UK government's climate advisers suggest a pathway towards net-zero aviation emissions by 2050
(photo: Heathrow Airport)
Tue 24 Sept 2019 – Emissions from international aviation and shipping must be included in the country’s net-zero emissions by 2050 climate target, says the UK government’s advisory Committee on Climate Change (CCC). However, the body accepts that even with improvements to fuel efficiency and the use of sustainable and novel fuels, zero-carbon aviation is highly unlikely to be feasible by 2050. In a letter and report to the UK Transport Secretary, the CCC proposes that demand growth be limited to at most 25% above current levels and the use of what it calls greenhouse gas removal offsets to deal with remaining emissions. Aviation, it says, is likely to be the largest emitting sector in 2050 and account should also be taken of the added climate impact of its non-CO2 effects. Formal inclusion of international aviation emissions in the net-zero target would complement agreed international policies, such as CORSIA, and should not be interpreted as a unilateral UK approach to reducing these emissions, says the CCC.
CCC scenarios suggest UK aviation CO2 emissions could be reduced from 36.5 million tonnes (Mt) in 2017 to around 30 Mt in 2050 through a combination of fuel efficiency improvements, limited use of sustainable fuels and by managing demand growth. It says it is unlikely there will be major technological breakthroughs in commercial aviation to make a significant difference to the level of emissions by 2050, given long development and certification lead times and slow turnover of the fleet.
However, the CCC foresees a continuation of the historic 1.4% annual improvement in fuel efficiency for UK departing flights on a seat-km basis. This could be achieved through more efficient engines, including both advanced conventional jet designs and some deployment of hybrid-electric aircraft in the 2040s. Its scenario expects hybrids could make up less than 10% of kilometres flown in 2050 and no full-electric aircraft are considered feasible, particularly for long-haul flights, by mid-century. Other improvements in aircraft design, such as high aspect ratio wings and composite materials, operational efficiencies and airspace management would also contribute to fuel efficiency gains.
The CCC’s scenario of a 10% uptake of sustainable fuels in 2050 is based around potential supply of biomass and strong governance to ensure genuine emissions savings. It advises government not to plan for higher levels of uptake at this stage, given the range of competing potential uses for biomass across the economy and uncertainty over which will be the most cost-effective.
In the absence of a true zero-carbon plane, demand cannot continue to grow unfettered over the long-term, warns the CCC. “Our scenario reflects a 25% growth in demand by 2050 compared to 2018 levels,” it says in the annex to the letter from Lord Deben, Chairman of the CCC to Transport Secretary Grant Shapps. “This compares to current government projections which are for up to a 49% increase in demand over the same period.”
The CCC provides ‘speculative aviation options’ to reduce emissions below 30 Mt in 2050. Further demand constraint, for example, could save up to 8 Mt in 2050. Other reduction possibilities include the use of synthetic carbon-neutral fuels, or power-to-liquid, which entail recycling captured CO2, for example through direct air capture, in conjunction with zero-carbon hydrogen into a drop-in replacement for kerosene. However, the costs of such technology and the price premium are substantial, points out the CCC, but if synthetic fuels fully replaced fossil fuel use then this could reduce aviation emissions to gross zero.
A less expensive approach to achieving net-zero aviation (and shipping) emissions would be through the use of scalable greenhouse gas removal (GGR) offsets on remaining emissions. GGRs include bioenergy with carbon capture and storage (BECCS) and direct air capture of CO2 with storage (DACCS). GGR offsets could be funded through a requirement on the aviation and shipping sectors to pay for removals or governments could generate revenues through an emissions trading system or carbon tax that can be used for government-procured removals. In principle, GGR offsets could be delivered through international policies, such as CORSIA, or domestic policies as long as they demonstrated genuinely additional removals within a robust governance framework. The CCC advises that it would make sense for a substantial proportion of these offsets to occur domestically as these would provide advantages to the UK relating to availability of CO2 storage capacity, offshore engineering expertise, and market regulation and design.
