It is sometimes said that wind turbines require more energy in their construction and for their operations, than they ever produce in the form of electricity. Nothing could be further from the truth. This Wall Street Journal blog illustrates the point and summary material from it is reproduced in the the chart above.
It shows that fossil fuels (coal, oil and natural gas) yield, on average, only a portion of their original energy when converted into electricity. That is because, by definition, fossil fueled generators require other fossil fuels in order to generate electricity. And that energy conversion process is very inefficient - most of the energy is lost as heat and only a portion is converted to electricity.
The emissions of fossil generators, such as carbon dioxide, sulphur dioxide and fly ash, also require a lot of energy to be mitigated. This fact has been demonstrated by Saskatchewan's Boundary Dam coal-fired carbon capture project - which requires 30 percent of total electricity generation simply to capture the carbon dioxide it emits.
On the other hand, wind energy, and other renewables such as solar and hydro, use fuels (wind, sun and water) which, after the initial plant has been built, are free for the life of the facility. Those renewable fuels also produce no waste.
This means that renewable generators - wind, solar and hydro - produce significantly more energy as electricity than is input as fossil fuels. The chart above shows that wind turbines demonstrate the best energy return on energy invested. A typical wind turbine will return 11.6 times more energy, as electricity, than it consumes over its life.
At the other end of the spectrum coal converts, to electricity, less than one third of the energy it consumes.