02 October 2020
The future of gas heating
Climate change has been a top priority in recent years and the race is on to find new ways to minimise carbon emissions and increase the efficiency of our buildings. The UK government has committed to reducing carbon emissions and one important way that it can help to do this is by phasing out gas heating.
Climate change has been a top priority in recent years and the race is on to find new ways to minimise carbon emissions and increase the efficiency of our buildings. The UK government has committed to reducing carbon emissions and one important way that it can help to do this is by phasing out gas heating. As part of this drive, in 2018 legislation was introduced to phase out inefficient gas boilers and a new regulation known as ‘Boiler Plus’ was introduced. This stipulates that all new combi boilers must be installed with an energy efficiency of 92%. The plan is to phase out the gas network almost completely by 2050 and in March 2019, I was confirmed that from 2025, installation of gas boilers in new homes will become illegal.
What’s the problem with gas heating?
Basically, the problem with gas heating is the emissions and the inefficiency caused by lost heat. Gas heating works by combustion which involves burning carbon based fuel to produce carbon dioxide and steam. Gas combustion emits 0.185kg of carbon dioxide (CO2) per kilowatt-hour (kWh) of heat generated with a system efficiency of 85% (source). This could be further increased to 0.203kg/kWh with distribution losses. Electricity in comparison emits 0.136kg of carbon dioxide per kilowatt-hour of heat with heat transfer offering a much higher system efficiency or up to 540%. (source)
What alternative fuels are there for heating?
The Committee on climate change recommends that the lowest cost, long term solution is to replace the millions of gas boilers across the UK with hydrogen alternatives alongside electric heating (generated from renewable sources). A hydrogen network could be the most viable alternative to natural gas. When burnt hydrogen, hydrogen produces only water and heat, there are no carbon emissions. Hydrogen can also be combined with natural gas to reduce carbon emissions. However hydrogen is produced by splitting water into hydrogen and oxygen (electrolysis) or by steam methane reforming (SMR), both of which would be expensive at the moment for the amount required. Production of hydrogen can also release carbon emissions and in order to make it completely carbon neutral, electrolysis would need to be powered by renewable energy and steam methane reforming would need to use carbon capture storage systems.
What other options are there to create heat?
There are also a number of alternative heat sources powered by electricity which have lowers carbon emissions than gas. Air-source heat pumps use heat from the ground, air or water to heat buildings and hot water. Ground source heat pumps absorb heat from the ground. Solar water heating systems also use solar panels fitted to the roof or the house to collect heat from the sun and use it to heat up water which is stored in a hot water cylinder. When combined with well insulated homes, these options could provide a viable alternative to gas heating.
Is green electricity the answer?
As the UK national grid is decarbonising rapidly, the carbon emissions from any form of electric heating will also fall. However, the national grid is unlikely to be able to reach the demand to heat all new houses with electricity. Other renewable energy sources such as solar panels and heat pumps powered by green electricity are an option but their energy transference has a relatively low-flow temperature when compared to a gas-fired boiler.
What heating systems can be used with renewable energy sources?
New heating systems that are installed will need to work with renewable heat sources in the future. Underfloor heating works with lower temperatures so is ideal for using with renewable heat sources including biomass boilers, solar thermal panels, air to water heat pumps and ground source heat pumps. It significantly reduces the call on heat sources compared to conventional radiator systems. They are more efficient but also have a slower response time than conventional heating, but it is possible to ensure that a comfortable temperature is maintained with the right control system. A system which divides a building into heating zones can also ensure efficiency by preventing the un-necessary heating of unused areas.
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