Green fuels: Not just a flight of fancy

Sustainable Aviation Fuels are steadily gaining traction globally, with the aviation sector working hard to reduce its carbon footprint.

In a pathbreaking move, United Airlines has recently placed a pre-order worth USD three billion for 15 Boom Overture supersonic aircraft. The Overture, capable of seating between 65-88 passengers, has a top speed of Mach 1.7, or 2,100 kph, therefore cutting flying time by half vis-à-vis a conventional commercial plane. Therefore, a New York to London flight would take just 3.5 hours. Watch their video here.

Unlike the legendary Concorde, which was neither fuel-efficient nor quiet, the Overture will be designed to be ‘net-carbon zero,’ by running on Sustainable Aviation Fuel (SAF). The first such green aircraft is slated to roll out in 2025 and carry its first passengers by 2029. Boom is collaborating with Prometheus Fuels, a start-up that uses nanotube membranes to produce jet fuels from carbon dioxide drawn from the atmosphere. 

Boom overture
Boom’s Overture: Half the flight time, with the potential to achieve net-zero carbon emissions. Image: Courtesy Boom.

As exciting as this development may be, it certainly isn’t the first instance of the deployment of SAFs. Globally, more than 40 airlines now have SAF experience, with an estimated 250,000 commercial flights using it since 2011 and 1.6 billion gallons of SAF committed to forward purchase agreements.

It was back in 2012 that Etihad Airways made an Abu Dhabi to Washington DC flight using plant-based fuels. Fast forward to 2019, and Etihad operated the first commercial flight from Abu Dhabi to Amsterdam on a Boeing 787 Dreamliner. “We did this using sustainable fuel derived from oil from the Salicornia plants, which were grown in Abu Dhabi and refined as part of the Seawater Energy and Agriculture System (SEAS) – the world’s first desert ecosystem designed to produce fuel and food in saltwater. In September 2020, Boeing and Etihad collaborated to have a 787-10 Dreamliner fly from Seattle to South Carolina in the US using a 50/50 blend of sustainable and traditional jet fuel,” explains a representative of the airline.

Etihad: Making their own biofuel in the desert. Image: Courtesy Etihad Airways.

The other lighthouse of the airline industry – Singapore Airlines – has been an active member of the Sustainable Aviation Fuel Users Group (SAFUG) since 2011. In 2017, they launched a series of green package flights from San Francisco to Singapore that incorporated SAF. In 2020, SIA worked with Stockholm’s Swedavia Airport to uplift sustainable aviation fuels on flights departing from the city.

And then, earlier this year, a KLM plane flew from Amsterdam to Madrid. The flight created a record of sorts by beings the world’s first to use certified synthetic kerosene, made from carbon dioxide, water, and renewable energy. Synthetic kerosene was developed in the Shell Technology Centre in Amsterdam, synthesised from hydrogen, recycled carbon dioxide, water, and renewable power from solar panels and Dutch wind turbines. Subsequently, Air France-KLM flew a biofuel-powered Airbus A350 from Paris to Montreal.

India is not to be left behind. In 2018, SpiceJet operated a Bombardier Q400 aircraft for a 45-minute, Delhi-Dehradun flight that was powered by 25 per cent biofuel.

The green context

A Boeing 747-400 jumbo jet carries 2,40,000 litres of jet fuel, about one per cent of the volume of an Olympic-sized swimming pool, and guzzles it at a rate of four litres per second.

Green fuels, flights, airlines
A Boeing 747-400 consumes four litres of jet fuel per second. Shutterstock/Eliyahu Yosef Parypa.

Prima facie, the aviation sector is not a major contributor to greenhouse gas emissions. Before COVID-19 all but stalled the industry, aviation accounted for about 2.4 per cent of global emissions. But if nitrogen oxide and contrails — icy vapour trails left in an aircraft’s wake — were to be factored, the burden to the environment rises to about 3.5 per cent.

Although CO2 emissions per passenger flight have fallen by nearly 55 per cent over the last three decades due to better engines and improved operations, the total volume of emissions has soared by 34 per cent over the past five years because of rising air traffic. By 2050, 10 billion passengers might be lining up to fly 20 trillion kilometres.

