Biomass not low-carbon says AECB
Burning wood as biomass produces twice the amount of carbon dioxide as burning natural gas, according to AECB, the sustainable building association.
In a new report, it criticises accepted thinking that biomass fuels are carbon neutral or low-carbon arguing that if the emissions produced by burning biomass are examined separately from the carbon dioxide sequestered by the growth of the fuel, “even standard gas boilers burning fossil fuel, are lower emitters of carbon dioxide than biomass boilers”.
Biomass is presented as a low-carbon fuel because the trees grown for fuel absorb the same amount of carbon over their lifetime as they produce when they are burned.
However, according to the AECB report, a much better way of reducing carbon would be to grow biomass fuels and use them for another purpose, such as for wooden flooring or furniture, instead using natural gas as an energy source.
Natural gas releases only half the amount of CO2 when burned as the equivalent amount of biomass, and using wood rather than burning it locks up the CO2 that has been absorbed over the tree’s lifetime.
The proposed approach would mean that for every tonne of CO2 being sequestered by biomass plants only half a tonne would be produced by burning gas for energy (see diagram below).
“Why should we assume that CO2 released from a gas boiler will cause climate change, while CO2 from a biomass boiler is simply food for trees? The trees can’t tell where the CO2 came from,” argues the paper.
The report’s authors conclude that promoting biomass as a renewable fuel key to cutting the UK’s carbon emissions is “fundamentally misguided” and that a better approach would be to provide incentives for planting more forest and making things from wood rather than burning it.
“Decoupling energy use from generation and biomass emissions from sequestration allows a more holistic approach to carbon accounting that is better suited to inform national climate change policy,” states the report.
It even goes as far as to warn that further uptake of biomass in the UK will not reduce carbon emissions, but significantly increase them.
The news came as the energy-sector watchdog Ofgem revealed that more than half of the biomass fuel used in the UK between April 2020 and March 2011 was not sourced using recognised environmental quality assurance schemes.
According to Ofgem’s annual sustainability report for the use of biomass under the Renewables Obligation, five million tonnes of solid biomass and energy crops were used in the UK, a 62% increase in energy crop use in 12 months.
The figures show that only 32% of the participating energy firms had sourced their feedstock using a recognised quality assurance scheme.