Whisper it softly, but a clean, green solution to the energy industry’s most intractable climate conundrums may be in sight — and it is almost as old as time itself.

Many experts believe that the transport industry can never be decarbonised using renewable energy alone; that heat cannot be produced on a massive scale without burning hydrocarbons; and that intermittent wind and solar will never be able to cover the so-called seasonal gap in winter, when there is simply not enough sun or wind to produce the energy needed to meet peak demand, no matter how much is stored in batteries or pumped hydro plants.