# Gas fermentation of food protein Microbial food protein grown by feeding hydrogen-oxidising bacteria a mix of hydrogen, CO2 and oxygen in gas-loop bioreactors — a land-free 'food from air' route now at commercial demonstration scale. Source: https://en.bioecon.ru/technology/gas-fermentation-food-protein/ Updated: 2026-08-18 ## Overview 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 | Level | Description | Key inputs/outputs | |:---|:---|:---| | **Gas preparation** | PEM electrolysers split water into hydrogen and oxygen; DAC or industrial capture supplies CO2; gases are compressed and dried. | **In:** Renewable electricity, water, air.
**Out:** Compressed H2, CO2, O2. | | **Fermentation** | Continuous culture of HOB in a gas-loop bioreactor at around 30 °C and pH 6.8, fed a non-explosive gas mix. | **In:** Gases, ammonia, mineral salts, trace metals.
**Out:** Microbial broth above 50 g/L cell density. | | **Concentration** | Disc-stack centrifugation and ultrafiltration raise the broth to a wet microbial paste, with water recycled. | **In:** Culture broth.
**Out:** Cell concentrate at 15–20% dry solids. | | **Downstream processing** | Brief high-temperature pasteurisation inactivates the culture and lowers nucleic-acid load for human consumption. | **In:** Cell paste.
**Out:** Inactivated, digestible protein paste. | | **Drying** | Spray drying of the paste against hot air into a fine free-flowing golden powder. | **In:** Paste, hot air near 180 °C.
**Out:** Dry protein powder below 5% moisture. | | **Food formulation** | Blending the powder into pasta, dairy and meat alternatives, snacks and supplements for B2B ingredient buyers. | **In:** Protein powder, recipe bases.
**Out:** Fortified finished foods. | 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. --- ## US 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. --- ## CN 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. --- ## EU 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. --- ## Leading companies and research institutes | Company / Institute | Country | Key products / platforms | Tech features | Status 2026 | |:---|:---|:---|:---|:---| | **Solar Foods** | 🇫🇮 Finland | *Solein* | H2/CO2 gas fermentation; Factory 01 at 160 t/yr, Factory 02 to 6.4 kt/yr | commercial | | **Air Protein** | 🇺🇸 USA | *Air Meat* | Oxyhydrogen (HOB) fermentation into meat analogues; NASA heritage | pilot | | **Deep Branch** | 🇬🇧 United Kingdom | *Proton* | (R)evolve CO2/H2 gas fermentation; mobile pilot unit | pilot | | **Calysta** | 🇺🇸 USA | *FeedKind* | Methanotroph gas fermentation of *M. capsulatus* | commercial | | **Calysseo** | 🇨🇳 China | *FeedKind (Asia)* | First commercial-scale gas-protein plant, Chongqing | suspended (plant idle; JV support withdrawn 2026) | | **Unibio** | 🇩🇰 Denmark | *Uniprotein* | Patented U-Loop methane loop reactors | commercial | --- ## Tech 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. --- ## Value 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.