The flaw in their reasoning is that, absent the construction of wind farms, all the economic activity that their model assigns to wind would not take place. Against this, they are counting the economic value of gas production in the UK, as if the gas would stay under the sea if it wasn't burned in new power stations.

Unless the construction of wind farms was actually going to crowd out other economic activity (which would require an overheated economy), it's not a fair comparison.

_{It is rightly acknowledged that people of faith have no monopoly of virtue - Queen Elizabeth II}