Energy and economic assessment of anaerobic digesters and biofuels for rural waste management
A technological and socioeconomic assessment of anaerobic digester feasibility for small to mid-size livestock operations was undertaken. Three full scale digesters and one pilot scale facility were under various degrees of monitoring and evaluation to assess design and operational problems as they affect the adoption and establishment of farm scale anaerobic digesters. Materials handling presented the greatest obstacle to satisfactory operation of the full scale systems. Conversion of the biogas to electricity via standard engine-generator sets is capital and maintenance intensive. Electrical conversion requires engine-generator sets which have conversion efficiencies of only 10 to 25%. The system becomes more economical if the biogas can be used on site for direct thermal loads, suggesting that the economic feasibility of anaerobic digesters is site specific and should be closely integrated with the total farming operation. Biogas production per pound of volatile solids added is nearly the same as for straight manure. Addition of the organic portion of MSW to small farm digesters could make marginal systems economically attractive. Preliminary refeed studies indicated that the digested manure may not have the same nutritional value as raw manure, and that the cost of dehydrating the effluent for refeed to the same animals could be cost prohibitive for the small to mid-size farming operation. The feasibility of growing hydrogen producing algae on the effluent to enhance biogas production was rejected for the northern United States due to temperature extremes and to the difficulty in culturing selected species. The need for adequate service and maintenance organizations, specific standards and codes applicable to design and construction of these units, and the need for support from insurance and financing institutions cannot be stressed enough if digesters are to be established on a wide scale.
- OSTI ID:
- 6920657
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
090122* -- Hydrocarbon Fuels-- Preparation from Wastes or Biomass-- (1976-1989)
32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION
320305 -- Energy Conservation
Consumption
& Utilization-- Industrial & Agricultural Processes-- Industrial Waste Management
320604 -- Energy Conservation
Consumption
& Utilization-- Municipalities & Community Systems-- Municipal Waste Management-- (1980-)
AGRICULTURAL WASTES
ALGAE
ALKANES
ANAEROBIC DIGESTION
ANIMAL FEEDS
BIOCONVERSION
BIOGAS PROCESS
BIOSYNTHESIS
DESIGN
DIGESTION
ECONOMIC ANALYSIS
ECONOMICS
FARMS
FINANCING
FOOD
FUNCTIONAL MODELS
HYDROCARBONS
HYDROGEN PRODUCTION
INSURANCE
MANAGEMENT
MANURES
MATERIALS HANDLING
METHANE
MONITORING
MUNICIPAL WASTES
OPERATION
ORGANIC COMPOUNDS
ORGANIC WASTES
PILOT PLANTS
PLANTS
POWER GENERATION
PROCESSING
SYNTHESIS
TECHNOLOGY ASSESSMENT
WASTE HEAT UTILIZATION
WASTE MANAGEMENT
WASTE PROCESSING
WASTE PRODUCT UTILIZATION
WASTES