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Limited scope for biofuels to cut aviation emissions, concludes CCC

The UK aviation sector cannot rely on biofuel use to offset emissions growth, new analysis from the Committee on Climate Change suggests in its report on biomass in a low carbon economy, published yesterday.

The report considers the limited supply of sustainable biomass likely to be available in future and how this should best be used to tackle climate change. While “some use of aviation biofuels may be desirable”, the report finds, “planning for high use of biofuel in aviation that does not materialise would risk diluting incentives for other ways of reducing emissions (i.e. fuel efficiency and limiting demand for flying).”

Specifically, the CCC advises that we shouldn’t plan for aviation biofuel to exceed 10% of total aviation fuel use by 2050. Any more than this, they argue, would risk diverting sustainable biomass from more carbon efficient uses, such as timber for construction, or industrial uses when combined with Carbon Capture and Storage (CCS). While it is not possible to capture the CO2 released by aircraft in flight, significant emissions are associated even with the manufacture of aviation biofuel, and to the extent that biomass is used for aviation, it essential that CCS technology is used in fuel production process. Producing and burning aviation biofuel without CCS technology could result in higher emissions than simply burning fossil fuels.

“The best use of biomass in 2050”, CCC analysis

Biomass should only be directed towards aviation at significant scale if three key tests are met, the report argues:

  1. Overall levels of abatement from producing and using aviation biofuels must be equal to or better than other biomass best-use applications (see chart above)
  2. Aviation biofuel production plants should be genuinely ‘CCS ready’, and 
  3. Biomass use in aviation beyond 10% uptake should be used to reduce emissions below 2005 levels, not as a substitute for other options.

The recommendation is at odds with figures from those advocating for very high levels of biofuel in aviation. The UK industry coalition Sustainable Aviation, for example, which brings together manufacturers, airports, airlines, and air navigation service providers, has long maintained that “sustainable aviation fuel” could plausibly represent 25-40% of global aviation fuel by 2050. And with growing recognition of the challenge posed by aviation in the context of achieving net zero emissions in the coming decades, a recent draft paper from the Energy Transitions Commission argued for a move towards 100% biofuel for aviation in order to decarbonise the sector.

The CCC maintains its longstanding recommendations that aviation CO2 emissions should, by 2050, be no higher than they were in 2005 (37.5 Mt), and that given the likely reductions in the carbon intensity of flying (including from new technology and fuels), this allows for no more than a 60% growth in passenger numbers during that period. Current government forecasts for aviation are that demand will grow by 80% by 2050, and that emissions will reach around 40 Mt, overshooting the 37.5 Mt planning assumption.

The importance of land use emissions

Meanwhile a separate CCC report, also published yesterday, argues for “fundamental changes” in land use. Subsidies currently given to farmers under the Common Agricultural Policy should instead be directed at climate mitigation and adaption through measures such as tree planting and the restoration of peatlands, CCC argues. Around 18 Mt CO2e is emitted annually from UK peatlands that have been degraded over time as a result of moor burning for grouse shooting, agriculture and peat extraction for horticulture. The “rewetting” of peatland could prevent 4-11 Mt of CO2 being emitted annually.

Heathrow Airport announced recently that it is investing in a peatland restoration pilot project in Lancashire. If successful, the airport hopes further investment will help it offset the emissions from some of the flights from a third runway. But today’s report shows that peatland restoration is clearly considered by the CCC not to represent an alternative to action on aviation emissions, but as necessary in parallel to meet the UK’s climate commitments. And if this is true even under the Climate Change Act as it stands, it seems very likely that there will be even less room for any growth in aviation emissions under a more stringent UK target in line with the ambitious temperature goal of the Paris Agreement.

What’s next?

The CCC will be publishing a more detailed report on land use next year, as well as an update to its 2009 advice on aviation, including a review of its passenger growth and emissions reduction recommendations for the sector. Around the same time, the Committee will publish its advice to the Governments of England, Scotland and Wales on: when the UK should reach net zero emissions; if that target should be set now; the implications for emissions in 2050; and how such reductions can be achieved.

On 30th October CCC launched a call for evidence in relation to this ‘net zero’ report, including on how both low-carbon technologies and behaviour change can be used to help reduce emissions close to zero in difficult sectors such as aviation. Responses are invited by 7thDecember.


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