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.