Elon Musk has said advances in battery technology could make electric planes commercially viable within three years. The Tesla boss made the claim just two weeks after the electric car maker published a research paper detailing vastly improved next-generation battery cells.

The breakthrough appears to have prompted Musk to revise a previous prediction from 2019 that it would be at least five years until commercial batteries achieve a 400Wh/kg energy density, which he calculated is necessary for flight, according to Novinite.

Several companies are already working on zero-emission planes, though Tesla is yet to commit to building one.

Musk has hinted several times that he is interested in creating one, even as far back as 2010 during his one-line cameo in Iron Man 2. “Got an idea for an electric jet,” he said.