When Emirates welcomed its 116th A380 in early December 2020, the delivery flight was powered by a blend of conventional jet fuel and biofuel produced from used cooking oil in Finland. It marked the first time the airline had used sustainable aviation fuel – a broader term describing synthetic kerosene that is preferred by the industry to aviation biofuels – to power an A380.

    “We are watching developments in sustainable aviation fuel very closely, and we look forward to a time when it can be produced at scale, and in a cost competitive manner,” said Emirates Airline’s president Sir Tim Clark after the delivery flight. “This is a positive step towards reducing our overall emissions.”

    Many delivery flights using sustainable aviation fuel have now taken place, along with other test flights trialling different types of biofuel over the years. And just a few days before the Emirates flight, Lufthansa Cargo and DB Schenker collaborated to operate a 777F cargo flight completely powered by sustainable aviation fuel. Regular CO2-neutral flights will begin in spring 2021, the partners said.

    So what does this all mean for the future of sustainable aviation fuel in aviation?

    Sustainable aviation fuel was produced from purpose-grown sugarcane as part of a project in southeastern Brazil involving Boeing and partners. Source: Boeing.
    Sustainable aviation fuel was produced from purpose-grown sugarcane as part of a project in southeastern Brazil involving Boeing and partners. Source: Boeing.

    No single solution

    The aviation industry is committed to decarbonising aviation and addressing the climate change challenge, and the move towards sustainable aviation fuel has implications for the MRO industry and the maintenance of aircraft, engines and components. But despite many years of progress, there is still a long way to go for sustainable fuel – several hurdles have become apparent, of which many have yet to be fully resolved.

    The production of some biofuel has raised concerns such as potential changes in the use of agricultural land, water use and the effect on food prices; as well as the impact of irrigation, pesticides and fertilisers on local environments, according to the Air Transport Action Group (ATAG), an industry body set up to promote aviation’s sustainable growth for the benefit of global society.

    “To avoid these negative environmental impacts, the aviation industry has been careful to promote only sustainably-sourced alternative fuels,” the association states. “This is why the industry uses the term ‘sustainable aviation fuel’ which has also sometimes been referred to as ‘next generation’ or ‘advanced’ biofuels.

    “Sustainable aviation fuel provides [the industry] with the capability to partially, and perhaps one day fully, replace carbon-intensive petroleum fuels. They will, over time, enable the industry to reduce its carbon footprint significantly.”

    The world’s two leading commercial aircraft manufacturers, Boeing and Airbus, are at the heart of sustainable aviation fuel programmes and development. Boeing Commercial Airplanes’ director of sustainability strategy Sean Newsum explains that it’s “a global issue that requires global co-operation – with no single solution.” On his company’s input, he says: “We’re actively involved in carrying out aviation’s ‘all of the above’ strategy to reduce CO2 emissions by advancing future airplane technology, improving network operational efficiency and transitioning to renewable fuels.

    “Sustainable aviation fuels are proven, used daily, and widely recognised as offering the most immediate and largest potential to decarbonise aviation over the next 20 to 30 years. Boeing has been a leader in fostering their development since before the first test flight in 2008. We worked with airlines, engine manufacturers and others to conduct further testing and gain certification for commercial use in 2011.”

    Boeing, Etihad Airways, Khalifa University and several others were founding members of the Sustainable Bioenergy Research Consortium near Abu Dhabi. Plants at the desert ecosystem are irrigated with seawater. Source: Boeing.
    Boeing, Etihad Airways, Khalifa University and several others were founding members of the Sustainable Bioenergy Research Consortium near Abu Dhabi. Plants at the desert ecosystem are irrigated with seawater. Source: Boeing.

    Boeing continues to collaborate with partners around the world to create regional supplies, Newsum says. “We’ve worked with partners to produce sustainable fuel from purpose-grown sugarcane in Brazil, nicotine-free tobacco plants in South Africa and plants in the United Arab Emirates irrigated with seawater, among other efforts. The UAE project is a good example of solving two problems at once. Oil from the plants is used to create sustainable fuel while farm-raised fish that fertilise the plants help feed a nation that imports nearly 85 per cent of its needs. Etihad Airways, another partner in the project, flew from Abu Dhabi to Amsterdam in January 2019 using the first batch of fuel from this endeavour.”

    When produced sustainably, scientific studies show that sustainable aviation fuel reduces CO2 emissions by up to 80 per cent compared to petroleum fuel over its life cycle, Newsum notes. Some sustainable aviation fuels even perform better than conventional jet fuel. “Their higher energy density means less fuel is required for the flight and they reduce particulate emissions,” he says.

