The measure of effectiveness with which energy is transformed or  used in processes requires consideration of properties other than energy alone. Entropy is the most important quantity in this  context. It permits to localize sources of ineffectiveness and calculate thermodynamic upper limits of efficiencies. Exergy is closely related to entropy and can be used for similar purposes; it also has the same dimension and order of magnitude as energy,  but is not a variable of state in a thermodynamic sense. In this memorandum, the formalism is introduced and discussed for a  (coal-fired) electric power plant, methanol production, and  negentropy technologies. It is proposed to favor entropy production or exergy consumption over the concept of wasted or "consumed" energy as a measure of the effectiveness of energy use or conversion.