There is a lot of synthetic jet fuel news to cover, having everything to do with the international conference on Synthetic Sustainable Aviation Fuels held in The Hague this month. The aviation industry is a big climate burden accounting for 2 to 3 percent of the global carbon dioxide emissions. Plenty of alternatives to fossil fuels are being studied but not one of them has made it past the experimental stage. A couple of years ago there was Richard Branson with his virgin-biofuel jumbo and there are now several serious biofuels to choose from and some not so serious. Last year Finnish company Neste added used cooking oil to the list (link) and Japan Airlines will at least fly once on fuel sourced from discarded clothes they promised (Link).

On a more serious note, this month carrier Britisch Airways announced it will invest in a new biofuel plant that has ethanol from agricultural waste as raw material (link). Also this month Velocys and Toyo agreed to build a new biomass-to-aviation-fuel plant in Japan, this time based on the Fischer-Tropsch process (link).

In other conference news it was revealed that a KLM flight several weeks ago to Madrid was made possible with 500 liters of synthetic kerosine made from hydrogen and carbon dioxide, courtesy of oil company Shell. The amount was not a lot, just 5% of the total fuel payload but the technology is an interesting departure from the biofuel circus thus far. Last time I have heard of a carbon dioxide to fuel infrastructure was the methanol economy that I blogged about 10 years ago here and here .

Has Shell entered the synthetic jet fuel industry? It seems they will do everything to upset the climate hippies, first offering carbon-offsetting every liter of petrol at the gas station for just a few cents (blog here) and now this. How green does it get. Produce hydrogen gas from green electricity, combine it with carbon dioxide captured directly from the air into jet fuel and the aviation industry can resume shuttling all those sun-starved millions of vacationers to the tropical beaches as if climate change (or covid) has never happened.

But how does it work? The only clue we get is that somehow Shell technology was involved. The television news showed footage of what looked like scientists busy at work in the Shell research facility in Amsterdam. There appears to be four stages. Stage one is hydrogen gas production, preferably green. Lot of things going on here (blogged about here). Stage two is carbon dioxide capture. A logical location for a scrubber plant would be near a fossil fuel plant exhaust pipe but company Carbon Engineering is a Canadian company that sucks it right out of the air and also with fuel production in mind (link, DOI)

Stage 4 requires carbon monoxide and therefore stage 3 is a carbon dioxide to carbon monoxide conversion step. This can be done in the so-called Reverse Water-Gas Shift reaction (RWGS), a highly endothermic reaction of carbon dioxide and hydrogen to carbon monoxide and water.
Finally stage 4 is old-fashioned FT with hydrogen gas and carbon monoxide. Kerosine is nothing special compared to petrol, the hydrocarbon chains are longer (8 to 16) and branched. FT is nothing new to a company like Shell, it has at least one working production plant for diesel fuel in Malaysia.

But how motivated is Shell about stepping into the synthetic jet fuels? Interestingly it was not Shell that offered the 500 liters to KLM but rather the Dutch government. The batch was ordered by the Dutch Minister for Infrastructure and Water Management and gifted to KLM (link).

In fact it appears that Shell has already pulled out of this market segment. In January it stepped away from a joint-venture with BA and Velosys and a plant to be built in the UK for the conversion of non-recyclable household waste (link). Enthusiastic backer of the venture, Boris Johnson was not amused. Instead Shell has forged a collaboration with the Canadian Varennes Carbon Recycling project, which is also a waste converter but with focus on low-carbon fuels? which probably means diesel fuels.

And by happy coincidence we now have a brand new Shell strategy report Link. In it the company pledges to be a net-zero emissions company by 2050 with a target of 20% in reductions by 2030. To achieve this goals it will rely heavily on carbon dioxide capture and storage with plants already in operation or planned. The company also want to sell more electricity and more hydrogen and continue with it's carbon dioxide compensation scheme. At the same time they will continue to invest heavily in oil and they admit they are doing it for the money. And the aviation fuel? Not a word, in the context of their hydrogen business only heavy-duty transport is mentioned.

The small print is interesting. Shell warns that readers should not place undue reliance on forward-looking statements such as "aim", "ambition", "anticipate", "believe", "could", "estimate", "expect", "goals", "intend", "may", "objectives", "outlook", "plan", "probably", "project", "risks", "schedule", "seek", "should", "target" or "will".

Well, forget about Shell. Other initiatives that look similar exist. The Finnish e-Fuel project (link) , is a research initiative backed by the Finnish government that aims to merge the water hydrolysis step with carbon dioxide sequestration in a single process, hence the e- prefix.

And academia? Last December a large research team headed by Tiancun Xiao and Peter Edwards (Oxford University) reported the direct conversion of carbon dioxide into jet fuel (Link) with a simple Fe-Mn-K catalyst. Conversion efficiency was 38% with 48% of the hydrocarbons in the kerosine range. This research was backed by Rolls-Royce and the national science institute of Saudi Arabia.

Synthetic jet fuel, never a dull moment.

Update 13-02-2021. Newspaper Volkskrant is well informed (Link). The synthetic fuel projects was not a side show for Shell, the company had around one hundred engineers working on it. The article does not confirm the companies ambitions in this business. Another article mentions Kerogreen (link), a research effort sponsored by the EU that aims to microwave carbon dioxide directly into carbon monoxide and oxygen in the synthetic jet fuel production chain.