It believes international policies are unlikely to overcome all barriers to decarbonising the aviation sector and domestic policies should also be pursued where these can help overcome UK-specific market barriers and do not lead to risk of carbon leakage.
With CORSIA due to end in 2035, the CCC calls for a long-term goal for global international aviation emissions consistent with the Paris Agreement.
“This would provide a strong and early signal to incentivise the investment in new, cleaner, technologies that will be required for the sector to play its role in meeting long-term targets,” it says. “This is particularly important in aviation given the long lifetimes of assets.”
To achieve this, it calls on government to support research, innovation and deployment in technology and alternative fuels. The largest contribution to reducing aviation emissions will come from new technologies and aircraft designs, it adds, and development of a UK market for aviation biofuels could be supported by achieving more of the government’s 2030 Renewable Transport Fuel Obligation target through aviation fuels, subject to strong sustainability criteria being put in place.
To limit growth in demand for air transport to at most 25% above current levels by 2050, the CCC suggests measures including carbon pricing, a frequent flyer levy, fiscal measures to ensure aviation is not undertaxed compared to other transport sectors (for example, fuel duty and VAT), reforms to the UK’s Air Passenger Duty or management of airport capacity. It calls on government to assess its airport capacity strategy in the context of net zero, adding: “Current planned additional airport capacity in London, including the third runway at Heathrow, is likely to leave at most very limited room for growth at non-London airports.”
Commented Chris Stark, Chief Executive of the CCC: “Now is the time to bring the UK’s international aviation and shipping emissions formally within the UK’s net-zero target. These are real emissions, requiring a credible plan to manage them to net-zero by 2050. Their inclusion in the UK target will complement international approaches and increase confidence that the Government is prioritising their reduction, ensuring the net-zero target covers all of the UK’s emissions.
“As the UK prepares to host the next major climate summit in 2020, we are well placed to show global leadership on this fundamental issue of international concern.”
Responding to the CCC letter, Neil Robinson, Chairman of UK cross-industry group Sustainable Aviation, said: “Climate change is a clear and pressing issue for people, businesses and governments across the world, and we welcome the leadership shown by Ministers in legislating for the UK to be net zero by 2050. We believe that through an international approach, with the right government support, and together with substantial investment from industry, net zero is within reach for UK aviation if we all play our part.
“Building on the work we’ve already done, we should continue to develop new technologies, including working with fuel producers to develop sustainable aviation fuels and the successful introduction of global offsetting schemes through which airlines will pay for any extra emissions they create. By investing tens of billions of pounds in new, cleaner aircraft, we have already decoupled growth in aviation from growth in emissions, and as a global industry we have a long-established plan to halve our emissions by 2050.
“Carbon reduction, however, is a global issue requiring a global response, with governments and industry working closely together, and for emissions to be managed within an international framework.
“If the UK climate ambition is not matched elsewhere, the global market would be distorted with carbon emissions simply exported to other countries, which would be bad for the environment and bad for British travellers. We are therefore urging Ministers to continue leading through ICAO to agree a meaningful global emissions reduction target for aviation, consistent with the requirements of the Paris Agreement.”
Heathrow Airport Chief Executive John Holland-Kaye said: “We welcome the recommendation to include aviation in the UK’s net zero emissions target by 2050, and the call on the government to introduce policies that avoid competitive distortion. Heathrow will work with industry partners and the government to ensure the UK leads the way in the development of sustainable fuels and continues to benefit from a thriving aviation sector while driving towards net-zero emissions.”
Cait Hewitt, Deputy Director of UK campaign group Aviation Environment Federation, said: “British people currently take more international flights than anyone else in the world but there’s a growing public recognition that this feels out of step with the action we need to take on climate change, and two-thirds of Britons say they support limiting air travel to address the climate crisis.
“The government has dodged the issue of aviation emissions for too long. With climate targets that are now tougher than ever, it’s time for them to look again at plans for new runways, bigger airports and more flights, and focus instead on delivering an effective plan to make the aviation sector accountable for its emissions.
“It’s worth remembering that demand for aviation growth is being driven by a minority of frequent flyers, with 70% of UK flights made by just 15% of the population.”