The Chancellor Rachel Reeves is suggesting airport expansion, including a possible third runway at Heathrow, as a way to boost economic growth in the UK.
This article is not going to deal with the economics of aviation expansion. But let’s just say that while it might be good for airlines, it’s not at all clear that it’s good for the UK economy.
Worryingly, Rachel Reeves has also suggested in comments to the media that this could be made compatible with the UK’s targets to reduce carbon emissions from fossil fuels.
She justifies this on the basis that another runway would stop planes having to circle over London, that electric planes will soon be available, and that Sustainable Aviation Fuel (SAF) will produce less pollution. Let’s just examine each of those ‘solutions’.
Stopping planes circling
There is very little research on how much pollution could be avoided by reducing the time planes spend circling above airports waiting for their turn to land.
The aviation industry’s own Net Zero Carbon Road-Map doesn’t even mention it specifically in its list of “Aircraft and Airspace operational measures”. But the total of all these measures delivers just a 4% cut in emissions. That would mean that the percentage of carbon savings are likely to be, at best, in the very low single figures.
If planes spending less time circling might help a (tiny) bit with carbon emissions, it will not help with pollution from ultrafine particles emitted by planes. This pollution at ground level could be linked to thousands of cases of high blood pressure, diabetes and dementia across Europe.
Around six million people – or around 9% of the UK population – that live around four major airports are being exposed to ultrafine particles from aviation.
Electric planes
Much of the attention on electric planes has focused on the possibility that they can replace conventional short-haul flights.
The problem is that even for fully-charged batteries the amount of power provided relative to their weight (they’re heavy) is still much lower than with conventional fossil fuels. The first commercial electric plane may take flight this decade – a 30-seater ES-30 model – with a fully-electric range of 200km (which would not even get you from London to Manchester).
Aviation analysts have estimated that to achieve a 30% reduction in the UK’s aviation emissions an electric plane would need to have a range of 3,500km. That is not even remotely in prospect. As their report goes on to say: “Absent a truly radical breakthrough in battery and aircraft design, longer range flights will remain beyond the capabilities of battery electric aircraft for a long time to come.”
The UK Government’s own modelling assumes that just 5% of air traffic movements (which, because of short ranges, will be well below 5% of overall UK emissions) will come from cleaner aircraft in 2040.
Sustainable Aviation Fuel
SAF is marketed as an alternative to fossil fuels, but would currently need to be combined with conventional kerosene in small quantities. SAF made up just 0.28% of all aviation fuel supplied in the UK in 2023, although the government has targets for this to rise to 22% by 2040.
There are a range of types of SAF. Many fall into the category of biofuels, which can be made from a wide range of sources including household food scraps, leftovers from the forestry industry, waste oils or crops such as wheat, sugar beet, rape or palm oil.
Debates about biofuels for surface transport were raging in the 2000s, and not a huge amount has changed. Done well, they could have a small beneficial impact. Done badly, they would cause widespread ecological and social damage. Biofuels that rely on crops being grown for the purpose are problematic because it increases pressure to turn more and more land over to biofuel production. It can also lead to chopping down forests for more agricultural land.
If the biofuel can be made from genuine wastes that would otherwise decompose or be burnt, then it may have some benefits. But there are serious concerns around the availability of suitable waste to be turned into fuel. Carbon Brief’s analysis shows that SAF will only cut emissions from the sector to 0.8% below current levels in 2040 because the carbon benefits are overwhelmed by the predicted rise in aviation demand.
The real game-changer would be so-called ‘e-fuels’ – if SAF could be made from a process using renewable power to create hydrogen, which would then be combined with carbon dioxide from the atmosphere to make a hydrocarbon fuel. These e-fuels might be able to make a significant dent in carbon emissions, but they are nowhere near technological maturity. The International Energy Agency also suggests they will remain much more expensive than kerosene, which airlines may not like.
The idea that there are new developments that will cancel out the rise in carbon emissions from expanding airports, including Heathrow, simply isn’t right. The suggested improvements will likely have a small impact. Innovations that could have major impacts on carbon reduction rely on technological and commercial developments that are far from assured.
