Environmental Impact of Wind Energy





Carbon Emissions and Pollution

Information on the effects of wind energy on carbon and other emissions can be difficult to interpret and highly debatable. Geopolitics and emissions trading have created an extremely complicated situation which can result in unexpected outcomes. For example Country A might replace 20% of it’s electricity production from coal to wind power. Most people would expect a large reduction in CO2 and other emissions from this change. However Country A might be selling those “reduced emissions” to Country B allowing them to increase their power production by building more coal power plants. Similar odd results occur due to subsidies, emissions taxing, and wind energy being an intermittent power source.

Hameldon Hill wind farm is a 4.5 MW wind farm that offsets 9,000 tonnes of carbon dioxide emissions per Image by Liz Dawson. License: CC BY-SA 2.0

Hameldon Hill wind farm is a 4.5 MW wind farm that offsets 9,000 tonnes of carbon dioxide emissions per Image by Liz Dawson. License: CC BY-SA 2.0

Disregarding these complexities wind turbines do offer significant reductions in emission of carbon dioxide, sulfur dioxide, nitrogen oxides, heavy metals, and volatile organic compounds. when compared to conventional energy sources. Obtaining 20% of America’s electricity from wind could reduce yearly electrical sector by 825 million metric tons. Cumulatively this would save 7,600 million metric tons by 2030.[1] Research in Massachusetts, USA concluded that 1 MW of wind energy can offset approximately 2,600 tons of carbon dioxide annually.[2]

One useful metric for analysis of the environmental impact that various energy sources have is Energy Payback Ratio. This is simply the total energy generated over the lifespan of a given technology divided by the energy required to construct, operate, and maintain it. Recently a study calculated the EPR (Energy Payback Ratio) for three large wind farms in the Midwest USA arriving at an average of 26.[3] This is much better than the EPR of coal (11) or nuclear (16) from the same study.

Ignoring the complexities and effects of energy markets on wind turbine’s ability to reduce emissions paints a favorable picture. While this is tempting what is possible isn’t necessarily what will happen. Converting to wind energy for environmental reasons is foolish if we continue to view reduced emissions as “savings” to spend elsewhere rather than part of a necessary global decrease.

Land Use Issues

Destruction of peat bogs for wind farms can release more stored carbon than the turbines offset. Image by Jan van der Crabben.

Destruction of peat bogs for wind farms can release more stored carbon than the turbines offset. Image by Jan van der Crabben. License: CC BY-SA 2.0

One important aspect to the environmental impact of wind energy is the site where a wind farm is constructed. Off shore wind farms can damage marine environments if they aren’t constructed, operated, and maintained properly. Studies have shown that when off shore wind farms are done correctly damage is minimal.[4] However they also point out that significant problems could occur if proper consideration and planning for the environment isn’t made. Oil spills, cumulative damage from turbines placed to close to one another, pile driving impacting marine mammals, and bird displacement and collision are all serious possibilities that need to be planned for in relation to offshore wind farms.

Scottland’s wind developers have run into problems when trying to site wind farms on land containing peat bog.[5] Opponents of such construction argue that the carbon released and environmental damage caused by destroying peat bog is significantly worse than any benefit wind energy could provide. Excavation close to peat bog could also change the hydrology of the land destroying these large carbon sumps that are crucial to the global environment. Species impacted by the alteration or destruction of their habitat may also have limited re-homing options.

Community Impact

Wind turbines can have a large impact on the local environment and community where they are erected.

  • Noise Pollution – Wind farms are subject to setback requirements in many areas. Setback distance is how far a wind turbine has to be located from buildings or other structures to prevent damage from turbine failure.[6] Unfortunately setback distances often are not designed to prevent other interference, like noise, to the same structures. Residents living at the edge of a wind turbine farm sometimes complain of excessive noise pollution. Often this is a problem with improperly maintained HAWT (horizontal) turbines and areas that don’t have setback requirements. Below is a video showing noise pollution from a wind turbine located at 1,600 feet from a home.

  • Surface and Ground Water Pollution – Although wind turbines don’t use oil for fuel they do use oil and grease for lubrication. Gears, hydraulic systems, and bearings all require oil based lubricants to operate properly.[7] When turbines malfunction and develop leaks or even catastrophically fail ejecting components both surface and ground water can be polluted by these oils. Residents relying on well water and the local ecosystem can be negatively affected. Below is a video showing grease or oil leaking from a turbine in Wisconsin, USA.

  • Shadow Flickering and Strobing – Another problem created by setback distances that only consider physical disturbance of surrounding structures is shadow flickering. Turbines cast long shadows and the rotating blades can create strobe light effects in homes and other buildings that fall within the shadow. Sometimes this is only a minor annoyance occurring for a few minutes or hours a day. Other times this strobe effect can be present for the majority of the day and force building inhabitants to essentially cover windows permanently. Video below shows this effect on homes from a wind farm that had a 1,000 foot setback distance. Residents say 1,000 feet isn’t far enough to prevent the noise and strobe issues.

  • Fire and Debris – Improper maintenance and operation of a wind turbine or even random acts can cause dangerous conditions resulting in fires, explosions, collision debris, and ice hurling. Under ideal operating conditions none of this should occur but the real world is rarely ideal. For example lightning strikes are a common cause of wind turbine fires. Fires occur around the generator that is housed at the top of the mast which can be hundreds of feet of the ground. Firefighting can be difficult at these heights which allows fires to burn longer and increases the risk of spreading to the ground. Video below shows a wind turbine fire and clearly shows how burning debris ejected from a turbine can reach the ground igniting secondary fires.

    Setback distances are determined based on the height, rotor diameter, and turbine operating specifications. When improperly calculated ice hurling or debris from turbine failure can be ejected causing damage, serious injury, and even death.[8] Below is a video displaying a catastrophic wind turbine failure due to the breaking system being damaged in a storm.

  • Aesthetics – Land that is ideal for wind turbines is typically located in rural areas or offshore. Additionally the taller a turbine the greater operating efficiency it can achieve. Unfortunately many residents in these areas choose to live there for the natural beauty and the presence of hundred foot tall wind turbines lining the horizon destroys that beauty.

When considering the environmental impact of wind energy it’s important to remember that these drawbacks are in comparison to existing conventional energy drawbacks. Viewed in this light wind energy is one of the cleanest and most environmentally friendly energy sources available. Wind turbines provide a viable alternative renewable energy source that is bringing us closer to our goal of environmentally friendly energy.

Sources:

1. 20% Wind Energy by 2030
2. Wind Energy: Facts
3. Net Energy Payback and CO2 Emissions from Wind Generated Electricity in the Midwest
4. Danish Offshore Wind
5. Wind Farms or Peat Bogs
6. Permitting Setback Requirements for Wind Turbines in California
7. Wind Turbine Oil Trends
8. Ice Tossing Turbines: Myth or Fact?

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