“I have a design for a plane,” said Elon Musk in a wide-ranging interview for the Joe Rogan Experience podcast broadcast live Thursday night on YouTube. The interview included the two men drinking whiskey and smoking weed.

Musk thinks his electric airplane would be better than current planes, capable of vertical take-off and landing (VTOL) and supersonic flight at high altitudes. The Tesla and SpaceX CEO admitted, however, that it’s not a priority for him. “Electric cars are important, solar energy is important, stationary storage of energy is important,” said Musk. “These things are much more important than creating electric supersonic VTOL.” Musk then became visibly emotional in describing our addiction to fossil fuels, calling it the “the dumbest experiment in human history.”

The spliff was introduced by Rogan long after the discussion of the plane. “It’s legal, right?” asked Musk before taking a single, tentative puff. The interview was conducted in the state of California where marijuana is legal for recreational use.

The airplane discussion begins at 1:15:08, the urging to accelerate the switch to sustainable energy begins at 1:19:16 and the weed smoking at 2:10:00.

”I’ve thought about this quite a lot, quite a lot,” Musk said of the electric jet design, although he admits that he’s only discussed it with friends and girlfriends. “The trick,” said Musk, “is that you have to transition to level flight. The thing you’d use for vertical takeoff and landing is not suitable for high speed flight.” Musk then describes in broad terms how he’d power the plane.

”The interesting thing about an electric plane is that you want to go as high as possible, but you need a certain energy density in the battery pack, because you have to overcome gravitational potential energy. Once you’ve overcome gravitational potential energy and you’re at a high altitude, the energy you use in cruise is very low, and then you can recapture a large part of your gravitational potential energy on the way down. So you really don’t need any kind of reserve fuel.”

Musk quickly conceded, however, that he has more important things on his plate that prevent him from taking his electric plane design further. “The electric airplane isn’t necessary right now,” said Musk. “Electric cars are important, solar energy is important, stationary storage of energy is important. These things are much more important than creating electric supersonic VTOL.”

Musk then sighed heavily, and became visibly emotional as he described the need to adopt sustainable energies more quickly.

”We’re really playing a crazy game here with the atmosphere and the oceans. We’re taking vast amounts of carbon from deep underground and putting this, putting this in the atmosphere, this is crazy. We should not do this. It’s very dangerous. We should accelerate the transition to sustainable energy. I mean the bizarre thing is that obviously we’re going to run out of oil in the long term. There’s only so much oil we can mine and burn. That’s totally logical, we must have a sustainable energy transport and energy infrastructure in the long term. So we know that’s the end point, we know that. So why run this crazy experiment where we take trillions of tons of carbon from underground and put it in the atmosphere and oceans. This is an insane experiment. It’s the dumbest experiment in human history. Why are we doing this, it’s crazy.”

“So we’re fucked?” asked Rogan later. “No we’re not fucked,” responded Musk. “But the momentum to sustainable energy is too slow.”

In 2017, Musk shared a vision of city-to-city travel using SpaceX rockets. The futuristic concept would allow passengers to make “most long-distance trips” in just 30 minutes, and go “anywhere on Earth in under an hour.”

Elon Musk wants to send you anywhere on Earth in under an hour Elon Musk wants to blast you from New York to London in 29 minutes. Posted by Verge Science on Friday, September 29, 2017

Elon Musk has a storied history of floating ideas like Hyperloops and tunnels long before they become official projects under his command. Of course, Musk also says plenty of things that never happen, and is currently facing an SEC investigation into whether he misled investors about taking Tesla private.