The comparative data for pollutant emissions can vary quite widely depending on the material used to make the briquettes, as well as its moisture content, and also the type of appliance they are burned in.
Briquettes made from clean, dry sawdust typically burn more efficiently than those made from mixed or high-moisture biomass, which can influence levels of particulate matter and other emissions.
From a carbon perspective, briquettes made from sawdust or other wood waste are generally regarded as carbon neutral. The CO₂ released during combustion is the same carbon absorbed by the biomass during growth, meaning it circulates within the short natural carbon cycle rather than adding new fossil carbon to the atmosphere. For this reason, briquettes are widely considered a low-carbon or carbon-neutral fuel compared with coal, oil, or gas.
It’s important to distinguish carbon neutrality from the cleanliness of combustion: even carbon-neutral fuels can still produce particulate matter (PM₂.₅) and other pollutants, particularly when burned in older or inefficient domestic stoves. Actual emissions can vary depending on fuel quality, stove type and operation.
A reasonable estimate for PM₂.₅ emissions from clean, sawdust-derived briquettes would be in the range of 6 – 26 g of PM₂.₅ per kilogram of fuel, subject to ignition conditions, stove design, combustion quality, and how “hot” or complete the burn is.
When burned in domestic wood stoves, clean sawdust briquettes generally fall within the same emissions range as seasoned hardwood logs, sometimes slightly lower on a per-kilogram basis, but this can vary depending on stove efficiency and operator technique.
However, emissions can be significantly reduced when briquettes are burned in appliances fitted with effective particulate filtration systems. Modern burners and biomass boilers equipped with technologies such as ceramic filters, cyclonic separators or electrostatic precipitators can typically capture a substantial proportion of particulate matter before it is released into the atmosphere. In many controlled or industrial settings, such systems routinely achieve:
- 80–95% reduction in PM emissions (depending on technology and maintenance);
- Lower visible smoke and odour;
- More complete combustion, which can also reduce CO and unburnt hydrocarbons.
When carbon-neutral briquettes are used within a properly engineered and filtered combustion system, the overall environmental impact is markedly improved – offering a much cleaner and more responsible alternative compared with unfiltered domestic wood burning.
