The use of sustainable aviation fuel is on the increase around the world. But what is this newfangled propulsion juice exactly, and is it the magic bullet to make aviation kinder to the environment?

Aviation gets a really bad rap worldwide for its impact on the environment. Being entirely reliant on fossil fuels means it’s a really carbon intensive way to travel. For most of us, one trip between New York and London would have almost the same carbon footprint as all the rest of our activities over the course of a year.

According to the Air Transport Action Group (ATAG), there were 35.8 million scheduled commercial flights in 2016 carrying 3.8 billion passengers. This equated to 781 million tons of CO2, around 2% of all man made carbon emissions. With aviation expected to grow to 6.9 billion passengers a year by 2035, effective action is needed to make aviation less damaging and more sustainable in the long run.

An exciting development working to tackle this issue is the field of sustainable aviation fuel. But what exactly is it, and is it the answer we’re looking for to make aviation possible in an increasingly environmentally conscious world?

What is sustainable aviation fuel?

Sustainable aviation fuels are almost identical to fossil fuels in their chemistry. This means they can be used in a standard jetliner with little or no modification required. However, the magic is that they are 80% less carbon intensive over their lifecycle, and can be created using a number of sustainable, renewable sources.

ATAG say that, in order for a sustainable aviation fuel to be viable, it must meet a number of criteria, not just in terms of its suitability as a fuel replacement. With some ‘biofuels’, the way it is produced is almost more harmful than simply burning fossil fuels, such as when it requires large amounts of fresh water, competes with food production or encourages deforestation. As such, sustainable aviation fuels usually come from sources such as:

• Municipal waste: Solid waste from homes and businesses can be turned into jet fuel. Sources include food scraps, newspapers, grass clippings and product packaging.
• Used cooking oil: Oils that have come from either plant or animal sources and are no longer useful for cooking can be repurposed into jet fuel.
• Forestry waste: Excess wood and other agricultural waste can be processed into synthetic fuel using something called the Fischer-Tropsch process.
• Energy crops: Certain plants such as camelina and carinata grow fast and can be harvested to produce jet fuels. Because they can be used in between food crop growing, they can be beneficial for growers as part of their normal crop rotation.
• Algae: These microscopic plants can be grown in polluted or saltwater and absorb large amounts of carbon dioxide. They are one of the most exciting developments in jet fuel production right now due to the speed they can grow.

ATAG say that sustainable jet fuels reduce carbon emissions by around 80% over their lifespan. This is because although the fuels are often carbon neutral themselves, they are also considering the carbon cost of production and transportation too.

Is anyone using sustainable aviation fuel?

Why, yes. Rather a lot of airlines are already using sustainable jet fuel as it happens. Just last week, All Nippon Airways (ANA) signed an agreement with LanzaTech to purchase sustainable aviation fuel. United Airlines have also recently renewed a contract to purchase 10 million gallons of sustainable aviation fuel over the next two years, and KLM has committed to 75,000 tons of sustainable fuel each year for the next 10 years.

Of course, there are reasons that not every airline in the world is switching to sustainable aviation fuel right away. One key consideration is the limited production of these fuels. Before an airline can switch to sustainable fuel, they need to know there is a reliable, affordable supply close to their hub. As with any new technology, these things take time, so as more refineries are built, so more airlines will have the opportunity to switch.

The worldwide aviation industry consumes around 278 billion liters of jet fuel each year. To replace this with sustainable alternatives is going to take a mammoth effort, but there is a huge amount of support for this industry worldwide. Right now, only Oslo, Los Angeles, Bergen and Stockholm have regular supplies of sustainable aviation fuels, but there are many others looking into it.

Will it save the planet? Probably not on its own, but it could be a game-changer for sustainable aviation in the future.