Biotech - Aerofilter for small scale anaerobic digestion plants

The anaerobic digestion of organic substrates (e.g. manure, sewage sludge, organic fractions
of household and industry waste) produces biogas. Biogas is made of carbon dioxide,
methane and traces of hydrogen sulfide. Hydrogen sulfide is particularly harmful when
biogas is used in combustion engines as even low levels of hydrogen sulfide are associated
with engine corrosion and wear. Consequently hydrogen sulfide needs to be removed before
biogas is utilised; current removal methods are costly and represent a significant expense to
the project operators - particularly those who operate small scale anaerobic digestion plants.
There are currently 78 small scale anaerobic digestion plants in the UK, the majority of which
convert their biogas into electricity. The number of small scale (farm based) plants is forecast
to reach 1,000 by 2020 in the UK. Similar growth trends are forecast for Europe and
internationally.
Most existing hydrogen sulfide removal technologies, e.g. water scrubbing and activated
carbon filtration, have been designed for much larger scale centralised installations. For small
scale operations (e.g. farms) this technology is not economically viable. There is a clear
demand for a biogas cleaning technology with lower capital and running costs to make the
process economically viable. Effective hydrogen sulfide removal will ensure that the biogas
is suitable for electricity generation and feedback into the national grid. It will directly support
the to UK achieve its ambitious target of increasing the number of small-scale on-farm AD
plants and help reduce greenhouse gas emissions associated with manure management.
Biotec’s proposed solution is to develop a filter medium to remove hydrogen sulfide and other
harmful gases from biogas. Unlike most conventional gas scrubbing