Novel biogas facility planned for Plymouth

A proposed biogas facility near Plymouth is hoping to divert 75,000 tonnes of waste from landfill every year to generate clean electricity.

AeroThermal Group and 4Recycling have submitted plans to Devon County Council for an innovative facility that uses autoclaving and anaerobic digestion on municipal solid waste (MSW) to generate biogas for electricity generation.

‘This system makes more of the material available, things like cardboard and paper can actually be digested having been autoclaved, whereas with other systems without autoclaving, the digestion process would not be able to deal with that material at all,’ said Tony Kimber technical director at AeroThermal Group.

AeroThermal have around thirty years’ experience using autoclaves, mostly for composites in the aerospace, motorsport and process engineering industries. They have worked with several formula one teams as well as Boeing and Airbus on their lightweight planes.

The company decided to diversify its business, citing the long lifespan of carbon composites and lack of repeat orders. They spotted a potential gap in the market that could easily be exploited with their existing technology.

‘Whereas our competitors have had to scale-up from laboratory sterilizing equipment, we’re actually scaling down if anything… the drum itself weighs 32 tonnes and is something like seven metres long,’ Kimber said of the autoclaving technology.

Their system takes MSW, which includes black bag refuse from households, commercial waste from restaurants and various other organic waste sources.

The waste is subjected to a pressure of six bar and temperature of 165°C, which breaks down all the organic material to create an ‘organic soup’ that is ideal for anaerobic digestion.

The biogas produced is used to drive two generators which feed directly into the power grid. The gas is also used to drive the autoclave in the previous step.

Based on the recent announcement from the Department of Energy and Climate Change pledging incentives for renewable heat, Kimber said they are also now considering ‘cleaning up’ the biogas to feed into the main gas grid.

‘Within the current economic climate and public expenditure cuts, many councils are now looking at the nonsense of having multiple collection of refuse — we don’t need that, we can accept the material mixed from one collection. Councils could half their collection cost,’ Kimble said.