A biogas plant is a container of a slurry of bacteria and wet organic matter that
produces methane and carbon dioxide. The methane-producing bacteria are anaerobic,
i.e. they do not work when oxygen is present. A cow’s gut contains a population of
bacteria that include anaerobic methanogens, so cattle dung is often used as feedstock
or as a starter for the digestion of other types of organic material. Since these
bacteria are adapted to a cow’s gut, they run best at 35°C (mesophylic), although
some also work at 55°C (thermophyllic). In colder climates the container must be
insulated and/or heated to maintain this temperature. The container must be gas tight
to retain the gas as it is given off and also to exclude air.
Biogas technology has a long history, especially in countries such as China, India
and Nepal. In UK, the rest of Europe and USA, it had a brief burst of interest in
the early 1980s, but was seen as uneconomic, when the oil price dropped. Since the
1990s, there has been a strong revival of interest in Germany, followed by Sweden,
Denmark and Austria. The UK has been very slow in following their lead, mainly because
the technology is still seen as uneconomic. Germany and other European countries
provide subsidised feed-in tariffs that allowed operators who generate electricity
from renewable energy, such as biogas, to earn a commercial income.
Biogas is a fuel gas that can be used in gas burners, for cooking and heating, or
in internal (and external) combustion engines to give shaft power or to drive an
electric generator.
Based on extensive experience of very successful biogas technology in Asia, Kingdom
Bioenergy Ltd is developing a biogas plant design for the UK and European market.
Pre-processing can improve the process of digestion and allow a much wider range
of materials to be digested.
