Biological carbon capture & utilization (bio-CCU: gas fermentation, CO2-to-protein, e-fuels)

01Overview and value chain

Markers: [EC: EU Carbon Removals Certification (CRCF) + CBAM | OECD: Carbon management, Circular bioeconomy | Regulator: EPA (USA), ADEME (France), NEA (China)]

Biological carbon capture and utilization (bio-CCU) converts captured carbon dioxide — from industrial point sources, biogenic emissions or the atmosphere — into fuels, chemicals, proteins and materials using microbial gas fermentation, engineered microbes or microalgae. It reframes a waste gas as a feedstock, displacing fossil carbon while generating revenue that can help finance abatement. LanzaTech’s gas-fermentation platform alone reported 55.8 million dollars of revenue in 2025, Newlight’s AirCarbon polyhydroxyalkanoate is certified carbon-negative, and Deep Branch’s Proton single-cell protein reaches about 70% protein content at roughly 90% lower carbon footprint than alternative proteins. On the catalytic-utilization flank, Carbon Recycling International’s Vulcanol renewable methanol embeds about 1.4 tonnes of CO2 per tonne of methanol, and its planned Iceland e-fuel plant targets up to 70,000 tonnes per year of sustainable aviation fuel. Policy now pulls demand: the US 45Q tax credit pays up to 85 dollars per tonne for captured and utilized CO2, the EU’s Carbon Removals Certification Framework is in force, and China’s green finance catalogue lists CCUS as item 1.5.1.

The key directions of biological carbon capture & utilization are:

1. Gas fermentation to fuels and chemicals (LanzaTech): autotrophic microbes ferment CO/CO2-rich syngas into ethanol and onward into SAF and marine fuel; LanzaTech’s municipal-solid-waste-to-ethanol pilot in Kuji City, Japan runs at about 400 t/yr at one-tenth commercial scale with guaranteed performance.
2. Microbial CO2-to-biopolymers (Newlight AirCarbon): an ocean-microbe-inspired process fixes CO2 and methane into polyhydroxyalkanoate — a carbon-negative, ocean-biodegradable polymer already in straws, utensils and eyewear.
3. CO2-to-protein and nutrition (Deep Branch, Cemvita): gas fermentation converts CO2 and hydrogen into single-cell protein (Proton, about 70% protein) and renewable oils (Cemvita FermOil, demonstrated at 75,000 litres).
4. CO2-utilization to e-fuels and methanol (CRI, Cemvita e-kerosene): catalytic and bio-catalytic hydrogenation of CO2 with green hydrogen yields renewable methanol (Vulcanol) and onward e-SAF, with CRI studying a 70,000 t/yr facility with Honeywell UOP.

Sectoral value chain

[CO2 source: industrial / biogenic / atmospheric] ──> [Capture & conditioning] ──> [Bio-conversion: fermentation / engineered microbes / microalgae]
                                                                                          │
                                                                              (product recovery and purification)
                                                                                          │
                                                                                          ▼
[End-use: fuels · feed protein · polymers · methanol] <─── [Circular carbon products]

Value chain levels

Cross-cutting technologies of the sector:

• Green hydrogen integration: CO2-plus-hydrogen routes (Deep Branch protein, CRI methanol) tie bio-CCU economics to the cost of renewable hydrogen and electrolyser scale-up.
• Synthetic biology and strain engineering: Cemvita and Newlight re-engineer microbial carbon flux to channel CO2 toward target products (oils, PHA, kerosene precursors) at higher titres.
• Carbon accounting and certification: ISCC PLUS, the EU CRCF and the US 45Q credit convert tonnes of utilized CO2 into bankable value, the linchpin of project finance.

02US

The United States leads bio-CCU commercialization through LanzaTech’s gas fermentation and Newlight’s carbon-negative polymers, with the 45Q tax credit (expanded under the Inflation Reduction Act to about 85 dollars per tonne for utilized CO2) anchoring project economics.

Gas fermentation, carbon-negative polymers, e-kerosene

• LanzaTech Global (LNZA): its gas-fermentation platform converts industrial emissions and gasified waste into recycled-carbon ethanol; 2025 revenue reached 55.8 million dollars, its Kuji City (Japan) municipal-solid-waste pilot produces about 400 t/yr at one-tenth commercial scale, and LanzaTech’s stake in LanzaJet rose to 53% by December 2025.
• Newlight Technologies: AirCarbon polyhydroxyalkanoate, made by methane-oxidizing ocean microbes from greenhouse gases, is a carbon-negative, ocean-biodegradable polymer shipping in straws, cutlery, eyewear and leather alternatives, with patented engineered strains improving carbon flux to PHA.
• Cemvita Factory: engineered microbes convert crude glycerin and CO2 into FermOil renewable natural oil, demonstrated at a 75,000-litre industrial scale (a 2,500-fold scale-up) at Bio Base Europe, and into bio-catalytic e-kerosene for aviation under the 45Q regime.

03CN

China’s carbon management is anchored by its energy majors running CCUS at industrial scale alongside microalgal CO2-utilization research, and CCUS now sits inside the national green finance catalogue as a bankable category.

CCUS scale, microalgal bio-conversion, green-finance inclusion

• Sinopec (600028): the integrated energy major runs point-source CCUS across refining, petrochemicals and enhanced oil recovery, and leads microalgal CO2-utilization research — comparing algal strains and culture conditions to turn captured CO2 into high-value bioproducts.
• CCUS as a green-finance category: China’s green finance catalogue now lists carbon capture, utilization and storage as item 1.5.1, covering the full capture-transport-utilize- store chain for power, steel, cement, chemicals and oil extraction.
• Institutional build-out: Sinopec helped found the International CCUS Innovation Cooperation Organization, framing bio-CCU and CCUS as a coordinated national priority under the dual-carbon goals.

