This question was asked of the British Government recently and here is their reply:
RE: Empirical measurement of fossil fuel displacement by wind power
Thank you for your Freedom of Information requests received on 1 May 2011.
Your requests, received 1 May from Dr John R. Etherington
“Has any attempt been made to relate the short term variation of ACTUAL fuel-use by load-following plant to metered wind power feed-in? If so, can the figures be provided, expressed as tonnes of CO2 actually saved per MWh of wind generated electricity?
If no such attempt has been made why not, as carbon-fuel displacement is the only justification for deploying expensive, and covertly subsidised wind power?”
We have considered your request in accordance with the Environmental Regulations 2004 (EIRs) as the information you sought disclosure of, does in our view, fall within the definition of `environmental information’ as stated in the EIRs. We have now completed searching for the information you requested.
In order to determine the relation of the short term variation of actual fuel-use by load-following plant to metered wind power feed-in, we would need to know what fuel use would have occurred in the absence of wind power (i.e. the counterfactual).
This counterfactual (the fuel use in the absence of wind power) depends on the proportions of nuclear, CCGT or coal investment that are being displaced by wind power and the effects on their subsequent operation. Such a counterfactual can only be calculated by modelling a world without wind power and by subsequently comparing it to the current data on emissions from the grid. No such analysis has been carried out by DECC.
HT: Phillip Bratby
And so we do not actually know the answer to that question. I think this response by the DECC is important for everywhere to realize the truth. No one actually knows the answer on whether wind turbines decrease CO2 emissions and likewise decrease other emissions from normal power plants. In this insane zeal to decrease pollution of all types we have grabbed this delusional thought that we must build the industrial monsters and in the end its nothing but a waste of time and resources. So why do people think they decrease CO2 emissions? That belief comes from the belief that we should only count one side of the equation, namely the side that shows the benefit of Wind Turbines and not look at how it increases emissions as well due to its intermittent nature. The numbers run at the above link indeed show that its likely that adding wind above a certain threshold actually INCREASES CO2 emissions and the best case scenario turns out to be 10% savings assuming everything works perfectly. So somewhere between -10% savings and 10% savings is the probable result of adding wind to the grid in terms of CO2 emissions. In other words, it’s just as likely that we save zero in CO2 emissions than we do not.
Until someone actually does the difficult job of figuring out the real result, adding more wind to the grid is a fool’s errand that only accomplishes higher power bills for the poor and tax breaks for the rich. Other than the regressive tax that wind really brings, which is probably good for the rich who buy into these pork barrel products, there is not one good thing to their name. I think its time to answer this question once and for all so that we stop enriching our rich land-owners at the cost of the poor for no reason.