If you actually read the NREL study referenced in that article, you'll find that it shows that wind reduces pollution and fuel use by as much or more than expected. In many cases, adding wind and solar actually increases the average efficiency of power plants by displacing the most expensive, and therefore least efficient, power plants first. The study uses real-world emissions monitors at power plants to confirm that, even after all cycling and other impacts are taken into account, wind produces 99.8% of the emissions savings that would be expected for a 1:1 displacement of fossil fuels. The claim that so-called "backup emissions" are significant has been conclusively put to rest. As I explained:
As wind energy’s growth has continued, spurred by improving technology and declining costs, wind energy’s role in reducing harmful pollution has become even clearer. Empirical data for the United States and Europe clearly indicates not only that wind energy results in the expected pollution reductions by directly offsetting the use of fossil fuels at power plants, but that by displacing the most expensive and therefore least efficient power plants first, wind energy results in even larger pollution savings than expected.
There is no dispute that every MWh of wind energy added to the power grid displaces a MWh that would have been produced by the most expensive power plant currently operating, which is typically the least efficient fossil-fired power plant. However, some have attempted to claim, without support, that adding wind energy to the power system can negatively affect the efficiency of other power plants, reducing the emissions savings produced by wind energy.
Fortunately, a large body of real-world data is now available to assess how wind energy affects the efficiency of other power plants, allowing one to approach the question from multiple angles. To start with, the U.S. Department of Energy collects detailed data on the amount of fossil fuels consumed at power plants, as well as the amount of electricity produced by those power plants. By comparing how the efficiency of power plants has changed in states that have added significant amounts of wind energy against how it has changed in states that have not, one can test the unsupported hypothesis that wind energy has a negative impact on the efficiency of fossil-fired power plants.
The data clearly shows that there is no such relationship, and in fact, states that use more wind energy have seen the efficiency of their fossil-fired power plants fare slightly better than states that use less wind energy. Specifically, coal plants in the 20 states that obtain the most electricity from wind saw their average efficiency decline by only 1.00% between 2005 and 2010, versus 2.65% in the other 30 states. Increases in the efficiency at natural gas power plants were virtually identical in the top 20 wind states and the other states, at 1.89% and 2.03% improvement respectively. The efficiency of fossil-fired power plants fared comparably well in the top 10 wind states (which obtain between 5% and 16% of their electricity from wind), with coal plant efficiency increasing by 0.51% in the top 10 wind-using states and declining by 2.65% in the other 40 states, while gas plant efficiency improved by 0.78% in the top 10 wind states and 2.17% in the other 40 states.
Similar results can be found in International Energy Agency data for Europe, which shows that the top 5 wind countries (which obtain between 7% and 23% of their electricity from wind) saw the average efficiency of their natural gas power plants increase by 11% as they ramped up their use of wind energy from 1999-2010, larger than the 7% increase in efficiency seen across all of OECD Europe. Over that time period, coal plant efficiency fell by 1% in the top 5 wind countries and remained unchanged across all OECD Europe countries.
Another method to assess whether wind energy is producing the expected emissions savings is to calculate whether increases in the use of wind energy are correlated with decreases in the amount of carbon dioxide emitted per MWh produced. A correlation coefficient of 0 would indicate that there is no statistical relationship between wind energy output and emissions intensity, a coefficient of -1 would indicate that wind output increases always coincided with increases in emissions, and the observed coefficients of nearly +1 indicate that increases in wind output nearly always coincided with major decreases in emissions. The correlation between increasing wind energy output and declining emissions intensity in the leading wind energy countries over the period 1999 to 2010 was extremely strong, with a correlation coefficient of.77 for Denmark,.82 for Germany,.86 for Portugal,.90 for Spain, and a whopping.96 for Ireland.
These correlation coefficients were far higher than for any other possible explanatory factors for the observed decreases in emissions intensity, such as increased use of hydroelectric or nuclear energy, increased use of natural gas instead of coal, changes in the efficiency of fossil-fired power plants, or changes in electricity imports or exports. If wind energy were causing large declines in the efficiency of fossil-fired power plants, zero or negative correlations would have been found, instead of correlations approaching 1.
These findings are further confirmed by the preliminary results of a new report from the National Renewable Energy Laboratory that uses empirical data from another source, EPA’s network of power plant continuous emissions monitors, to evaluate the impact of wind energy on the efficiency of all fossil-fired power plants in the Western U.S. The in-depth, multi-year, and peer-reviewed analysis found that even in a scenario with wind providing 25% of all electricity in the Western U.S., wind’s total impact on the efficiency of fossil-fired power plants would be “negligible,” accounting for less than 0.2% of the emissions savings produced by wind energy. As a result, carbon dioxide emissions declined by 29–34% in the 25% renewable energy case. Moreover, the analysis found that adding wind energy to the grid actually slightly increases the average efficiency of coal and natural gas combined cycle power plants by offsetting the least efficient plants.
No matter how one approaches the question, the data is clear that wind energy greatly reduces fossil fuel use and pollution. Moreover, the results discussed above are in addition to a large body of independent grid operator, utility, and government analyses and data that have already examined how wind energy interacts with the power system and unanimously found that wind energy produces pollution savings that are as large or larger than expected.
American Wind Energy Association