Future integrated waste, energy and pollution management (WEP) systems exploit pyrotechnology

Energy production, waste disposal, and the minimization of pollution are ke y problems that must be addressed for sustainable cities of the future. For the foreseeable future, fossil fuels will be the major source of energy, b ut due to the dwindling resources of oil and gas and the need for fuel secu rity, coal is likely to become the major source of energy for heat and powe r. The need for clean coal technology precludes, the construction of new co nventional pulverized fuel power stations and new technology is required. C oincidentally, the total heat content of municipal waste in Britain now tot als about 30% of that of the coal used for present needs. The current best technology for the low pollution disposal of this waste is incineration wit h the production of electricity, and heat for district heating. Unfortunate ly, current electrical generation efficiencies for coal burning plant and w aste incinerators are only about 37% and 20% respectively. In this paper various pyrotechnology systems are discussed which integrate the use of fossil fuels with waste processing in order to provide superior electrical power production efficiencies. The optimized integration of steam from an incinerator with the steam part of a conventional gas-fired combined cycle can provide a greater overall ef ficiency than that achieved if the fuels are used independently. Furthermore, a high temperature heat exchanger can be used in a recuperativ e gas turbine to achieve generation efficiencies of 60% without the use of a steam cycle. One integrated pyrotechnology system is proposed in which the steam from a conventional 'mass burn' waste incinerator is gasified with coal to yield a mixture of (environmentally clean) carbon monoxide and hydrogen which in t urn is used in a combined gas turbine/steam cycle. Perhaps more significant than the efficiency improvement is the dramatic effect on pollution contro l. The massive investment in flue-gas clean-up in a conventional pulverized fuel power plant is no longer required. Sulphur, in particular, is removed in saleable, elemental form in place of landfill of the vast amounts of ca lcium sulphate presently produced. In the longer term, 'excess enthalpy' re action principles may yield benefits for electrical energy production from the combustion or direct gasification of certain wastes. In addition to flue-gas clean-up, the need to clean or eliminate all discha rges from the overall Waste, Energy and Pollution Control (WEP) plant requi res the elimination of liquid effluents and conversion of ashes to usable p roducts by thermal treatment. High waste transport costs and low pollution leads to the conclusion that plants based on these technologies can be acce ptably located within cities. This not only reduces the electrical distribu tion losses but also permits the 'waste' heat to be used in the plant local ity resulting in overall CHP efficiencies greater than 80%.