The Energy Economics branch of the Scottish Government and the Institute for Energy and Environment at the University of Strathclyde were asked in 2010 for evidence about the carbon balance regarding wind turbines. References on how to evaluate greenhouse gases and two academic style papers were received from the government. One paper dealt with the way that the total carbon saving from mining of raw materials to building, operating and dismantling a turbine could be calculated in the future.  The other gave details of how to calculate energy use, the monetary cost and greenhouse gas emissions, again in the future. We had asked for direct references of hard evidence from existing turbines.

The references from a senior researcher at Strathclyde University were more focussed One paper from the Low Countries compared several ‘emission free’ power plants including turbines.  Unfortunately the numbers used are derived from previous studies. One key point made is

“IT IS REGRETTABLE THAT IN THE LITERATURE THE RESULTS SEEM TO DEPEND ON THE POINT OF VIEW OF THE RESEARCHER AND ON THE GOAL OF THE STUDY”.

The second paper from Denmark compared the energy and emissions for onshore and offshore turbines. Particular turbines were used as a basis for the study though again assumptions were used in the calculations. Interestingly the damages due to NOISE and VISUAL IMPACT out of the total damages were in terms of energy use  offshore 1%   onshore 39%   Most of the fourteen other cited papers were based on turbines which actually exist.  Whilst confirming the expected relatively low carbon impact of wind turbines the facts are that great variation exists from site to site.  

The use of wind turbines is generally justified through having less of an impact on the environment than fossil fuel alternatives.  Many studies have been done on the Life Cycle Assessment ( LCA) of wind turbines and other renewable energy technologies to examine their environmental impact and their relative contribution to greenhouse gas emissions. 

In general these have been carried out to agreed international standards which break the lifecycle of the construction, operation and end of life removal for turbines down into individual components.  The LCA then builds up the environmental impacts from these.  These studies are generally site specific.  The amount of energy generated by a particular wind turbine depends on its specific location.  Assessing how effective it is therefore varies, depending on the site. 

The studies also do not deal in a satisfactory way with uncertainties and errors at the individual component levels.  There is also a recognised problem with the comprehensiveness of the LCA component breakdown and the impact that this might have on the overall results. 

However the pattern of results from these studies suggests that windpower, photovoltaic and nuclear energy technologies have markedly less impact on the environment than traditional fossil based fuel technologies.  None of the references addressed tidal turbine technology as a source of renewable energy.  

None of these studies examines what mix of technologies is required to provide a stable, secure source of energy which will meet demand on an hour by hour basis.  The stability, security and demand matching requirements for our energy supply will almost certainly lead to a base level of energy supply from non renewables added to our energy mix which will lessen considerably the environmental benefits being claimed through the use of windpower or other renewables alone.

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