Manufacturing, Innovation, Insight and Future Strategy

Professionals involved in the manufacturing process and the day-to-day management need to keep up to date with the new and current technologies and equipment to ensure the efficient running of the manufacturing site. Sustainable aviation fuels will become an increasingly vital part of the effort to limit emissions from aircraft over the coming years. Who is producing what, and how?

Covid-19 may have hogged the civil aviation headlines for the past two years but sustainability and the search for lower emissions never went away. It is generally agreed that popular sentiment has reached a tipping point and national populations are now fully seized by the need to cut fossil fuel use to minimise the growth of global warming.

The public interest in November’s COP26 conference in Glasgow, together with the increasing frequency of extreme weather events, shows that even seemingly small increases in average global temperatures above pre-industrial era levels can have major effects. These include the melting of the polar ice caps and subsequent rising sea levels, plus both abnormal rainfall and summer temperatures. Parts of the Persian Gulf, for example, are experiencing increasingly common summer temperatures of 50°, close to what is bearable for humans.

Aviation is reckoned to account for around 2.5% of global CO2 emissions but the rise in global air transport means this figure is expected to rise to at least 4% in coming years if no mitigating measures are taken. Sustainable aviation fuels (SAF) are regarded as the essential way forward, although SAFs made from feedstocks other than fossil fuels are themselves increasingly regarded as a stopgap measure until alternative power sources, such as hydrogen fuel cells are developed in the mid-to-late 2030s.

There are multiple technical routes to producing SAFs. “To date, there are seven SAF production technologies approved by the American Society for Testing and Materials, which is the organisation that drafts and produces international technical standards, including for aviation fuels,” said Joël Navaron, president, Aviation, TotalEnergies. “Among these technologies, some have a higher level of industrial maturity, already making it possible to manufacture biofuels that can be incorporated up to 50% into conventional aviation fuel.”

Total Energies lists some of the methods as:

HEFA (hydroprocessed esters and fatty acids): This is the only method currently at the commercial stage. The raw material comes from materials, such as used cooking oils.

ATJ (alcohol to jet): This technology could offer flexibility on raw materials, such as industrial gases or lignocellulose (vegetable waste), used to produce ethanol.

FT (Fisher Tropsch): This production route is based on so-called advanced raw materials, such as agricultural and forestry residues or municipal waste. This path requires very high investments for large-scale commercialisation.

“Among the SAF family, we can also include e-fuels, synthetic fuels produced from hydrogen – ideally from renewable electricity and CO2 – which can be extracted from ambient air or industrial effluents. These technologies, for the moment at the R&D stage, remain extremely expensive but could become a particularly promising path in the longer term.”

Producing SAF from waste oils is the method currently used by TotalEnergies, (which is also looking at developing other production pathways, such as hydrogen and e-fuels) and by Finland-based Neste, which started investing in renewable production facilities in 2005, with refineries at Porvoo near Helsinki, Rotterdam and Singapore.

“We’re using various oils and fats to produce hydrocarbons,” said Sami Jauhiainen, vice-president business development at Neste’s renewable aviation business unit. “Most of its renewable fuels capacity has, until now been used to produce renewable diesel but further distillation of the material produces jet fuel.”

The challenge involved in reaching anything approaching a significant contribution towards lowering CO2 emissions is obvious. It is, however, a challenge that the industry must meet if it is to continue to thrive. The International Air Transport Association’s (IATA) AGM in Boston in October approved a resolution for the air transport industry to achieve net zero carbon emissions by 2050. This would align with the Paris Agreement goal for global warming not to exceed 1.5°C. IATA director-general Willie Walsh admitted that achieving net zero emissions “will be a huge challenge. The aviation industry must progressively reduce its emissions while accommodating the growing demand of a world that is eager to fly”.