Houston cleantech startup Cemvita Factory has scored a $5 million investment from United Airlines Ventures, the venture capital fund of the Chicago-based airline.

The equity investment is aimed at propelling commercialization of sustainable aviation fuel through a process involving carbon dioxide (CO2) and synthetic microbes.

Oxy Low Carbon Ventures, a subsidiary of Houston-based Occidental Petroleum that’s a founding investor in Cemvita, and United Airlines Ventures are financing the startup’s work on sustainable jet fuel. United Airlines operates a hub at George Bush Intercontinental/Houston Airport.

If that work pans out, the United and Occidental investment arms plan to form a joint venture to commercialize the technology. The joint venture might include construction of plants for the production of sustainable aviation fuel.

Sustainable aviation fuel, known as SAF, is an alternative to jet fuel that uses non-petroleum feedstock and offers lower greenhouse gas emissions.

Founded by brother-sister team Moji and Tara Karimi in 2017, Cemvita Factory relies on synthetic biology to turn carbon dioxide into chemicals and alternative fuels, including SAF. The startup, founded in 2017, is among the first companies to employ this technology to support heavy-industry decarbonization and find ways to take advantage of microbiology to convert CO2 into fuel.

“The use of SAF is a promising approach that we believe can significantly reduce global emissions from aviation and further decarbonization initiatives to combat climate change,” Richard Jackson, president of operations for U.S. onshore resources and carbon management at Occidental, says in a news release.

Cemvita is the third SAF-related startup to receive an investment from United Airlines Ventures.

The partnership among Cemvita, Occidental, and United is among many initiatives seeking to ramp up production of SAF. For instance, the U.S. Department of Energy is collaborating with the U.S. Department of Transportation, the U.S. Department of Agriculture, and other federal agencies to develop a strategy for scaling SAF technology.

The global SAF market is projected to grow from $219 million in 2021 to more than $15.7 billion by 2030, according to Research and Markets.

The International Air Transport Association says more than 370,000 flights have been fueled by SAF since 2016. Over 26.4 million gallons of SAF were produced last year.

Last month in France, aircraft manufacturer Airbus flew a A380 test jet for about three hours with one of the four engines operating solely on SAF. The three other engines ran on conventional fuel.

In December 2021, United flew a 737 MAX 8 jet from Chicago O’Hare International Airport to Washington Reagan National Airport outside Washington, D.C., with one of the two engines operating only on SAF. It was the first commercial flight with passengers aboard to use SAF in that capacity. The other engine ran on conventional fuel.

United CEO Scott Kirby, who was aboard the historic flight, said the flight was “not only a significant milestone for efforts to decarbonize our industry, but when combined with the surge in industry commitments to produce and purchase alternative fuels, we’re demonstrating the scalable and impactful way companies can join together and play a role in addressing the biggest challenge of our lifetimes.”

For now, airlines are allowed to use up SAF for up to 50 percent of the fuel on commercial flights.