The paper gives a review of a project initiated by the Berlin-Brandenburg Academy of Sciences (formerly the Prussian Academy of Sciences) entitled â€œWaste energy utilisation â€” A contribution to an entropy economyâ€. It covered not only the technical aspects of a better waste energy utilisation but studied also the social, economical, political and legal implications, as well as existing impediments. As the term entropy economy indicates a purely quantitative assessment of energy and its losses on the basis of energy balances is not very helpful. Instead, entropy balances permit a qualification of energy and the development of strategies for better waste energy utilisation. The paper is meant as a general introduction into the following papers, where technical aspects of a better waste energy utilisation are discussed.