Despite growing calls for the wider adoption of community scale biomass power plants, new research released yesterday suggests that the environmental benefits of smaller scale facilities may have been overstated.

The study from the Tyndall Centre for Climate Research at the University of Manchester assessed the environmental impact of 25 bioelectricity systems in the UK, analysing the full lifecycle impact through crop production, transport and energy generation.

It found that while all the plants studied delivered reductions in carbon emissions compared to grid electricity larger facilities delivered significantly lower levels of emissions per unit of electrical output than smaller scale community projects.

Community scale biomass plants powered by waste material, wood chips or sewage and capable of providing power to a small business or housing estate have been widely touted as a potentially viable source of clean energy. In a report released earlier this week, the Green Building Council argued that community scale renewable energy plants should form a key component of the government's plans to ensure all new homes are "zero carbon" by 2016.

Advocates of the approach argue that such facilities are particularly efficient as the waste biomass provided by the community only has to travel a short distance to the power plant.

However, the University of Manchester study concluded that the energy consumption, greenhouse gas emissions and environmental pollutants associated with haulage lorries visiting bio-electricity plants is relatively insignificant when compared to the efficiency gains attained by larger plants.

Presenting the research at the UK Energy Research Centre's Sustainable Energy UK conference in Oxford yesterday, report author Dr Patricia Thornley said that while biomass power plants represented a means of delivering substantial reductions in greenhouse gas emissions those investing in the technology had to remember that it still has an environmental impact.

"It is not emission free and, when account is taken of airborne emissions, ecological and other impacts there is arguably greater potential for direct environmental impact than is the case for most other renewable energy technologies," she said. "These factors make it particularly important to consider the whole system – including crop production and transport – and to choose an appropriate scale, technology and type of biofuel."