Comment by Beth Warnock, Senior Power Systems Engineer, at Energy Systems Catapult.

I know when my gas boiler needs to be replaced, I will replace it with a heat pump. I will think about the cost, the hassle of installation and the uncertainty of heating my home in a different way. When I think about having a heat pump I only think about my home and the impact on my family. When I come to work as a power systems engineer, I start to think about the other side of the meter and the impact on the electricity network. In this blog it is the impact on the network I am going to consider.

Why a heat pump?

I have made a big assumption that I will have a heat pump in the future, but I have based this on project findings from Energy Systems Catapult. From the Electrification of Heat Demonstration Project, I have learnt that a heat pump can provide a warm home and is suitable for all property types. The Innovating to Net Zero 2024 report told me that millions of heat pumps will be installed as part of a low-cost Net Zero energy system.

Impact on the electricity network

I know I will be comfortable in my home with my heat pump, but when there are millions of them how will the electricity network be impacted? Consider the example of a street where every home has a heat pump. During an average winter day where the temperature is above freezing the heat pump demand will vary across the day. During an extremely cold day where the temperature is below freezing, the heat pump demand will be extremely high across the day for all homes in the street. Our ‘Neighbourhood Green’ project modelled this extreme cold scenario and found that distribution networks could be overloaded with the high demand.

I experienced a power cut when it was snowing, and my heating went off. Thankfully it was only a few hours and when my electricity came back on my gas boiler was able to heat my home up quickly. In the future when every home in a street could have a heat pump and there is a long power cut in cold temperatures, the impact on the network will be very different. The Catapults ‘Cold Start’ project, which looked at the impact of starting up heat pumps following an electricity outage, found that the peak demand could be double normal levels. In a worst-case scenario, it could take up to 10 hours to return to normal levels, potentially overloading the network and impacting consumers in their homes.

Peak heat

When I change my gas boiler for a heat pump I will be placing new demands on the electricity network. The most challenging times will be when it is coldest, when I most need to heat my home. So, what does the electricity network need to do to be ready for me to connect my heat pump?

As an industry we need to better understand how the weather affects heat pump demand on the electricity network. We need to understand the stresses that will be placed on the network when we have cold snaps and temperatures are below freezing for days and weeks at a time. We need to make sure our planning standards and security of supply standards consider these peak heat scenarios. Finally, we need to create planning and regulatory frameworks that allow distribution network operators to reinforce networks ahead of need to support the demands of a rapid roll out of heat pumps.

To maintain system resilience and reliability and to ensure we stay warm when we most need it, we need to start considering peak heat now. Please watch our short video highlighting these challenges and get in touch to see how the Catapult can help you meet the challenge of ‘peak heat’.