Green Aviation – reality or greenwash?

The expansion of Southampton airport is forecast by its owners to produce an additional 370 kt CO2eq emissions per year, taking the total to over 600 kt (equivalent to all homes, businesses and transport in the entire Borough of Eastleigh. Or up to twice that amount, according to a recent report by the New Economics Foundation – see our blog about this report).
The airport would have us believe that this is a necessary blip on the way to zero carbon aviation, with promises of greener fuels like hydrogen and electric planes. Because these are decades away, the aviation industry sees Sustainable Aviation Fuel (SAF, or biofuel) as a transitionary fuel. We look at all these below.

But even when or if they become commercially available, is the low cost carrier that Southampton’s extended runway is designed to attract going to immediately swap its planes for cleaner, greener, quieter ones? For example, Easyjet have 37 A320s out of a total of 49 aircraft in service, their average age is 5.6 years out of a planned 25 year lifetime – they will be with us for another 19 years!

Electric planes
To supply the same amount of energy to a plane as fossil fuels do, batteries need to be 14 times heavier, which limits the size of electric planes. Wright Electric are developing a 180-seat fully electric jet that can fly for only around 500km – e.g. Paris to London – but the batteries they will need for this don’t yet exist!
At the Eastleigh Planning meeting which approved the runway extension, much was made of the potential for electric planes, with one of the airport’s presenters explaining with a straight face that a commercial flight had taken off from Exeter Airport This demonstration flight was just a 6-seater aircraft and later phases will use a 19-seat hybrid-electric. Such aircraft won’t need the extended runway! And to reach its promised 3 million passengers a year, Southampton would need 432 of these planes per day!

Liquid hydrogen
Hydrogen technology isn’t ready yet, and even its proponents agree a realistic timescale for introduction of hydrogen planes is no earlier than 2040. A recent industry seminar presented a graph showing the timescale for the shift to hydrogen (LH2).

graphs showing claimed timeline of transition hydrogen… starting 2040


It is clear that even this isn’t fast enough for complete decarbonisation by 2050. Moreover, this graph looks very similar one presented by the industry 20 years ago, except that then they were predicting the transition to hydrogen would start in 2015 and complete by 2025!
The Cryoplane project of 20 years ago was not followed up at the time because it was incredibly expensive. It still will be. Recently a hydrogen plane crashed on a test flight This is the the UK company the government was promoting to get to a 100-seater by 2030.
Huge amounts of electricity will be needed, and unless this comes from green sources (currently in only 40% does in the UK, or 26% globally), using hydrogen won’t help. Worldwide electricity generation would have to double just to keep aviation at today’s levels, and flights from Heathrow alone would need a constant input of 50 gigawatts – basically doubling the size of the UK grid for one airport! Or 15 Hinkley Point C’s. The Committee on Climate Change says that to make enough hydrogen for every sector of the UK economy we would need 300 Gigawatts, which is 6 times current peak demand!
Making hydrogen requires vast amounts of water. Researchers propose using seawater to avoid taking precious fresh water – but electrolysers require pure water and that could mean huge additional electricity use for desalination.

Sustainable Aviation Fuel (SAF)
The Committee on Climate Change does not expect electric or hydrogen planes to make a significant impact at all by 2050 and does not include them in its modelling, and the aviation industry sees Sustainable Aviation Fuel (SAF) as the transitional fuel until hydrogen and electric planes are available. SAF is a blend of 50% biofuel and 50% fossil fuel sourced aircraft fuel. SAF supplier BP and Swedish airline Braathens Regional Airlines demonstrated a flight that claimed 46% emissions reductions versus the same route flown by a conventionally fuelled aircraft On this basis, use of SAFs would still mean the expansion of Southampton airport leading to an additional 324 kt CO2eq, when the industry has to achieve a reduction. Moreover, many sources say SAF’s claimed improvements are based on offsetting emissions the feedstock would have released anyway, meaning the improvements are accounting tricks and not genuine reductions. The BP study shows that while the SAF could eventually give an 80% reduction in emissions, it can only be blended at up to 50% with normal kerosene-based fuel. So that’s still 60% of normal emissions, before supply chain emissions are accounted for.
This kind of SAF is just a rebranding of biofuel, whose production takes resource away from food production and other agriculture
Some researchers even claim that the growing of biofuels only absorbs 37% of the carbon emitted later in the process of refining and transport, meaning they are actually worse than fossil fuels and definitely not a solution.
Rather than biofuels, the Committee on Climate Change favours the direct capture of CO2 from the atmosphere and combination with renewably generated hydrogen to make synthetic fuels However, if the energy requirements discussed above for converting Heathrow to hydrogen sound bad, wait until you add carbon capture and hydrocarbon synthesis to it. How many Hinkley Points do we want to build?

Airport growth now should not be pinned on promises of zero carbon flight being “just around the corner”, when in reality it will be two or more decades away.

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