1. Introduction      Recent discourses on environmental problems have usually started from discussions regarding "end of the pipe" technologies. Considerable research studies and substantial dialogue have been conducted on this topic. It has been suggested that if mankind continues to add environmental stress to the earth, our society will face the very dangerous prospect in the future.      In 1972, Meadows et. al., argued in The Limits to Growth(1) that human society would be disrupted if economic growth proceeds at its current pace. In 1987, the World Commission on Environment and Development focused on "Sustainable Development. (2)"      In 1992, the first international Earth Summit convened in Rio de Janeiro, and the United Nations General Assembly passed a resolution to establish a UN Commission on Sustainable Development.      In 1992, D. Meadows et. al., explained in Beyond the Limits(3) that the rate of exhaustion of natural resources and the production of wastes by mankind was exceeding the sustainable limit, and if the use of materials and energy continues unabated, the global economy would be disrupted in several decades. They urged steps to achieve a rapid increase in material and energy efficiency.      As illustrated above, it is increasingly recognized throughout the world that humankind must reduce the rate of resource exhaustion in order to establish the sustainable economy.
Copyright(C)2001,The Takeda Foundation.Allrightsreserved.