The owner of British Gas has placed a £1.5bn bet on the UK’s future reliance on fossil fuel imports after striking a deal to buy Europe’s biggest gas import terminal.

Centrica plans to partner with a US private equity firm to acquire the Isle of Grain terminal in Kent, which can import 15m tonnes of liquefied natural gas a year, even after Britain’s gas demand fell last year to its lowest level since the early 1990s.

The pair will buy the gas terminal from the FTSE 100 energy company National Grid, which in recent years has sold off its interests in Britain’s gas infrastructure in favour of investing in electricity grids.