Siloxanes in biogas cause progressive, costly damage to CHP engines. We provide specialist sampling and speciation analysis to quantify your risk and protect your plant.
Siloxanes are organosilicon compounds (L2, L3, L4, D3, D4, D5, D6) naturally present in biogas from anaerobic digestion of sewage sludge, food waste, and municipal solid waste. They are volatile, odourless, and invisible — but when combusted inside a CHP engine they form silicon dioxide (SiO₂): essentially glass.
This hard, abrasive deposit accumulates on pistons, cylinder liners, valves, spark plugs, and catalysts. The result is accelerated wear, loss of compression, increased oil consumption, and — without intervention — catastrophic engine failure. Even concentrations as low as 5 mg/m³ can cause measurable degradation over time.
Volatile siloxane compounds vaporise during AD or landfill gas extraction and mix with the methane stream.
At combustion temperatures, siloxanes oxidise to form solid silicon dioxide — a hard, ceramic-like deposit.
SiO₂ accumulates on pistons, liners, valves, and plugs — acting as an abrasive that accelerates wear with every cycle.
Left unmanaged, siloxane damage leads to costly unplanned downtime, major overhauls, or total engine failure.
We provide representative biogas sampling and full siloxane speciation analysis at AD plants, sewage treatment works, and landfill gas sites across the UK.
Quantification of all major cyclic and linear siloxane species: L2, L3, L4, D3, D4, D5, and D6 — not just a total siloxane figure. Results are compared directly against your engine manufacturer's limits.
Sampling at the gas engine inlet, upstream of filters, and post-upgrade to quantify total siloxane loading, assess filtration performance, and identify breakthrough.
Where siloxane levels exceed safe thresholds, we provide guidance on filtration system sizing, media selection, and replacement frequency to bring concentrations within engine limits.
Regular scheduled sampling programmes to track seasonal and feedstock-driven variability in siloxane concentrations — giving you early warning before engine damage occurs.
Results delivered with a plain-language interpretation of risk to your engine, concentration trends, and specific recommendations — not just raw data.
All samples are analysed by UKAS-accredited laboratories using validated methods, ensuring results are defensible and suitable for engine warranty and insurance purposes.
Any site using biogas to fuel a CHP engine is potentially at risk. Siloxane concentrations vary significantly by feedstock — sewage sludge and food waste AD sites typically carry the highest loads.
Get in touch for a no-obligation quote. We respond within one business day.