Resources, Scarcity, Growth and the Environment

The term`resources' is used in many ways in different disciplines. For purposes of this paper, a resource is an essential input to the economic process. Resources may be material or immaterial (e.g. information) and material resources may be of natural origin or man-made. Services provided by nature (e.g. `assimilative capacity') are also sometimes called resources. However, in this paper, the term natural resources is restricted hereafter to energy – actually exergy– carriers and raw materials extracted from the natural environment by intentional human activity. The word energy is widely misused, and for the sake of precision I will introduce a different term, exergy that is less familiar but more precise. Energy is a conserved quantity (the first law of thermodynamics) , which means that it can only change form or quality (e.g. temperature) but can never be created or destroyed.. Energy and mass are equivalent (E = mc2) and inter-convertible in principle. (Nuclear reactions convert infinitesimal amounts of mass into energy, for instance.) But when a non-nuclear fuel burns, both the mass and the energy-content of the fuel (and air) are exactly the same as the mass and energy-content of the waste products. What has changed is the availability of the energy in the fuel for doing work. This availability is quantifiable. A number of terms have been used for it, includingàvailable work', `availability', andèssergy', but by general agreement (in Europe at least) it is now denotedèxergy.' The formal definition of exergy is the maximum amount of work that can be extracted from a material by reversible processes as it approaches thermodynamic equilibrium with its surroundings. Exergy is therefore a quantity that is not definable