Waste is unavoidable

Image from http://www.nucleartourist.com/systems/ct.htm
Courtesy KKN Liebstadt NPP

If you read my previous post on perfect engines, then you might have thought a heat engine that did not discharge any heat would be more efficient.  However, this would contravene the second law of thermodynamics, which requires that every real process must generate an increase in disorder, in this case by the discharge of waste heat.  Thermodynamicists like to call this increase in disorder, an increase in ‘entropy’.

A consequence of the second law of thermodynamics is that the entropy, or disorder, of the universe is always increasing; but now I have strayed from engineering to physics.  Together with Bob Handscombe, I wrote a book on this topic called the ‘Entropy Vector: Connecting science and business’.  It was not a best-seller but it got some good reviews, see http://www.worldscientific.com/worldscibooks/10.1142/5365#t=reviews.



  1. If society is stuck with non-ideal engines and irreversible cycles then there is a continual creation of entropy – ie we waste our precious energy reserves. You seem to be suggesting that engineers are valuable as they do all they can to design efficiently and minimise entropy generation – ie conserve our precious energy reserves. Yet efficient use of science and technology leads to economic growth, development and the generation of more entropy and faster depletion of those reserves…
    Seems to me that engineers think they are part of the solution when actually they are the cause of the problem.
    Fred Luddite
    The Cave
    Olde Englande

    1. Of course, there is a large element of truth in Fred’s comment. There is a nice quote from Kurt Vonnegut in ‘Man without a Country’ along the lines that we ‘have now all but destroyed this once salubrious planet as a life-support system in fewer than two hundred years, mainly by making thermodynamic whoopee with fossil fuels’, for which both engineers and society should take responsibility. Many engineers would argue that they simply provide what society wants, because most of them are in employed in organisations driven a by a bottom-line that is profit. I would argue that as engineers we have a responsibility to take the lead in moving towards a more responsible approach which involves both innovative design and educating society. We can do better. Perhaps sustainability is not achievable as defined in the Merriam-Webster dictionary, i.e. ‘of, relating to, or being a method of harvesting or using a resource so that the resource is not depleted or permanently damaged’ (http://www.merriam-webster.com/dictionary/sustainable) but perhaps we can manage the definition developed in the Brundt report: ‘meeting the needs of the present without compromising the ability of future generations to meet their own needs’ (see http://www.iisd.org/sd/).

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