<P> In a typical study of a wind farms Life cycle assessment (LCA), in isolation, it usually results in similar findings as the following 2006 analysis of 3 installations in the US Midwest, were the carbon dioxide (co2) emissions of wind power ranged from 14 to 33 metric ton per GWh (14 - 33 g CO / kWh) of energy produced, with most of the CO emissions coming from the production of concrete for wind - turbine foundations . </P> <P> However, when approached from the effects on the grid as a whole, that assess wind turbines' ability to reduce a country's total electric grid emission intensity, a study by the Irish national grid, a grid that is predominately (~ 70%) powered by fossil gas, (and if it was 100% gas, would result in emissions of 410 - 650 g CO / kWh .) found that although "Producing electricity from wind reduces the consumption of fossil fuels and therefore leads to (electric grid) emissions savings", with findings in reductions of the grid - wide CO emissions to 0.33 - 0.59 metric ton of CO per MWh (330 - 590 g CO / kWh). </P> <P> These findings were of relatively "low (emission) savings", as presented in the Journal of Energy Policy, and were largely due to an over-reliance on the results from the analysis of wind farms LCAs in isolation . As high electric grid penetration by intermittent power sources e.g. wind power, sources which have low capacity factors due to the weather, either requires the construction of transmission to neighbouring areas, energy storage projects like the 292 MW Turlough Hill Power Station, that have their own additional emission intensity which must be accounted for, or the more common practice of requiring a higher reliance on fossil fuels than the spinning reserve requirements necessary to back - up the more dependable / baseload power sources, such as hydropower and nuclear energy . </P> <P> This higher dependence on back - up / Load following power plants to ensure a steady power grid output has the knock - on - effect of more frequent inefficient (in CO eg / kW h) throttling up and down of these other power sources in the grid to accommodate the intermittent power source's variable output . When one includes the intermittent sources total effect it has on other power sources in the grid system, that is, including these inefficient start up emissions of backup power sources to cater for wind energy, into wind energy's total system wide life cycle, this results in a higher real - world emission intensity related to wind energy than the in - isolation g / kW h value, a statistic that is determined by looking at the power source in isolation and thus ignores all down - stream detrimental / inefficiency effects it has on the grid . In a 2012 paper that appeared in the Journal of Industrial Ecology it states . </P>

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