England’s opening World Cup match against Croatia on June 17 could cause a sharp rise in electricity demand across the UK. Grid operators expect many fans to switch on kettles and kitchen appliances during breaks in play.

The National Energy System Operator (NESO) expects demand to jump by as much as 800 megawatts during the match. The biggest surge could come at half-time as hundreds of thousands of viewers make tea and prepare snacks.

That figure is higher than the 600-megawatt surge recorded during England’s 1966 World Cup victory. To handle the increase, grid operators will rely on power stations and storage facilities, including the Dinorwig hydroelectric plant in Wales.

Britain’s electricity system has changed dramatically since 1966. Coal supplied nearly three-quarters of the country’s electricity at the time. Today, the UK generates more than half of its electricity from wind and solar power.

The expanded World Cup includes 40 extra matches. Experts say this could raise total tournament-related electricity demand by up to 60%. However, modern televisions use less energy than older models. As a result, electricity use linked to watching matches has fallen by about 20% since 1998.

“This year’s World Cup will almost certainly be powered by the cleanest electricity in history,” Craig Dyke, Director of System Operations at NESO, said in a statement.

Football matches have triggered power surges across Europe for decades. In the UK, the largest football-related surge came during England’s 1990 World Cup semi-final against West Germany. Electricity demand jumped by 2.8 gigawatts within seconds. The surge matched the power needed to run more than one million kettles at the same time.