A Minneapolis startup company wants to become a leader in  the emerging carbon capture and storage market. 

Carba, cofounded by U of M Chemical Engineering Professor Paul Dauenhauer and his former student, Andrew Jones (B.C.E. ’09, B.S. ’10), has developed a portable reactor that converts plant waste into a charcoal-like substance called biochar. That material can then be buried to seal carbon in place for generations.

The company’s backers believe it could prove to be an inexpensive and energy-efficient method to remove carbon dioxide from the atmosphere—something the latest U.N. Intergovernmental Panel on Climate Change report says will be necessary for preventing the most devastating effects of climate change. “There’s a huge negative emissions problem and nobody has the technology to scale without using a ton of energy or capital,” says Jones, who is also Carba’s CEO. “We believe we have cracked that nut.”

Trees and plants are the world’s biggest carbon sink. Through  photosynthesis, they store carbon dioxide throughout their lives, but after they die, they decay and release that carbon back into the atmosphere. Carba’s technology offers a way to lock that into a solid form instead. The company promises to consume a fraction of the energy of other technologies, such as direct air capture methods. Those technologies also demand either centralized plants or investments of hundreds of millions of dollars per site.

Locking carbon underground

Carba’s answer: Let trees and plants do the work of pulling carbon from the atmosphere, and then lock that biomass into a stable form before it can decay. Jones believes biochar should be buried to remove any chance of carbon release. “If we harvest all the biomass waste out there and convert it to something more stable, like a char, then bury it underground, we’re reversing the coal mining process,” Jones says. “We can take 1 trillion tons of CO2 that we’ve dug up and put into the air, suck it into the trees and the plants, take their waste product, bury it underground, and store it indefinitely.” 

The company was recently named a finalist for an incubator program by Minnesota clean energy accelerator Grid Catalyst, and is partnering with trash and recycling giant Waste Management to deploy its first reactor at a Twin Cities waste facility.

Waste Management said in a prepared statement that it seeks to reduce its carbon emissions by 42 percent by 2032 and sees biochar as a potential solution. Wood waste at its suburban facility currently either becomes compost or is burned for energy. The company says it’s “excited to partner with Carba on this sustainability research project that has the potential to demonstrate tangible scientific progress towards climate solutions.”

Jones says biochar offers co-benefits for Waste Management. It helps contain environmentally destructive elements such as the fluoridated forever chemicals (widely known as PFAS), mercury, methane, and odors. “That’s a benefit to the whole community,” he says.

Modeling energy efficiency

Grid Catalyst founder and president Nina Axelson says Carba merges energy innovation and clean energy ecosystems. “I feel like Carba sits exactly between those two because it’s carbon capture technology, but there’s a very big energy efficiency component to their technology,” she says.

Jones met cofounder Paul Dauenhauer at the University in 2005 while he was a chemistry undergraduate. Dauenhauer holds an endowed chair, runs his own research lab, and has won many awards, including a MacArthur Foundation “genius grant” in 2020. The serial entrepreneur has spun off his research into three startup businesses involving biomass. The two previously cofounded Activated Research Company, which provides chemical analysis for greenhouse gases, biofuels, sustainable aviation fuels, jet fuels, and pyrolysis products.

An inexpensive, scalable technology like Carba is the key to combating carbon emissions, Dauenhauer says. The energy consumption is a fraction of what direct air capture would consume. “I think a lot of people may be good at chemistry or physics and they understand how to sequester carbon but don’t know how to do it cheaply,” he says. “You have to cut every cent out of the processing and logistical sequence of getting that carbon underground. And that’s where we excel.”

The North American market alone creates a billion tons of biomass annually, which means the company shouldn’t be limited by supply chain shortages. Carba’s technology is also feedstock agnostic, so it can use whatever waste materials are cheaply available.

The mobile reactors can also move to different dropoff sites to reduce miles traveled by truckers hauling biomass. The size of a wood chipper, the reactors heat plant waste in an oxygen-less environment to a temperature around that of a commercial pizza oven in a process known as torrefaction.

Initially, Carba considered building a biomass plant before deciding that would take too long, cost too much, and require years of studies and permitting, Jones says. However, that remains the problem of carbon capture facilities at coal or other fossil fuel plants—the cost can top $1 billion, and the infrastructure takes years to build.

Mobile, compact, cost effective

Several other companies are pursuing similar approaches to carbon capture. CDR.fyi, a community-driven initiative to monitor the carbon removal market, wrote in a Medium post that biochar delivered 87 percent of the carbon removed from the market last year. Of the 10 most active companies, nine targeted biochar for carbon removal.

Jones and Dauenhauer wrote a peer-reviewed article for ACS Engineering that reported torrefied carbon requires just a small energy input compared to direct carbon capture.

Carba believes the bioreactor will cost less than $200 to break down a ton of biomass. Through selling credits on the evolving carbon removal market, Carba should more than pay for the bioreactor’s production costs and generate profits, Jones says.

Carba plans to build and own the reactors, with revenue coming from the sale of carbon removal credits in voluntary markets. The markets reward producers with more money for permanence, defined as carbon storage for at least 100 years.

The global carbon removal market is expected to grow from nearly $2 billion in 2020 to $7 billion by 2028, Fortune Business Insights predicts. CDR.fyi reports 593,000 tons of carbon were purchased last year: a 533 percent increase over 2021.

Last year Stripe, Alphabet, Shopify, Meta, McKinsey Sustainability, and a handful of other companies announced they would invest $925 million in carbon removal companies. More than 3,000 companies have committed to being net zero in the future, a goal that will likely lead to buying carbon dioxide removal credits from Puro.earth, Carbonfuture, or other marketplaces. Jones identifies travel, bank, and technology sectors as leaders in the carbon dioxide removal market, with even oil and gas companies expressing interest.

Brendan Jordan, vice president of the Great Plains Institute, says carbon removal technology and markets will become increasingly crucial to reducing global greenhouse gases. The International Energy Agency and the Intergovernmental Panel on Climate Change predict the world will “overshoot carbon budgets, and that’s why there is so much interest in carbon removal strategies,” he says. 

Frank Jossi is writer based in St. Paul. He has also been a Humphrey Policy Fellow at the U of M.