This is the backdrop for global airlines to have far pledged to halve net emissions by 2050. Before COVID-19, the International Civil Aviation Organisation (ICAO) reckoned that CO2 emissions from international air travel could be curbed by as much as 63 per cent by 2050 if airline turbine fuel is completely replaced by SAF.

The European Union plans to require airlines to use a minimum percentage of SAF, made from waste oil, biomass or synthetically with renewable power. Currently, regulations require that sustainable aviation fuel is blended with fossil jet fuel, up to a 50-50 ratio.

SAFs, broadly, refers to jet fuel that is produced from renewable feedstocks instead of fossil fuels. Possible feedstocks for sustainable aviation fuel encompass used cooking oil, energy crops, agricultural and forestry residues, and municipal solid waste. SAFs can be used directly to power a plane, without the need to modify its fuel combustion and management systems.

Burning fossil fuel releases CO2 into the atmosphere. The gas stays in the atmosphere, for a long time, contributing to the greenhouse gases causing global warming. SAFs also use carbon, but the critical difference is that the process involves recycling of carbon that’s already in the atmosphere.

Many shades of green

Flight plus trees
Going green is not quite so black and white. Image: Pexels/Sam Willis.

In 2019, 50 million litres of SAFs were used in flights, which accounted for just 0.01 per cent of global aviation fuel. This fell well short of the industry’s goal to reach a level of six per cent use by 2020. The simple fact is that SAFs are currently three to four times more expensive than conventional air turbine fuel OR kerosene. What heightens the price differential is the fact that the latter receives tax subsidies.

But low production volumes of SAFs is the primary reason for the difference in economic viability between conventional fuels and SAFs. Globally enforceable emission reduction mandates could incentivise a boost in supplies. But experts warn that pushing the aviation industry to use more biofuels before reliable sources are in place could lead airlines to switch to low-quality, unsustainable food-based biofuels – such as those made from palm oil and linked to deforestation. In any case, different parts of the world have their own feedstock to produce SAFs, so consistency of quality and pricing are tricky subjects.

Synthetic fuels, on the other hand, have more potential to be scaled up. But there is almost no production right now. To be truly low carbon, these fuels also need to fit a strict sustainability criterion, made using clean electricity as well as a source of carbon captured from the atmosphere in the first place. This stipulation further raises costs.

So, what is the solution?

Regulatory mandates are the short answer. Europe is leading the way. Starting next year, flights departing from France will be required to use one per cent SAF, in keeping with European Union (EU) goals to reach two per cent levels by 2025 and five per cent by 2030 under the EU’s Green Deal policy. But many airlines seek exemption from this mandate for long-haul flights. They argue that a pro-SAF mandate restricted to Europe could provide an unfair edge to foreign competition.

Meanwhile, UK’s Heathrow Airport has successfully incorporated SAFs into the main supply for use across all flights. In Germany, one third of fuel used in domestic flights by 2030 will come from sustainable sources, according to a new roadmap. In the Netherlands, Canadian biofuels producer Enerkem, Shell and the Port of Rotterdam are working to transform the Rotterdam waste-to-chemicals project to waste-to-jet to meet growing demand for SAF.

Europe’s intentions might be in the right place, but progress is slow. There is a case for the 80:20 principle. In 2019, just 39 of 1,657 EU airports accounted for 80 per cent of the volume of conventional fuel used by departing aircraft in the bloc. Therefore, experts feel that instead of distributing SAF evenly over all EU airports, it would be more efficient to concentrate on the fuel supply chain at these 39 airports. Currently, only seven of these 39 airports have the capability to supply SAFs.

Flights, planes, green fuel, airports
In 2019, just 39 of 1,657 EU airports accounted for 80 per cent of the volume of conventional fuel used by departing aircraft in the bloc. Image: Pexels/Pixabay.

Private business jets often land in small airports that do not have SAF. European airports are in the process of instituting a ‘Book and Claim’ scheme, wherein the jets can pay for the fuel at an airport that doesn’t have it and claim it at an airport that does.

There are voluntary efforts too. In late April, prominent global companies came together to launch the Sustainable Aviation Buyers Alliance (SABA) to boost investment in SAF. Some of its founders include Netflix, JPMorgan Chase, Microsoft, Boeing, and Boston Consulting Group. Green warriors Rocky Mountain Institute and Environmental Defence Fund are also part of this alliance.

The new green revolution will be in the skies. And it is gathering momentum.

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