Traditional heating systems utilize carbon compounds such as coal, oil and gas in a combustion reaction to release heat; this also releases dioxides of sulphur, nitrogen and carbon as well as particulate matter such as soot. This concoction compromises local air quality and presents a danger to human health, while the increasing carbon dioxide levels are becoming dangerous.
Emissions from UK buildings – much of which can be attributed to heating them – represented 19% of the UK’s overall emissions in 2017. With around 85% of UK homes utilizing the gas network for heating and amid rising concerns over the environmental impact this is having, the Government has realized that we need to rethink the way we heat our homes.
But changing how we do this isn’t going to be easy; there is no ‘best way’ or ‘winning fuel’, and it is going to require investment whichever route is taken.
The UK Committee on Climate Change – who offer independent advice to the Government on building a low carbon economy and preparing for climate change – explain that the Government requires all homes to have an energy efficiency rating of band C by 2035, and no new homes connected to the gas grid from 2025. They expect to reduce the emissions from heating UK buildings by using heat pumps and low-carbon heat networks.
Clean heating utilizes heat pumps or solar thermal panels combined with thermal energy storage to provide heat without releasing carbon dioxide, noxious gases or particulate matter. Heat pumps transfer and concentrate heat from one place to another, rather than converting electricity to heat.
Air source heat pumps transfer heat from the outside to the inside of a building using a compression cycle to concentrate the heat from air outside up to the temperature required to heat the building inside. Ground source heat pumps also transfer heat from the outside of a building to the inside, but requires less electrical input as the ground is always warmer than the air.
Utilizing heat pumps is efficient as the electricity it consumes is used to transfer existing heat, rather than converting electricity to heat. For comparison:
- An electric bar heater converts 1kW of electricity into 1kW of heat.
- An air source heat pump transfers 2.5-3kW of heat into a building using 1kW of electricity.
- A ground source heat pump transfers 3.5-4kW of heat into a building using 1kW of electricity.
Heat pumps can also be used for cooling in the summer, with air source pumps requiring more electricity as they are pumping heat against the natural direction of travel. Ground source pumps are more efficient as heat will move freely towards the cold ground given a chance.
It’s estimated that heat pumps could be used in over half of the four million UK households not connected to the main gas network, and could be supplemented with other technology. This may well represent a low-cost option where homes are sufficiently insulated, or could affordably be made so. Hybrid heat pumps or biomass boilers might be a viable alternative on harder to insulate homes where fitting an all-electric heat pump might be expensive.
Utilizing hydrogen instead of natural gas to heat buildings is another idea also under consideration, but this needs to be fully explored and proven safe. The use of hydrogen is still in its infancy, and there are many issues still to be resolved, including how hydrogen will be produced and distributed as well as those concerning its cost and required expertise.
There are steps to be taken even before clean heating is considered. Homes should be reducing their demand by becoming more energy efficient – using less is the cleanest and cheapest way forward. New builds are expected to be as energy efficient as possible, and incentives should be offered to bring older homes up to the same level. Since the cost of hydrogen technology, heat pumps and hybrid pumps are all fairly similar, it’s clear that there is no easy solution to decarbonizing heating, but any route chosen is a step in the direction of reducing carbon dioxide emissions and improving the health of the population and the planet.
References and Further Reading