Laura Stieghorst was sitting in the back of a University of Miami classroom in November 2021 when she got the email that would change her life.
As her professor lectured the class on sustainable development, Stieghorst, then a senior studying environmental science and policy, learned that Elon Musk — founder of Tesla and SpaceX, new owner of Twitter and the world’s richest man — was about to give her a $100,000 grant to fund her research proposal to fight climate change.
“I just wanted to jump out of my seat,” said Stieghorst, who graduated from UM in December.
She had applied for the money as part of the XPRIZE for Carbon Removal, a Musk-backed competition that promised to give 23 student-led research teams $100,000 grants to study ways to slow climate change by removing carbon dioxide from the atmosphere.
When she submitted her proposal a month earlier, Stieghorst didn’t expect to win. Now, as she stared at her laptop screen, it dawned on her that this money was about to launch her career. “It was wonderful, and it was also scary,” Stieghorst said, “because it was like, ‘Oh man, now I really have to do this. It’s not just a proposal anymore — this will be my job now.’”
The grant helped Stieghorst found Básico, a startup specializing in carbon removal research, and fund a collaboration with UM’s Rosenstiel School of Marine, Atmospheric, and Earth Science.
Básico aims to test whether the world’s oceans can be used to soak up carbon through a pioneering but unproven concept called ocean alkalinity enhancement, which involves mixing alkaline minerals into seawater. If Stieghorst’s ambitious research succeeds, she could help create a new marine-based market where businesses and industries pay to remove carbon from the atmosphere to offset their carbon emissions.
Supercharging the ocean's CO2 sponge
Scientists have been dreaming about fighting climate change through OAE since the 1990s.
“This idea has been kicking around for a long time,” said Chris Langdon, a UM marine biology professor who partnered with Stieghorst to study the technology at his Virginia Key lab. “I’ve been talking about it in lectures for years.”
But the technique also has been viewed as a long shot, and it hasn’t attracted much funding through traditional research grants. Without the XPRIZE money, Langdon said he and the grad students who work in his lab wouldn’t have been able to study it. “Being able to actually buy supplies and equipment and pay a stipend to the students was all made possible by this funding.”
There is a reason why the technique is so intriguing. Oceans already are a sponge for carbon dioxide. They’ve absorbed about 30% of the CO2 human beings have pumped into the atmosphere since the dawn of the industrial revolution, according to a 2019 paper from an international team of scientists led by NOAA. OAE is envisioned as a booster shot of sorts that would increase the amount of carbon the oceans can absorb.
In theory, OAE should work like this: From shore sources, or potentially from ships in the future, alkaline minerals would be mixed into seawater. “Alkaline” is the opposite of “acidic.” So boosting ocean alkalinity could have two benefits. First, it could reverse ocean acidification, a man-made phenomenon that has hurt coral and other sea life. And second — according to the laws of chemistry — more alkaline water should be able to absorb more carbon dioxide and slow climate change.
But so far, it remains a theory. No one has tested OAE thoroughly enough to say just how much carbon the strategy could remove from the atmosphere and — another critical question — whether it would harm sea creatures. That’s where Básico comes in: The startup’s first mission is to calculate how much carbon the concept actually captures and to test its impact on coral.
To do that, Langdon and a team of student researchers spent three months adding alkaline minerals to coral tanks at a UM lab on Virginia Key this summer. The team measured the impact of the minerals on coral health, and then raised the temperature in the tanks to see if the minerals helped the corals stay healthier under heat stress.
Meanwhile, Langdon’s team added alkaline minerals to a 9,000-gallon wind and wave simulation tank to replicate how the minerals might behave in the ocean. Then, they measured how much extra carbon the seawater in the tank had absorbed.
The team hasn’t yet published its findings. But Riley Palmer, a master’s student in Langdon’s lab who ran the coral research, said the minerals “didn’t have any negative impact on the corals.”
Carbon capture controversy
OAE is just one of several strategies for carbon capture, the process of taking carbon dioxide out of the atmosphere to slow the process of climate change. If startups like Básico can demonstrate that these techniques effectively capture carbon at a reasonable cost, then businesses can invest in carbon capture as a way to offset their own emissions and meet their climate goals.
Carbon capture has drawn scorn from some environmental activists, who point out that it’s often hard to verify how much carbon these projects actually remove from the atmosphere. They also argue that ineffective carbon capture projects will give companies an excuse to keep emitting carbon while pretending to address climate change. Greenpeace, for instance, has excoriated what it calls “the great carbon capture scam.”
But the UN’s Intergovernmental Panel on Climate Change has said carbon capture will be necessary to help the world avoid the worst effects of global warming. In April, UN climate scientists wrote that carbon capture is “unavoidable” if the world hopes to meet its climate goals.
Even if carbon capture catches on, it’s still unclear whether OAE will be the method scientists and business owners embrace. Alternative techniques, like planting groves of trees or building machines that suck carbon dioxide out of the air and convert it into rocks, have already attracted billions of dollars in investment. OAE startups, meanwhile, are still working to prove how much carbon they can capture per dollar spent.
“It’s really hard to measure how much carbon is being captured once it’s in the ocean,” said Stieghorst. “From a theoretical perspective, this is an amazing solution. But from a business perspective, it would be easier to sell this solution if you had all the carbon stored in once place where you could hold it and count it and sell carbon credits against it.”
That’s why Stieghorst applied for her $100,000 XPRIZE grant under the competition’s “measurement, reporting, and verification” category, which is dedicated to funding research that proves how much carbon a certain technology can capture.
Stieghorst, who grew up in Coral Gables and graduated from Coral Gables High School, has since won a second $100,000 grant to continue her work as a climate entrepreneur. This time, the money came from Reddit cofounder Alexis Ohanian.
In June, Stieghorst was named one of 20 winners of the Ohanian-backed 776 Fellowship, which gives entrepreneurs under 23 a cash prize and two years of mentorship from Silicon Valley stalwarts to pursue their ideas to fight climate change.
Partnering with the Rosenstiel
Langdon was one of the few professors who believed in Stieghorst’s project early on. In August 2021, Stieghorst invited UM students and professors to a talk on campus in which she explained OAE and tried to recruit members of the audience to help her apply for the XPRIZE grant. It was a tough crowd.
“During the Q&A portion, one chemistry professor just told me, straight up, ‘This isn’t going to work. Why would you work on this?’” Stieghorst said.
But there was at least one friendly face in the crowd of about 25 students and faculty. “She was cracking jokes and I was the only one who laughed,” Langdon recalled. “It’s tough to convince professors of anything, and this is such a non-traditional approach to things that most of them didn’t want to get involved.”
Even so, Langdon saw the potential in Stieghorst’s idea. He joined the project a week later, along with a half dozen UM students. After a frenzied seven-week sprint to assemble their proposal — “the most insane scramble I’ve ever experienced,” Stieghorst says — the team submitted its application.
Now, a year later, Langdon says he’s “jazzed” to be working on the project. “For years I’ve been studying the problem, and people always ask, ‘Well, when are you going to do something about it?’” said Langdon. “This is a chance to be part of the solution.”
This climate report is funded in part by a collaboration of private donors, Florida International University and the Knight Foundation. The Miami Herald retains editorial control of all content.
This story was produced in partnership with the Florida Climate Reporting Network, a multi-newsroom initiative formed to cover the impacts of climate change in the state.