04EU

Europe pairs bio-CCU start-ups with the world’s strictest carbon framework: the Carbon Removals Certification Framework, the Emissions Trading System and the Carbon Border Adjustment Mechanism, which together create demand for verified utilized carbon.

Single-cell protein, renewable methanol, certification pull

• Deep Branch (UK/NL): its Proton single-cell protein is made by gas-fermenting industrial CO2 with hydrogen into an ingredient holding about 70% protein — roughly double soy — at around 90% lower carbon footprint, for aquaculture and livestock feed, backed by EU H2020 funding.
• Carbon Recycling International (Iceland): its Emissions-to-Liquids process makes Vulcanol renewable methanol (ISCC PLUS certified, about 1.4 t CO2 per tonne of methanol) and is studying a 300 MW, up-to-70,000 t/yr e-SAF plant with Honeywell UOP and IdunnH2.
• Regulatory pull: the EU CRCF defines certified carbon removals and utilization, while the CBAM prices embedded carbon at the border, giving bio-CCU products a measurable premium in chemicals, fuels and feed.

05Leading companies and research institutes

06Tech stack and innovations

The bio-CCU technology stack rests on four pillars: gas-fermentation biology, microbial polymer synthesis, single-cell protein production, and CO2 hydrogenation to methanol and e-fuels — together turning point-source carbon into merchant products.

1. Gas-fermentation biology:
   • Autotrophic acetogens (LanzaTech) and hydrogen-oxidizing microbes (Deep Branch) fix CO/CO2 into ethanol and protein; LanzaTech’s 55.8 million dollar 2025 revenue shows the route reaching commercial tonnage from waste gases.
   • Strain tolerance to syngas impurities (tar, sulfur) and gas-liquid mass transfer set the ceiling on reactor productivity and feedstock flexibility.
2. Microbial polymer synthesis:
   • Newlight’s AirCarbon uses methane-oxidizing ocean microbes to channel CO2 and methane into polyhydroxyalkanoate granules, yielding a polymer that is carbon-negative and ocean biodegradable.
   • Patented engineered strains tune carbon flux toward PHA, raising titre and lowering the energy cost of cell harvest and polymer extraction.
3. Single-cell protein production:
   • Deep Branch’s Proton ferments CO2 with hydrogen and oxygen into a single-cell protein of about 70% content, replacing soy and fishmeal in aquafeed at roughly 90% lower carbon footprint.
   • The bottleneck is gas-fermentation scale-up and feed-grade safety clearance rather than biology, making partners and offtake decisive.
4. CO2 hydrogenation to methanol and e-fuels:
   • CRI’s Emissions-to-Liquids process catalytically hydrogenates CO2 into Vulcanol methanol (about 1.4 t CO2 per tonne), which Honeywell UOP’s eFining can upgrade into e-SAF.
   • Economics hinge on cheap green hydrogen and electrolyser capacity, tying bio-CCU to the broader power-to-liquids build-out.

07Value chains and production pipelines

Industrial pipeline of recycled-carbon ethanol via gas fermentation (ISCC PLUS)

┌───────────────────────────┐      ┌───────────────────────────┐
│ 1. CO2-rich syngas supply  │ ───> │ 2. Gas-fermentation        │
└───────────────────────────┘      │    (acetogens)            │
                                    └───────────────────────────┘
                                                  │
                                                  ▼
┌───────────────────────────┐      ┌───────────────────────────┐
│ 4. Ethanol purification   │ <─── │ 3. Broth recovery         │
└───────────────────────────┘      └───────────────────────────┘
              │
              ▼
┌───────────────────────────┐      ┌───────────────────────────┐
│ 5. Derivatization (SAF)   │ ───> │ 6. Certification & offtake │
└───────────────────────────┘      └───────────────────────────┘

Stage 1: CO2-rich syngas supply

Industrial emissions (steel, refining) or gasified municipal solid waste provide a CO/CO2-rich syngas; LanzaTech’s Kuji City plant gasifies MSW to feed its roughly 400 t/yr ethanol pilot at one-tenth commercial scale.

Stage 2: Gas fermentation

Autotrophic acetogens in the bioreactor ferment the syngas to ethanol, with gas-liquid mass transfer and strain tolerance to impurities setting reactor productivity; this is the core biology LanzaTech and Deep Branch share.

Stage 3: Broth recovery

Cells and spent media are separated from the ethanol-laden broth by centrifugation and filtration, with cell mass returned or valorized and the beer advanced to distillation.

Stage 4: Ethanol purification

Distillation and molecular-sieve dehydration lift the broth to fuel-grade recycled-carbon ethanol, the merchant intermediate that anchors LanzaTech’s 55.8 million dollar 2025 revenue.

Stage 5: Derivatization to SAF

The ethanol is converted to sustainable aviation fuel (via alcohol-to-jet) or marine fuel, routing through LanzaJet — in which LanzaTech’s stake reached 53% by December 2025.

Stage 6: Certification and offtake

The finished fuel is certified under ISCC PLUS and the EU CRCF, with CO2 utilization documented for the US 45Q credit, enabling airline and maritime offtake that closes the carbon-utilization loop.