Northern Ireland’s first minister, Arlene Foster, admits that her scheme has become a “debacle”

A botched green energy scheme that has ignited a political crisis is on course to cost taxpayers more than £1 billion.

The Treasury faces the bill after a massive overspend on subsidies encouraging farmers and businesses in Northern Ireland to run eco-friendly power schemes. The Renewable Heat Incentive (RHI) was supposed to cost £25 million in its first five years but the bill is likely to reach £1.15 billion over 20 years.

The Treasury can claw back £490 million from the block grant to Northern Ireland, leaving £660 million to be financed by taxpayers in England, Scotland and Wales. The scandal threatens the future of Northern Ireland’s first minister Arlene Foster, leader of the Democratic Unionist Party (DUP). She was the minister responsible when the