Gas fermentation of food protein

01Overview and value chain

Markers: [EC: Novel Food Regulation (EU 2015/2283) & GRAS framework | OECD: Sustainable food systems & alternative protein | Regulator: FDA (USA), EFSA (EU), MARA (China)]

Gas fermentation of food protein produces edible single-cell protein by growing hydrogen-oxidising bacteria (HOB) — the so-called Knallgas bacteria, chiefly Cupriavidus necator — on a gas mix of hydrogen, carbon dioxide and oxygen inside pressurised gas-loop bioreactors. The dried biomass reaches 65–70% crude protein with all nine essential amino acids, and decouples calorie and protein production from farmland, weather and pesticides. By 2026 the route has crossed from pilot to commercial demonstration: Solar Foods’ Factory 01 in Finland produces up to 160 tonnes of Solein a year from a 20,000-litre bioreactor, and the company has verified a 100-fold scale-up of the process. Hydrogen is delivered by on-site PEM electrolysers and CO2 partly by direct air capture, so the protein’s land and water footprint is roughly a twentieth of plant protein and a hundredth of animal protein. Independent modelling projects renewable-electricity protein (e-protein) falling from 5.5–6.1 €/kg in 2028 toward 4.0–4.5 €/kg by 2030 as electrolyser and bioreactor costs decline.

The key directions of gas fermentation of food protein are:

1. Hydrogen-oxidising bacteria (Power-to-protein): autotrophic HOB fix CO2 through the Calvin cycle using hydrogen as the energy carrier, the dominant food-protein platform behind Solein and Air Protein.
2. Methanotroph gas fermentation (Gas-to-protein): obligate methanotrophs such as Methylococcus capsulatus grow on natural gas or biomethane, the most mature world-scale platform (FeedKind, Uniprotein) and the technical base gas-fermentation food protein builds on.
3. Archaea and acetate routes: methanogenic archaea and acetate-adapted yeasts excrete amino acids or build biomass from CO2-derived intermediates, broadening the feedstock base beyond pure hydrogen.
4. Food formulation and B2B ingredients: spray-dried microbial powder blended at low inclusion into pasta, dairy alternatives, meat analogues and snacks, where neutral flavour and high digestibility matter more than headline price.

Sectoral value chain

[PEM electrolysis + DAC CO2] ──> [Gas-loop fermentation (HOB)] ──> [Cell concentration] ──> [Thermal lysis]
                                             │
                                  (Cupriavidus necator)
                                             │
                                             ▼
[B2B food ingredients] <─── [Spray drying] <─────┘

Value chain levels

Cross-cutting technologies of the sector:

• Gas-loop bioreactors: U-shaped or multi-circuit loop reactors that inject gases under pressure into the downflow, lifting the gas-to-liquid mass-transfer coefficient five- to ten-fold over stirred tanks to beat hydrogen’s low solubility.
• PEM electrolysis integration: polymer-membrane electrolysers supply high-purity hydrogen directly from wind and solar power, and their waste heat is recovered to pre-heat the spray-drier air, pushing overall energy efficiency toward 85%.
• Explosion-proof gas handling (ATEX): sensor and auto-valve systems hold the H2/O2 mix permanently outside the detonable envelope of Knallgas, keeping the fermenter headspace and gas loop safe.

02US

The United States anchors the venture-backed food-protein developers and routes gas protein into alternative-meat and ingredient markets under the FDA’s GRAS framework.

Air Protein, GRAS pathway, NASA heritage

• Air Protein and hydrogen fermentation: founded by Lisa Dyson on NASA 1960s closed-loop food research, Air Protein grows oxyhydrogen microbes into a meat-mimicking protein and runs a pilot facility in California.
• Regulatory pathway: the firm pursues self-affirmed GRAS and a high-protein food-composition patent (US20260130392A1, 2026) covering microbial protein in meat and dairy analogues.
• Investment base: Air Protein is backed by ADM Ventures, Barclays and climate investors, positioning gas protein as a structured alt-meat ingredient rather than a bulk powder.

03CN

China treats gas-fermentation protein as a strategic food- and feed-security tool to cut soy and fishmeal imports while serving its carbon-neutrality goals.

Chongqing gas-protein plant, MARA approvals, novel-food roadmap

• Calysseo at Chongqing: the Calysta–Adisseo joint venture runs a commercial-scale gas-protein plant in Chongqing, the first such facility in China supplying the Asian aquaculture and feed sector.
• MARA approvals: China’s agriculture regulator cleared microbial gas protein for aquafeed use, opening multi-tonne offtake to major feed mills.
• Novel-food pathway: the NHC is studying Singapore’s and the US’s Solein clearances to build a domestic novel-food control regime for human-grade gas-fermented protein.

04EU

The European Union is the global hub of food-grade gas fermentation, led by Nordic developers and backed by the EU hydrogen IPCEI and Horizon programs.

