There is lots of excitement among greens this morning over an article by Mark Lynas, which purports to show that wind farms do not increase carbon emissions.
From analysing National Grid data of more than 4,000 half-hour periods over the last three months, a strong correlation between windiness and a reduction in gas-fired generation becomes clear. The exchange rate is about one for one: a megawatt hour of wind typically meant the UK grid used one less megawatt hour of gas-derived electricity. This means that actual CO2 savings can be calculated from the data with a high degree of accuracy – these are not guesstimates from models, but observations of real-world data.
Over a year, based on the amount of electricity wind is currently generating each day, wind turbines save around 6.1m tonnes of carbon dioxide, or about 4% of the UK's emissions from electricity (based on CCGT plants emitting around 350 kg CO2 per mWh). This figure provides independent confirmation for the trade body RenewableUK's estimate of a current reduction in annual emissions from the entire UK wind fleet of about 6m tonnes.
I haven't had a chance to go through this thoroughly, but at first glance the article appears to be entirely risible. The wind-sceptic argument is that efficiency losses in gas-fired generators offset (perhaps more than offset) any emissions savings from wind. So to show that wind power replaces gas-fired generation on a one-to-one basis is completely irrelevant seems to miss the point - it is a statement of the patently obvious, since supply (we hope) has to meet demand.
The question that needs to be addressed is that of the efficiency of the gas-fired generation that is still operating.
Or am I missing something in Lynas's argument?