The UK – despite assurances to parliament from energy secretary Amber Rudd this summer – is on a trajectory to come up 50TWh shy of its pledged 15% 2020 obligation to the EU, a shortfall of nearly 25%, a letter written by Rudd and leaked to the environmentalist magazine shows.

The government is considering bridging the gap with biofuel production and purchasing renewable energy from countries such as hydropower giant Norway, as well as buying "credits" from outside Britain.

The