The government has outlined three possible pathways towards the decarbonisation of the economy in its long-awaited Net Zero Strategy.
The strategy noted that the three scenarios – high electrification, high resource and high innovation – are only intended to be illustrative, representing a range of practical ways in which net zero could be delivered rather than the mostly likely or preferred solutions.
High electrification
The high electrification scenario would see the widespread electrification of transport, heating and industry supported by the deep decarbonisation of the power sector. A majority of buildings would use electric heating, with the rest connected to low-carbon heat networks.
Annual electricity generation would more than double to 690TWh, primarily through the deployment of renewables and nuclear, although there would also be some solar, gas with carbon capture and storage (CCS) and bioenergy with carbon capture and storage (BECCS).
A significant share of this electricity would be used to power the production of green hydrogen through electrolysis. Overall hydrogen production would rise to 240TWh per year by 2050, with some also being produced from bioenergy and waste. None of this hydrogen would be used to heat buildings or for electricity generation, instead being split equally between transport and industry. No blue hydrogen would be produced by reforming natural gas.
Residual emissions from aviation, agriculture and waste would offset using afforestation, BECCS and direct air carbon capture and storage (DACCS).
Energy generation and end uses
Residual emissions and offsets
High resource
In this scenario, most heat demand for buildings would be met using hydrogen, although electric heat pumps and heat networks would still play a significant role.
Accordingly, hydrogen production would be much greater at 500TWh per year, with blue hydrogen accounting for the vast majority. There would be increased demand for hydrogen in the transport and some would also be used to generation.
Annual electricity generation would be slightly lower at 610TWh and a much smaller proportion would come from nuclear.
More trees would be planted to offset the additional residual emissions from blue hydrogen production.
Energy generation and end uses
Residual emissions and offsets
High innovation
In the high innovation scenario, improvements in aviation, carbon capture and negative emissions technology would allow other sectors such transport, buildings, agriculture and industry to decarbonise to a lesser extent.
Annual electricity generation and hydrogen production would fall in between the previous two scenarios as 670TWh and 330TWh respectively. Nuclear power would account for a lower proportion of electricity generation than in first scenario.
Like the second scenario, hydrogen would be used to heat building and generate electricity, and most of this would be produced by reforming natural gas, although a higher proportion would come from electrolysis.
Energy generation and end uses
Residual emissions and offsets
Insights and uncertainties
Despite the differences between its illustrative pathways, the government said some broad conclusions can be drawn.
Extensive decarbonisation will be required across buildings, transport and industry given the need to offset residual emissions in other sectors such as aviation and agriculture and possible limitations on the deployment of greenhouse gas removals, and extensive energy efficiency improvements across these sectors will be beneficial in reducing energy demand and costs.
Demand for electricity and hydrogen will grow significantly and both will need to be produced with very low levels of emissions by 2050. Energy sources will diversify and will become more interdependent to ensure security of supply.
Given the need for some residual emissions, it is appropriate to plan for greenhouse gas removals, including carbon capture which is likely to play a significant role in wider decarbonisation, for example in the power sector.
One of the most significant decisions affecting the UK’s pathway to net zero will concern the balance of low-carbon heating solutions deployed in buildings – mainly electricity and hydrogen – which will have a substantial impact on the overall demand for each.