It’s a freezing cold overcast, windless winter day with all our fossil-fuelled and nuclear power stations shut down by the ‘greens’ and ‘nuclear-frees’ – whatever that may mean (since all carbon-based life is radio-active due to ingested potassium).

How do Eric Alexander and David Hampton (Free Press, October 3) propose that I get some electricity to run my home: from a dynamo fitted to my exercise bike? – Roderick Taylor, Bourne End