Articles
Decarbonising Heating
Carbon emissions from the National Grid are falling each year
With rapid decarbonisation of the National Grid, carbon emissions from electric heating are reducing each year. Defra publishes projections of the carbon grid intensity of the grid each year in grams of CO2 emitted for each kWh generated: gCO2/kWh.
By 2020 the carbon emissions from direct electric heating, using Grid electricity, will be lower than the carbon emissions from burning natural gas on site.
It is worth reviewing what the relative carbon emissions will be in 2022 for different forms of heating, using the BEIS projected grid carbon factor of 108 gCO2/kWh, compared to burning natural gas for heating:
| Fuel | Mechanism | System efficiency | Fuel carbon factor gCO2/kWh in 2022 |
Emissions vs natural gas |
| Coal | combustion | 75% | 321 | +98% |
| Biomass | combustion | 75% | 305 | +88% |
| Oil | combustion | 85% | 247 | +34% |
| LPG | combustion | 85% | 215 | +17% |
| Natural gas | combustion | 85% | 184 | - |
| Direct electric | resistance | 100% | 108 | -50% |
| Electricity / ASHP | heat transfer | 240% | 108 | -79% |
| Electricity / GSHP | heat transfer | 340% | 108 | -85% | Electricity / GSHC | heat transfer | 540% | 108 | -91% | Green Electricity / GSHC | heat transfer | 540% | - | -100% |
The lesson from the table is that if we want to reduce carbon emissions from heating we need to stop combustion.
Heating by heat transfer is the attractive alternative.
When is electric heating cheaper than gas heating?
It is already cheaper to run electric heating than gas heating in 2016 if using a ground source heat pump with a Co-efficient of Performance of 3.4 (compared to a gas boiler with a conversion efficiency of around 85%).
That is even before receiving the RHI.
A well installed commercial GSHP installation should achieve a CoP of well over 5 if recycling the heat derived from cooling in the summer through the ground for heating in winter: joined-up heating.
The savings will also be higher if a well-tuned control system is exploiting Demand Side Response to reduce the average cost of electricity used.
That was the position in 2016.
By 2020, when even direct electric heating will emit less CO2 than gas, the CO2 savings of using a ground source heat pump will be 82%, compared to burning natural gas. Savings would be 100% if green electricity were used.
The route to lower carbon emissions for heating
If we are serious about controlling carbon emissions, we need to stop combustion of carbon fuels and move towards the electrification of heat.
That means installing ground source heat pumps now.
Not just for off-gas grid areas, but for all on-electric grid areas as well.
See video on Balancing supply and demand for electricity.
Accumulated Carbon Emissions on BEN Project
The graph shows the accumulated carbon emissions from the BEN project over the next 20 years in blue.
The level of carbon emissions if the project had been continued to be heated by gas boilers is shown in orange.
The orange lines increase by the same amount each year.
The carbon emissions from using heat pumps decreases each year as the grid is decarbonised.
The graph uses projected decarbonisation rates for grid carbon intensity published by DEFRA.
The projected carbon emissions savings of using the Heat Sharing Network at LSBU amount to 7,287 tonnes of CO2e over twenty years.
Click on the graph for more detail.
