Phasing out 'unabated fossil fuels': the importance of defining 'abatement'

Please note, this briefing paper has been updated since its original publication in October 2024 to reflect new research and evidence on the topic.

This briefing paper has also been published individually as a webpage: Phasing out 'unabated fossil fuels': the importance of defining 'abatement'

Authors: Dr Alaa Al Khourdajie, Dr Chris Bataille and Jennifer Bird. 

Media enquiries: grantham.media@imperial.ac.uk  
Research enquiries: a.alkhourdajie@imperial.ac.uk 
Policy enquiries: j.bird@imperial.ac.uk   

Ahead of COP28 (in 2023), several influential stakeholders — including the UK, G7 and European Council — called for the phase out of 'unabated fossil fuel'. This was different to calling for the phase out of fossil fuels (which refers to phasing out all fossil fuels) because it would have permitted some continued usage of fossil fuels, so long as they were 'abated'. The final COP28 text emphasised: “transitioning away from fossil fuels in energy systems in a just, orderly and equitable manner, accelerating action in this critical decade, so as to achieve net zero by 2050 in keeping with the science” as well as “accelerating efforts towards the phase-down of unabated coal power”.

The issue is that while 'abated' is generally understood to mean that some form of Carbon Capture and Storage (CCS) technology would be used to capture the emissions, there is currently no formally agreed definition of the standard to which this would be expected to operate either for coal or other fossil fuels.  A clear definition is needed for all fossil fuels to avoid ambiguities and to help guide international negotiations, policy development and investment decisions. 

This background briefing explains why defining 'abatement' is important, how it could be defined and the limitations of abatement (specifically, how it relates to carbon capture and storage technology). 

Key points

• To achieve our climate goals, total global fossil fuel production needs to fall substantially, even in a scenario where 'abated' fossil fuels are permitted.
• The primary purpose of fitting fossil fuel plants and industrial facilities with Carbon Capture and Storage (CCS) is to almost entirely eliminate their carbon dioxide emissions. In practice, however, many applications fall short of this standard. The label 'abated' should properly refer only to this state of near-complete decarbonisation, as this is the level of performance necessary to meet the goals of the Paris Agreement. The critical issue is that 'abatement' lacks such a formal, internationally agreed definition. This ambiguity allows for inconsistent application, creating a significant risk that facilities with suboptimal capture rates are deemed compliant, thereby undermining the Agreement's core objectives.
• To be Paris Agreement compatible, the label ‘abated fossil fuels’ needs to apply to CCS applications with net-zero greenhouse gas emissions on a lifecycle basis. This requires four things:
  1. Carbon dioxide capture rates of more than or equal to 95% of carbon dioxide emitted
  2. Permanent geological storage of captured emissions, with adequate monitoring and evaluation
  3. Reducing upstream and end-use fugitive methane emissions to less than 0.5% and towards 0.2% of gas production (and an equivalent for coal); and
  4. Any remaining emissions to be counterbalanced through permanent carbon dioxide removal (CDR)