4.5.6. Biogas engine and digester
One of the purposes of this study is to perform a comparative
techno-economic analysis between diesel engine and biogas engine
operation. The price of gas engine and diesel engine are slightly
different in the market and the fuel price might influence the O&M
cost of the system. The biogas is produced locally from cattle
manure in the community and this biogas production can be relatively
expensive. There are many commercial biogas digesters in
the market that are very different in operation, construction, the
amount of biogas production and cost. To make the biogas engine
more cost effective, cheap solutions which are available locally
should be considered in the system design. In this case study, a plug
flowreactor which is a dry anaerobic digestion technology has been
selected [48]. The reactor is chosen to be an in-ground tubular tank
which is relatively cheap with easy installation and maintenance
scheme. The total solid percentage of the input material is around
20e40% and the HRT (Hydraulic Retention Time) is around 20e30
days.