Monday, 22 March 2010

Anaerobic Digestion to Energy: Electricity, Heating and Cooling

Material Suitable for Anaerobic Digestion
  • Dairy Farm and piggery etc waste slurries
  • Dairy Product and other Food Processing wastes
  • Arable Farming Wastes
  • Household Food Waste with or without Green Waste
  • Brewing Industry effluents and wastes
  • Supermarket Waste*
  • Municipal Solid Waste from Kerbside collections of Green Waste
  • Municipal Solid Waste from Kerbside collections of Green Waste and Kitchen Waste*
  • Catering Industry Wastes*
  • Organic Market Wastes*
  • Sewage Treatment Works sludges
  • Silage/ley crops (may be included and kept in storage to provide a feedstock for use to augment feed during winter seasons when the availability of other feed materials will be reduced)
  • Other organic wastes available locally from other process industries.
* - When considering acceptance of some wastes, early thought should be given to the effects on the plant of Animal By-Products Regulations compliance, and necessary provision for handling and processing ABPR waste. ABPR applies to the EU states, but equivalent regulations should also be in force elsewhere to avoid cross contamination health risks (eg Foot and Mouth disease).

Biogas Yield and Energy of Common Agricultural Feedstocks (Livestock Farms) and Food Waste

The following is DEFRA and Anderson Centre data and is approximate only.
Feedstock
Number of animals to produce 1 tonne/day
Dry Matter Content
Biogas
 Yield
(M3/t)
Energy
Value
(MJ/m3) Biogas
Cattle Slurry
20-40
12
25
23-25
Pig Slurry
250-300
9
26
21-25
Laying Hen Litter
8,000-9,000
30
90-150
23-27
Broiler Manure
10,000-15,000
60
50-100
21-23
Food Waste n/a 15 46 21-25
Wheat Chaff n/a 89 200 21-25
Palm Kernell Pellets n/a 88 450 21-25
Brewers Waste
n/a
0
120
21-25

It has to be noted that AD technology has been well used in Northern Europe, in Germany for instance, also in the far East and China where over 6 million small scale AD systems supply electricity to local communities.

In hotter climates no additional heating is required to initiate the AD process and thus outputs can be greater in energy terms.

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