Explainer: What You Need to Know About Sustainable Aviation Fuel

The world's insatiable appetite for flying is fueling concerns about how to shrink the carbon footprint of air travel, today the source of about 2.5 percent of humanity's planet-warming emissions related to energy.

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While that is a relatively small share of total global emissions, it looks set to increase in the decades to come, as significantly cutting emissions is still a distant technological prospect for commercial aircraft, even as other sectors, such as road transport, are doing so by going electric.

For airlines and governments across the world, the solution is sustainable aviation fuel (SAF), which backers say can cut emissions by more than 80 percent, without requiring aircraft modifications.

SAF is designed to be a drop-in fuel for planes, needing no new additional infrastructure at airports. Current technology allows up to 50 percent of SAF to be blended with fossil fuel-based jet fuel.

Here are some key things to know about SAF:

HOW IS SUSTAINABLE AVIATION FUEL (SAF) MADE?

The fuel can be made from a variety of raw materials, or feedstocks, using different techniques, but today virtually all of it is made from hydroprocessed esters and fatty acids (Hefa).

The Hefa production process involves stripping oxygen from the fat molecules of natural oils and fats and replacing it with hydrogen. Hefa fuel has various uses, including in aviation.