Pathways & process fundamentals

Technology atlas

Connect the reaction to the reactor, the reactor to the plant, and the plant to its economics. Readiness belongs to a demonstrated system—not a reaction equation.

10pathway profiles

3value-chain stages

9tracked projects linked

0universal TRL ratings assigned

Capture & supply

Separate CO₂ from a gas mixture and deliver it at the purity and pressure a downstream process needs.

01 / CAPTURE & CONDITIONING

Point-source capture by amine absorption

Chemical absorption removes CO₂ from flue or process gas, then heat regenerates the solvent and releases a concentrated CO₂ stream.

CO₂ + 2 RNH₂ ⇌ RNHCOO⁻ + RNH₃⁺ (carbamate formation, primary amine)

Inputs: Flue gas or process off-gas · Aqueous amine solvent · Regeneration heat
Products: Concentrated CO₂ · CO₂-depleted gas
Main scale-up question: Regeneration heat demand and its source

No tracked project yetExplore pathway

02 / CAPTURE & CONDITIONING

Direct air capture

Liquid or solid sorbents take CO₂ directly from ambient air; regeneration then delivers concentrated CO₂ for storage or use.

2 KOH + CO₂ → K₂CO₃ + H₂O (liquid-solvent route, simplified)

Inputs: Ambient air (~420 ppm CO₂) · Sorbent or solvent · Heat
Products: Concentrated CO₂
Main scale-up question: Energy demand from a very dilute source

No tracked project yetExplore pathway

Conversion

Turn CO₂ into fuels, chemicals or polymers. The product decides how long the carbon stays out of the air.

03 / CATALYTIC HYDROGENATION

CO₂ to methanol

CO₂ and hydrogen react over a copper/zinc-oxide catalyst to make methanol, a fuel and chemical building block.

CO₂ + 3 H₂ → CH₃OH + H₂O

Inputs: Purified CO₂ · Hydrogen
Products: Methanol · Water
Main scale-up question: Hydrogen cost and electricity supply

6 tracked projectsExplore pathway

04 / CATALYTIC HYDROGENATION

CO₂ methanation

The Sabatier reaction combines CO₂ with hydrogen over a nickel or ruthenium catalyst to make synthetic methane.

CO₂ + 4 H₂ → CH₄ + 2 H₂O (Sabatier, strongly exothermic)

Inputs: CO₂ or biogas CO₂ · Hydrogen
Products: Synthetic methane · Water · Process heat
Main scale-up question: Hydrogen cost and electrolyser utilisation

No tracked project yetExplore pathway

05 / THERMOCHEMICAL SYNTHESIS

CO₂ to synthetic hydrocarbons (RWGS + Fischer–Tropsch)

CO₂ is first converted to CO-rich syngas—by reverse water–gas shift or co-electrolysis—then Fischer–Tropsch synthesis builds liquid hydrocarbons such as e-kerosene.

CO₂ + H₂ ⇌ CO + H₂O (reverse water–gas shift)

Inputs: CO₂ · Hydrogen
Products: Synthetic kerosene, diesel and naphtha · Waxes · Water
Main scale-up question: Hydrogen cost and supply continuity

2 tracked projectsExplore pathway

06 / ELECTROCHEMICAL REDUCTION

Electrochemical CO₂ conversion

An electrolyser uses electricity to reduce CO₂ at a cathode to CO, formate, ethylene or other products.

CO₂ + 2 H⁺ + 2 e⁻ → CO + H₂O (cathode half-reaction)

Inputs: CO₂ · Water · Electricity
Products: CO or other products, depending on catalyst and reactor
Main scale-up question: Carbonate formation and carbon losses

1 tracked projectsExplore pathway

07 / BIOLOGICAL CONVERSION

Gas fermentation

Acetogenic bacteria convert CO, CO₂ and H₂ from industrial off-gas or electrolysis into ethanol and other chemicals.

6 CO + 3 H₂O → C₂H₅OH + 4 CO₂ (CO-rich off-gas)

Inputs: Steel-mill or other CO-rich off-gas · CO₂ + hydrogen · Nutrients
Products: Ethanol · Acetate and other chemicals · Microbial protein
Main scale-up question: Low gas solubility and mass transfer

No tracked project yetExplore pathway

08 / POLYMER CHEMISTRY

CO₂-based polycarbonates and polyols

CO₂ is copolymerised with epoxides to make polycarbonates or polyether-carbonate polyols that partly replace fossil feedstock in polyurethanes.

n C₃H₆O + n CO₂ → [–CH(CH₃)CH₂O–C(O)O–]ₙ (propylene oxide copolymerisation)

Inputs: CO₂ · Epoxides (e.g. propylene oxide) · Starter molecules
Products: Polyether-carbonate polyols · Aliphatic polycarbonates
Main scale-up question: Limited CO₂ mass fraction per tonne of product

No tracked project yetExplore pathway

09 / PHOTOCHEMICAL CONVERSION

Photocatalytic CO₂ reduction

Semiconductor photocatalysts use sunlight to drive CO₂ reduction with water directly, without a separate electrolyser.

