Mary Yap has always been a stargazer. As a child growing up in the Seattle area, she would regularly sneak out of her room late at night, plant herself on the bathroom floor and stare up at the stars through the skylight, filled with wonder.
Her contemplative nature, along with an urgent desire to make change, eventually led Yap to entrepreneurship. Earlier this year, she cofounded Lithos Carbon, along with two Earth Sciences professors. The startup works with farmers to permanently remove CO2 from the atmosphere and enhance crop yields by spreading basalt dust — waste created when quarries crush basalt rock for other uses — onto farmlands.
Lithos — the Greek word for stone — uses proprietary software to custom-deploy the basalt based on variables such as soil chemistry and crop nutrition. It also measures how much CO2 is removed and sells carbon credits to companies, providing a share of the payment to the farmers it works with. Lithos, which says it has captured more than 2,000 tons of carbon in 2022, is selling the credits through Frontier, a $1 billion advance market commitment led by Stripe, Alphabet, Shopify, Meta and McKinsey.
Based on a natural process called rock weathering, Lithos’ technology was invented by Yap’s cofounders, Noah Planavsky, associate professor of Earth and Planetary Sciences (and her mentor) at Yale, and Chris Reinhard, associate professor of Earth and Atmospheric Sciences at Georgia Tech. The startup’s use of science and technology to create a cost-effective and scalable climate solution quickly caught the attention of investors. Just two months after launching in March, Lithos announced a $6.29 million round of seed funding, from a group of investors that included Union Square Ventures, Greylock Partners and Bain Capital Ventures.
As the granddaughter of an entrepreneur and descendant of Taiwanese farmers, founding an agriculture-based climate startup might seem like an obvious career choice for Yap, 30, but her path to entrepreneurship was anything but a straight trajectory. At 18, she abandoned plans to become a doctor to head to Silicon Valley, where she spent six years scaling other people’s companies, including social payments startup Tilt, acquired by Airbnb. Following the unexpected deaths of two close friends, she took a year to travel and soul search, which ultimately led her to pursue sustainable architecture. She got into Yale through the Eli Whitney Students Program, designed for students who’ve taken a nontraditional path to college, and majored in urban studies. She later added a second major, earth and planetary sciences, which led to lab work with Planavsky and eventually to Lithos.
I recently spoke to Yap about her young startup, life as an entrepreneur, the path she took to get there, and what inspires her.
The conversation has been edited for clarity and length.
CJ Clouse: Can you walk me through Lithos’ process and how the technology works? First, where does the basalt come from?
Mary Yap: Basalt is a volcanic rock. If you think about Iceland or Hawaii, basalt is the black rock those places are made of, but it can be found all around the world. It’s mined regularly for use in concrete, asphalt, construction … and there’s rock dust that’s created during that process, which has no commercial value. The waste dust is what we’re upcycling.
Clouse: How do you convince farmers to use your technology? Do you sell it as an income stream from the sale of carbon credits?
Yap: We do give them a carbon credit kickback. We want to be very generous there. But I don’t focus on the carbon capture part when I first talk to a farmer. Usually, they’re more excited about this because we replace the limestone they’re using to de-acidify their soil and restore nutrients with something that can do a better job. We’re able to give them [customized] rock dust that has the specific nutrients necessary to restore the soil, and it can improve their crop yields, up to 40 percent in some cases. And because we’re able to completely replace the limestone they’d otherwise be using, that’s a cost savings for them out of the gate.
Clouse: So they sprinkle the basalt on the crops, and it helps the soil capture more carbon? What happens to the basalt in the end?
Yap: One key thing to know about our process is that it’s different from storing organic soil carbon, where you’re trying to keep carbon in the ground. What we do is create dissolved inorganic carbon or bicarbonate. When it rains, the basalt reacts with the rainwater, converting carbon dioxide from the atmosphere into dissolved bicarbonate. The bicarbonate then washes off in the rivers and groundwaters and ends up in the ocean, where it eventually sinks to the bottom, the deep ocean, where it’s trapped and locked away permanently.
Clouse: How many farms are you working with now? And where are they?
Yap: We primarily operate in the Midwest and parts of the East Coast today. We’re working with over 1,000 acres right now, about 14 farms, but we’re scaling up. We’ve got a long wait list of farmers.
Clouse: You were able to secure a round of seed funding quite early on. Did having contacts from your former life in Silicon Valley help with that?
Yap: A little bit, but this is a different space than what I was in before, which was consumer software. I do know folks out here in the valley, and it was helpful to get advice from other founders and investors. A climate tech company is a hard tech company, and sometimes those can be harder to fund. And beyond that, there’s no playbook for success. There’s no playbook for deploying a bunch of rock dust to farmers, who use it to capture carbon from the atmosphere.
Clouse: Has anything about the experience launching your own company surprised you? Has anything been easier or harder than you expected?
