Nature of Energy Demand

Abstract

This being an evening lecture open to the public, is suited to rather general considerations and I will mainly explore the nature of energy demand. Figure 1 is an appropriate starting point and the first point to understand is the distinction between primary, secondary, final, and useful energy. Primary energy is a gift of nature and cannot in general be used as such: oil, coal or uranium first have to be converted in central power stations, refineries or other facilities in order to become a more flexible and useful form of energy. Only in one particular case namely natural gas there is no difference between primary energy and secondary energy. Secondary energy is the electricity at the output of a power plant or the gasoline at the output of a refinery. But then you have to transport the secondary energy to the places of consumption for instance the petrol station or an electric plug in a factory or residence; the energy delivered to the end-user is called final energy. When transforming primary energy into secondary energy there are inevitably losses which may be small as in a refinery or very large as in an electricity generating plant; these losses are rejected waste heat energy.

Version based on recorded transcript of the delivered lecture.