Saturday, January 09, 2010

hubbert on the nature of growth

EnergyBulletin | Testimony to Hearing on the National Energy Conservation Policy Act of 1974, hearings before the Subcommittee on the Environment of the committee on Interior and Insular Affairs House of Representatives. June 6, 1974.

It is my understanding that the present hearings pertain primarily to the bill H.R. 11343, ``A bill to provide for the establishment of a comprehensive energy conservation program in order to regulate the national rate of growth of energy use, to establish a Council on Energy Policy, and for other purposes.'' In Sec. 7(a) of this bill it is stipulated that one of the duties of such a Council shall be ``to develop and transmit to the President and to the Congress ... a comprehensive report setting forth the proposed legislation it deems necessary to achieve a maximum rate of growth in energy consumption of 2 per centum per year'' [Italics added].

Instead of discussing the merits or demerits of this proposed legislation, I think that it may be more helpful if I discuss some of the aspects of growth in general in an effort to see the bearing which these relationships may have upon our evolving social system.

The earth and its biological inhabitants comprise an evolving system in which various of its components change in magnitude with time. To describe these changes we may use the term ``growth'' in a generic sense as being synonymous with change. Thus a given quantity may be said to exhibit positive growth if its magnitude increases with time, negative growth if it decreases with time, and zero growth if it remains constant.

Two terms applicable to an evolving system are of fundamental importance. These are steady (or stationary) state and transient state. A system is said to be in a steady state when its various components either do not change with time, or else vary cyclically with the repetitive cycles not changing with time. A system in a transient state is one whose various components are undergoing noncyclical changes in magnitude, either of increase or decrease.

In distinguishing these two states the time scale needs also to be taken into account. Actually, an ideal steady state on the earth is impossible. For example, a pendulum clock driven by a weight or a spring is an almost perfect example of a cyclical steady state, with one exception: the weight falls or the spring unwinds. This latter characteristic is a transient phenomenon. Similarly on the earth many quantities vary cyclically on a diurnal or annual scale and yet change very slowly over periods of thousands of years. However, even these quantities which approximate a steady state over intermediate periods of time become transient phenomena on a longer time scale. On a time scale of the solar system even the sun's radiation is a transient phenomenon due to the fact that the sun is slowly exhausting the supply of hydrogen upon which its radiation of energy depends.