When Elon Musk isn’t mulling over self-driving cars or rocket launches, he has another thing on his mind: electric airplanes.

In a recent interview with Marketplace, the Tesla Motors and SpaceX founder said he believed the future of transportation — including everything from cars to airplanes and ships — will be fully electric-based.

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Musk is particularly keen on the idea of electric airplanes. In the Marketplace interview, he said he has a design in mind for a “pretty cool supersonic, vertical take-off and landing electric jet” that would be “really fun.”

He also likes the idea of an airline company based solely on electric power. See the video here.

This isn’t the first time Musk has expressed interest in electric planes. During MIT’s Aeronautics and Astronautics Centennial Symposium last fall, Musk briefly mentioned building an electric supersonic aircraft but said that as much as he would like to do it, he thinks “his mind might explode.” See video below.

If Musk’s vision eventually does turn into a reality, it could help improve the air transportation industry, which, according to the Natural Resources Defense Council (NRDC), emits far more pollution than any other method of transportation. By their measure, every ton of cargo moved by plane adds over 4.5 times more particulate matter and nearly 25 times more nitrous oxides to the environment than if it were transported by ship.

Musk has obviously been thinking electric for quite some time now, having devoted his time, energy and investments to Tesla Motors’ electric vehicles, such as the new sedan Model S and the first fully efficient SUV, the Model X.

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At Tesla, he’s also working on the PowerWall, a home battery that uses electricity generated from solar panels for charging, powers homes in the evening and provides a backup electricity supply. Then there’s Tesla’s $5 billion lithium-ion-battery-producing Gigafactory in Nevada that’s currently under construction.

Although Musk has a lot of interest in electric-powered transportation and homes, the rockets he’s developing for SpaceX are not driven by electricity. Even though rocket launches are rare, they’re harmful to the environment when they do blast off, with the reactive gases emitted causing ozone molecules to break apart.