CO2 is everywhere. Every year, around 230 million tonnes of it are used across the globe — and that figure is expected to grow to 2.5 gigatonnes by 2050. It keeps crops growing in greenhouses, adds fizz to your favourite drinks, and plays a critical role in food preservation and medical applications.
But behind its versatility lies a challenge: most of the CO2 used in industry today comes from new emissions from fossil fuels. It’s typically captured as a by-product of processes like hydrogen production, fertiliser manufacturing, or natural gas processing, then refined and repurposed. In other words, the bubbles in your drink are, quite literally, delayed fossil fuel emissions – but that may not be the case for much longer.
In 2024, 36% of the US merchant market’s crude CO2 came from ethanol production, a more sustainable source. The US market is leading the way in utilising CO2 generated from this process, but in recent years, more sustainable CO2 sources are becoming available. This shift signals a move away from the volatility, supply challenges, and environmental cost of fossil carbon.
What if we could rethink our relationship with carbon — replacing industry’s fossil carbon backbone with circular, sustainable sources? We’ve explored where this new path is taking us, breaking down what makes CO2 sustainable, where it comes from, and how the world is quietly revolutionising this essential commodity.
What is sustainable CO2 and why is it important?
When we look at “traditional” fossil carbon dioxide, in comparison to sustainable CO2 sources like biogenic production or direct air capture, there’s a very clear distinction:
- Fossil CO2 is heavily carbon positive.
- Sustainable CO2 (biogenic, direct air capture) is carbon neutral.
Fossil CO2 is primarily sourced from the combustion or conversion of fossil fuels such as coal, oil, and natural gas, releasing long-buried carbon deposits and causing a net increase in atmospheric CO2 — hence, carbon positivity.
Sustainable CO2 can be sourced through biogenic processes (processes which mimic nature or utilise plants, trees, crops, or animal waste), or by pulling carbon directly from the atmosphere via direct air capture. It is carbon neutral, as these methods do not disturb the natural carbon cycle.
However, when the CO2 is used in a process which durably stores it — such as mineralising it in rock or carbonating building materials — its usage results in a net reduction of atmospheric CO2 levels, making it carbon negative.
Sustainable CO2 sources are crucial for displacing the use of fossil carbons, decarbonising products, and driving the transition to a low-carbon economy. The business case for sustainable CO2 is compelling: beyond its environmental benefits, it opens up new revenue streams and opportunities. What’s more, by integrating circular CO2 sources, carbon-based companies can directly address emissions across scopes 1 to 3, helping to defossilise their supply chains and products.
High quality sustainable CO2 obtained through sources like direct air capture can also offer new revenue streams through enabling the creation of carbon removal credits if stored underground, alongside the development of new products like sustainable building materials or synthetic aviation fuel if used in manufacturing processes. This not only diversifies product portfolios but positions businesses to lead their industries in the green transition.
Biogenic sustainable CO2
One of the main classes of sustainable CO2, biogenic CO2, is produced or brought about by living organisms. Put simply, when biomass – organic material from plants, trees, crops, or animal waste – is processed (for example, burned) it releases carbon dioxide as a by-product. As this CO2 was originally sourced from the atmosphere or ocean, it’s classified as part of a biogenic cycle. When used to replace fossil CO2, this carbon isn’t counted as a new emission as it’s part of the natural carbon cycle and would’ve been returned to the atmosphere anyway.
Biogenic CO2 can be sourced from various places, and is often a by-product of another process, such as power generation or fermentation. Common sources of biogenic CO2 include:
- Bioenergy with carbon capture: CO2 released from burning biomass such as wood or crop residues for energy;
- Ethanol and biogas production: CO2 released during fermentation (e.g. in ethanol production) or anaerobic digestion of organic materials like agricultural waste, manure, or food waste.
Strengths of biogenic CO2
- Low carbon footprint: Biogenic sources create circular and, therefore, sustainable CO2 ;
- Accessible pricing: While cost can vary depending on geography and pathway, it’s possible to source sustainable biogenic CO2 at marginally more than fossil carbon, with many additional benefits. In some cases, waste materials like discarded food and sawdust from timber mills can be used to source biogenic carbon, bringing down costs and turning this waste into value;
- Harnesses natural carbon cycles: The biomass that releases biogenic CO2 has already captured this carbon from the atmosphere, meaning no additional resource is needed for this step of the process;
- Proven at scale: Within the last ten years, biogenic sustainable CO2 production has become established as an accessible solution and fossil replacement;
- Purer CO2 output: Biogenic carbon released via fermentation, a by-product of ethanol production, requires less purification than fossil carbon.
Limitations of biogenic CO2
Not all biogenic CO2 is made equal, with an array of different processes and biomass sources playing into the final product. We’ve given a blanket overview of some of the potential limitations of biogenic carbon dioxide, but it’s worth keeping in mind that biogenic sustainable CO2 should be assessed on a case-by-case basis.
