Ninety-five. That’s the number of times we've mentioned hydrogen on The Big Switch over the past 18 episodes. This week, we’re taking a step back to ask what IS hydrogen? And how can it help decarbonize the economy?

It turns out, there’s a whole rainbow of hydrogen fuel – gray hydrogen, blue hydrogen, even pink hydrogen. But the kind of hydrogen that’s most important for a net zero future is green hydrogen. It’s made with carbon free-electricity, and it could go a long way toward  decarbonizing sticky parts of the economy, like industry and shipping.

In this episode, we talked to a very musical scientist – Dr. Julio Friedmann, chief scientist and chief carbon wrangler at Carbon Direct, about the promises and challenges of hydrogen. Prepare for lots of singing.

Guests: Dr. Julio Friedmann is chief scientist and chief carbon wrangler at Carbon Direct, and non-resident fellow at the Center for Global Energy Policy at Columbia University. 

The Big Switch is produced by Columbia University's Center on Global Energy Policy in partnership with Post Script Media. This episode was produced by Alexandria Herr and Daniel Woldorff. Theme music and mixing by Sean Marquand. Story editing by Anne Bailey. A special thanks to Natalie Volk, Kirsten Smith and Kyu Lee. Our executive editor is Stephen Lacey.