Originally published by NPR’s Marketplace. Listen to the full interview.

“It’s summer, and that means blockbusters. And for “Marketplace Tech,” it means an occasional look at sci-fi movies and their visions of the future.

In 1985, “Mad Max Beyond Thunderdome” hit the big screen. Mel Gibson and Tina Turner battled in a post-apocalyptic wasteland. You might remember the crazy cars, the eponymous Thunderdome — basically Cirque du Soleil with chainsaws. In the film, fossil fuels are gone. The main energy source is methane from … pig feces.

“Marketplace’s” Jed Kim spoke with Matthew Kahn, an economist at Johns Hopkins University, about the energy technology and economics on display in “Mad Max.” He said that for him, the movie shows how free markets falter in a post-apocalyptic world. The following is an edited transcript of their conversation.”