CO2 rendering

Carbon Dioxide Removal: The Startup View

Four carbon dioxide removal company CEOs weigh in on challenges, innovations, and the path to scale the industry.

According to the UN Intergovernmental Panel on Climate Change (IPCC), achieving climate stability by the end of the century requires rapidly reducing global emissions and deploying Carbon Dioxide Removal (CDR) technologies. While commercial solutions for cutting climate pollution exist today, the path to scaling a global CDR industry within a few years remains largely uncharted. RMI is rising to this challenge by supporting the financing, policy, and scientific innovation required to responsibly scale CDR solutions.

RMI has published a first-of-its-kind Applied Innovation Roadmap (AIR) report for CDR. The report assesses the path to market readiness for 32 distinct CDR solutions, including risks, opportunities, required research, development & deployment (RD&D), and roadmaps to guide industry, policy, and investment decisions.

RMI translates report insights into action through initiatives like Third Derivative, our climate tech startup accelerator program. Third Derivative’s First Gigaton Captured (FGC) initiative supports a diverse portfolio of 12 CDR startups along their RD&D journey. Our portfolio represents eight distinct CDR approaches operating across ten countries.

In light of the AIR report, we sat down with four visionary FGC CEOs to discuss their experiences, perspectives, and innovative strategies for scaling RD&D. The following edited excerpts provide a glimpse into the unique approaches of Rewind, RepAir, Airhive, and Cella. These interviews shed light on their challenges, innovations, and aspirations in the fast-evolving landscape of carbon removal.

Meet the startups

The AIR report assesses 32 approaches for capturing, processing, and storing atmospheric CO2. Each of our interviewed startups represents one of these approaches.

Rewind is developing a biogenic CDR (bCDR) approach that leverages plants’ photosynthesis process, converting CO2 to a stable form of organic carbon in biomass, and then storing it underwater. “Specifically, we sink forestry residual plant matter in the Black Sea, naturally storing the plant-embedded carbon for millennia,” explains Ram Amar, the CEO and founder. Just as centuries-old wooden shipwrecks can stay intact underwater, Rewind’s biomass will not decompose in the oxygen-free environment of the Black Sea, storing carbon in the biomass for centuries.

In contrast to biogenic approaches, the AIR describes synthetic CDR (sCDR) pathways as engineered systems that separate diluted CO2 gas from the ambient air or water into a purer stream of gas that can be permanently stored in rocks or utilized for other services. Direct Air Capture (DAC) technologies are sub-categories of sCDR. The AIR maps 10 distinct DAC approaches, with FGC startups RepAir and Airhive representing two.

RepAir vanguards the use of a continuous electrochemical process for a selective separation of CO2 from the air. “Our novel DAC system is based on electrochemical cell technology, consuming 70 percent less energy than other DAC approaches,” says Amir Shiner, CEO and founder.

Alternatively, Airhive is taking a different strategy for DAC ​commercialization. Rory Brown, the CEO and founder, explains how Airhive is bypassing the development of whole novel systems and components. “We are leveraging widely available industrial process equipment and low-cost minerals for our filtering ​sorbent materials. We see our DAC technology significantly lowering the cost potential” says Brown.

Regardless of the carbon capture approach, most solutions in the AIR rely on geologic CO2 storage to keep climate-warming emissions out of the atmosphere for centuries to come. Cella is a prominent startup in the field of CO2 storage via mineralization. “Cella injects captured CO2 into volcanic rock underground, speeding up the natural mineralization process to create storage that is permanent and highly verifiable. With the need for scale in mind, our proprietary technology improves injection efficiency, expands the range of geographies where we can store carbon underground, and relies on off-the-shelf industrial equipment,” says Corey Pattison, co-founder and CEO.

Source: RMI

Barriers to scale

As promising as these novel solutions are, each faces barriers to scaling. A fundamental part of the AIR analysis assessed the risks for each approach to achieve a safe, scalable, and affordable solution in the foreseeable future.

The AIR notes that bCDR direct biomass storage companies, like Rewind, face land use and long-term storage verification risks. Amar of Rewind confirms that measuring reporting and verification (MRV) in the Black Sea is a fun challenge to tackle. Amar adds that beyond the technical issues, regulations can present a hurdle to scientific advancement: “Rewind’s biggest challenge to scaling in the next five years is acquiring a permit to store shredded and bagged forestry biomass residue in the Black Sea.” Amar explains how securing such permits can be complicated even for research- and pilot-scale projects, requiring strategic partnerships.

