[olau]

The UK used to have very high subsidies for offshore wind for some reason. The last I've heard, subsidies for new plants are much lower today.

As for being cost effective, onshore wind is probably the cheapest option, and I think it's hoped that offshore will come close to that once more of the learning curve has been traversed. Perhaps fossil gas from the North sea is still cheaper for now, if you ignore the external cost.

I think solar power is even cheaper, but doesn't deliver much in the winter so far up north.

Backup: Batteries are cost effective for short term shortages. For long term shortages, you'd fire up thermal plants, either biomass or biogas (fossil gas for now).

It doesn't make sense to back up wind with nuclear. Nuclear has a high capital cost and relatively low running costs, so you don't save much from being standby but you still need to pay back the loans.