Closing the Gap: the case for a GGR mandate

In October 2025, the Government published the Whitehead review, an independent review of greenhouse gas removals in the UK. For aviation, expected to be one of the sectors with the largest residual carbon emissions in 2050, it proposed a ‘Net Zero Aviation Mandate’, a mechanism to expand the scope of the SAF mandate to allow in greenhouse gas removals (GGRs). AEF has worked with independent consultant Matt Finch to suggest ways such a mechanism might be designed; here are his thoughts:

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Almost every major roadmap that outlines how aviation could get to net zero by 2050 does so by including greenhouse gas removals (GGRs): that is, some mechanism that can take carbon out of the air and bury it permanently back under the ground, and in doing so equal and offset the residual fossil carbon emissions from planes. Indeed, the UK’s Jet Zero Strategy suggests that some 19 million tonnes of removals will be needed in 2050. 

Exactly zero of the roadmaps proposed exactly how these removals would come into being, or who would pay for them. Whenever you asked an industry executive about this, they would generally cast their eyes down, mumble something then change the subject. The problem, as ever, was that the industry didn’t want to pay for it. 

At the same time, every serious policy wonk that has worked on the question of how to get an entire GGR industry into existence has concluded that the aviation sector should pay a substantial proportion of the costs. The reason is simple: it will be one of a small number of sectors that will need it to balance its emissions come 2050 (there is an outside chance that it will be the only one).

There are many ideas of how this problem could be solved – an extra tax on plane tickets, a higher carbon price – but there is currently no serious comprehensive policy proposal available for how to scale GGRs.

The missing pillar

Squaring this circle, and seemingly from nowhere, a Government-commissioned review from Alan (now Lord) Whitehead was published at the end of October. It proposed a new policy incorporating GGRs into aviation decarbonisation policy. In doing so, it showed that there is serious consideration somewhere in the Government on how to introduce this missing decarbonisation policy pillar. 

At its heart, the proposal was simple: tweak the Sustainable Aviation Fuel (SAF) mandate and incorporate GGRs into it. The SAF mandate was a landmark achievement in that it was, and is, the only policy that requires the sector to depart from its total reliance on fossil kerosene. The theory of SAF is sound: make something that is chemically identical to fossil jet fuel and burn that instead. Yes, there would still be carbon emissions out the tailpipe, but that carbon would not have come from fossil sources. And since climate change doesn’t care where the carbon saved, or the carbon not burnt has come from, adding GGRs into the SAF mandate sounds seductively simple. 

But.

In practice, SAF and GGRs are different things. They are different industries that have different needs, goals, supply chains and expertise. The SAF mandate has ensured that the business and investor community has started to work through the problems (of which there are many!) and get some liquid fuel developed. The GGR community now needs its own certainty. Crucially, lumping them both in together means that the potential of one to displace the other could mean that both become too risky for investors, and we end up with neither. 

The answer is, of course, simple. Put in place a separate, but complementary GGR mandate scheme that ensures carbon is removed from the atmosphere. 

The UK Government is actually quite good at this now. Not only is there a SAF mandate, but we have the ZEV (Zero Emission Vehicle) Mandate, the RTFO (Renewable Transport Fuels Obligation) scheme and the Clean Heat Market Mechanism. 

A GGR mandate would guarantee demand – which is what the fledgling GGR industry craves, but there are all sorts of other questions that need ironing out. Specifically, which companies are obligated? What actually counts as a ‘permanent’ GGR? Does it matter where the carbon is sequestered? What happens if the obligated party doesn’t procure any / enough GGRs? Some initial reactions have cited the possible negative impact of such a mandate on the development of e-fuels, others say that it accepts the continued use of kerosene, but there are potential solutions to all these concerns.

The proposal

There are also dozens of other questions, but in the spirit of offering solutions, here is what a GGR mandate could look like:

• A dedicated, stand-alone mandate requiring fuel suppliers to procure and retire certified, high-quality, permanent, approved greenhouse gas removals in direct proportion to the fossil fuel emissions coming from the jet fuel they supply.
• Removals could happen anywhere in the world, but extra credit could be given to removals that occur in the UK, or by British-headquartered companies.  
• Short-term removals – ie from reforestation – would be strictly excluded with only permanent removals (200+ years) being allowed.
• The amount of removals required would equal a specific, annually escalating percentage of fuel supplied. 
• To start in 2030 at a low percentage rate.
• Rising to 100% in 2045: the figures suggested by the Whitehead Review. 
• As per the ZEV and SAF mandates, the GGR mandate would have a ‘buy-out’ price, for those companies unable or unwilling to procure removals.
• Revenues from this buy-out would be funnelled directly back to the Aerospace Technologies Institute (ATI), enabling more work to happen on zero-emission planes. 
• This would only apply to the resultant emissions specifically from fuel supplied in the UK. 
• This would be regulated by DESNZ, which is the Government department that already has the requisite GGR expertise in house, with advice from the DfT. 

Unlike the Whitehead review suggestion, the SAF mandate would not be changed in any way under this proposal. Primarily this is to ensure that continuing investment already committed to the development of 2nd generation alternative fuels is not undermined, but it doesn’t mean that the two schemes would not interact: if a supplier provided more SAF than required by the SAF mandate, then, by definition, they would have a lower GGR obligation.

It’s perhaps easier to visualise what this looks like in percentage terms below:

You can see that fossil fuel still dominates for the next two decades. Indeed the industry standard is for a 2% growth in fuel use per year, meaning that even though the SAF mandate encourages increasing volumes of alternative fuels, those volumes only cover the growth of demand. Regardless of your thoughts about GGRs, something else is still needed.

Of course, fuel suppliers could also reduce their GGR obligations by simply selling less fossil fuel. And that would happen if airlines demanded less, which would happen when they start switching planes to newer, more efficient versions, which this policy would incentivise through channelling money to the development of zero-emission flight.

Industrial opportunity

Clearly there is a massive industrial opportunity behind this proposal. Implementing this mandate would position the UK as a, and probably the, global GGR leader. As other nations follow the UK’s lead in decarbonising aviation, the UK could export not only the engineering and policy expertise that would be produced, but also the services industry that would grow up around the GGR industry. A GGR mandate also “de-risks” the prospect of the SAF mandate failing for some reason.

Next steps

So what should next steps be? Both the Jet Zero Strategy and Sustainable Aviation’s latest decarbonisation roadmap had carbon removals as a core tenet of the long-term solution. The Whitehead Review sketched out a credible, high-level proposal of how to implement this tenet. What we have outlined is another proposal, with a bit more flesh on the bones. If GGRs are to be a core part of UK aviation’s decarbonisation journey, then it will need a policy to be implemented soon. But policies work best when, broadly, they have been agreed by all stakeholders. So over to you, dear reader. What are your thoughts? What’s good? And what’s bad? What should the next steps be?

Let’s keep the conversation going.

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