CO₂ + 2 H₂O → CH₄ + 2 O₂ (overall, 8-electron)

Inputs: CO₂ · Water · Sunlight
Products: CO, methane, methanol or formate (catalyst-dependent) · Oxygen
Main scale-up question: Low solar-to-fuel efficiency

No tracked project yetExplore pathway

Mineralization

Bind CO₂ as solid carbonate—the most durable fate available to a utilization route.

10 / MINERALIZATION

Carbon mineralization

CO₂ reacts with calcium- or magnesium-rich materials such as slags or concrete to form stable carbonates.

CaO + CO₂ → CaCO₃ (simplified net reaction)

Inputs: Reactive alkaline material · CO₂
Products: Carbonates · Construction materials where qualified
Main scale-up question: Reactive feedstock supply

1 tracked projectsExplore pathway

Compare pathways side by side

Theoretical anchors come from stoichiometry or thermodynamics only. They are lower bounds, not plant performance, and different units mean the rows are not directly comparable.

Technology pathway comparison
Pathway	Theoretical anchor	Where the carbon goes	Tracked projects
Point-source capture by amine absorptionCapture & conditioning	0.5 mol CO₂/mol amine0.119 GJ/t CO₂	Capture alone stores nothing. The fate of the carbon is set by the downstream use or storage route.	—
Direct air captureCapture & conditioning	0.438 GJ/t CO₂	Atmospheric origin is necessary but not sufficient for removal: the CO₂ must then be stored durably. Used in fuels, it is re-released.	—
CO₂ to methanolCatalytic hydrogenation	1.374 t CO₂/t methanol0.189 t H₂/t methanol	Methanol used as fuel releases its carbon at combustion; methanol converted into durable chemicals or materials holds it longer.	Kassø e-methanol facility Jiangsu Sailboat CO₂-to-methanol plant POSEIDON Mannheim pilot George Olah renewable methanol plant Shunli CO₂-to-methanol plant Haru Oni e-fuels demonstration plant
CO₂ methanationCatalytic hydrogenation	2.743 t CO₂/t CH₄0.503 t H₂/t CH₄	Carbon returns to the atmosphere when the fuel is combusted, typically within months to a few years of production.	—
CO₂ to synthetic hydrocarbons (RWGS + Fischer–Tropsch)Thermochemical synthesis	3.137 t CO₂/t –CH₂–0.431 t H₂/t –CH₂–	Carbon returns to the atmosphere when the fuel is combusted, typically within months to a few years of production.	ERA ONE power-to-liquid plant AirPlant One e-fuels facility
Electrochemical CO₂ conversionElectrochemical reduction	1.571 t CO₂/t CO1,914 Ah/kg CO	Depends on the product: CO or formate for fuels re-release carbon; multicarbon products used in materials hold it longer.	AirPlant One e-fuels facility
Gas fermentationBiological conversion	1.911 t CO₂/t ethanol0.263 t H₂/t ethanol	Depends on the product: ethanol used as fuel re-releases carbon quickly; chemicals and polymers made from it hold carbon for their service life.	—
CO₂-based polycarbonates and polyolsPolymer chemistry	0.431 t CO₂/t polymer	Bound in the polymer for the product's service life; end-of-life incineration releases it, landfill or recycling retains it longer. Not permanent storage.	—
Photocatalytic CO₂ reductionPhotochemical conversion	8 mol e⁻/mol CH₄	Most target products (CO, methane, methanol) are fuels or fuel precursors, so carbon is typically re-released at use.	—
Carbon mineralizationMineralization	0.785 t CO₂/t CaO	Carbonate minerals are stable over geological timescales if not recalcined or acid-leached; durability is the strongest of any CCU route.	HEIM Berlin concrete mineralization site

The atlas is a foundation, not a ranking

Each profile explains process fundamentals and the evidence still needed for a commercial conclusion. No universal TRL or commercial viability score is assigned: readiness belongs to a specific plant, and project-level evidence lives in the project tracker. Accounting terms are explained in CCU vs CCS vs CDR.