Where bCDR companies like Rewind are solving the challenges around the MRV process, DAC and CO2 storage companies have to overcome a completely different set of challenges. The AIR finds that DAC and CO2 storage approaches have a risk associated with their engineered systems’ costs and energy consumption. CEOs like Shiner, Brown, and Pattison confirm these are the challenges their companies are facing today.

To overcome these challenges, they describe how they must invent novel technologies and processes while securing funding for first-of-a-kind (FOAK) pilot projects. According to Shiner: “In addition to RepAir’s low energy consumption and low cost, we also excel in our potential to scale up rapidly. Our battery inspired, low-cost approach, facilitates a swifter scale up as it leverages existing production materials. Most importantly, our simple, modular ‘StackDAC’ approach allows for the shortest path to deployment, with ‘click-to-connect’ units that stack one on top of the other. To address our scale up challenges we are actively seeking Engineering, Procurement and Construction (EPC) partners as we transition into mass production.”

In contrast, Brown of Airhive foresees their biggest challenge as validating the whole DAC system’s high-potential performance characteristics at increasing scales. Airhive plans to scale from several thousands of tons of CO2 captured per year to a commercial scale of over 100,000 tons per year. “Our key partner to succeed will be an engineering firm with experience designing and operating large-scale industrial facilities using process technology similar to ours,” says Brown.

Pattison of Cella says their key challenges are “sourcing CO2 at volumes sufficient to meet our storage capacity today and diversifying the capital stack for FOAK demonstration projects to prove the benefits of our solution at increasing scales.”


Every challenge is also an opportunity for innovation. Building on its understanding of the risks, the AIR maps the most crucial RD&D activities to scale each CDR approach to its full potential.

For example, the AIR highlights the importance of investing in the RD&D of marine MRV systems. The report estimates that investing about $100-300 million per project for marine monitoring can boost the deployment of at least five distinct CDR approaches described in the report. Rewind’s advances in deep-sea MRV can support other marine CDR approaches and projects in their own monitoring needs. At FGC, we are excited to support the startups and innovations that can unlock progress not just for themselves but for their industries, too. Investing in these types of companies and RD&D projects has a multiplier impact effect.

The AIR shows that critical funding for CDR RD&D from private and public sources is growing globally. Yet a funding gap remains, and there is a clear need to boost global coordination. That is why the AIR summarized investment priorities along five critical pathways, from small lab and pilot-scale projects unlocking advancements in basic science all the way to mass commercialization investments in the most mature approaches.

Yet, our CEOs remind us that successful RD&D requires more than an open checkbook. Here is the one ask each has.

Amar at Rewind emphasizes the importance of a supportive regulatory landscape: “We’re looking for prominent entities like the Science Based Targets initiative (SBTi) and the EU Commission to establish clear frameworks for businesses and governments to incorporate CDR into their voluntary or regulated climate action plans.”

Brown at Airhive asks governments to “fast-track development of an intermediate scale DAC sites in the next couple of years. We don’t need Megaton-scale commercial opportunities on 5–7-year development timelines. We need the middle step of 5,000-50,000 tonnes per year sites where DAC technology developers can deploy their technology to start generating significant revenue and prove their technology, at scales that are tractable from a financing and offtake perspective.”

Pattison at Cella, too, seeks new sites where they can test and scale their technology: “We need to increase scale quickly and incrementally, and key to that strategy in the near-to-medium term are sites where we can rapidly test, measure, and scale in the real world–including with corporate partners who can host pilots on their sites, help with permitting, and provide CO2 feedstock to our in-situ mineralization solution.”

The journey to responsibly scale carbon removal is both challenging and inspiring, as illuminated by the insights from the AIR and perspectives shared by Amar, Shiner, Brown, and Pattison. These visionary CEOs underscore that progress extends beyond overcoming technical RD&D obstacles. It involves forging meaningful partnerships, embracing innovation, and contributing collectively to a more sustainable future. Third Derivative is committed to supporting climate technology and carbon removal entrepreneurs who are making a tangible impact in the world. For a deeper understanding of the research guiding this transformative journey, we recommend reading and engaging with the AIR report. Together, we can advance carbon removal innovation alongside emissions reductions for a more sustainable and resilient world.