Carbon Brief today has a decent post on whether offshore wind farms will become less expensive in the next decade. To summarize the post they say that offshore wind is expected to become cheaper, but that technology cost reductions may be partly offset by the need to build offshore wind farms in deeper water. They quote Guy Doyle of Mott MacDonald saying:
Doyle says the costs of offshore wind will go down as more efficient turbines are developed and economies of scale start make developing wind farms easier. But the more turbines are built, the further out to sea they will be – so building them in deeper water will offset some of the cost reductions by making the process more difficult.
This is true, but there are some important caveats. Consider regions around the UK at different depth bands, and bare in mind that currently the deepest offshore windfarm is about 45m, and currently planned offshore windfarms are no deeper than about 60m.
What leaps out is that the sea bed depth problem is much more of an issue for Scotland’s offshore windfarms. This is probably why the Scottish government has already proposed giving higher subsidies for deep offshore windfarms. For context around 40% of the UK’s offshore wind resource is off the Scottish coast. So, in summary the claim that “the more turbines are built, the further out to sea they will be” is true, but it is more much truer in some parts of the UK than others.