Knowledge Base

Biogas plants are industrial installations and, like any facility managing organic waste, require proper engineering to manage odour, noise, and safety. A well-designed plant addresses each of these aspects through a combination of containment, process design, and monitoring. The concerns are real but manageable and should be assessed openly in any planning or permitting process.

How odour is managed at a biogas plant
Odour is the most common community concern associated with biogas plants. It arises primarily during feedstock reception and digestate handling, rather than from the digestion process itself, which takes place in sealed tanks. HoSt’s insulated double-membrane roofs are designed for minimal biogas leakage. For feedstocks with strong odour profiles, reception areas can be enclosed and ventilated through biofilters. Digestate storage tanks can be similarly covered. The digestion process itself consumes the organic matter that would otherwise decompose in open storage and generate far larger odour emissions: a properly operated biogas plant typically produces less odour than the unmanaged storage of the same feedstock. The thick fraction is stored indoors after separation to avoid smell.

What noise levels can be expected from a biogas plant?
Noise originates primarily from mechanical equipment: pumps, mixers, feeders, the combined heat and power (CHP) unit, or gas upgrading compressors. HoSt plants are engineered with continuous automated operation as the objective, which means equipment runs steadily rather than in intermittent high-noise bursts. Equipment can be housed in insulated containers or buildings to reduce noise at the boundary. For sites near residential areas, a noise impact assessment is a standard part of the permitting process and will determine whether additional mitigation is required.

How safety is built into a HoSt biogas plant
Biogas is flammable and contains hydrogen sulphide (H₂S), a toxic gas, in its raw state. These properties mean safety must be addressed explicitly in plant design. HoSt states clearly that all its AD plants are implemented with safety at the forefront of our thinking. Key safety measures built into HoSt plants include: in-tank H₂S removal using a biological process under the membrane roof, which reduces H₂S concentrations before the gas reaches any downstream equipment; activated carbon filters (HoSt Carbon Clean) for polishing residual H₂S; gas detection sensors across the plant; pressure relief valves; biogas flares for safe disposal of gas during maintenance or start-up; and a fully automated control system with remote monitoring from HoSt’s control room. The absence of internal heat exchanger piping in HoSt’s external heat exchanger design is cited as removing a leakage risk. Digester tanks are made of reinforced, coated, and insulated concrete, built to be gas-tight.

Biogas plants are classified as hazardous installations in most regulatory frameworks, which means they are subject to permitting requirements covering explosion risk zones, equipment certification, and operational procedures.

A properly engineered biogas plant, operated and maintained according to design, presents a risk profile comparable to other industrial energy installations. The risk is managed through design, not eliminated by ignoring it. We are aware of the risks and mitigate the risks in our design.