A biogas facility typically has two or more cylindrical digesters with heating pipes integrated into the walls and floor. The walls are insulated and clad with weatherproof panels. The digesters are built above ground to reduce costs and facilitate maintenance, and their cylindrical shape ensures maximum engineering and thermal soundness.
Biogas Energy digesters are covered with double-membraned roofs that protect from the elements, allow easy access to the digester's contents, and contain built-in gas storage. The roof's outer membrane has withstood harsh Northern winter climates for over a decade, while the inner membrane expands and contracts as a built-in gas holder for up to 10 hours of biogas production.
Between the two membranes an air pump maintains pressure to give the outer membrane its stability while applying pressure to the gas storage. By including gas storage as standard equipment, we reduce costs and gain considerable energy production efficiencies. For example, when the CHP unit is turned off for routine maintenance, the gas can be stored until operations continue. That way, our customers don't lose a cubic foot of methane to flaring. Every minute of gas flared is money lost, so gas storage adds directly to the bottom line.
If an issue arises within the digester, the roof can be unhitched and folded back to give instant access; impossible with a steel or concrete roof. This ease of access means repairs take a few minutes, not days, so downtime is reduced to a minimum. With the ability to store gas while also enabling quick, easy access to the insides of the digesters, the roofing system saves considerable money in the long run.
The contents of each tank are mixed with either submerged agitators or external pumps to foster optimal bacterial proliferation and ensure steady, reliable methane production. The agitators adjust automatically or manually and ensure a complete, pervasive mix of substrate for an optimized climate for bacterial proliferation and pathogen treatment. Agitators have an expected lifetime of 8-10 years since they only run for 5-20 minutes each hour. Should an agitator require repair or replacement, it's simply matter of folding back the roof, lifting out the unit, and replacing it in minutes. Unlike digesters with concrete roofs or central mixing devices, there is minimal downtime and no loss of operations
After desulphurization, the biogas is converted into electrical and thermal energy in a combined heat and power (CHP) unit, also called a cogeneration unit. All of the facility's equipment, including the digester heating, runs on power generated by the CHP unit. Surplus electricity (typically 95% of the amount generated) is fed into the public grid and sold to the local power utility. Surplus heat can be used to heat homes or buildings as well as for agricultural and industrial processes that require significant heat.
The Biogas Energy digester design can process high-liquid/high-energy feedstocks like glycerin or grease, and it can also proces high-solids feedstocks like food scraps and green waste.
Don't box yourself in with the limited functionality of a 'dry' digester or lagoon. Build a system that can expand as you do.
Complete mix mesophilic digesters are the most widely deployed AD technology in the world. While there are perhaps a dozen projects operating in the US (our team built six of them), over five thousandare going strong in Europe. As a licnesed contractor in California, Biogas Energy will build your project from start to finish.
Cow manure is a primary feedstock for anaerobic digestion; the right bacteria are in the poop! But just about any biodegradable organic material is a potential feedstock for AD, from food waste to grass clippings to whey... and lots more. Contact us and we'll work with you to figure out what is possible.
The primary content of biogas is methane (CH4), or natural gas. Biogas can be fed directly to a combined heat and power generator such as an internal combustion engine or a fuel cell to generate electricity. It's also possible to clean the other gasses out of the biogas (like CO2 and H2S) to produce pipeline-quality natural gas either for pipeline injection or to produce bio-CNG.