Ambitious targets to reduce the UK's carbon emissions to zero by 2050 means heating boilers are at the top of the 'hit list' for change, says Nik Holland.
06 January 2020 | Nik Holland
One of the most challenging aspects of the government's ambitious 2050 carbon zero target involves how we will heat buildings without the use of fossil fuels.
Heating accounts for over a third of the UK's greenhouse gas emissions; it's likely that by 2050, fossil fuels we burn for heat will have been phased out. This includes gas and oil - key components in the 40 million domestic and commercial central heating systems now in operation across the UK.
Alternatives to fossil fuels exist, but there isn't a convenient option. Chris Stark, CEO of the Committee on Climate Change, admits that "it will be extraordinarily difficult to hit 2050 without a plan in place for heat very quickly".
In recent years, adoption of electric heat pumps and biomass boilers has climbed but the numbers remain low.
Going off the boil
There are around 26 million commercial boilers in the UK, which will all need phasing out by 2050. Schemes are being introduced that will involve the replacement of boilers with electrically driven heat pumps, either a ground or air source.
The government estimates that to meet its 2050 targets, two million heat pumps will need to have been installed by 2025 and 15 million by 2035.
While exchanging a small boiler for a heat pump would create warmth, most buildings use radiators sized for a boiler that outputs water at 80°C. At best, a heat pump can achieve a water temperature between 50 and 55°C, and the efficiency deteriorates the higher this temperature is pushed.
Radiators used in most small commercial heating systems are too small to transfer sufficient heat from such a low temperature heating medium. In new-builds, this is less of an issue as their construction can incorporate underfloor heating with the entire floor acting as a heat exchanger and capable of accepting a much lower temperature heating medium.
But retrofitting underfloor heating is both expensive and disruptive. Replacing radiators with underfloor heating involves ripping up floors to lay pipes, screeding, installing new pipe manifolds and control systems and can only be done if the building has solid floors - floorboards with a void below present new issues.
Boilers within industry can be many orders of magnitude larger than those we are familiar with in smaller offices, and many industrial processes can require heat at many hundreds of degrees or even higher - for which heat pumps are not a solution.
It's gas, only greener
Using biomethane or biogas to replace natural gas that would burn in a conventional boiler is a possible solution. They are more carbon-friendly but their availability is limited.
Produced by small-scale units, biogas is often a by-product of other processes or produced from landfill, sewage works and food waste. Generating larger quantities through expanded biogas plants would be challenging, especially when current measures of biogas now entering the grid are so small they are practically irrelevant.
Hydrogen may be the only substance we can burn where nothing else can replace fossil fuels - some high temperature heating in industry, for example, that can only come from a flame/combustion may have to be done with hydrogen.
However, it's not clear how practical it is at scale for space heating. For most applications, you'd be better off just using the electricity it would take to make the hydrogen in a non-heat pump electric heater.
Businesses need to consider how they will adapt, and for any refurbishment or construction of new buildings now or in the near future, the time to act is now.
Nik Holland is manager - operations and regulatory intelligence at Kinect Energy Group