A world ‘first’ and it’s very much a British one: at 11.35 on 2 November RAF pilot Group Captain Peter ‘Willy’ Hackett took to the air at Cotswold Airport (Kemble) in a Rotax-engined Comco Ikarus C42 microlight fuelled with ‘non-fossil’ synthetic avgas produced using renewable energy. 

Involving a small group of onlookers including members of the RAF project team, personnel from fuel company Zero Petroleum, investors and a handful of journalists and cameramen, the modest scale of the event should not be allowed to mislead you. Lasting ten minutes, this short flight and the tiny quantity of fuel available for it – the C42 was filled with just eight and a half litres of Zero Petroleum’s pilot production run of UL91 spec synthetic avgas – represent an acorn that will not grow into just the proverbial mighty oak, but a whole forest: the fuel production process, which combines hydrogen liberated through electrolysis of water with carbon dioxide captured from the atmosphere, can be scaled up and modified to produce turbine fuel and the RAF is confidently predicting that ‘Zero Petroleum can defossilise [sic] all RAF aviation fuel by 2040 using just 127 wind turbines and at a cost within range of fossil fuel prices’.   

Initiated in June 2021 by the RAF’s Rapid Capabilities Office, Project MARTIN – the design, construction and commissioning of the compact pilot plant – was completed in just three months. Mounted in a trailer, the plant was towed to Billia Croo, Orkney where it was powered by electricity generated by the grid-connected wave energy test site, built in 2003. Using ‘Direct FT’, a proprietary and specialised version of the Fischer-Tropsch process, and operating through September and October, the plant produced just sufficient fuel – a targeted range of hydrocarbons that required no further processing other than the removal of a small proportion of heavier components – for the necessary laboratory and engine tests before the first flight.  

So, something for nothing, in terms of taking energy from the environment and using water and air as the feedstock? It might be hard to credit were it not for the organisations and individuals involved. Alongside the RAF (and isn’t it wonderful seeing the Air Force again playing the supporting role that it did with Frank Whittle and his concept of the jet engine) Zero Petroleum may be a new player but its founder and CEO Paddy Lowe comes with a towering reputation in F1 engineering – he was Technical Director at McLaren and Executive Director at Mercedes – and the man behind the chemistry, Professor Nilay Shah, is Head of Chemical Engineering at Imperial College.    

The Fisher-Tropsch process is established technology and was used during WWII by Germany to synthesise petrol from feedstock produced by the gasification of coal. The wartime product was of low quality, with an ON (Octane Number) of between 40 and 70. Zero Petroleum’s Direct FT technology provides a much higher ON and meets the specification for UL91 avgas without the need for further refining, blending or additives. CFS Aero completed the engine tests prior to the first flight and Technical Director John Rowley told Pilot of his surprise and delight at how closely the power and torque curves match between what is now being called ZERO SynAvGas and UL91 fossil fuel.  

Zero Petroleum says its Direct FT process is close to carbon-neutral because, aside from the energy coming from renewable sources, the main carbon combustion product in the exhaust stream, CO2, is recaptured from the atmosphere in producing SynAvGas (and, in future, SynAvJet). This represents an 80-90% carbon saving over traditional fossil fuels.     

Of course, the beauty as far as light aviation is concerned is that something like ninety per cent of the existing fleet – certainly aircraft powered by Rotax and most Continental engines – should be capable of operation on Zero Petroleum’s UL91-spec fuel. In making what will surely be seen as a historic flight, the RAF and Zero Petroleum have not only demonstrated a magnificent triumph for the Royal Air Force but secured a welcome win for general aviation. 

Image(s) provided by:

Philip Whiteman