Biomass resources for biogas production - The Biogas: Science, Production and Applications - page 20

Table 2.1 (Continued)

DM a
(%)

VS b
%of
DM

Type of
feedstock

Organic
content

C:N
ratio

VS
(%)

Methane
yield
(m 3 CH 4 /
kg VS)

Methane
production
(m 3 CH 4 /m 3 )

Energy crops
Grass silage 17 15-40 90 0.45

<

Maize silage
Fodder beet
silage
Sewage sludge
Waste water
sludge

5 75 3.75 0.4 15.0

Conc. wastewater
sludge

10 75 7.5 0.4 30.0

Food remains 10 80 0.5-0.60

a Dry matter.
b

Volatile solids.

utilization of biogas feedstocks (Wellinger, 2009). Although its utilization as
a biogas feedstock is still in the research phase, aquatic biomass is one of the
biomass types with the highest potential for renewable energy production as
well as various industrial applications and a possible future alternative to
energy crops.

2.2.1 Agricultural biogas feedstocks

The feedstock substrates used for biogas are primarily derived from the
agricultural sector, which accounts for the largest potential for biogas
feedstocks (Steffen et al., 1998). These feedstocks consist mainly of various
residues and by-products, of which the most important are animal manures
and slurries collected from farms (from cattle, pigs, poultry, etc.). Along
with manure and slurry, crop residues, by-products and wastes (e.g. straw,
grasses, leaves, fruits, whole plants) are also used. Over the last decade, new
categories of feedstocks have been tested and are now used in AD plants;
this is the case of energy crops (maize, grasses, beets, sunflowers, etc.),
grown specially for biogas production.

￿ ￿ ￿ ￿ ￿ ￿

Animal manure and slurries

Animal farming is an important part of the agricultural sector in most
countries, accounting for 18% of worldwide greenhouse gas emissions (Info-
Resources 2007). Most of these emissions originate from the 13 billion tons
of animal manure and slurries estimated to be produced annually around