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.
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 UK to 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.
Aerocover’s proposed solution is to develop a filter medium to remove hydrogen sulfide and
other harmful gases from biogas. Unlike most conventional gas scrubbing systems, it will not
use chemicals and will be a cheaper alternative to activated carbon filtration.