Carbon dioxide - CO2 : Friend or Foe?

To understand life, climate, geology and the human experiment, we must realise carbon and CO2. This is the central thesis of Peter Brannen’s book: The Story of CO₂ Is the Story of Everything: How Carbon Dioxide Made Our World (2025).  The book takes different perspectives; from a deep time, perspective where the author traces how CO₂ has cycled through the atmosphere, oceans, rocks, and life across billions of years. He demonstrates how CO₂ levels and climate states have varied considerably, encompassing episodes of “Snowball Earth,” greenhouse hothouse states, mass extinctions triggered by shifts in carbon cycling, and periods of relative climatic stability.

The book explains that CO₂ is both the thermostat of the planet (governing temperature, climate, ocean acidification) and the raw material for life (the carbon in all organic matter comes, ultimately, from CO₂).

The structure of modern society is deeply intertwined with fossil carbon and unlocking (burning) the reservoir of stored carbon, the prehistoric solar energy locked away for millions of years, was a pivotal moment leading to the industrial revolution and an economy based on extraction and combustion. The reservoir buildup took about 300M years, the burndown about 300 years with unintended climate and tipping point consequences. 

Paul Hawken’s Carbon (2025). The book is part of a series: Drawdown focused on solutions to reduce emissions, Regeneration on restoring life, and Carbon on reimagining how we relate to the element that sustains life, energy and materials. The author treats carbon not merely as a problem but as a flow — a fundamental, dynamic element flowing through atmosphere, land, plants, oceans, and living beings. Carbon as the backbone of life is not the problem, the imbalance is: too much in the atmosphere, too little in the soil and forests. Hawken makes the important point that nature cannot be commoditized. “Credits” and “Ecosystem services” turn living systems into abstractions, the deeper work is reconnecting with nature and move from “less harm” thinking to regenerative thinking. 

Regenerative 

Carbon flow is a physical and ecological reality, regenerative thinking is more a design lens, a way of aligning human activity so that it harmonizes with and enhances these natural flows. This means:

• Seeing carbon as a resource, not just as a waste 

• Design for circularity, not only linear (extract-burn-emit) 

• Net positive impacts: restore carbon balance by drawing down carbon into living systems

Carbon capture and utilization

To utilize carbon, it needs to be captured. Industrial carbon capture accounts for the majority of captured CO₂, biogenic sources have higher concentrations of CO₂ and fermentation or gasification are pathways to biogas production. CO2 capture involves separating CO2 from a gas mixture into a pure stream using a series of chemical selectivity and thermochemical or electrochemical desorption cycles. The main solutions are solvents, sorbents, membranes, cryogenic, and electroswing. CO2 capture is a capital-intensive solution. Energy consumption, associated with the desorption of CO2, is the fundamental cost driver. Materials innovation may reduce this energy requirement. 

Uncertain policy support and investor pull back create a more challenging environment for carbon capture and a shift towards Europe can be expected. Leading capture companies like Entropy and Svante build out commercial pipelines. 

If, big if, all announced CO2 capture capacity is realised and the current growth trend continues, global capacity could reach Net Zero levels by 2030. Reducing project lead times, particularly related to the development of CO2 storage, will be critical to achieve those levels (IEA 2025). 

Early infrastructure investors take notice as illustrated by the recent acquisition by Blackrock Infrastructure Partners of a minority holding in ENI’s CCUS business with projects in  Netherlands, the UK and Italy. 

The dominant targeted end use of captured CO2 is permanent storage, with Enhanced Oil Recovery in second place. Scaling carbon utilization is a solution to the end use challenge. 

Carbon Capture & Utilization is the process of capturing CO₂ emissions from industrial sources (like power plants, cement, steel, or chemical production) and then converting it into useful products instead of storing it underground. 

CCU benefits are the reduction of emissions, circular carbon, substitution of fossil based raw materials and the possibility of renewable energy integration (using excess electricity to produce hydrogen for CO₂ conversion). 

Key CCU pathways are:

• Chemical (polymerization, catalytic) 

• Mineralization (curing, carbonation) 

• Biological (fermentation, photosynthetic) 

CCU opens a range of products possibilities in chemicals, synthetic fuels, polymers, building materials and food ingredients. 

Scaling CO2 utilization is essential to secure the viability carbon capture investments and choosing the product with the highest emissions reduction impact against the lowest cost is critical. Concrete and synfuels may provide near term opportunities, but hydrogen dependent pathways face more challenging scaling pathways and require industry collaboration. 

Electrochemical and biological pathways, but also plasma and photocatalysis, may overcome some of the obstacles for CCU adoption like the energy inputs required (thermodynamically challenging) and the investments required to produce at scale. Another obstacle is permanence: CO2  to concrete can be seen as permanent storage, where downstream combustion takes place temporarily, and it is difficult to create carbon credits. Pathways to fuels will require low cost of renewable energy and access to feedstock, based on waste streams. Nevertheless, cost parity will be challenging and upcoming investment decisions will provide a good window into the viability of the pathway. 

Pathways to chemicals vary in maturity. Some, like e-methanol, are in demonstration phase. Others, like fermentation-based ethanol production are in laboratory and pilot phase. Few, however, are ready to be integrated with major CO2  capture projects. 

New platform technologies like synthetic biology may unlock viable opportunities to lower cost of CO2   conversion or to produce differentiated products. Engineered microbes could improve CO2  fixation, open pathways to platform chemicals or carbon-based materials. Synthetic biology contributes to the transition towards carbon circular industries. 

CCS and CCU are twins and are usually paired: capture → purification → conversion. The efficiency, cost, and climate benefit depend on the source of CO₂ (fossil vs biogenic) and the energy inputs for utilization. Incentives and subsidies will be necessary for some of the e-fuels, competing with biobased alternatives. Permanence and feedstocks are increasingly shaping the accreditation and subsidies awarded to projects by regulators. 

Circling back to the buildup of fossil fuel that took about 300M years, and humanity’s burndown about 300 years, causing an imbalance. In 2023, humans emitted about 37–40 gigatons of CO₂ (GtCO₂) from fossil fuels and industry. Land-use change (like deforestation) adds another 3–4 GtCO₂.

To stop emissions growth (net-zero) means that whatever we still emit (after reductions) must be balanced by removals. Most net-zero scenarios assume 5–10 GtCO₂ per year of removals by mid-century (to offset the hardest-to-abate emissions, e.g. aviation, cement). However, to restore climate stability (1.5 °C warming limit), the IPCC claims 100–1000 GtCO₂ needs to be cumulatively removed during the 21st century to draw concentrations back down roughly 5–20 GtCO₂ per year for several decades beyond mid-century.

To return to preindustrial CO₂ (~280 ppm vs. today’s 420 ppm) would require removing over 1000 GtCO₂ — basically all the excess added since the Industrial Revolution, far beyond current technological capacity, but it frames the scale.

Circular carbon is an attractive long-term vision, but the current removal capacity relies mainly on nature (oceans, soils, forests) and engineered removal is still very modest in scale. Scaling capture is a massive challenge and can benefit from additional revenue streams through CO2 conversion into valuable products. 

Scaling a circular carbon infrastructure will take time and has many dependencies, multiple removal pathways need to be developed and to buy humanity time, solutions to complement reduction and removal may be needed.