Energy supplies are on a "rollercoaster" that's heading "downhill fast", the head of regulator Ofgem has warned.
Ofgem Chief Executive Alistair Buchanan told consumers and businesses to prepare for higher prices as power plants close, foreign gas supplies shrink and increasing demand tightens the British energy market.
Writing in The Daily Telegraph, Mr Buchanan said, "We have to face the likelihood that avoiding power shortages will also carry a price".
"If you can imagine a ride on a rollercoaster at a fairground, then this winter we are at the top of the circuit and we head downhill - fast," he continued. "Within three years we will see reserve margin of generation fall from below 14 percent to below five percent".
"That is uncomfortably tight", Mr Buchanan added.