Burning biomass fuel may be responsible for higher carbon emissions than previously estimated and lead to less energy efficient buildings, according to a study from a sustainable building association and reported in Building.
The AECB-commissioned study claims it is fundamentally wrong to define biomass as a low carbon fuel, as it releases similar CO2 emissions per unit of heat to burning coal, and twice that of burning gas.
The findings could effect biomass’s inclusion in the coalition government’s Renewable Heat Incentive (RHI), to be launched next April, which would pay building owners an incentive to generate heat from renewable sources.
The AECB claims that although biomass timber contains a high level of sequestered CO2, absorbed during a tree’s lifespan, the material should not be used as a fuel. Instead, it argues, the timber should be left unburnt and put to other uses.
Meanwhile, a building’s heating requirements should instead be provided by sources that emit less CO2 than the trees have absorbed in the first place.
Meanwhile, the role of heat pumps under the RHI has also come into question following the publication of a report from the Energy Saving Trust, which found that 80% of heat pump devices it tested in a field study performed so badly they would not qualify as renewable energy under proposed European standards.
The peer-reviewed study, based on largest ever field study of ground and air source heat pump devices in the UK and reported in the Guardian, found that of the 83 devices the EST monitored for a year, roughly 87% did not achieve an efficiency of 3, which the Trust considers a ‘well-performing’ system. And 80% failed to achieve an efficiency of 2.6, the minimum level being considered for achieving classification as a renewable source of energy under the EU Renewable Energy Directive.
The EST blamed the high levels of under-performance on poor installation and the UK’s use of multiple contractors to fit systems, unlike in Europe where a single contractor is the norm. It also found wrongly-sized systems, complicated controls and poor knowledge among householders of how to use them.
Simon Green, head of Business Development for the EST told the paper: “This trial shows that when installed and operated correctly, heat pump technologies will save significant amounts of CO2 in the UK, when replacing oil or traditional electric heating. But there is no doubt that the results are more varied than were expected, with results showing both high- and low-performing heat pumps.”