Yap: Honestly, the trucking logistics was pretty hard. Finding the right kind of trucks to move all this material around and getting those trucks to the quarries. Figuring out the scheduling for all of that and getting things delivered on time. I spent many mornings calling a bunch of truckers, and that wasn’t exactly what I’d originally envisioned. Plus, I don’t have any experience with trucks. I had little toy trucks when I was a kid, but that’s about it.
Clouse: That’s as good a segue as any to the next question: What kind of kid were you? What was your childhood like? And your family?
Yap: My mother immigrated to the U.S. from Taiwan, where she’d grown up on farm in the highlands. My father grew up in Malaysia. So my whole family is in Southeast Asia; it’s really just my mom, my little sister and me here in the States. My mom and dad divorced when I was 7, and he moved back to Malaysia. Growing up in Seattle, I spent a lot of my childhood out in nature, literally staring at plants, wondering how they grow, staring at spiderwebs, all of those kinds of things. We didn’t have a TV, and I didn’t get a phone until I came to San Francisco when I was 18, so you just kind of learn from the world around you. I also read a lot of books about astronomy, actually. I’m obsessed with the stars, with the idea of space and how we are so small in the universe. The first thing I ever wanted to be was an astronaut. The second was a marine biologist. I’m also obsessed with the ocean.
Clouse: When you were working in the startup world, something happened that changed your life. Two of your friends passed away. Can you tell me a little bit about that? And I’m sorry, that must have been horrible.
Yap: It was a rough year. I had helped launch a couple of startups, and everything was going well. I loved what I did, I loved the team I was leading. But in 2016, I got a call at work — one of my best friends had been on a trip with her parents, she got hit by a logging truck and died on the spot. She was the same age as me, 24, and had so much potential. Then I lost another friend a couple months after that, in another accident. Sometimes these horrible, tragic things bring you a sense of clarity — survival is not guaranteed for us as individuals or as a society. I suddenly realized I don’t know how long I have here; I could get hit by a bus in two years. So I want to be working on the most important problem, and that was not consumer software, no matter how much I liked it.
Clouse: So you took a year off to do some traveling, some soul searching. What did this lead to?
Yap: I actually met with a bunch of farmers when I was in Indonesia, who were having problems growing rice. I thought, the climate crisis, urgency, we need to do something. That’s it. And my father happens to be an architect and I’d heard a lot from him about the work he does. So I went back to school. I was trying to take a data-driven, technical approach to decarbonizing cities. I wanted to build more cost efficient, more environmentally efficient buildings that use less energy.
There’s no playbook for success. There’s no playbook for deploying a bunch of rock dust to farmers, who use it to capture carbon from the atmosphere.
Clouse: And how did you get from architecture and greening cities to farms and carbon capture?
Yap: After my first year at Yale, I got a fellowship that paid for me travel abroad [again], for the summer, and shadow urban planners and architects in 11 different countries, in Scandinavia and Southeast Asia. I saw how they were building new cities from scratch, and I was a little disappointed. There was so much greenwashing in the field. For example, there’s a city in Malaysia, built on this artificial island where there used to be a bed of seagrass. And now the nurseries have crashed, and the fishermen aren’t able to catch fish. This is the opposite of sustainability.
When I came back to Yale, I thought, we need to take a science-driven approach to this. I ended up going deep into the science of carbon cycling. I took classes in fossil fuels, renewable energy, oceanography… And three of my classes ended up being taught by Noah Planavsky. He and Chris [Reinhard] had been researching something called rock weathering, which the Earth has been doing for 4.5 billion years. This process removes carbon from the atmosphere to the tune of about 1 billion tons every year. It’s massive. Without it, our planet would look like Venus, covered with greenhouse gases. I thought, if the Earth is so good at this, is there some way we can manipulate this process, speed it up, and actually make this a carbon removal technology?
Clouse: I was curious about your grandmother being an entrepreneur. Did you learn anything from her or take any inspiration from her? Is she still living?
Yap: Yes, she is. She is 96 and still so sharp. She grew up as a farmer and married a fisherman, and she was a secret entrepreneur before women could be entrepreneurs. In the 1940s, she started what was essentially a fertilizer business. She realized that a lot of families who had pigs just left manure lying on the ground. Early in the morning, when it was still dark, she would go collect pig manure that nobody was using, and turn that into fertilizer, then take it to another part of the island and sell it to other farmers. I only connected the dots after we started the company, and I thought, wait, my grandma built a circular economy in farming! So I am really inspired by her.
Clouse: Are you still inspired by the stars? Still a stargazer?
Yap: For sure. Sometimes, when I’m feeling stressed, I’ll go out and sleep on the roof or somewhere, because it’s stuffy inside, and I just need to be outside. It’s good to look at the stars. You can’t see quite as many of them in San Francisco, but they’re still there.
