Climate goals: airlines are pinning their hopes on sustainable aviation fuel

The global aviation industry is relying on a massive ramp-up in production of sustainable aviation fuel (SAF) over the next three decades to meet its target of "net zero" carbon emissions by 2050.

However many airlines lament the lack of supply on the market and the prohibitive price - SAF costs around three to five times more than traditional jet fuel. There is also concern about how to sustainably meet supplies as demand grows.

A growing number of companies are making bulk purchases of SAF from producers, airlines and corporate travel agencies as they look to reduce carbon emissions to meet environmental targets and encourage mass production of cleaner fuels.

Airlines like Virgin Atlantic are also trying to highlight the issue, with a 100% SAF-powered flight taking off from London's Heathrow airport on a flight to New York on Tuesday to underline the fuel's importance.

It is a liquid fuel that can be blended with conventional jet fuel without the need to develop new planes or engines. It can reduce carbon emissions by up to 80%.

The emissions are saved throughout the production process because the feedstocks used to make SAF have lower lifecycle emissions than conventional jet fuel.

SAF'S chemical composition is similar to normal jet fuel, meaning it can be used in engines that can take traditional fuel without changes to machinery.

SAF makes up only around 0.1% of the fuel currently in use, but many airlines have a target of 10% by 2030 and the industry's goal of "net zero" emissions by 2050 relies on SAF accounting for 65% of fuel.

New EU rules will require fuel suppliers to ensure that 2% of fuel made available at EU airports is SAF in 2025, rising to 6% in 2030, 20% in 2035 and gradually to 70% in 2050.

It can be produced from a number of sources including oils and fats, green and municipal waste and non-food crops.

The dominant feedstock at present is vegetable oil, including waste oil from cooking and virgin oil.

KPMG has said that the availability of vegetable oil feedstock will be limited by overall supply as well as rival uses in road and maritime fuels that are less complex to produce and offer easier profit potential.

Some SAF feedstocks, in particular palm oil, have raised sustainability concerns because of the risk farmers will switch from other crops, as well as the difficulty of tracing the feedstock origins, according to the World Economic Forum (WEF).

The European Union does not consider palm oil to be a sustainable fuel because of deforestation in top palm oil producing countries in Southeast Asia to increase land dedicated to palm oil plantations.

European non-governmental organisation Transport & Environment has also warned that if some animal fats currently used in food and feed and to make soap and cosmetics are used in SAF, palm oil will be the cheapest and most likely substitute.

If virgin oils are used in the process, demand could drive up prices of vegetable oils.

The growing amount of SAF required to meet environmental targets has companies looking for new and more sustainable feedstocks.

Options being researched include power-to-liquids that would convert renewable electricity, hydrogen and carbon into synthetic fuels, which KPMG said has the strongest potential for large-scale SAF production in the longer term.

However synthetic fuels are even more expensive to produce, at up to ten times the cost of traditional jet fuel and more than biofuel-based SAF, and there's very little supply available on the market.

Hydrogen is also an alternative but engines that can be powered by hydrogen will only be available in the mid-2030s and even then would only be able to power shorter-haul flights.