? Is it large enough to justify its construction, bearing in mind that the energy required to produce the metals is likely to be mainly from fossil fuels?

  2. Great idea Barry, but I'd like to see these stats over the last 20 years. Coal is a mature technology, so price and efficiency of construction are somewhat stable. Renewables are getting cheaper and more efficient with every generation, which is why we should be building them.

  3. Some times I wonder why so called Centres of Excellence of Science and engineering do not produce about 100 Ph.D. on various aspects raised above and then come up with some directions?Fully possible,partially possible etc.
    Teaching institutes have to take a lead because they do not have bias to one or the other;; less expensive because they have excellent results


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