Options, Choices, Actions: How could the UK be low carbon by 2050?

Originally published in 2015, the ‘Options, Choices, Actions’ report illustrates two cost-optimised decarbonisation pathways for the UK energy system to meet its 2050 climate targets.

Delivered by Energy Systems Catapult for the Energy Technologies Institute (ETI) the updated report provides two plausible scenarios, Clockwork and Patchwork. These scenarios were developed using the internationally peer-reviewed Energy System Modelling Environment (ESME) – a national whole energy system planning capability managed and maintained by the Catapult.

  • Clockwork: this scenario uses socio-economic assumptions based largely on central government projections with the key exception that population is based on the Office for National Statistics “low migration” projection.
  • Patchwork: this scenario represents a qualitatively different economy, with a higher population projection and GDP growth.

Key points


  • The UK can achieve an affordable transition to a low carbon energy system over the next 35 years. Our modelling shows abatement costs ranging from 1-2% of GDP by 2050, with the potential to achieve the lower end of this range through effective planning.
  • The UK must focus on developing and proving a basket of the most promising supply and demand technology options. Developing a basket of options (rather than a single system blueprint) will help to limit inevitable implementation risks.
  • Key technology priorities for the UK energy system include bioenergy, carbon capture and storage (CCS), new nuclear, offshore wind, gaseous systems, the efficiency of vehicles and efficiency/heat provision for buildings.
  • It is critical to focus resources in the next decade on preparing these options for wide-scale deployment. By the mid-2020s crucial decisions must be made regarding infrastructure design for the long-term.
  • CCS and bioenergy are especially valuable. The most cost-effective system designs require zero or even “negative” emissions in sectors where decarbonisation is easiest, alleviating pressure in more difficult sectors.
  • High levels of intermittent renewables in the power sector and large swings in energy demand can be accommodated at a cost, but this requires a systems level approach to storage technologies, including heat, hydrogen and natural gas in addition to electricity.


  • Economic wealth is fuelled by innovation.
  • Limited potential for negative emissions meaning a more comprehensive reduction of gross emissions is required.
  • Electric systems provide over 70% of space heat by 2050.
  • Sales of internal combustion engine vehicles peak in 2020 – market shifts towards plug-in hybrid electric vehicles and pure battery electric vehicles – requiring substantial upgrades to electricity networks
  • By 2050 overall energy use for industry falls by 30% relative to today.
  • Industry adopts hydrogen early on.
  • Wind energy is the dominant electricity generation source – but the Patchwork18 electricity system can’t be fully decarbonised until after 2040.

The report shows that the capital cost of Clockwork (£2.26tn) and Patchwork (£2.39tn) is very similar reaching around 1% of GDP by 2050, with transport accounting for the bulk of this investment cost.

Visit the ETI’s website for more information.

Read the Report

Options, Choices, Actions: How could the UK be low carbon by 2050?

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