Lift-off for sustainable aviation fuels

Article by Adam Duckett

Johnson Matthey and bp license US$4bn US plant for agricultural waste, while Wizz Air signs deal to buy jet fuel made from human faeces

THE PUSH for sustainable aviation fuel (SAF) is taking off with the licensing of existing technologies and development of new processing routes for feedstocks as varied as hydrogen and human faeces.

The production of SAF has seen a dramatic rise, with the International Air Transport Association (IATA) reporting that last year it doubled to 500,000 t and is projected to treble to 1.5m t by the end of 2024. That step climb is still only enough to meet 0.5% of aviation fuel demand so producers have a way to go yet to help industry go net zero by 2050.

DG Fuels is among those looking to increase output after they signed a deal to license the Fischer-Tropsch technology from Johnson Matthey (JM) and bp so it can turn farm waste into 600,000 t/y of jet fuel at a new US$4bn plant in the US.

JM and bp’s process was awarded the Research Project Award and the Oil and Gas Award by IChemE in 2017.

DG Fuels expects to buy US$120m of sugar cane waste, with a third supplied by local farmers in Louisiana, to feed the plant. The so-called FT CANS process converts synthesis gas produced from this waste biomass into synthetic crude oil which in turn is processed into kerosene. DG Fuels expects the plant to start production in 2028 and has already secured deals to sell the SAF to Air France-KLM and Delta Air Lines.

It will be the largest deployment of the FT CANS technology, seven times the size of any previous project.

Fischer-Tropsch development

In 2002, JM and bp built the Nikiski demonstration plant in Alaska using conventional tubular reactor technology to convert pipeline natural gas into synthetic crude.

To apply the technology to smaller scale applications using waste biomass, the team set about lowering costs and improving efficiency. It resulted in a novel catalyst carrier. These cannisters are stacked inside a reactor tube to effectively create mini-adiabatic radial flow reactors with intercooling.

This radial flow allows the use of smaller catalyst particles which improves selectivity. Taken altogether, the technology results in a three-fold increase in productivity, a 95% reduction in tube numbers, and halves capital costs. Because the catalysis is held inside a cannister, it doesn’t have to be filtered from the product. The catalyst-containing cannister is simply removed, making it easier to recover and eliminating any interaction with the hazardous cobalt catalyst.

Michael Darcy, CEO of DG Fuels, said: “This innovation will take DG Fuels’ SAF from the sugar cane fields of Louisiana to cleaner skies all across the world.”

Wizz and poo

So far, so normal. But what if one day your flight abroad is powered by human waste? It’s not as fanciful as it first sounds, with Firefly Green Fuels pushing to build a first-of-a-kind commercial-scale plant that could start commercial production as early as 2030.

It has developed a hydrothermal liquefaction process that uses high pressure and heat to turn sewage sludge into crude oil which would then be refined into jet fuel. The company has signed an agreement with Haltermann Carless, owner of a refinery site in Harwich, UK where Firefly will build a pilot facility to prove the technology. It would then build a commercial-scale operation at the same site.

The sludge for the pilot plant will be provided by Anglian Water. Process plant technology firm Chevron Lumus Global will provide the equipment for the refinery. And airline Wizz Air has signed an agreement to buy fuel from the commercial plant in a deal that would be worth almost US$1bn over 15 years.

“The signing of these agreements marks a significant leap forward in realising our ambitions to develop a sustainable SAF industry here in the UK,” said James Hygate, Firefly’s CEO. “Opening up this new sewage pathway will bring new jobs and growth to the UK, helping us to secure a greener and more prosperous future.”

This article is adapted from an earlier online version.

Article by Adam Duckett

Editor, The Chemical Engineer

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