Lawmakers have been pushing for measures to fight climate change as President Joe Biden’s administration has called for the U.S. economy to have net zero greenhouse gas emissions by 2050, meaning removing as much carbon from the atmosphere as is emitted.

It was not immediately clear whether the sustainable aviation fuel bill would have Republican support. Republicans have opposed the administration’s climate policies, arguing they risk damaging the economy by hurting the drilling and mining industries.

Air travel contributes around 2% of global emissions, according to the Air Transport Action Group, a coalition of aviation experts focused on sustainability issues.

“In addition to improving aircraft efficiency and reducing excess flying, scaling use of sustainable aviation fuel is critical for the aviation sector to reduce its fair share of carbon emissions for a safe climate future,” said John Holler, senior program officer for climate cooperation and sustainable fuels at World Wildlife Fund.

While U.S. sustainable aviation fuel use has risen in recent years, it remains a fraction of the larger traditional petroleum-based jet fuel market.

Producers of sustainable aviation fuel can earn the tax credit if the fuel achieves at least a 50% lifecycle greenhouse gas emissions reduction compared with petroleum-based jet fuel, according to the legislation.

The credit would expire at the end of 2031.

A coalition of trade groups representing pilots, flight attendants and other aviation industry personnel, sent a letter and documents on Tuesday to Congressional committee members that outlined ways to reduce carbon emissions. Solutions included the tax credit.