Thursday, November 15, 2012

A Disadvantage of Wind Farms May Be Direct Local Climate Warming

The wind industry in many countries has experienced a remarkably rapid expansion of capacity in the last few years, and this fast growth is expected to continue, and yet there is a disadvantage of wind farms not previously known. 

Governments in many countries are willing to subsidize the technology which is seen as low risk compared to many other renewable energy systems, and yet the renewable energy source already holds many disadvantages, when compared to say anaerobic digestion plants.

In the UK a large number of onshore and offshore wind turbine projects are now moving into the construction stage, with an unprecedented number of onshore wind farms having received planning consent over the last 12 months. Other nations are likely to be in a similar position within the current wind turbine technology and investment bubble.

With all that activity the casual observer would, we think it is fair to say, expect that the sustainability argument for wind turbines would have been well established with all aspects well studied. Investment on this scale is surely not being pumped into a technology which will in future years be found to have undiscovered disadvantages and not be as green as was expected - or is it?

The assumption that wind turbine technology is green has recently been brought into question in a study completed by Liming Zhou, Yuhong Tian, Somnath Baidya Roy, Chris Thorncroft, Lance F. Bosart and Yuanlong Hu, which is reported in the July 2012 edition of the Nature Climate Change Journal.

The researchers point out that while converting the wind's kinetic energy into electricity, wind turbines also modify surface-atmosphere exchanges and the transfer of energy, momentum, mass and moisture within the atmosphere.

They postulate that these changes, if they are present over large enough areas, may have potentially significant impacts on local to regional weather and climate, and they continue in their paper to provide observational evidence for such impacts based on the analysis of satellite data for the period of 2003-2011 over a region in west-central Texas.

They have chosen well, as this is where four of the world's largest wind farms are located. And, they say that their results show a significant warming trend of up to 0.72 degrees C per decade, particularly at night-time, over wind farms relative to nearby non-wind-farm regions. They go on to attribute this warming primarily to wind farms as its spatial pattern and magnitude couples very well with the geographic distribution of the wind turbines studied. So this may be a big disadvantage of wind farms.

The researchers go on to say that their study is not definitive and the data used only crudely represents the effects of wind turbines at this stage. However, 0.72 degrees C per decade sounds like a large rise to us, and large enough to raise a very significant question over the sustainability of wind farms for the local environment, and regional effects may also be present.  This could come to be seen as a big disadvantage of wind farms.

In our view, and in agreement with the authors, we believe that this study should wake up the scientific community to this concern, which is an important issue that requires further investigation. To quote the authors of this paper;

"We need to better understand the system with observations and better describe and model the complex processes involved to predict how wind farms may affect future weather and climate."

Beyond that, should not this sort of basic research to investigate this disadvantage of wind farms have been completed by modelling before, and not after, such a large investment goes ahead?