The world’s largest offshore wind farm is not going to be expanded, at least for now. Covering 100 square kilometres, the London Array is not exactly small, but you might argue it is beautiful. (Its vast scale can be seen in satellite photos.) However the potential threat to a bird, the red throated diver, has resulted in expansion plans being held back. We are to await “certainty” about the impacts of the expansion on the red throated diver. Now, as someone who works in mathematical ecology, I am somewhat aware of how difficult it is to get certainty on this. And anyone who has read government rulings on these things will know a large element of subjective judgement enters the business. How many birds can a wind farm kill each year for it to threaten the population? Science can only really give a rough quantitative answer. It can also only provide a rough estimate of how many birds the wind farm will kill. Uncertainty reigns. However government rulings will require something more concrete, while lobbyists (often invoking the precautionary principle) will demand a much lower “bird kill” threshold.
The decision to go ahead with this thing is therefore not based on anything particularly rigorous, and is rather dependent on how much value you would put on a red throated diver. Here we get to the problem of the precautionary approach to things. If we do not build this wind farm we will have to build something else. Is there evidence that alternative is preferable? Making offshore wind farms more expensive in order to protect the occasional bird will do something rather obvious: make them more expensive, and perhaps increase carbon emissions. Which is worse? A little more carbon dioxide in the atmosphere or a few dead birds.
And wind farms are damned well expensive already. Do we need to make them more expensive? Greater environmental restrictions on offshore wind farms may result in more nuclear power plants being built. Is nuclear power better for birds? The evidence for or against this proposition has never been put together, as far as I know.
A very simple calculation. The power density of the London Array is about 2.5 watts per square metre, while British electricity consumption is a bit over 40 GW on average. If Britain wants to get all of its electricity from offshore wind then, using the London Array as a base case, we will need to cover about 20,000 square kilometres of sea in wind farms, or to put that in the typical British unit: an area the size of Wales. This is shown in the map below. And if we want to decarbonise the economy we will likely have to at least double, maybe triple electricity production. Can we really build offshore wind on this scale without environmental groups compromising on some of their principles? Are we really able to find enough “right places” as defined by the Royal Society for the Protection of Birds? And will we abandon the precautionary approach for something more suited to the day?