Heatpumps or Hydrogen? The future of clean energy

Heat accounts for 45% of the UK’s energy use. As part of our push for Net Zero Carbon 2050, we must tackle the decarbonisation of heat. The obvious way is to omit fossil fuels from the mix. 

Electricity is set to become the main source of future clean heat.  As our electricity network continues to decarbonise, through renewable energy generation, so will our heating.* 

Heatpumps

Electrification of heat isn’t new, resistive heating (including Infra-red heating) has been deployed for decades and is incredibly efficient (1kW electricity used ≈ 1kW of heat output). However, heatpumps (which work via a reverse refrigeration cycle) offer increased efficiencies, with a Seasonal Co-efficient of Performance (SCOP) with an average of 3-4. This means for every kW of electricity used, 3-4kW of heat is provided. Therefore, heatpumps are an essential part of the UKs decarbonisation strategy.

Reducing the demand for energy

If we simply replace reliance on fossil fuels with electrification on a kW for kW basis, we may have an issue. The ratio factor (SCOP) is important. The average peak demand for gas in the UK is currently about four times peak winter electricity demand. 

Reducing the thermal demands of existing buildings through extensive retrofit strategies and ensuring Near Zero Energy Build (NZEB) standards are embedded in new builds, lowers energy demand.

Thermally efficient buildings require less energy for heating. In some instances, direct electrification of heat can be considered. NZEBs and Passivhaus designed buildings need such low thermal input that heatpumps may be an ‘over engineered’ solution.  Infrared panel heaters, electric underfloor heating and smart electrical thermal storage all become viable options. 

They provide both lower product and installation costs, reduced / eliminated maintenance costs and lower embedded CO₂ and energy. They also remove any concerns about ‘F’ gas losses in manufacturing and maintenance. Smart thermal storage can also aid in balancing the grid. This is currently being trialled with ECA Associates, Glen Dimplex and the Kaluza platform.

Hydrogen

Hydrogen is likely to play a part in providing clean heat.  There is considerable investment in this area and Hydrogen-ready boilers are already appearing. The village of Winlaton, near Newcastle will soon be running on 20% blended hydrogen as part of a test case.  However, hydrogen should only be considered where it is produced solely through excess renewable energy generation (green hydrogen). Even then, it is far more efficient to use electricity. 

Our heating systems of the future will involve a mix of technologies and a useful projection can be seen in the following graphic from UK Energy Research .

Source: UK Energy Research Council The pathway to net zero heating https://d2e1qxpsswcpgz.cloudfront.net/uploads/2020/09/The_pathway_to_net_zero_heating_UKERC_briefing.pdf

*Note: SAP 10.1 already cites electricity as having 0.136 CO₂e per kWh vs 0.21 CO₂e per kWh for natural gas