Solar Foods Factory 01, EFSA novel food, IPCEI hydrogen

• Solar Foods and Factory 01: Solar Foods operates the world’s first commercial-scale gas-fermentation food-protein plant, Factory 01 near Helsinki, producing up to 160 tonnes of Solein a year since April 2024 from a 20,000-litre bioreactor.
• Factory 02 scale-up: the company finalised the advanced concept design of Factory 02 in March 2026, targeting 6,400 tonnes a year in two phases (first 3.2 kt by end-2028), with GEA as exclusive process-equipment partner.
• Regulatory and funding stance: Solein holds Singapore novel-food and US self-affirmed GRAS status; the EFSA novel-food dossier (filed 2021) is expected to clear in 2026, and Factory 01 is the first EU hydrogen IPCEI project to be built.

05Leading companies and research institutes

06Tech stack and innovations

The modern gas-fermentation food-protein plant is built on three engineering pillars that move poorly soluble gases into living cells, recover the biomass as food, and integrate cleanly with renewable power.

1. Gas-loop bioreactors:
   • Loop reactors recirculate the broth at several metres per second through a pressurised downflow where static mixers shatter the H2/CO2/O2 bubbles, raising the volumetric mass-transfer coefficient five- to ten-fold over stirred tanks.
   • Solar Foods verified a 100-fold scale-up from pilot to the 20,000-litre Factory 01 vessel, holding productivity near 0.8 g/L/h and an O2/CO2 energy-efficiency ratio of 2.7.
2. Integrated electrolysis and CO2 capture:
   • On-site PEM electrolysers feed the fermenter with high-purity hydrogen from renewable electricity, while DAC or industrial-capture units supply the carbon, making the protein genuinely land-independent.
   • Heat recovery from the electrolyser stack and the exothermic bacterial respiration pre-heats the spray-drier inlet air, pushing the integrated energy efficiency toward 85%.
3. Food-safe downstream and drying:
   • Disc-stack centrifugation concentrates the cells into a paste, followed by a short high-temperature step that inactivates the culture and cuts nucleic acids to keep purine load safe for humans.
   • Spray drying at around 180 °C turns the paste into a stable golden powder of roughly 65–70% protein, below 5% moisture, packaged under inert atmosphere for B2B ingredient buyers.

07Value chains and production pipelines

Industrial pipeline of hydrogen-to-food-protein production in gas-loop bioreactors (HACCP / ISO 22000 food safety)

┌───────────────────────────┐      ┌───────────────────────────┐
│ 1. PEM electrolysis &     │ ───> │ 2. Continuous gas-loop    │
│    CO2 capture            │      │    fermentation           │
└───────────────────────────┘      └───────────────────────────┘
                                                  │
                                                  ▼
┌───────────────────────────┐      ┌───────────────────────────┐
│ 4. Pasteurisation &       │ <─── │ 3. Degassing &            │
│    cell inactivation      │      │    centrifugation         │
└───────────────────────────┘      └───────────────────────────┘
              │
              ▼
┌───────────────────────────┐      ┌───────────────────────────┐
│ 5. Spray drying           │ ───> │ 6. QC, packing & food     │
│    (180 °C)               │      │    formulation            │
└───────────────────────────┘      └───────────────────────────┘

Stage 1: Gas generation and conditioning

PEM electrolysers split demineralised water into hydrogen and oxygen using renewable electricity, while DAC or industrial capture supplies CO2. The gases are compressed to a few bar, dried, and metered into a non-explosive blend such as 60% H2, 20% CO2, 10% O2, 10% N2 that stays outside the detonable Knallgas envelope.

Stage 2: Continuous gas-loop fermentation

The gas blend is injected continuously into a loop bioreactor holding an aqueous mineral medium (nitrogen, phosphorus, potassium, trace metals). Cupriavidus necator fixes CO2 via the Calvin cycle at around 30 °C and pH 6.8, with ammonia controlling pH and supplying nitrogen; spent gas is separated in a degasser and recycled, keeping the cell density above 50 g/L.

Stage 3: Degassing and concentration

Broth is drawn off into a vacuum degasser that strips any residual explosive gases, then onto a disc-stack centrifuge. Cells concentrate into a wet paste at about 15–20% dry solids, and the clarified centrate returns to the fermenter for a closed water loop.

Stage 4: Pasteurisation and inactivation

A plate heat exchanger flash-heats the paste to about 85 °C for tens of seconds, fully inactivating the culture and degrading intracellular RNA to lower purine load for human consumption; the paste is then cooled before drying.

Stage 5: Spray drying

A high-pressure pump atomises the paste into a spray-drying tower against a counter-current of sterile hot air near 180 °C. Moisture flashes off instantly and the dried microbial cells fall as a fine golden powder, recovered by cyclones and bag filters below 5% moisture.

Stage 6: Quality control, packing and formulation

QC verifies crude protein (target above 65%), moisture, the essential amino-acid profile, and absence of pathogens and heavy metals. The powder is packed in barrier-foil bags under inert atmosphere and shipped to food manufacturers, who blend it into pasta, dairy alternatives, meat analogues and snacks.