Energy represents for every industrial site a fundamental process input which can only be substituted with great difficulty and without which industrial manufacture in general is impossible. The requirement is hereby concentrated on the utilization of distinct types of thermal energy for the process steam and heating, as well as for power and light. According to WOLF (1987) the total demand in 1981 for energy for industrial purposes in the Federal Republic of Germany was divided as follows — 75.9% for the manufacturing process, 10.9% for space heating and 13.2% for power and light. Although several energy resources were used equally for the production of heat, power and light were generated almost without exception by means of electricity. Heat as well as power and light, or rather electricity, are all commodities which have only a limited storage capacity. This leads to considerable procurement problems when the energy requirement fluctuates.