Here's a quick overview of the case for synthetic 'ElectroFuels' for aviation by @ChrisGoodall2 in the @Independent.

It's crucial to note that this is entirely different from what the industry means when it talks excitedly about 'Sustainable Aviation Fuels', or SAFs.

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SAFs are highly problematic, because just like other #Biofuels, they rely on a ready supply of Bio-based materials to use as 'feedstock' & each type brings with it a variety of #energy, environmental & #biodiversity complications.

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For instance, SAF feedstocks include material with high Cellulose & Lignin content, such as wood or straw.
In addition, animal fats, vegetable oils, or sugars can be used.

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These feedstocks can be by-products of timber or #food production, which sounds great, however they're not just lying around waiting for #aviation to buy up, convert to fuel & burn; endless industries, processes & businesses already make use of them.

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Side note:
The conversion of these feedstocks into aviation fuel, is not without its own carbon emissions & the Government's advisor, @theCCCuk, recommends that all #biofuel production should be equipped with carbon capture & storage ( #CCS).

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The gigantic scale of SAF production needed to make a dent in aviation's #Carbon emissions, would therefore displace existing uses for all sorts of feedstocks & require them to source something else instead - that doesn't cut #emissions, it just shifts them elsewhere.

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This leads to another, well-known issue with large-scale Biofuel production: competition with the food system.

It's both simpler & cheaper not to bother with by-products & instead grow crops specifically for conversion to Biofuels.

We're familiar with one already: #PalmOil

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Sadly, agriculture already has a huge impact on the #environment, climate & #biodiversity, so adding the burden of growing crops for aviation fuel to the mix, has some obvious & very serious undesirable consequences, not to mention huge Greenhouse Gas #emissions.

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One more proposal for making sustainable aviation fuels, is using household #waste as feedstock.

This consists of:
1. Extracting the organic, or #food waste for processing, similarly to other biomass.

2. More ambitious plans, to convert unrecyclable #plastic waste.

But...

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...if turning the ubiquitous problem of #plastic waste, into liquid fuel for aeroplanes sounds a little too good to be true, I'm afraid it is and it's not hard to see why....

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Plastic waste is a huge issue, for all sorts of reasons, but it does represent a store of fossil hydrocarbons in a solid, stable form.

Converting #plastic into transport fuel however, means that whenever it's used, that stored carbon is released into the atmosphere.

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So, in #carbon terms, jet fuel made from plastic is similar to burning the oil/gas it took to make the plastic in the first place (plus the emissions from multiple production steps).

In exchange, we get a few minutes use, of an often superfluous material.

Sustainable? No.

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This leads us finally to the case for synthetic 'electrofuels' & Mr Goodall's article.

(NB: There's a ref to #Hydrogen as less energy dense than Kerosene - it's volume, not weight per unit of energy, that's the problem.)

13/n https://www.independent.co.uk/voices/climate-crisis-synthetic-fuels-heathrow-third-runway-expansion-flight-airport-a9367411.html

Thoughts on the article:

As pointed out, sourcing sufficient #Co2 is challenging.

Drax power station in Yorkshire has been burning imported wood pellets in four of its six furnaces (converted from #coal) for years & is committed to figuring out how to capture its Co2.

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As & when it's capturing carbon, Drax will be representative of a 'negative emissions' technology, the like of which IPCC climate stabilisation pathways are heavily dependent on: Bio Energy with Carbon Capture & Storage ( #BECCS).

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BECCS understandably has its critics & I'm far from enthusiastic about relying on such a contentious technology to reach our climate goals, however it looks like we're stuck with it, so worth considering as a source of Co2 for electrofuels, at least in the medium term.

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Another medium-term technology we're stuck with, is the fleet of combined cycle gas turbines, currently producing ~ 38% of the UK's electricity.

Gas combustion produces >40% less Co2 than coal for equivalent energy, but nevertheless, we should be capturing the Co2 emitted.

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On the #Hydrogen side, the challenge is clear, although no less significant: securing massive amounts of renewable electricity.

My view, is that alongside legislating for escalating electro fuel content, the Government must require production to be vertically integrated.

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That is to say, the energy majors & other aviation fuel partners, should not be allowed to cannibalise the electricity grid, to power Hydrogen via electrolysis.

This will spur competition, investment & innovation within the industry, of efficient Hydrogen production.

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The advantage of this approach is threefold:
1. It separates aviation e-fuel production from the wider global energy market, removing exposure to price, supply & exchange rate volatility.

2. It removes the perverse influence of aviation demand for Bio feedstock.

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3. Finally, it creates a reliable global market & supply chain for green #Hydrogen, which is generally expected to be needed well beyond 2050 in liquid form, to power long-haul flights, either via combustion, or fuel cells to power electric motors.

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Of course, Hydrogen has long been a vital part of the world economy, but most of its production is dependent on natural gas & very #carbon intensive.

By harnessing the aviation sector to drive innovation & scale in green #Hydrogen, the benefits will cascade across sectors.

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Further reading:
https://theicct.org/blog/staff/if-we-use-livestock-feed-biofuels-what-will-cows-eat

https://www.vivideconomics.com/wp-content/uploads/2019/09/Greenhouse_Report_Gas_Removal_policy_options.pdf
https://theicct.org/sites/default/files/publications/ICCT_advanced_alt_fuel_pathways_20190723.pdf

https://www.theccc.org.uk/wp-content/uploads/2018/11/Biomass-in-a-low-carbon-economy-CCC-2018.pdf

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