Will the switch to heat pumps cause more blackouts?

OPINION | By Ali Ehsan and Robin Preece, The University of Manchester > In its bid to achieve the target of net-zero emissions by 2050, the UK government aims to install 600,000 heat pumps a year by 2028. The increased electricity demand caused by heat pumps could place an unmanageable strain on the electricity grid putting it at risk of blackouts.

Without additional investments in our electricity networks and additional innovations in how we use electricity, such blackouts will be more likely. There are solutions out there to reduce this risk but these cost money and need government policies, financial incentives and public acceptance.

Currently, more than 80% of domestic heating in Great Britain is supplied by gas boilers. This is not compatible with the target – set in law by the UK Government – of reducing greenhouse gas emissions to net zero by 2050. The International Energy Agency have called for global action to ban gas boilers from 2025, driving a switch to heat pumps instead. Heat pumps use electricity and collect heat from the air or ground outside and use this to warm your home. They are more efficient than just using electric plug-in radiators. As with vehicles, this electrification will only result in decarbonisation if the electricity is green. Fortunately, the UK’s national grid is getting greener year on year with more wind and solar generation, and the closure of fossil fuel power plants. It is forecasted that the UK electricity production will be zero carbon by 2035.

The challenges

The future challenges for improving the electrical grid – the network of overhead lines and cables that gets the electricity from generators to consumers – are twofold.

The first challenge will be handling the network constraints with all the extra demand that comes from electrifying heating. There’s only so much power you can get through a line or cable before it overheats and fails – leaving the consumers without power. For instance, 6.30pm is the daily electricity demand peak on account of many people getting back home and turning on their appliances. If everyone were to use their heat pumps at the same time, there would be large parts of the grid which cannot handle the power demand.

The grid is built on the basis that we don’t all do the same thing at the same time. We put the kettle on at different times. We use our electric showers at different times. Just like we don’t build roads to handle all cars at once, we build electrical networks that can cope with the busiest peak-time demand. Adding in lots of synchronised heating demand will result in lots of network bottlenecks. So it will be vital to physically upgrade the electricity network, incurring cost to be added on to everyone’s bill. One study estimates that 5.7 million heat pumps installed by 2035 would require reinforcement of 42% of the distribution network at a cost of £40.7Bn. That’s quite a hefty £1500 per electricity consumer.

That first challenge is about getting the electricity through the network to where it’s needed. This assumes that there’s enough generation to provide the power needed at the right times. This isn’t at all guaranteed.

The second major challenge is the combination of increased electricity demand coupled with inflexible generation. Heat usage fluctuates depending on the time of day and year, and so heat pumps will not only increase electricity demand but will also make it spikier. At the same time, the generation mix is mostly switching to inflexible sources that cannot respond to the sudden changes in demand, including wind power because of unpredictable weather and nuclear power due to slow start-up. This is already making it more costly to maintain the electricity demand-supply balance – the balancing costs during 2019-20 reached £1.3B, a 50% increase from 2015-16 (£867M).

The solutions

So we will need to use the electricity when it is available, and when the network has the spare capacity to get it to where it needs to be. This can be achieved using flexibility services such as demand side management – which basically shifts electricity usage from peak periods to the times when there is more electricity available across the country. A study at Imperial College found that flexibility solutions can save up to £4.7 billion a year by 2030 by deferring the upgrade of generation and network capacity.

This would mean people would need to heat their homes when it’s cheap to do so and not just when they want the heating on. But this needs well insulated homes to lock in the heat, and a change in behaviour that may will probably need to be driven by financial incentives. For example, residents in apartment blocks already use night storage heaters to benefit from Economy 7 tariffs with cheap electricity overnight.

We will need better insulation and innovative building materials to make buildings more energy efficient, along with advances in Internet of Things applications that will make smart devices ‘talk’ with each other to optimise electricity usage in the background. For example, smart charging points ensure that the electric vehicles are charged overnight at homes at the best times; whether that’s when electricity is cheapest, or even when it’s greenest. Heat pumps will likely go the same way – optimised by smart thermostats to save energy. We already see smart thermostats creating automatic temperature settings based on their daily routines and heating needs with sensors and artificial intelligence. If this can be extended to optimise usage against cost and energy availability as well – this should help to curb rising electricity demands.

The alternative, if these solutions are not effectively implemented, would be to rely on gas power plants for the spikes in electricity, particularly during low wind and cold spells when there is not enough renewable energy and demand for heat is high. That will mean that we’re still effectively using gas to heat homes which defeats the purpose of using heat pumps in the first place.

Heat pumps are a key step in our transition to net zero. But we must invest in our electricity network and become more flexible in how we use energy to keep the lights (and the heating) on.

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