Heathrow 'forced to shut down because of net zero' --Airport bosses face accusations that back-up power supply failed after they replaced diesel generator with biomass version | 21 March 2025 | Heathrow is facing accusations that it was forced to shut down because it replaced its diesel generator with a net zero-compliant biomass alternative. More than 1,300 flights to and from the UK's busiest airport were cancelled or turned away after it was forced to close following a fire that knocked out a electricity substation. Richard Tice, the deputy leader of Reform UK, said he had been told by an industry expert that the airport changed its back-up systems from a diesel generator to an environmentally friendly biomass version. He said the biomass generator appeared to have failed because it was designed only to work alongside the National Grid, and not independently if the Grid was shut off... The accusations came as it emerged counter-terrorism police were leading the investigation into the fire. The Telegraph understands specialist detectives are on site at the North Hyde electrical substation after a blast there shortly before midnight.