The British company Firefly Green Fuels has developed a new aviation fuel that is produced without the use of fossil resources. The company worked with experts from Cranfield University, who confirmed that the new fuel has a 90% lower carbon footprint than the fuel used in aviation today, the BBC reports. Tests by independent regulators have confirmed that the new fuel is almost identical to standard A1 aviation fuel.

Although the fuel is not yet commercially available, the company says it is on track to bring it to the global market and will have the first commercial production plant up and running within five years. Firefly Green Fuels already entered into a partnership with the low-cost airline Wizz Airwhich will supply fuel from 2028.

The fuel is made from human waste, which the company sources from water companies in the UK. Wastewater undergoes a process called hydrothermal liquefaction, which turns liquid waste into sludge or oil. The solid by-products can then be made into fertilizer. The company claims that the carbon footprint of the entire process is only 7.97 grams of carbon dioxide per megajoule (gCO²e/MJ). In comparison, the carbon intensity recorded for jet fuel ranges from 85 to 95 gCO²e/MJ.

Firefly’s solution makes it possible to produce fuel in a matter of days. It is not yet clear whether sustainable jet fuel will be more expensive or cheaper than what is currently available. However, the company’s CEO James Hygate mentioned in a statement that the use of human waste is a “cheap raw material (that) will never run out”.