This subsection presents the results of a life-cycle analysis of energy inputs and outputs over the 20-year time frame used in this study. The basis is 1 ton of MSW at the curb.

Energy Required for Processing

The composting process is low-temperature oxidation, but it recovers no energy. On the average, composting consumes about 100,000 Btu per ton for simple yard waste or leaf composting, and about 300,000 Btu per ton for MSW preparation and composting.

Energy requirements for particular composting systems are approximately as follows:

Preprocessing of MSW requires 140,000 Btu per ton (see Appendix G, page G-37). These requirements are comparable to the energy requirements for mixed waste materials recovery facilities but lower than those for RDF preparation (see Appendix A).

Energy Required for Separate Collection of Yard Waste

No published data on actual energy expended for separate collection of yard waste were found. Data for one city in California obtained by SRI International (City of Palo Alto, 1991) show that 2.3 million Btu were required per ton of yard waste collected. Additional details are provided in the later subsection entitled "Integrated Strategy Example" and in Exhibit II.

Cost Considerations


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