 and from the Doris Duke Foundation. Hey, welcome back to How I Built This. I'm Guy Raz. You're listening to an excerpt from the show. To hear the full episode, check out How I Built This wherever you get your podcasts. And if you're just joining us, my guest today is Cody Finke, co-founder and CEO of Brimstone. They've developed a carbon negative process for manufacturing cement, which could have a massive impact in reducing carbon emissions around the world.