EDITORIAL
Electrical heating and thermal pollution Electrical resistance heaters indirectly cause a substantial amount of unnecessary thermal pollution
O
f the various kinds of pollution confronting the world, one of them, thermal pollution, is relatively little understood. It is easy to see litter or smog and to smell or be irritated by offensive materials. On the other hand, raising the temperature of a river or a lake by several degrees does not produce any immediate human discomfort; hence thermal pollution generally does not excite people as much as the other kinds do. Moreover, a group of volunteers can scarcely go out and extract heat from our lakes or streams as they might pick up empty cans and other debris from our roadsides. Nevertheless, thermal pollution in some specific geographic sectors is a serious problem, a problem that is recognized by ecologists, many of whom have expressed concern about the long-range effects. But it is not my purpose in writing this editorial to emphasize the gravity of the problem, for I am quite prepared to accept the conclusions of experts in this regard. However, I do want to comment on what I believe to be unnecessary thermal pollution and what steps might be taken to diminish it. By "unnecessary" I refer to that which can be avoided, at least in part, by alternative means for achieving otherwise desirable ends. For reasons indicated below, it is clear that a substantial amount of unnecessary thermal pollution indirectly accompanies the use of electrical resistance heaters. Examples of offending devices include hot water heaters, stoves and ovens, clothes dryers, and house heaters, excepting, in principle, those using efficient heat pumps. I do not have precise estimates of the extent to which this is going on, but it is certainly substantial. From basic thermodynamic considerations, it follows that electrical resistance heating not only contributes unnecessarily to thermal pollution, but also wastes fuel. Since elimination of unnecessary thermal pollution would also help conserve fuel, there is a double reason for initiating appropriate corrective measures.
The specific arguments supporting these assertions follow. Suppose a certain amount of combustible gas would serve to heat some water; then in accordance with the second law of thermodynamics, a much greater quantity of gas or equivalent fuel would have to be burned to produce the electrical energy required to heat that water by the same amount. This follows because no cyclical heat engine, however perfect, can convert more than a fraction of the heat supplied into electrical energy. The most efficient fossilfueled steam plants convert about 40% of the heat of combustion of the fuel into electricity and the nationwide average is less than 3 3 % . The substantial amount of heat ( about two thirds of the total) not converted into electricity at the power plant must be discharged into the surroundings, such as a lake or river. This is the principal source of thermal pollution, which in many instances has serious consequences depending upon where and how the heat is discharged. Even if the heat effect at the power plant were of no consequence, the overall process still wastes fuel. Accordingly, it is definitely more efficient to burn gas in a hot water heater than to burn gas to generate steam to make electricity for the heater. I use gas as an example, but the argument is valid irrespective of the kind of fuel employed as long as one deals with thermal equivalents. (Through gasification of coal, one can use gas in a home, for example, without depending on natural gas alone.) People generally think of electric heat as clean and hence desirable from the standpoint of keeping our environment unspoiled. This is true where the electricity is used but it is not necessarily true at the power plant. Although there is some compensation in the efficiency attending the operation of a large-scale power plant, the conclusion is still inescapable that, from the standpoints of thermal pollution and fuel conContinued on page 62
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