Frontier bets $58.3M on carbon removal startup Vaulted Deep

The Stripe-backed fund placed its biggest CO2-removal order yet with the 7-month-old startup, which injects waste biomass slurry” deep underground.
By Maria Gallucci

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Vaulted Deep is injecting carbon-rich slurry at its site in Hutchinson, Kansas. (Vaulted Deep)

Squat metal wellheads rise from a grassy field in central Kansas, surrounded by red steel containers. Years ago, oil and gas companies came here to deposit their liquid waste into the teardrop-shaped salt caverns hundreds of feet below the surface.

Now, a company with a wholly different mission is filling those same impermeable caverns with other kinds of waste material.

Vaulted Deep recently began injecting slurry made from the organic residues of nearby landfills, feedlots, wastewater treatment facilities, and paper mills. This biomass is rich in carbon — and Vaulted is working to keep it from returning to the atmosphere as carbon dioxide by trapping it underground.

Last week, the Houston-based startup announced it had removed more than 2,000 metric tons of CO2 during its first four months of operations in Hutchinson, Kansas. The Frontier coalition — a carbon-removal fund whose members include Stripe, Shopify, and Alphabet — purchased credits in advance to help launch this first commercial-scale run.

On Wednesday, the two organizations said they’re ready to significantly scale up their arrangement.

Frontier’s members agreed to pay Vaulted $58.3 million to remove 152,480 metric tons of CO2 between 2024 and 2027. While that doesn’t come remotely close to undoing the damage caused by burning fossil fuels, it’s not a trivial amount of CO2 either. The amount Vaulted aims to remove is equal to roughly 40 percent of the annual emissions from a single U.S. gas-fired power plant.

The offtake agreement is the most lucrative that Frontier has signed since it launched in April 2022. Last year, the coalition struck similar deals with the companies Charm Industrial, which makes bio-oil” from crop waste, and Lithos Carbon, which uses crushed rocks to sequester CO2. Frontier’s members aim to spend nearly $1 billion on permanent carbon removals by 2030.

We’re really excited about Vaulted’s ability to deliver at scale in the near term,” Hannah Bebbington, the strategy lead at Frontier, told Canary Media.

Not only is that great from a climate perspective,” she added, but that type of tangible, concrete delivery is what enables investors to come in. It gets other entrepreneurs excited about doing carbon removal, and it generates more momentum in the market overall.”

An illustration depicts Vaulted’s method of removing CO2 via underground injection of waste biomass. (Vaulted Deep/Frontier)

Vaulted, which launched in September 2023, is a relative newcomer in the fast-growing field of carbon dioxide removal, though its core technology is already being deployed at commercial scale for industrial waste operations nationwide.

The startup is a spin-off of Advantek Waste Management Services, a company that helped to pioneer the use of deep disposal wells for particularly problematic types of waste, including oil field slurry and discharges from wastewater treatment plants. The U.S. Environmental Protection Agency regulates and issues permits for the wells, which can range between 3,000 and 7,500 feet deep — far beneath the zone where groundwater is found.

Vaulted is now using Advantek’s know-how on injection techniques, federal permitting, and environmental safety to inject carbon-laden liquid into the ground in Kansas, as well as at an existing Advantek operation in Los Angeles.

It’s not that we just invented this and now we’re off to the races,” said Omar Abou-Sayed, who co-founded Vaulted and is the executive chairman and former CEO of Advantek. We can move fast because we spent decades creating the through-line to get to this starting position.”

The fuzzy, complicated math of biomass

Vaulted is just one of the hundreds of companies worldwide developing novel ways of removing planet-warming gases from the sky, including by running giant air filters, baking trays of limestone, and storing CO2 in seawater.

Climate scientists agree that at least some carbon removal is necessary to achieve net-zero emissions by 2050 — in addition to phasing out fossil fuels and drastically reducing greenhouse gas emissions. In the United States, experts say, at least 1 gigaton of carbon-removal capacity will be needed to decarbonize the economy by mid-century. That’s equal to roughly 20 percent of the country’s total CO2 emissions in 2023.

