Energy consumption relationships for mesophilic and thermophilic digestion of animal manures
The energy consumption for operation of methane fermentation plants for animal manures is critical to the economics of the system. Energy used in the operation of the plant is not available for use or sale elsewhere. An evaluation of the energy use of these plants when operated at 35 degrees C and 60 degrees C has been performed for all four major waste types (beef, swine, dairy and poultry) using systems analysis and a dynamic mathematical model and studying two options for effluent heat recovery (no heat recovery and 50% heat recovery). Typical thermophilic animal operations uses a significantly less percentage of the total energy than a comparable mesophilic plant when 50% of the effluent heat is recovered. When effluent heat is not recovered, thermophilic digestion for beef and swine waste uses approximately 3% more energy when compared to mesophilic digestion. Dairy and poultry thermophilic digestion, however, still uses less energy than mesophilic digestion. This is surprising, but the apparent reason for this result is the much smaller-compact size of the thermophilic plant and the heavier loading permitted at the elevated temperature. The net energy output (GJ/YR) of both plants (mesophilic and thermophilic) is approximately the same for each individual waste type. Therefore, based on net energy production alone (economics not considered), mesophilic and thermophilic digestion appear as equals.
- Research Organization:
- Auburn Univ., AL
- OSTI ID:
- 5283779
- Journal Information:
- Trans. ASAE; (United States), Journal Name: Trans. ASAE; (United States) Vol. 26:3; ISSN TAAEA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
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AGRICULTURAL WASTES
ALKANES
ANAEROBIC DIGESTION
ANIMALS
BIOCONVERSION
BIOMASS CONVERSION PLANTS
BIOREACTORS
BIRDS
CATTLE
COMPARATIVE EVALUATIONS
DESIGN
DIGESTION
DOMESTIC ANIMALS
ENERGY
ENERGY ANALYSIS
ENERGY CONSUMPTION
ENERGY RECOVERY
FOWL
HEAT RECOVERY
HYDROCARBONS
MAMMALS
MANAGEMENT
MANURES
MATHEMATICAL MODELS
MESOPHILIC CONDITIONS
METHANE
NET ENERGY
ORGANIC COMPOUNDS
ORGANIC WASTES
PROCESSING
PRODUCTION
RECOVERY
RUMINANTS
SWINE
SYSTEMS ANALYSIS
THERMOPHILIC CONDITIONS
VERTEBRATES
WASTE MANAGEMENT
WASTE PROCESSING
WASTES