Aether Fuels has raised $30.4 million of a $34.3 million round, according to an SEC filing.

The e-fuels startup is working on producing fuel for aviation and maritime shipping using carbon dioxide and other waste carbon streams. The new round would give the company’s bank account a healthy bump; Aether Fuels had previously raised $8.5 million via convertible notes in late 2023.

The startup was spun out of Xora Innovation, an early-stage, deep-tech incubator run by Temasek. A company spokesperson did not immediately respond to a request for comment.

Since then, Aether Fuels has been working to refine its technology. The company says that its technology can use carbon from a range of waste streams, including industrial pollution, methane from landfills, and leftover plant debris from farms.

Not much is publicly known about exactly how Aether Fuels converts carbon dioxide to fuels, though a patent application filed in January suggests the company is exploring one avenue that involves using natural gas. The process gasifies solid waste, blends it with natural gas, and then transforms the mix into a liquid fuel (with any waste carbon dioxide captured along the way). 

In February, it announced a deal that gave it access to a gas-to-liquid program started by GTI Energy, a natural gas nonprofit. 

Airlines and maritime shipping companies have been pursuing bio-derived sustainable aviation fuel (SAF) and e-fuels as a way to decarbonize their energy intensive industries. However, those efforts have been nascent at best. The amount of SAF produced today, for example, only amounts to less than 0.1% of total use, and SAF is a much more mature industry than e-fuels.