The UK has achieved a remarkable reduction in Carbon Intensity of the UK grid from 1990 base levels. There are a number of different statistical time series published.
For the graph opposite we have combined the historical data from BEIS , UK Greenhouse gas Emissions National Statistics 1990-2018 (2018 provisional series) with reference points provided by the UK Government GHG Conversion Factors for Company Reporting (2015- 2019 series) which provides figures for generation and transmission and distribution. The projected figures are taken from BEIS EEP2018 projected Figure 5.2: Emissions intensity (all power producers) modified to include transmission and distribute and scaled to match 2018/208 Greenhouse gas reporting series. We have the extrapolated 2035 projected data to netzero by 2050. This provides a single reference set of carbon intensity from UK grid electricity as delivered from 1990 to 2050.
This second graph is the time period from 2018 to 2035 on the same basis as above. Also on the same graph we have plotted the effective carbon intensity of heat supplied by natural gas. The number shown (0.242tCO2e) is assuming a high efficiency condensing gas boiler.
The diagram shows that UK national grid average will be lower than gas as early as 2021 and this in turn means that even electric resistance heating will offer carbon savings over gas from 2022 onwards. In actual fact it will be possible to deliver heat through electricity at much lower carbon intensities following several pathways – See Heat Trajectory.
The above trajectory for carbon intensity of grid electricity shows that grid electricity will offer very significant carbon savings from 2020 to 2035. Moreover , this is the grid average figure. If power is used intermittently then it will be possible to consider a strategy to time switch to use power preferentially at times when the grid carbon intensity is lower and shed load when it is higher. See https://carbonintensity.org.uk/ This site has regional and time of day data.
See here for data plotted as dashboard: https://www.mygridgb.co.uk/dashboard/
The falling carbon intensity of the grid also means that where there are on-site renewable energy assets, the carbon credit for export of power will also fall. Therefore to obtain maximum carbon benefit from those assets power generated locally should be used locally to reduce overall grid consumption.