A decade ago, University of Washington oceanographers Julian Sachs and Alex Gagnon were working in a tropical paradise, studying the impacts of climate change on coral reefs surrounding remote islands in French Polynesia.
They were focused on ocean acidification, which is happening as seawater soaks up much of the excess carbon dioxide produced by burning fossil fuels.
The scientists were interested in the ocean conditions predicted for the end of the century, so they devised a system for pulling carbon dioxide out of seawater from deep in the ocean and using it to create more acidic conditions at their experimental site. The technology worked well.
“Being able to work on a solution – or potential solution – to the problem is a blessing. It’s a gift.”
– Julian Sachs, cofounder of Banyu Carbon
But what if instead of simulating a dire future for coral reefs, thought Sachs and Gagnon, they removed even larger amounts of the ocean’s carbon dioxide and disposed of it? What if they tried to prevent the most severe climate outcomes, instead of forecasting them?
Two years ago the professors co-founded Banyu Carbon, a Seattle-based startup developing technology for extracting carbon dioxide from the ocean, which in turn lowers the levels in the atmosphere.
The effort so far is going swimmingly. Banyu, which is an Indonesian word for seawater, has raised $8.5 million from investors. It has a $500,000 deal with Frontier to remove 350 tons of carbon dioxide by 2026. It has support from programs including the U.S. Department of Energy, Activate Fellows, and Ocean Visions, a nonprofit advising carbon removal efforts.
Banyu is located in CoMotion Labs, a startup incubator on the UW campus. Drizzly Seattle is arguably less appealing than the sunny tropics, but Sachs is thrilled to be addressing climate change.
“After studying what the problem is, teaching about what the problem is, being able to work on a solution — or potential solution — to the problem is a blessing,” Sachs said. “It’s a gift.”
Pulling carbon from the ocean
As the world hurtles toward dangerously warmer temperatures, international experts advise that carbon removal will be essential to avoiding the worst climate outcomes. Many startups are devising approaches that pull carbon from the air and capture it. One of the big challenges, however, is that atmospheric carbon dioxide exists at levels that make it difficult to vacuum up efficiently.
Sachs and Gagnon’s solution takes advantage of the ocean’s natural ability to concentrate carbon dioxide at higher levels than are found in the air — and other startups are following suit. The nonprofit [C]Worthy lists 19 startups in marine-based carbon dioxide removal.
“Emerging carbon dioxide removal technologies that leverage the ocean’s vast size and natural chemical processes hold promise as tools to draw down carbon at scale,” said Ocean Visions’ senior program officer Nikhil Neelakantan, in announcing its latest “Launchpad” program cohort that includes Banyu.
Startups are pursuing removal strategies such as growing seaweed or using electrolysis. The secret sauce in Banyu’s technology is a special chemical called a “reversible photoacid.”
In a demo at the startup’s lab, a blood-red solution of the photoacid stirs in a flask. Sachs flips on an LED light that shines into the glass, triggering a reaction.
“It’s causing the photoacid molecule to change its shape,” Sachs explains. “And when it does, it’s going to shed protons. It going to change colors. It’s going to start absorbing light in a different way.”
Like a magic trick, the liquid rapidly fades to orange and then pale yellow. The released protons turn the solution acidic. The effect is reversed when the light is removed and the chemical “relaxes” back into its original condition, turning the solution basic again.
In the startup’s carbon dioxide removal system, sunlight will activate the chemical, and the acidic protons will flow into a tank of seawater. That will cause carbon dioxide gas to bubble out of the water, something like it does in a highly carbonated soda. The system captures the carbon dioxide for disposal and transfers the protons back to the photoacid. The seawater is returned to the ocean.
The photoacid is something of a wonder chemical that can be recycled and reused for 10 days before it starts to degrade, and the researchers are working to extend its lifespan. It’s made from relatively inexpensive ingredients and doesn’t contain hard-to-come-by metals, or trace or toxic elements.
And because the system needs sunlight anyhow, Banyu’s cofounders are adding solar panels to their device, harnessing the excess rays of light to produce energy that can help drive the setup’s pumps and machinery.
‘Absolutely a commodity’
This summer, the Banyu team will deploy a test version of their technology at the UW’s Friday Harbor Labs. The marine research station is already pumping in seawater for scientific pursuits, and the startup will take a small fraction for their efforts. Their goal for the project is to remove a kilogram of carbon dioxide.
From there, the Banyu is working with partners in preparation for a commercial demonstration in Port Arthur, Texas, near the largest oil refinery in the U.S. — and an area that is also building infrastructure for carbon capture and geological storage.
The company has six employees and has funding to pay for at least five more. Banyu has raised two venture capital rounds, a nearly $2 million pre-seed round led by the Grantham Foundation for the Protection of the Environment, and a $6.5 million seed round with investors including Grantham, United Airlines Ventures, Carbon Removal Partners and ReGen Ventures.
The startup also received a $270,000 Small Business Innovation Research grant from the National Science Foundation.
Banyu’s technology, once proven out, could be deployed in wide-ranging locations, Sachs said. The necessary features are ocean access and a means of locking away the captured carbon in a geological formation, or recycling it into a product such as sustainable aviation fuels. The system also needs land. A setup big enough to remove a kiloton of carbon dioxide per year is expected to require about 5,000 square meters — a space slightly smaller than a football field.
And while the technology has been promising in the lab, there are significant hurdles ahead.
Companies aiming to extract carbon dioxide from seawater face multiple challenges, said David Ho, an oceanographer at the University of Hawaii. That includes accurately monitoring, reporting and verifying the volume of carbon dioxide removed. When carbon dioxide is subtracted from sea water, the ocean gains new capacity to absorb it from the air, but that amount can be hard to calculate.
There are also risks to ocean ecosystems and marine life from pumping out water from the sea.
At the same time, Ho, who co-founded [C]Worthy to address marine carbon dioxide removal accounting, sees the overall approach as “having a better chance to scale” than land-based strategies.
Banyu’s greatest strength, according to Ho, is the energy efficiency of its approach. “The challenge for Banyu,” he said, “has to do with their photoacid and their ability to make it work at scale and economically.”
Sachs acknowledged the cost issues, and said they’re aiming for a price tag of $100 or $200 per ton of carbon dioxide removed. The current deal with Frontier costs a little under $1,400 per ton.
“Nobody cares where the permanent carbon removal comes from — every CO2 molecule is the same if you can verify it’s going away forever,” he said. “People are just going to buy the cheapest ones. It’s absolutely a commodity. Price is everything.”
