First microwave-powered home boiler could help cut emissions
The creators of the world’s first microwave-powered boiler have said it can provide a straightforward, zero-emissions replacement for the gas boilers that heat most homes in the UK.
The boiler uses electricity to heat water which can then be pumped through existing radiators and to taps and showers and baths. The company, Heat Wayv, is building prototypes and expects to trial the boilers in homes by the end of 2022, with the first sales to customers targeted for 2024. It says a unit suitable for a three- or four-bedroom home would cost about £3,500, the same as an equivalent gas boiler.
Heating produces 14% of the UK’s carbon emissions, and is one of the most difficult obstacles in the drive to reach net zero emissions by 2050. Gas boilers will be banned in new-build homes from 2025 and are expected to be phased out entirely by the mid 2030s.
The government is encouraging the installation of heat pumps, which are extremely efficient and cheap to run but have high upfront costs, can be disruptive to install and are not suitable for all properties. Hydrogen is also being suggested as a replacement for gas, but most experts think the supply of low-carbon hydrogen will be limited and expensive and would be best used for heavy industry and transport.
The Heat Wayv unit is the same size as a gas boiler and has 10 metres of pipe coiled inside, which is heated at multiple points along its length. The microwaves are produced by solid state components, which can be tuned specifically to heat water and better targeted than the magnetrons used in microwave ovens.
The electricity load will be about the same as an electric oven, the makers say. They say the boiler is 84% efficient in converting electricity into hot water, and another 12% of waste heat is recycled, giving a total efficiency of 96%. The company’s first product, a portable microwave heater, is now in production for military customers.
“The end of the gas boiler is inevitable and scheduled,” said Phil Stevens, a co-founder of Heat Wayv. He said heat pumps would have a place in the market for suitable homes, but his product was “a clean technology where the boiler will cost the consumer the same to buy and install as a gas boiler”.
Paul Atherton, another co-founder, said: “The beauty of our microwave boiler is that it is completely compatible with existing home radiators.” He said the company would initially target the 170,000 new homes built each year, which will not be allowed to install gas boilers from 2025. The company’s first product, a portable microwave heater, is now in production for military customers.
Experts contacted by the Guardian said the microwave boiler appeared credible, though the details of the product are confidential. The ability to be dropped in as a replacement for a gas boiler is a significant benefit, they said, though they would use more electricity and therefore cost more to run than heat pumps and gas boilers. One expert said the cheaper purchase price meant there was clearly a lifetime cost calculation to do to see how the costs balance out.
The rollout of electric vehicles already means the national electricity grid needs to be bolstered to accommodate the extra load, and the very widespread adoption of microwave boilers would add to that challenge, the experts said. The microwave boiler is not able to provide instant hot water, as gas boilers can, so it has a hot water storage tank inside the unit.
Some experts said homeowners may need to upgrade the main fuse in their home and may need their local electricity network to approve the installation of a microwave boiler, as required for larger heat pumps. Atherton said he did not envisage this but the company would be working closely with all stakeholders.
A US patent for a microwave-powered boiler was lodged in 1996, but this has expired, and in any case it proposed using a magnetron heater. “They are very much the sledgehammer of the microwave world,” said Stevens, unlike more the precise solid-state microwave generators.
• This article was amended on 16 March 2021 to clarify that while the microwave boilers are expected to cost the same as a gas boiler to buy and install, they will cost more to run.