The efficiency of resource recovery from solid waste

Economics does not always adequately reflect the scarcity of physical resources. The contribution which resource recovery from waste makes to the conservation of energy and materials may be measured conveniently by its implications for primary energy use. Process energy analysis is applied to evaluate both the primary energy inputs to an option for waste disposal, treatment or resource recovery, and the savings implied by the use of recovered fuel and material products. The results are expressed as two self-consistent measures of net energy efficiency, differing in whether or not savings from materials recovery are included. The techniques are demonstrated by a case study of some thirty representative options, using the best information available. The results suggest that the use of pulverised waste directly as a fuel is particularly efficient, followed by production of various solid refuse-derived fuels. Options based on incineration or pyrolysis are currently uncompetitive from either a resource conservation or an economic point of view. The energy specific investment in producing a refuse derived fuel is shown to be comparable to that in oil from the North Sea.