    Bringing down barriers

    The main challenges now are scale, technology and cost. For Newsum, the most immediate barrier to wider production and use of sustainable aviation fuel is the broader availability of government incentives “to close the cost gap for our airline customers”. He explains: “Government incentives to producers and users are critical to accelerate development of commercial-scale supplies at competitive prices. New sustainable fuel pathways continue to be developed that can create fuels from a larger variety of feedstocks and different processing technologies. Costs should come down as production scales up and additional technologies mature in concert with government support, which should drive additional market growth.”

    According to Newsum, 14 sustainable fuel production plants and refineries around the world are in operation, under construction or in advanced planning stages. These facilities have a potential annual capacity of 3.5 billion litres by 2025.

    The Etihad Airways crew who flew a passenger flight from Abu Dhabi to Amsterdam in January 2019 using the first batch of fuel from the pilot UAE project. Source: Etihad Airways.
    The Etihad Airways crew on the passenger flight from Abu Dhabi to Amsterdam in January 2019 using the first batch of fuel from the pilot UAE project. Source: Etihad Airways.

    It is also important to note that sustainable fuel can be made from a wide variety of sources: non-edible plants, agricultural and forestry waste, non-recyclable municipal waste, industrial plant off-gassing, and other feedstocks. Chicago area-based LanzaTech has produced sustainable aviation fuel by capturing carbon at industrial plants, Newsum notes. Fulcrum Bioenergy is working on producing fuel from municipal waste, with plants in Nevada, USA, and the UK. “Future production pathways could include electrofuels and other bio-based sources of sustainable fuel that sequester carbon during their growth cycle,” he adds.

    The majority of aviation emissions – around 80 per cent – come from flights longer than 1,500km. Newsum believes sustainable fuels are therefore key to long-term, large-scale emissions reductions from larger aircraft that fly these routes while other renewable energy solutions will be developed for shorter-range markets and future advanced aircraft.

    Commercial prospects

    Some 40 million litres of sustainable aviation fuel will have been produced in 2020, according to the International Air Transport Association (IATA), representing just 0.015 per cent of total jet fuel. Seven technical pathways exist to generate sustainable aviation fuel, the association says, with a further eight in the pipeline for testing and approval over the coming years. Each pathway widens the opportunities for more sustainable aviation fuel to be supplied over time.

    ATAG offers a clear route to commercial viability. “Since the first test flight in 2008, the technological progress has been remarkable. However, the actual uptake of sustainable aviation fuel is modest relative to total industry demand. This is in part due to these fuels still being produced in relatively small quantities,” the association says.

    “Without economies of scale the unit cost of production remains, in general, higher than traditional fuel and this price impediment is limiting its wider use. For sustainable aviation fuels to be scaled up to commercially viable levels, substantial capital is required to develop the refining and process capacity.

    Lufthansa Cargo and DB Schenker recently collaborated to operate a 777F cargo flight completely powered by sustainable aviation fuel. Source: Lufthansa Cargo.
    Lufthansa Cargo and DB Schenker recently collaborated to operate a 777F cargo flight completely powered by sustainable aviation fuel. Source: Lufthansa Cargo.

    “Moving a technology from the research to the commercial phase can be extremely challenging and requires substantial investment. Building a small-scale demonstration facility requires a fraction of the capital required to develop a commercial scale facility. However, even if a demonstration scale facility performs as expected, moving from small scale to commercial scale can still be risky.

    “Addressing this funding gap should be a priority for policy makers who have the available tools and mechanisms to bridge the gap and enable progress in this new industry. However, once the cost of production facilities has been de-risked, it is likely that the cost of the new fuel will drop considerably, as has been seen in other renewable energy markets.”

    In its Waypoint 2050 report, which brings together experts from across the aviation sector to “see how the industry can accelerate working together to contribute to the world’s climate action mission”, ATAG says: “It is likely that aviation will need around 450-500 million tonnes of sustainable aviation fuel per annum by 2050. Analysis shows that this is achievable, with rigorous sustainability criteria ensuring a transition that does not impact food or water use. Rather than relying on a single option, there are a range of feedstocks available, from non-food crops to waste sources and eventually a shift to power-to-liquid fuels made from recycled or directly-captured CO2 and low-carbon electricity.

    “The scale-up will be a significant challenge, although with the right support from government and the energy sector, it is far from insurmountable. Policy will play a core role in this shift – government support to channel feedstocks towards aviation and not to other transport sectors, where alternative energy sources are already available.”

    *This feature is taken from the December 2020 issue of MRO Management, which you can read here.