Fires at biogas plants: the most common causes, prevention and firefighting principles
Fires at biogas plants most often start in the CHP unit, electrical installations, silage stores and dryers. An overview of causes, prevention, equipment and firefighting principles.
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A fire at a biogas plant most often starts in one of five places: the CHP container or hall (overheating, an oil leak, a gas leak), the switchgear and electrical installation, the biomass store (self-heating), the dryer, and during hot work. The consequences depend on whether biogas is involved in the fire: an electrical fire can usually be brought under control with standard means, but a fire involving gas requires the fuel to be cut off first and special caution because of the risk of explosion.
Typical causes
| Area | Cause | Example of the mechanism |
|---|---|---|
| CHP | overheating, a ruptured fuel line, an oil leak onto hot components | a spark or hot surface ignites oil or gas |
| Electrical installation | loose connections, overload, moisture, equipment defects | an electric arc in a cabinet |
| Gas installation | a leaking flange, valve or penetration | gas accumulates and is ignited by a source |
| Silage, straw and hay store | self-heating of biomass | the temperature rises in material that is too wet or poorly compacted |
| Dryer | dust, heater, control error | ignition of dust or material |
| Hot work | welding, cutting with an angle grinder | sparks near gas or combustible materials |
| Arson, lightning | no lightning protection | a lightning strike |
Technical prevention
- Leak checks of the gas installation (detectors, measurements, pressure tests) according to schedule.
- Thermography of switchgear, control cabinets and engines at least once a year and after repairs.
- Ventilation of the CHP container and methane and smoke sensors, linked to gas shut-off and engine shutdown.
- Cleanliness — removing dust, oil residues and combustible material from around the engine and switchgear.
- Lightning protection and earthing — periodic measurements.
- Shut-off valves and gate valves in easily accessible places, marked and checked.
- Constant supervision of the biomass — temperature measurement in clamps, proper compaction and covering.
Organisational prevention
- A hot work procedure with a written permit, a survey of the surroundings, the presence of a person with a fire extinguisher and extended supervision after the work is finished.
- A fire safety manual and training for staff and subcontractors.
- Drills with the local fire brigade unit, including a discussion of the hazards associated with gas.
- Up-to-date site plans available at the entrance: the location of tanks, valves, cabinets and hydrants.
- Vehicle access — fire roads and water supply.
Firefighting principles
| Situation | Action |
|---|---|
| Electrical fire in a cabinet | disconnect the power, use powder or gas extinguishers, not water |
| Burning gas leak | cut off the fuel supply (valves), cool the surroundings with water, do not extinguish the flame without closing the supply |
| Oil fire in the CHP | powder or foam extinguisher, shut down the engine, ventilate |
| Burning biomass | separate it, dismantle the clamp, use water with control of the run-off, cooperate with the State Fire Service (PSP) |
| Fire of a gas tank | evacuation, cooling, decisions made by the incident commander |
The key point: do not extinguish a gas flame if the supply cannot be cut off — unburned gas in an enclosed space can explode on re-ignition.
The role of the flare and safety systems
In the event of a CHP failure, excess gas should be burned in the flare and not released into the atmosphere. Membrane roofs are protected by overpressure valves; their operation must be checked and they must be kept clean (foam and condensate can block them).
Insurance and reporting
Insurers often expect documented inspections and thermography. Keep an inspection register; it also makes risk assessment after an incident easier. Every fire or serious incident is worth analysing: the cause, the response time, the effectiveness of the procedures — and the emergency plan should be updated.
Checklist
- Does gas and smoke detection work in the CHP and the technical rooms?
- Are the shut-off valves operational and marked?
- Was thermography carried out within the last 12 months?
- Is the hot work procedure applied?
- Does the PSP know the site?
- Are the silage clamps monitored?
- Is the firefighting equipment in working order and positioned according to the manual?
Self-heating of biomass — how to detect it
Material that is too wet or poorly compacted (hay, straw, silage with air ingress) can heat up as a result of microbiological and chemical processes. Symptoms: a smell of burning or baking bread, water vapour above the clamp, subsidence of the surface, an internal temperature of several tens of degrees and rising. Measurement with a probe at several points is recommended, and once the threshold set in the manual is exceeded — digging out and cooling under supervision. A strongly heated clamp must not be raked apart without prepared firefighting support, because the inflow of air can lead to ignition.
Lessons after incidents
Analyses of incidents show a recurring pattern: the cause is a lack of maintenance, housekeeping neglect or work without proper supervision, not rare failures. Systematic inspections and discipline in hot work are the cheapest protection.
Summary of the most important principles
The order: people, cutting off the source, the alarm, limiting the spread, extinguishing. If there is no certainty about safety, keep your distance and hand over the running of the operation to the emergency services.
