Scaling the production of Sustainable Aviation Fuels (SAFs) to meet aviation’s needs, and doing so with the absolute lowest emissions production methods possible, will be critical to meeting aviation’s net zero goals. Synthetic fuels, sometimes called e-fuels, power-to-liquid or power-to-fuel, are a key part of scaling to that future, so we sat down with Paddy Lowe, cofounder and chief executive officer of synthetic fuel producer Zero, to learn more about their process — and a new production facility that will be operational within the next two years.
One of the issues around the early sets of SAF pathways is that their scalability is limited. For SAF created from waste oils, for example, those oils have to be available in sufficient quantity, quality and at the right location — and sufficiently predictably over an industrial investment timescale — to see longterm success.
Synthetic fuels differ from other kind of SAFs in their method of production, but their usage is in essence identical: full drop-in aviation kerosene. They are sometimes called power-to-energy or power-to-liquids, because the process uses electricity to turn air and water into a liquid fuel. Essentially, they capture carbon from the atmosphere and combine it with hydrogen (sourced from electrolysed water) to create a hydrocarbon fuel like SAF.
If it sounds potentially revolutionary, it may well be. Airbus says it sees the technology “as having huge potential, not only in terms of climate impact, but also in cost and scalability”.
Overall, synthetic fuels are estimated — assuming best case construction, production and power sources — to offer 85 percent lower lifecycle emissions than similar fossil fuels, thanks to the way they are produced.
“Synthetic fuels are made in a circular loop in which carbon, as carbon dioxide, is extracted from the atmosphere, not the ground. The same amount of carbon is released back into the atmosphere when the fuel is burned, maintaining a constant balance — an industrial carbon cycle — just like the balance of the biological carbon cycle,” Lowe tells us. “The manufacturing process involves three distinct steps. Carbon is extracted from the air using direct air capture. Water is converted into hydrogen using electrolysis with oxygen as a byproduct. The carbon dioxide and hydrogen are then combined through Direct FT, a Fischer-Tropsch (FT) process that uses Zero’s proprietary catalyst system to make the hydrocarbon fuels.”
The power-to-energy and power-to-liquids monickers make it clear that a key part of the process is electricity, so ensuring that the power used is carbon-neutral or very-low-carbon makes a fundamental impact to the fuel’s sustainability.
While this means some scalability assumptions around the availability of green electricity at the scales required, these assumptions are by no means wild or beyond the realms of feasibility.
Technology and factory
Beyond power, the process, technology and production facilities are crucial to the sustainability of synthetic fuels. Here, Zero is working with engineering procurement and construction specialists Global E&C to create a first of its kind facility — Plant Zero.1 — as a first step towards scaling synthetic fuel production.
“Plant Zero.1 is the company’s first permanent production facility. It will include the world’s first fully-featured synthetic fuel plant alongside a research and development laboratory and will lead the way to providing the technical and commercial blueprint for the global deployment of synthetic fuels at scale,” Lowe says. “The plant will be used to demonstrate production processes for jet fuel, gasoline and diesel fuels and support certification efforts with industry groups, regulatory agencies, and equipment manufacturers. Zero aims to gain ASTM [American Society for Testing and Materials] International certification in early 2024 for standard grades of these three fuels.”
Zero has already designed and developed a digital twin of the factory, its machinery and its processes, using Formula 1-style computational fluid dynamics as part of its modelling process. Partnering with a more traditional engineering house like Global E&C to benefit from current experience in fuel production is also a smart move.
“We have signed an agreement with Global E&C to utilise their expertise from the fossil fuels industry, as much of the work we do is very similar, only far cleaner! We use all the same technical safety, process, piping, mechanical, design and electronics engineers. In fact, there really is not a part of the industry that we are not using,” Lowe explains. “Zero’s inhouse team is developing the core technology. We create all the specifications, working with their teams and using their experience of building out equipment, and from then-on we use their skills for design, manufacture, procurement and commissioning.”
Production, timing and scaling
“Zero plans to begin manufacturing engineering-grade fuels at Plant Zero.1 from Q3 2023 at an anticipated rate of up to 30 litres per day. Plant Zero.2, Zero’s first commercial scale facility, will be grown out of the technical and operational development achieved at Plant Zero.1 and has already been committed to as the next phase of scale-up,” Lowe says. “Once in operation, Plant Zero.2 will scale to produce 5,000-100,000 tonnes of synthetic fuels per year.”
While there will inherently be sunk carbon in their construction, the operation of the plants will be carbon negative given the process of removing carbon from the air to convert to fuel — although Lowe freely admits that this will then be released back into the atmosphere to return to near emissions neutrality.
“The core plant design has been developed such that it can be scaled in size to meet any output requirements and can be sited as close to the end user as possible — for example, close to an airport or shipping port — or close to the location of energy generation,” Lowe says. “Delivery from the facility to the end user will follow existing approaches, using pipelines, tankers fuelled synthetically, and/or filling stations.”
Fundamentally, this geographic balancing of fuel production is likely to reduce emissions even further compared with today. Rather than tankering fossil fuel oil around the world, producing synthetic fuels locally to airports — many of which are located in coastal regions where offshore wind farms are a real opportunity to decarbonise electricity supply — is substantially more efficient in emissions terms.
Author: John Walton
Published 17 August 2023
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