October 17, 2024 Biomass Boilers
How Biomass Boilers Affect Air Quality: Myths and Facts
The impact of biomass boiler emissions on air quality is negligible. In fact, the use of bioenergy as a heat source is a net positive for air quality, because the typical use case of a wood heat boiler is in a rural setting off the gas grid, when biomass is typically replacing an oil- or a coal-fuelled boiler, from which particulate emissions can be 5-12 times higher.
There are plenty of misconceptions and misleading statistics about wood heat and air quality, but here is why wood heat is no threat to the environment or to air quality.
Particulate emissions from biomass boilers
Particulates are microscopic airborne particles that the lungs can absorb. Generally, when discussing particulates, we are talking about PM2.5 — particulates smaller than 2.5 microns.
The Renewable Heat Incentive (RHI), which subsidised biomass heat using payments for fuel usage, mandated that boilers’ particulate emissions must not exceed 30 mg/MJ, and testing revealed that over half emitted less than 20 mg/MJ.
Now, those figures are from around 2012, and it is worth noting that biomass technology has only improved since then, and sophisticated biomass systems like ETA also offer additional measures like electrostatic precipitators (ESP), which filter out 99% of particulate matter at the flue.
It is also vital to consider contextual factors when considering relative particulate emissions. The relevant comparison for biomass emissions is not gas boilers, but oil and coal boilers.
Air quality compared: biomass vs fossil fuel
Burning natural gas tends to burn with low particulate emissions (c.1 mg/MJ), but to consider the real-world impact of biomass on air quality, gas boiler particulate emissions are largely irrelevant.
That is because in the majority of cases, a new biomass heating system is not replacing gas, but oil or coal. Buildings that are off the gas grid have historically relied on oil or coal to fuel their heating systems, and biomass represents a sustainable way to heat remote properties, especially when those properties are difficult to insulate.
Oil boilers produce upwards of 50 mg/MJ of particulates, and coal boilers are likely to emit over 120 mg/MJ. If a biomass boiler were to emit particulate levels of 20 mg/MJ, it would be six times cleaner than a coal boiler, and over twice as clean as an oil boiler.
In 2021, 3.5% of households used oil for heating. In that year there were 28.1 million UK households, meaning close to a million used oil. There were about 280,000 non-domestic buildings that were not on the gas grid. Assuming we replaced oil with biomass at the particulate emissions figures above, replacing those heating systems even with relatively unsophisticated biomass heating systems would result in particulate emissions over two times lower for well over 28 million buildings.
That, of course, is only considering particulate emissions. The other dramatic improvement would be carbon emissions.
Heating a typical house for a year takes 20MW/h of power. In creating that power, natural gas emits about 4,040kg of CO2, oil emits 5,200kg, and coal emits 7,260kg. Wood pellets with 10% moisture content emit only 300kg. That is even without taking into account the circular carbon cycle of wood, in which living trees capture carbon before they release it in combustion.
All in all, biomass boilers are significantly better for the environment than gas, oil, or coal.
How to future-proof your energy
Whether there are ESG targets to hit, Net Zero commitments to meet, or simply running costs to reduce, lots of businesses are very urgently seeking to decarbonise their energy and heating systems.
Fortunately, Innasol is available to advise and assist with your transition to green power. We are experts in green heat for business, as well as commercial solar power, and we have a nationwide network of highly trained and deeply dedicated installers and engineers who can help you plan your energy transition.
Read our guide to green business energy for more details on how to future-proof your heat and power, and call 01621 892613 to speak to your local sustainability specialist.
