Molecules
CO₂ CO₂
In a molecular-energy system CO₂ is not only an emission to be avoided. For every carbon-containing synthetic fuel it is an essential raw material — and usually the scarcest one.
Waste stream, feedstock and constraint
What it is
Carbon dioxide appears in the molecular-energy system in three distinct roles: as the emission that the transition is intended to avoid, as a feedstock required to make any carbon-containing synthetic fuel, and as a constraint, because the origin and accounting treatment of the carbon determines whether the resulting product qualifies as low-carbon at all.
How it is produced
Industrial point-source capture
From ammonia plants, ethanol fermentation, cement, steel, refineries and power generation. Cost varies enormously with the concentration of the source — a concentrated fermentation or ammonia stream is far cheaper to capture than dilute flue gas.
Biogenic capture
From biogas upgrading, fermentation and biomass combustion. Commercially valuable because the carbon is biogenic, which materially improves the standing of any fuel made from it.
Direct air capture
Extracting CO2 from ambient air. Unconstrained by location and by far the most energy-intensive and expensive route; currently early in deployment.
Conversion
CO2 combines with hydrogen to produce methanol, synthetic methane and, via Fischer-Tropsch or methanol-to-jet routes, synthetic liquid fuels including sustainable aviation fuel. It is also used directly in food and beverage, greenhouses, and in some mineralisation and building-materials processes.
Storage
Geological storage in saline aquifers and depleted hydrocarbon reservoirs is the established route for permanent sequestration. For utilisation, CO2 is stored as a liquid or supercritical fluid under pressure at industrial scale.
Transport
Pipelines at scale, and ships, rail or road for smaller volumes. CO2 pipeline networks are well established in some regions and absent in most, and building them is frequently the practical bottleneck for both capture and utilisation projects.
Infrastructure
Capture plant, compression and conditioning, transport, and either permanent storage or a conversion facility. Shared CO2 transport and storage infrastructure is often only economic at cluster scale, which is a large part of why industrial clusters matter in this sector.
Economics
Capture cost scales inversely with source concentration, so a concentrated biogenic stream can be an order of magnitude cheaper than direct air capture. For a synthetic fuel project, CO2 is a raw material cost and a compliance question at once — price matters, but origin and accounting treatment frequently matter more, because they decide market eligibility.
Applications
- Feedstock for methanol, synthetic methane and e-fuels including SAF
- Permanent geological storage as a mitigation measure
- Enhanced recovery operations
- Food, beverage and greenhouse use
- Mineralisation into building materials
Commercial challenges
- Concentrated biogenic CO2 is limited and increasingly contested between projects
- Fossil-derived CO2 raises unresolved accounting questions for fuel products
- Transport and storage infrastructure is largely absent outside a few regions
- Direct air capture remains expensive and energy-intensive
- Utilisation in fuels is not sequestration, and conflating them damages credibility
Questions
Does using CO2 in fuel count as removing it?
No. When a synthetic fuel made from CO2 is burned, the carbon returns to the atmosphere. Utilisation displaces fossil carbon in the fuel rather than removing carbon from the air, and only geological storage constitutes sequestration. Conflating the two is a credibility risk in any serious carbon claim.
Why is biogenic CO2 worth more than fossil CO2?
Because the carbon was recently taken from the atmosphere, so a fuel made from it can be treated as closer to carbon-neutral under most accounting frameworks. Fossil-derived CO2 produces a fuel whose carbon accounting depends on rules that are still evolving, which introduces commercial risk.
Is direct air capture necessary for e-fuels?
Not today, and not where concentrated point sources exist. Point-source capture is much cheaper and is where near-term projects source carbon. Direct air capture matters in the longer term, because point sources should be shrinking if the transition works.
Where co₂ matters
How we can help
Carbon & Lifecycle
What a pathway actually emits, consumes and requires — measured, not asserted.
Read more →Techno-Economic Analysis
Levelised cost modelling with the assumptions exposed and the sensitivities tested.
Read more →Technology Assessment
Independent, criteria-driven comparison of the technologies competing for your project.
Read more →Working with co₂?
Whether you produce it, buy it, build for it or are deciding whether it fits your region, the starting point is the same conversation.