More pollutants from burning biomass

Biomass facilities emits up to 2.8 times more pollutants than their non-biomass counterparts

The transition away from fossil fuels to sustainable renewables is gaining momentum across the developed world with many governments, including Switzerland’s, turning to woody biomass as a clean, green, domestic source of energy. The implications for future emissions, air quality and health impacts remain largely underreported and under-appreciated however.  

Burning woody biomass releases greenhouse gases, gaseous pollutants, fine particles and ozone precursors that damage both the climate and human health (add link to your health section).  

Moreover, woody biomass is often pretreated to improve fuel quality. These techniques include: leaching, drying, densification and washing, but pelletisation is the most common and best known treatment. Wood pellets are touted as clean, but their production emits particulate matter and volatile organic compounds such as acrolein, while burning them produces more toxic emissions, greenhouse gases and toxic ash (add link to Energy Wood We Expose No. 2).

Global wood pellet production has increased from 2 million tonnes in 2000 to 32 million tonnes in 2017. In Switzerland, 434,000 tonnes of pellets were sold in 2022, according to ProPellets, of which 367,000 tonnes were produced domestically (up +13.5% compared to 2021) and sales of pellet burners increased by 20%, with burners of 20-50 kW (private houses and flats, ie. without filters) and 50-100 kW (district heating) selling the most.

This represents a lot of extra CO2 released into the atmosphere. How much? Well, it depends on a number of factors including feedstock and the type of facility, but it can range from 1.6 to 1.80 tonnes of CO2 per tonne of wood pellets!

It also represents a lot of extra pollution as both biomass pretreatment and bioenergy generation deteriorate air quality. Even more worrying is the finding that emissions from biomass-fuelled burners can be up to 2.8 times higher than non-biomass burners per unit energy. This figure comes from a 2023 study, conducted in the USA (the world’s largest pellet producer), that looked at emissions arising from both domestic bioenergy production (largely wood-based biomass) and the manufacture of wood pellets. The study found that the 2.3 million people who lived within a 2 km radius of a biomass plant could be exposed to adverse health effects and that emissions from biomass and wood combustion had overtaken coal as the leading source of mortality impacts.

Swapping one air pollution-and-greenhouse-gas-emitting fuel source (fossil fuels) for another (woody biomass) is not a pathway to a healthy energy system. 

Health and Forest calls on the Swiss government to stop pushing and subsidising this false and downright health-and-climate damaging solution.

March 2024