- Limited feedstocks: Biomass is, of course, a finite resource especially when sourced from waste products, meaning that there are limits on just how sustainable biogenic carbon can be. Often, multiple biogenic sources are required to meet CO2 demands, multiplying procurement, logistics, and operations needs;
- Environmental impact: Without careful regulation, deforestation, biodiversity loss, and land use change (e.g. by felling natural forests and replacing them with dedicated biomass fuel) are all possible consequences of unregulated biogenic CO₂ production;
- Land footprint: Forests and other natural crops call for huge amounts of land to create a regular supply of biomass. As biogenic CO₂ production scales beyond waste streams of biomass, the need for dedicated land grows substantially;
- Geographically dependent: Biogenic sustainable CO₂ sources are restricted by the natural distribution of biomass and seasonal fluctuations, which can often bump up transportation and gas handling costs, and their associated carbon emissions;
- Complex supply chain: The end-to-end biogenic process is difficult to monitor and track accurately for its overall carbon impact, with many steps that take place in multiple locations, making it more challenging to limit associated emissions.
Direct air capture sustainable CO₂
Direct air capture CO₂ is sourced directly from the atmosphere — effectively recovering humankind’s historic carbon emissions to be recycled or stored permanently underground. Although many different direct air capture technologies are evolving, at Mission Zero Technologies we’ve developed a heat-free electrochemical direct air capture technology that uses renewable energy and water to strip carbon from the atmosphere.
Direct air capture CO₂ strengths
The benefits of direct air capture go beyond the supply of a reliable, circular feedstock of carbon, making it stand out amongst other sustainable CO₂ sources.
- Carbon-negative CO₂: Direct air capture removes CO₂ from the atmosphere, enabling truly net-zero or net-negative emissions pathways;
- Dedicated CO₂ supply: Direct air capture is not the by-product of another value chain, but operates independently of other industrial processes to provide a reliable and consistent stream of sustainable CO₂;
- Traceable and measurable: The amount of CO₂ recovered by DAC is easily quantifiable and verifiable, allowing for transparent carbon accounting and certification;
- Geographically flexible: DAC systems can be deployed across a wide range of locations, providing access to sustainable CO₂ in areas where alternative sources may not be viable;
- Small land footprint: Compact systems are less land-intensive and less disruptive than the large infrastructure needed for fossil-based or some biogenic CO₂ sources;
- Minimal purification needed: The CO₂ our systems recover from the air is already up to 99% pure, reducing the need for energy and cost intensive cleaning;
- Minimal transport: Direct air capture can be located close to storage or usage sites, reducing logistics and infrastructure needs, and their related carbon emissions;
- Supports renewable energy build-out: Electric DAC systems can help to absorb excess or curtailed renewable electricity generation which would otherwise go unused, supporting grid stability and making the most of clean energy investments.
Carbon-neutral CO₂ limitations
- Power demand: Direct air capture must be powered by renewable sources to earn its carbon-neutral classification, meaning site selection and energy sourcing are critical to maximising DAC’s climate benefits;
- Cost challenges: Right now, sustainable CO₂ sources like DAC are still coming down the cost curve. However, fossil carbon can carry hidden costs as a result of mechanisms like the Emissions Trading Scheme (ETS), which puts a price on new CO2 emissions, something sustainable CO2 sources are exempt from;
- Direct air capture is still scaling: Although DAC is scaling rapidly, gigatonne carbon removal targets are still on the horizon. At Mission Zero, we’ve put three DAC plants on the ground to date, taking real-world data and using this to continue to grow this essential climate solution. Our systems are using proven technology to scale direct air capture quickly to meet global CO₂ demands.
What sets direct air capture apart from CCS technology?
DAC is often confused with carbon capture and storage (CCS) technologies, since both involve capturing CO₂. Yet, they serve fundamentally different purposes and the sustainability of the resulting CO₂ is worlds apart.
CCS captures CO₂ directly from fossil fuel sources, preventing new emissions from entering the atmosphere. Unless this captured CO₂ is permanently stored, it eventually returns to the air, meaning that any fossil CO₂ captured using this method and put to use is still carbon-positive overall. In contrast, the atmospheric CO₂ recovered through DAC is carbon-negative when stored, and carbon-neutral when utilised.
Ultimately, for CCS to be truly effective, all captured CO₂ should be stored rather than used, ensuring it doesn't contribute to net emissions. This is already being encouraged by policymakers, with the USA’s 45Q Tax Credit offering a greater incentive for permanent carbon storage vs. utilisation.
Learn more: DAC vs. CCS technology
The future of sustainable CO₂
The shift to sustainable CO₂ is already underway. From biogenic sources to direct air capture, a growing range of fossil-free carbon feedstocks are now available to help decarbonise supply chains and reduce our global dependence on fossil carbon.
For businesses, this creates a powerful opportunity: to align with climate goals, strengthen sustainability strategies, and unlock new revenue streams through low-carbon products and services. Sustainable CO₂ means a circular, more resilient, and climate-positive economy.
Sustainable CO₂ sources are maturing rapidly, and as momentum builds, it’s essential to tap into every viable solution — because no single technology can meet the scale of demand alone. Creating a truly sustainable CO₂ economy means diversifying supply, accelerating the deployment of fossil alternatives, and rethinking our relationship with one of the world’s most critical resources.
