Biogas and anaerobic fermentation

01Overview and value chain

Markers: [EC: EU RED III Biomethane & RePowerEU | OECD: Bioenergy | Regulator: EPA (USA), ADEME (France), MOA (China)]

Biogas and anaerobic fermentation use mixed microbial consortia to break down manure, energy crops and food-industry residues in the absence of oxygen, producing a raw biogas of roughly 55–65% methane plus CO2. Upgrading strips the CO2 to yield biomethane above 95% methane — a drop-in substitute for fossil natural gas. Nature Energy’s Abed plant in Denmark alone will produce about 20 million cubic metres of biomethane per year from 100,000 tonnes of beet pulp, while Clean Energy Fuels’ East Valley Cattle facility in Idaho runs six digesters processing over 5 million gallons of dairy manure into negative-carbon-intensity RNG. Europe operates over 18,000 biogas plants and the global biomethane output is targeted to multiply several-fold under RePowerEU, with anaerobic fermentation as the workhorse conversion route.

The key directions of biogas and anaerobic fermentation are:

1. Farm and livestock digestion (Farm & Livestock AD): dairy and poultry manure digested on-site into RNG — Brightmark’s 15 Midwest projects and DQY’s chicken-manure plant.
2. Energy-crop and co-substrate digestion (Energy-Crop Co-digestion): beet pulp, maize silage and straw co-digested with manure to raise yield — Nature Energy and PlanET.
3. Biogas upgrading (Biogas Upgrading): membrane, water-scrubbing and PSA systems lifting methane to >95% — EnviTec EnviThan with Evonik SEPURAN Green membranes.
4. Grid injection and RNG fueling (Grid Injection & RNG Fueling): biomethane fed into the gas grid or compressed for heavy-duty transport — Clean Energy Fuels and Nature Energy.

Sectoral value chain

[biomass / manure] ──> [anaerobic digester] ──> [raw biogas]
                                │
                        (microbial fermentation)
                                │
                                ▼
[grid / vehicle] <─── [upgrading] <─────┘

Value chain levels

Cross-cutting technologies of the sector:

• EnviThan membrane upgrading (EnviThan Membrane Upgrading): containerised Evonik SEPURAN Green hollow-fibre membranes.
• Thermophilic co-digestion (Thermophilic Co-digestion): high-rate digestion of mixed manure and crop substrates.
• SATAT CBG model (SATAT CBG Model): India’s compressed-biogas offtake scheme anchoring rural plant economics.

02US

The US leads dairy-manure RNG, driven by the Renewable Fuel Standard and LCFS credits.

dairy RNG, Chevron JV, LCFS-driven offtake

• Brightmark RNG Holdings: Chevron–Brightmark joint venture, first gas at 10 Midwest projects expanding to 15 across Iowa, Michigan, South Dakota, Wisconsin and Ohio.
• Clean Energy Fuels: East Valley Cattle (Jerome, Idaho) — eighth dairy RNG facility, six digesters processing over 5 million gallons of manure into negative-carbon-intensity RNG.
• RFS and LCFS: federal Renewable Fuel Standard and California’s Low Carbon Fuel Standard price the negative-CI RNG that anchors project economics.

03CN

China runs the world’s largest household and industrial biogas base, scaled around livestock and rural waste.

livestock biogas, rural programs, organic fertiliser loop

• Beijing DQY Agriculture: one of China’s largest chicken-manure biogas plants, coupling egg production with on-site anaerobic fermentation and organic-fertiliser return.
• Rural biogas program: Ministry of Agriculture household and village digesters, plus growing industrial-scale livestock-biogas projects.
• Digestate-to-fertiliser loop: the sector couples biogas with organic-fertiliser output, though biomethane grid injection remains less developed than in Europe.

04EU

The EU leads biomethane scale and technology, anchored by Danish producers and German plant builders.

Nature Energy, EnviTec, PlanET, RED III

• Nature Energy (Denmark): the Abed plant on Lolland — ~20 million m³/year of biomethane from 100,000 t/year of beet pulp supplied by Nordic Sugar.
• EnviTec Biogas (Germany): EnviThan upgrading with Evonik SEPURAN Green membranes, 14th Danish project at Hærup feeding the local gas grid.
• PlanET Biogas (Germany): agricultural AD plants exported globally, including India’s SATAT CBG facility in Palnadu, Andhra Pradesh.

05Leading companies and research institutes

06Tech stack and innovations

The stack couples microbiology, gas separation and grid logistics into a renewable-gas supply chain.

1. Thermophilic anaerobic digestion (Thermophilic AD):
   • mixed methanogenic consortia run at 50–55 °C for high-rate manure and co-substrate conversion.
   • East Valley Cattle’s six-digester array processes over 5 million gallons of dairy manure.
2. Membrane-based upgrading (Membrane Upgrading):
   • Evonik SEPURAN Green hollow-fibre membranes in EnviTec’s EnviThan container lift methane above 95%.
   • 935 Nm³/h upgrading capacity per Hærup unit feeding the Danish gas grid.
3. Grid injection and RNG fueling (Grid Injection & RNG Fueling):
   • pressure boosting and metering for gas-grid entry, plus compression to CNG/LNG for transport.
   • Clean Energy Fuels routes negative-CI RNG into the interstate pipeline for national fleet use.

07Value chains and production pipelines

Industrial pipeline of an agricultural biomethane plant (RED III, ISO 14001)

┌───────────────────────────┐      ┌───────────────────────────┐
│ 1. Feedstock intake       │ ───> │ 2. Anaerobic digestion    │
└───────────────────────────┘      └───────────────────────────┘
                                                  │
                                                  ▼
┌───────────────────────────┐      ┌───────────────────────────┐
│ 4. Grid injection         │ <─── │ 3. Biogas upgrading       │
└───────────────────────────┘      └───────────────────────────┘
              │
              ▼
┌───────────────────────────┐      ┌───────────────────────────┐
│ 5. Digestate return       │ ───> │ 6. Off-take & metering    │
└───────────────────────────┘      └───────────────────────────┘

Stage 1: Feedstock intake

Manure, beet pulp, maize silage or straw are received, weighed and blended into a biomass slurry at the Nature Energy Abed plant (100,000 t/year of beet pulp) or East Valley Cattle (5M+ gallons of manure).

Stage 2: Anaerobic digestion

The slurry is fermented by mixed methanogenic consortia in heated digesters over 20–40 days, yielding raw biogas at 55–65% methane and a nutrient-rich digestate.

Stage 3: Biogas upgrading

Raw biogas passes through EnviThan membrane units (Evonik SEPURAN Green) or water-scrubbing to remove CO2 and H2S, producing biomethane above 95% methane.

Stage 4: Grid injection

Biomethane is compressed, odorised and metered into the local gas grid — Nature Energy’s Abed plant delivers ~20 million m³/year, and EnviTec’s Hærup unit feeds the Danish grid at 935 Nm³/h.

Stage 5: Digestate return

The separated digestate is returned to farmland as a low-odour bio-fertiliser, closing the nutrient loop and displacing synthetic fertiliser.

Stage 6: Off-take and metering

Biomethane is delivered to gas-grid, CNG/LNG transport or industrial offtakers under RED III, RFS or LCFS crediting, with the negative-CI RNG marketed at a premium to fleets.