Wind power reduces CO2 emissions

New Dutch report misinformed on wind power and emissions. In fact, much of the data indicates that the emissions savings of wind energy are even larger than expected because wind farm plants tends to disproportionately displace dirtier and less flexible coal plants.

As we’ve noted many times before, the fossil fuel industry and allied groups are engaged in a desperate misinformation campaign to muddy the waters about one of the indisputable benefits of wind energy: its proven record of greatly reducing fossil fuel use and harmful pollution.

Each of these attacks has been roundly rebutted by government data and studies by independent grid operators conclusively showing that pollution and fossil fuel use decline significantly in lockstep as regions ramp up their use of wind energy.

In fact, much of the data indicates that the emissions savings of wind energy are even larger than expected because wind farm plants tends to disproportionately displace dirtier and less flexible coal plants relative to less dirty and more flexible natural gas plants. We’ve also pointed out numerous critical flaws in each of these fossil fuel industry-funded attacks on wind energy.

The latest incarnation of this misinformation campaign against wind turbines comes from a Web posting by a Dutch anti-wind farm activist, C. le Pair. While we wouldn’t ordinarily expect non-peer-reviewed attacks on wind energy on an obscure Dutch anti-wind farm website to receive much attention, in this case major publications like The Atlantic and The Guardian have covered his claims. Fortunately The Atlantic and The Guardian articles were duly skeptical of the anti-wind farm activist’s claims and included quotes from professors and other experts pointing out many reasons why the anti-wind turbines claims were false.

However, the quotes from those experts did not comprehensively address all of the flaws in le Pair’s work, so we will do so here:

Power Grid Operations

As others have pointed out, le Pair’s attack is based on a serious and fundamental misunderstanding of how the power grid operates. Le Pair assumes that changes in the output of each wind turbine must be compensated by corresponding changes in the output of a fossil-fired power plant.

First of all, le Pair fails to understand that the output of all wind turbines connected to the power grid is combined, which greatly reduces the variability of their aggregate output. Dozens of studies have found that when hundreds or thousands of wind turbines spread over hundreds of miles are aggregated, changes in output at one wind turbine are almost always canceled out by changes in the output of the other wind turbines. (www.vtt.fi/inf/pdf/tiedotteet/2009/T2493.pdf)

The short-term variability in wind farm output is the most greatly reduced, as it takes hours for a single weather event to affect a significant share of a wind fleet spread over hundreds of miles. This short-term variability is the most important as this is what grid operators must accommodate by using fast-acting, expensive, and inefficient reserve generation, and fortunately wind energy adds little to the need for these reserves. Longer-term (over an hour or more) variations are far more easily and efficiently accommodated by grid operators.

Second, le Pair fails to understand that changes in aggregate wind farm output are combined with all other sources of variability on the power system, which cancels out many of the changes in wind output. Since the dawn of electricity more than a century ago, power grid operators have been kept busy 24/7/365 continually changing the output of power plants to accommodate changes in electricity demand and supply.

Electricity demand changes drastically as people turn appliances on and off and as factories come on and offline. Small changes in the weather can drastically change the number of people running air conditioners or electric heaters. Many changes in electricity demand are unpredictable or imperfectly predictable, which make them harder for grid operators to accommodate. Because most of these changes in electricity use are random, much of the time electricity demand is decreasing when wind output is decreasing or vice versa, meaning that the changes in wind output are canceled out.

Similar to the unexpected changes in electric demand, all conventional power plants experience unexpected outages on a fairly frequent basis due to mechanical or electrical failures. These outages occur instantaneously and without warning, requiring grid operators to maintain enough fast-acting backup reserve generation 24/7/365 to replace the largest power plant on the grid, which is often the 1000+ MW needed to replace a large coal or nuclear plant. As noted above, these reserves are far more costly and inefficient than the slower-acting reserves that modestly increase in need at high penetrations of wind energy.

Le Pair also assumes that all changes in supply and demand must be accommodated by fossil fuel power plants, even though in many parts of the world hydroelectric plants provide the needed reserves without any emissions penalty at all.

Le Pair’s rough and obsolete estimates for the emissions/efficiency penalty for operating a fossil fuel power plant at less than full load or cycling the plant are also considerably higher than real-world data indicates, as many fossil fuel plants can decrease their output by 1/3 or more without experiencing more than a trivial decline in efficiency. This is particularly true of modern fossil plants that are designed to operate very flexibly with minimal reductions in efficiency.

Finally, Le Pair ignores the findings of other studies that the emissions savings of wind energy are even larger than expected because wind energy tends to disproportionately displace dirtier and less flexible coal plants relative to less dirty and more flexible natural gas plants.

As a result of these flaws, le Pair’s estimates greatly overstate the challenge of integrating wind energy and any emissions penalty associated with integrating wind. The theoretical power system he envisions is completely different from how the actual power system operates.

Consequently, his results and conclusions that lead him to attack wind are a pure fiction that bears no relationship to what happens on the real power system. As a result, it is not surprising that his conclusions are contradicted by a large body of government and independent grid operator data and peer-reviewed studies, referenced in the links at the beginning, showing that wind energy does result in the expected savings of fossil fuel use and emissions.

