THE SECOND LAW

But there is still the second law of thermodynamics to save the day and ensure orderly catastrophe and holocaust. While energy cannot be destroyed, it can be degraded to waste heat; so all is well again and the end is nigh.

The trouble is most ecoscholars have never heard the Second Law, let alone understood it. What it says in its simplest form is that it is impossible to do work by cooling a body below the temperature of the coolest point of itself or its surroundings. It then follows by deductive reasoning (found in any textbook on thermodynamics) that among the various forms of energy, heat has a special place: While it is possible to change all of a given form of energy into heat it is not possible to change all of a given amount of heat back to other forms of energy; in any type of energy conversion, some small part of the energy is irreversibly changed to heat.

But that does not mean that the energy that is, in practice. wasted as heat must be wasted as heat. For example, the heat appearing in an automobile exhaust is dissipated into the atmosphere and wasted. But there is nothing in the Second Law that says this is the way it must be. There are methods to make use of that heat instead of wasting it; they are called bottoming cycles, since (unlike topping cycles) they work at the bottom end of the temperature range. As fuel gets more expensive and the drive for efficiency strengthens, such methods may well become commonplace. There are many reasons why they are not used at present but none of them has anything to do with the Second Law.

But if every energy conversion results in some irreversible heat at the expense of other forms of energy. the whole universe must eventually die a thermal death, right?

Only if "eventually" means in an infinitely distant time. As for our sun, it has enough (nuclear) energy to keep its life-giving radiation going for between 500 million and 1 billion years.