Vaulted is also among the growing subset of startups that are looking to biomass waste — organic residues from plants and animals — to draw carbon dioxide from the atmosphere. Charm Industrial uses a fast pyrolysis” process to turn cornstalks and leaves into a viscous, carbon-rich oil that it injects deep underground. Graphyte takes rice and timber scraps, packs them into polymer-sealed bricks, and buries them in a pit.

Charm sources corn stover from farms in the Midwest–Great Plains regions, including this site in Kansas. (Charm Industrial)

Given that the world produces only so much corn stover and cow manure, the increased focus is stirring debate among researchers and policymakers about how to prioritize the finite supplies. Certain forms of biomass can also be refined into alternative fuels that can help decarbonize aviation or trucking, or turned into chemical products or clean hydrogen. Which solutions could deliver the biggest benefits in terms of the world’s climate goals is contested.

Another challenge is verifying whether biomass-based approaches actually remove CO2 from the atmosphere as intended.

The key question really comes down to, what do you consider to be a waste?” said Eamon Jubbawy, founder and CEO of Isometric, a new registry for carbon-removal credits. We’re pushing towards a consensus around this … but waste’ is not a word that has a standardized definition.”

Isometric, which raised $25 million in seed funding last year, aims to bring more scientific certainty and transparency to the nascent, evolving world of carbon removal. In April, the registry published a peer-reviewed protocol for biomass geological storage,” which describes biomass waste in a counterfactual way: not storing the materials would result in CO2 being released into the atmosphere.

Frontier considers waste” to include materials that cannot be used for some other higher and better purpose, and is not leading to indirect land-use changes or other indirect consequences,” Bebbington said. She noted that the coalition’s technical team vets every delivery of CO2 removal to ensure the feedstocks meet those criteria.

Trapping CO2, and contaminants, deep underground

For its part, Vaulted says its process can handle a mix of moisture-rich materials that aren’t safe or suitable for other uses, including contaminated organic waste from wastewater treatment plants, manure ponds, and paper mills.

Consider anaerobic digesters, which process wastewater to produce biogas” for heating and powering buildings. At the end, a sludgy digestate” still remains. The concentrated byproducts are commonly spread on farms as a fertilizer — but growing evidence shows they’re full of hazardous forever chemicals” like PFAS. And as the digestate decomposes, it emits more CO2 and methane.

By injecting that material underground, we can avoid those contaminants and pathogens from going back out into local communities as part of our solution,” said Julia Reichelstein, Vaulted’s co-founder and CEO.

Vaulted's operation in Kansas repurposes a former oil-and-gas waste disposal well. (Vaulted Deep)

With the $58.3 million offtake agreement from Frontier, Vaulted plans to expand existing operations in Kansas and Los Angeles. The startup also aims to bring three new sites online by 2027, all of which will ideally be in places with large amounts of geological storage capacity, strong regulatory processes, and easy access to organic waste.

Reichelstein said that grinding, mixing, filtering, and straining materials into an injectable slurry doesn’t require huge amounts of money or energy. That means the key to driving down Vaulted’s operational costs — and reducing the company’s own emissions — will be shrinking the distance between injection wells and waste sources.

Vaulted measures the volume of carbon removed first by weighing the carbon in the biomass, then by subtracting emissions generated at every stage in the process. Right now, the company says it can deliver 1 metric ton of fully net-negative” carbon dioxide removal for every 3 metric tons of waste it handles.

If we’re not paying for transportation, we’re more efficient and we don’t have those emissions,” she said. And that really helps us get down below 100 bucks a ton” of carbon removal, she noted, referring to an industry-wide target for achieving economic viability.

Isometric issued and certified credits for the first 2,000 tons of CO2 that Vaulted removed in Kansas, and it will do so for its future large scale-up operations as well. Isometric is also working towards issuing credits” to bio-oil startup Charm Industrial and potentially a handful of other ventures, Jubbawy said.

Carbon removal needs to find that balance of rigor and quality, and doing things in a scientific manner — but also really quickly,” he said. Vaulted is one of the companies that is well on their way to figuring out how to do all of those things at the same time.”

Maria Gallucci is a senior reporter at Canary Media. She covers emerging clean energy technologies and efforts to electrify transportation and decarbonize heavy industry.