Abstract
While many factors contribute to the ability of any society, whether industrialized or developing, to achieve sustainable development, one of the most important is a supply of energy resources that is fully sustainable. Of course, for a society to attain or try to attain sustainable development, much effort must be devoted not only to discovering sustainable energy resources, but also to increasing the efficiency of processes utilizing these resources. One scenario of energy efficiency, the theoretical cogeneration of electricity and heat in Ontario, demonstrates that energy resources and their utilization are intimately related to sustainable development.