Thursday, November 21, 2013

How much does wind energy reduce carbon emissions?

Claims of wind energy reducing carbon emissions and water use are like my taking a walk and then claiming I prevented the emissions of driving instead. Except neither I nor anybody else might have made that drive, and I didn't check if anybody’s driving was actually prevented or displaced by my taking that walk.

Claims of wind energy reducing carbon emissions and water use are made only on the basis of how much electricity is generated by wind turbines and multiplying that by the average (if they are that rigorous) carbon intensity of the rest of the grid.

But that ignores several factors that likely reduce that equivalence:
  • Because wind is variable, it is more likely to displace no-carbon hydro and lower-carbon natural gas, not coal, because those generators can ramp up and down much more quickly than coal plants are able to.
  • In balancing the variability of wind, fossil fuel plants are forced to run less efficiently, i.e., burn more fuel per unit of energy generated.
  • Wind also takes advantage of the redundancy already built into the grid that keeps a substantial amount of capacity on spinning standby to be able to instantly switch to generation in case of a major failure of supply elsewhere — or a dip in wind generation. Therefore, at modest penetration levels (perhaps up to around 6%), wind probably has no effect on emissions at all, instead only switching already running backup plants between generation and standby more often. At greater penetration levels, connections to other grids (such as Denmark’s to Germany and the rest of Scandinavia) are used for that purpose.
That’s why wind’s benefits are always reported in terms of equivalences. Its advocates tireless avoid presenting actual data of less burning of fossil fuels, because, for the reasons given above, such data do not show much, if any, benefit at all.

wind power, wind energy, environment, environmentalism