The NREL report also conclusively puts to rest the fossil fuel industry myth that wind energy’s pollution savings are smaller than expected because fossil-fired power plants run at lower efficiency when wind is generating electricity. Even at the very high level of renewable energy use examined in the report, the impact on the efficiency of fossil-fired power plants was found to be “negligible,” reducing the carbon emissions reduction benefits of wind and solar by only 0.2 percent, so that on net wind and solar produced 99.8 percent of the expected emissions savings.
A chief reason for the study’s findings is that electric utility system operators can reliably and efficiently integrate wind and solar energy using the same tools they have used for more than a century to accommodate large swings in electricity demand as well as abrupt failures at conventional power plants. Dozens of studies have demonstrated that wind and solar energy only slightly add to total power system variability, and that most changes in wind and solar output are canceled out by much larger opposite changes in supply and demand. System operators in the Midwest and Texas have each been able to integrate more than 10,000 megawatts of wind energy with only very small increases in their need for operating reserves.
As shown above, the study found that one megawatt-hour of wind energy, the amount produced by a typical wind turbine approximately every 90 minutes, saves 1190 pounds of carbon dioxide pollution on average, equivalent to the amount produced by a cross-country drive in a fuel-efficient car. As indicated below, the negative impact on the efficiency of fossil-fired power plants reduced those carbon dioxide savings by only 2.4 pounds, the amount produced by a typical drive to the grocery store.
Some representatives for competing energy sources have spent years propagating the myth that wind energy’s emissions savings are less than expected, despite having no peer-reviewed analysis to support their claims and being contradicted by all independent grid operator data and analysis. It is simple economics and science that wind energy directly displaces the output of the most expensive power plant, which is almost always the least efficient fossil-fired power plant.
Some advocates for competing energy sources have even called for an analysis based on real-world data from emission monitors at power plants. With today’s study they got it, though they may not like the results. It is now impossible for anti-clean energy advocates to continue sticking their heads in the sand denying the reality of wind’s environmental benefits.
Today’s study used real-world hourly emissions data from nearly every power plant in the Western U.S. and was reviewed by 55 experts including representatives from eight utilities. The analysis of wind’s impact on fossil-fired power plants was largely conducted by engineers at Intertek who specialize in optimizing the operation of power plants for utility clients.
Today’s study also produced an interesting result with regard to the cost of cycling conventional power plants. For two of the three natural gas price scenarios analyzed, wind and solar energy (shown below as HiMix) actually reduced the total costs associated with cycling conventional power plants, and in the other scenario those costs only amounted to 0.5 percent to about 2 percent of the $7 billion in annual fuel cost savings produced by wind and solar energy. In addition, previous work by NREL and others has demonstrated that the addition of any new low-marginal-cost energy source, whether a new nuclear, coal, or wind plant, would lead to the same result of additional cycling at existing power plants.
NREL’s report is available here.