Resources and Conservation最新文献

The First International Workshop on Biogasification and Biorefining of Texas Lignite was held June 10–11, 1986 at the Woodlands, Houston, Texas. The meeting was sponsored by Houston Lighting and Power Company and involved the participation of selected research workers in an overall project dealing with biotechnology applied to fossil fuels. This innovative concept of university participation has the objective of increasing the potential for utilization of Texas lignite through modern biotechnology. Reports on sponsored research at this meeting were primary focused on methane production. Also included were presentations on the broader potential for a biotechnology-based system for profitable utilization of Texas lignite, i.e., extension to a biorefinery.

An international project on energy recovery from biomass is described for organic wastes, such as agriculture residues and crops grown for energy recovery. The bioconversion to fuel gas of all these is based on “controlled landfilling”, a low-capital-cost batch digestion method associated with the managed recovery of methane from sanitary landfills. An engineering analysis predicts the digester size for small-scale biogas production. The digestibility of seven municipal and agricultural wastes in laboratory batch systems was experimentally determined by eight investigators on five continents. The reported bioconversion ranged from 0.1 to 0.4 m³ biogass per kg substrate. The relative consistency of the results offers encouragement to evaluate the fuel-gas generation potential in developing countries. An appendix presents a mathematical model of a landfill bioreactor.

The processes of liquid-liquid absorption can contribute to the solution of problems in conservation and storage of energy. The sulphuric acid-water process has been proposed as one of the best processes to be used in a chemical heat pump and heat transformer system. In the present paper the principal applications of the process are described, several schemes are suggested and discussed, pointing out the technical and economical problems for each application. Experimental results, together with the state of the art of research in this field, are reported.

A second, 3-month demonstration of RIM-NUT, an advanced physico-chemical process based on selective ion exchange and chemical precipitation, confirmed the possibility to prevent eutrophication by removing ammonium and phosphate ions from municipal secondary effluents and to recover quantitatively magnesium ammonium phosphate, a slow-release premium quality fertilizer, in a simple and technically affordable manner. Economic projections for a 5.3 MGD (20,000 m³/d) plant indicate that RIM-NUT is cost effective. The overall costs are almost completely covered by the value of the fertilizer recovered and the non-eutrophic potential of the wastewaters discharged. Based on these results, a U.S. RIM-NUT demonstration will be performed in 1986 by the U.S. Environmental Protection Agency and the Italian National Research Council in the City of South Lyon, Michigan.

The gradual and then rapid reduction of crude oil prices, the impact of U.S. Gramm-Rudman-Hollings legislation (to reduce budget deficits) on R&D (research and development) budgets, the partial elimination of renewable-energy tax credits, and the possible elimination of all energy tax credits and forgiveness via tax reform, are all taking their toll on energy research and commercialization ventures. However, it appears that “biofuels” will survive and continue to exhibit modest increases in contributions to primary energy demand. A comprehensive assessment of renewable-technology options has shown that biofuels is the only option capable of making significant contributions to all energy sectors. The total contribution of renewable energy to primary energy demand in the U.S.A. is about 7.2EJ/y (6.8 quad/y); biofuels provide about 40% of the total. Research on short-rotation intensive-culture (SRIC) trees and herbaceous and aquatic biomass has identified specific species for development. Some of these species appear to be near economic feasibility as energy crops now. Commercialization of biomass and waste combustion systems has shown a spurt in growth because of the business opportunities offered by laws encouraging cogeneration. Thermochemical gasification research on advanced technology systems has reached the point where scale-up is being considered. Commercialization of state-ofthe-art technologies has slowed, but applications for small-scale producer gasifiers, particularly in developing countries, continue to expand. Thermochemical liquefaction research has concentrated mainly on high-temperature pyrolytic conversion methods that can increase yields and selectivities. Significant research achievements have been made in anaerobic digestion, but whatever its future as a large-scale source of methane, it is clear that digestion capacity will have to increase many-fold before biological methane can attain its potential. The mandated reduction in lead content of gasolines presents substantial marketing opportunities to alcohol-fuel producers. If projections for ethanol-fuel markets materialize, conversion of low-cost lignocellulosic materials will be necessary. Research to develop this technology is now in progress.