Do wind farms create more CO2 than they save?

Good question and here is part one of the answer with links to parts two to five. I warn you it's not a simple read;l here's an extract:

'This model, or calculator, provides a framework for the considerations involved and an interim assessment of their effects until sufficiently comprehensive studies can be performed in the areas indicated. It shows the impact on fossil fuel consumption and CO2 emissions compared to typical claims by wind proponents and other bodies, including some government policy makers. As it is parameter driven, the calculator allows examination of the sensitivity of these considerations. The result is that the typical claims are not supported, except by ignoring most of the following considerations:

* The amount of wind mirroring/shadowing backup required.
* Inefficient operation imposed on the mirroring/shadowing backup, in terms of both the fossil fuel consumption and CO2 emissions, treated separately.
* The need to make comparisons, with respect to gas plants, of:
o Case A – The more efficient Combined Cycle plants (CCGT) operating alone, in other words without the presence of wind, versus;
o Case B – The appropriate mix of gas plant type used to balance wind’s volatile output. This includes the need to introduce less efficient, but faster-reacting, Open Cycle Gas Turbine gas plants (OCGT) to mirror/shadow the wind production, especially as wind penetration increases.
* The effect of reduced wind capacity factor.
* The effect of wind output exceeding 1-2 percentage points of a total electricity system, on a country or regional basis.'