As an added case study to illustrate the real-world emissions and fossil fuel use savings of wind energy, let’s look at Spain’s success with wind energy.The data for Spain shows a remarkable success story of wind and solar energy drastically cutting Spain’s fossil fuel use and emissions. Between 2005 and 2009, Spain’s CO2 emissions from coal and natural gas consumption fell from 150.5 million metric tons to 117.1 million metric tons, a decline of 22% over just four years.

Electricity production from wind steadily grew from 20.1 billion kwh in 2005 to 34.8 billion kwh in 2009. Hydroelectric output also increased as a result of 2005 being a poor water year, going from 17.7 billion kwh in 2005 to 26.0 billion kwh in 2009. Total electricity generation in Spain was flat over this time period, with 272.1 billion kwh produced in 2005 and 275.1 billion kwh produced in 2009. So wind grew from providing 7.4% of the country’s electricity in 2005 to 12.6% in 2009, while hydroelectric increased from 6.5% to 9.5%.

Solar power also helped out by growing from almost zero output in 2005 to 5.8 billion kwh in 2009. Spain became a net exporter of electricity over that time period, going from exporting 1.3 billion kwh in 2005 to 8.1 billion kwh in 2009, so one can’t argue that an increased reliance on imports allowed Spain to keep its emissions low. If one wants to remove the impact variability in hydroelectric output may have on the results, one can use 2006 as the base year, since 2006 and 2009 had nearly identical hydroelectric output.

With 2006 as the base year, wind farm output increased from 22.1 billion kwh to 34.8 billion kwh, growing from 7.9% of electricity generation to 12.6% of electricity generation. CO2 emissions fell from 144.6 million metric tons in 2006 to 117.1 million metric tons in 2009, a decline of 19%. All of the data is available here:

http://www.eia.gov/cfapps/ipdbproject/IEDIndex3.cfm?tid=6&pid=29&aid=12

Lifecycle emissions

Le Pair claims that it takes 1.5 years for a wind turbine to produce enough energy to offset the energy that was used to build and install the turbine. The only cited basis for this claim is a very rough back-of-the-envelope estimate from a private email sent to le Pair by an acquaintance.

Even worse, that estimate only roughly guesses at the energy needed for the steel and concrete, the two largest energy consuming components of a wind turbine, and then roughly doubles that number to account for other energy uses with no effort to precisely quantify those factors. Le Pair also assumes a 25% capacity factor for the wind turbine, even though typical wind turbines in the U.S. produce about 1/3 more energy than that. Correcting that discrepancy alone brings the energy payback time back to about one year.

In contrast to the rough and unsubstantiated estimates in le Pair’s work, a number of peer-reviewed studies have thoroughly accounted for the energy inputs and outputs for wind turbines and all have found the energy payback period to be around 6 months. Here are a couple of the comprehensive peer-reviewed analyses, each finding an energy payback period of under one year, that le Pair should have referenced instead of relying on an unsubstantiated back-of-the-envelope calculation:

http://www.springerlink.com/content/3m51630210q0q078/

http://www.sciencedirect.com/science/article/pii/S1364032109001403

Le Pair also entirely ignores the fact that a significant amount of energy and carbon emissions are involved in constructing and operating all types of conventional power plants and providing them with fuel . Coal, gas, nuclear, and hydroelectric plants are all built out of massive quantities of energy-intensive materials like concrete and steel. In addition, significant amounts of energy are involved in mining and transporting coal, natural gas, and nuclear fuel. Of course, the most important factor is that after the brief energy payback period a wind turbine will continue providing zero emissions energy for decades, while a fossil plant will continue to consume fossil fuels and belch pollution for decades. Again, all peer-reviewed analyses have concluded that the lifecycle emissions of wind farm plants are at most a small fraction of those from conventional plants.

Le Pair also makes the entirely unsubstantiated claim that wind plants have considerable onsite energy use. In fact, the onsite energy use of wind plants is minimal, considerably less than the onsite parasitic losses associated with pumping water at conventional steam plants, operating pollution control equipment at fossil plants, drying and crushing fuel at coal plants, etc.

Despite the facts, the desperate misinformation campaign to muddy the waters about the benefits of wind energy continues. So far in this case it appears that the facts have prevailed, as the obscure, unsubstantiated, and deeply flawed website posting of a single Dutch anti-wind farm activist has been treated with the skepticism it deserves when directly contradicted by a large body of government and independent grid operator data and peer-reviewed studies showing that wind energy does result in the expected savings of fossil fuel use and emissions.

In the interests of space we won’t repost all of the data and citations here, but they can be found at the following links:

http://www.renewableenergyworld.com/rea/news/article/2010/09/the-facts-about-wind-energy-and-emissions

http://www.awea.org/newsroom/realstories/The-Facts-about-Wind-Energy-and-Emissions.cfm

http://archive.awea.org/newsroom/pdf/04_05_2010_Colorado_emissions_response.pdf

http://www.awea.org/blog/index.cfm?customel_dataPageID_1699=9289

http://www.awea.org/blog/index.cfm?customel_dataPageID_1699=9958

By Michael Goggin, American Wind Energy Associatio Manager-Transmission Policy, www.awea.org/blog