Biogas
is a renewable energy source with many different
production pathways and various excellent opportunities
to use.
Biogas
typically refers to a gas produced by the anaerobic
digestion or fermentation of organic matter
including manure, sewage sludge, municipal solid
waste, biodegradable waste, energy crops or
any other biodegradable feedstock. Biogas is
comprised primarily of methane and carbon dioxide.
One main
advantage of biogas is the waste reduction potential.
Biogas production by anaerobic digestion is
popular for treating biodegradable waste because
valuable fuel can be produced while destroying
disease-causing pathogens and reducing the volume
of disposed waste products.
Biogas
burns more cleanly than coal, and emits less
carbon dioxide per unit of energy. The carbon
in biogas was recently extracted from the atmosphere
by photosynthetic plants. Releasing it back
into the atmosphere adds less total atmospheric
carbon than burning fossil fuels.
Thus,
biogas production kills two birds with one stone:
it reduces waste and produces energy. In addition,
the residues from the digestation process can
be used as high quality fertilizer. This closes
the nutrient cycle.
Therefore,
biogas is a perfect energy source including
many benefits!
Biogas
- The Feedstock
Feedstock
production for biogas is very diverse, ranging
from livestock waste, manure, to harvest surplus.
Also, wastewater sludge, municipal solid wastes
and organic wastes from households can be used
as feedstock. Recently, dedicated energy crops
are more and more used as feedstock source for
biogas production. Finally, biogas can be collected
from landfill sites.
One main advantage of methane production is the ability to use so-called “wet biomass” as feedstock source. Wet biomass can not be used for the production of other biofuels such as biodiesel or biomethane. Examples for wet biomass are sewage sludge, manure from dairy and swine farms as well as residues from food processing. They all are characterized by moisture contents of more than 60–70 %.
The use of waste materials is not only excellent suitability for biogas production it also creates some additional benefits. Thus, it contributes to reduce animal wastes and odors. Digestion effectively eliminates environmental hazards, such as overproduction of liquid manure. Therefore biogas production is an excellent way for livestock farmers to comply with increasing national and European regulations of animal wastes. In addition it destroys disease-causing pathogens existing in waste materials. Nevertheless, using animal feedstock can be critical as well. For instance anaerobic degradation of poultry excrements with high contents of organic nitrogen produce high concentrations of ammonium. Furthermore, new economical and ecological solutions for the treatment of animal by-products are required due to the BSE-crisis. However, it is often the combination of environmental, economical and legal reasons that motivates farmers to use digester technology for waste treatment.
Apart from waste materials, suitable feedstock also includes dedicated energy crops. The suitability of energy crops for biogas production was received through improvements in the fermentation process.
