By Barny Evans – Technical Director, WSP
For heat there are two main choices: electricity or hydrogen. Both can deliver very low-carbon heat. The challenge is that, unlike electric vehicles or LED lighting, the solutions are not all win-win. Electric vehicles not only enable us to decarbonise surface transport, they are also more reliable, quieter, faster and cheaper to run than fossil fuel vehicles. They will even be cheaper to buy soon. The issue for heat is that neither electricity nor hydrogen will be cheaper to buy or operate than gas in the near future.
For heating buildings, electric heat pumps are a wonderful solution used around the world. They emit no air pollution and are very low carbon. They are very efficient, delivering around three units of heat for each unit of electricity it takes to run them. In contrast, a gas boiler provides 0.8 units of heat per unit of gas. But with a residential price for electricity of 15p per kWh and 3p per kWh for gas, heat pumps are not going to save you a lot of money, if any. And installing a residential heat pump system will cost £6k to £10k, compared to around £2.5k for a boiler.
The government is effectively mandating heat pumps for new-build homes from 2025, but that still leaves the existing building stock. For the time being, gas boilers will endure in many buildings, although natural gas may be blended with hydrogen. This may provide a small reduction in CO2 emissions from domestic heating and other gas-boiler systems before buildings can be retrofitted with low-carbon heating.
For the high temperature heat sector, the cost of hydrogen or electrification is also the problem in the near term. Hydrogen can be made from natural gas, but this process is only 75% efficient, and you still need to capture the CO2 emissions from the process. Electrolysis can also be used to generate hydrogen, but this is even less efficient. With electrification, heat pumps don’t work at high temperatures needed for some industries, so you have to use electricity directly, meaning you only get one unit of heat per unit of electricity and the cost is several times that of natural gas.
The good news for both buildings and the high-temperature heat sector is that there are solutions. Heat pumps will get cheaper and serve more sources, electricity prices will fall, hydrogen can be made in a variety of ways and will get cheaper – with carbon capture and storage also coming on stream. There are plans to make electricity and hydrogen prices more competitive, through a carbon tax or more equal loading of environmental taxes, and the requirement for new-build homes to use heat pumps will develop the supply chain.
The end result will be a zero-carbon sector emitting much less air pollution, but we need to act now if we are to achieve net zero by 2050; in some cases the next time we replace a heating system maybe the last before that date. The public needs to understand that heating technologies are changing. The commercial sector needs to make long-term investment plans for moving buildings to low-carbon heating, with government mandating its use and easing the transition. High-temperature industries need to trial electric and hydrogen solutions, supported by government. And for homes, there needs to be a long-term approach to retrofitting low-carbon heating – addressing the supply chain, skills and energy literacy.
We all have a role to play. At WSP, we first called for all-electric cities in 2014. More recently we have worked with home builders on a zero-carbon heating plan, worked with a global retailer on a heat decarbonisation programme, and are working on the HyNet North West programme on hydrogen CO2 pipelines. We welcome conversations with those on the same journey; because we need to talk about heat.