Energy Return on Investment (EROI).
This is the text of a book review that I wrote, and which has just been published online in the journal Science Progress.
Energy Return on Investment: A Unifying Principle for Biology, Economics and Sustainability. CHARLES A. S. HALL, Springer 2017 ISBN 9783319478203; xii + 174 pp; £37.99
The preeminent mathematical physicist, James Clerk Maxwell, famously described energy as being “the ‘go’ of things”. Thus, “energy” is the fundamental, underpinning driver and enabler of all processes in the universe. Since it takes energy to produce energy, in order to survive, animals must derive more of it from the food they stalk and hunt down than they expend in getting it, while to provide food and to serve all the other functions of a complex human society, it is necessary to recover very much more energy, overall, than is consumed in acquiring that energy. Such energy requirements may be gauged from Energy Return on Investment (EROI), the definition of which is deceptively simple: i.e. it is the amount of energy delivered to society, divided by the energy consumed in delivering it (and therefore not available to society for other purposes). As this ratio falls, fewer units of energy are made available for each unit of energy that is consumed in the production process. In the limit, for an EROI of 1:1, there is no net profit, since the amount of energy consumed is equal to that produced, thus rendering the exercise self-limiting and pointless (and for an EROI < 1:1, an energy sink is identified). EROI is a useful metric for determining the viability of an energy source, and we see that unconventional oil sources (e.g. oil sands and oil shale) tend to be more difficult to produce from than their conventional counterparts, and deliver fewer units of energy to society for each unit of energy that is consumed in the production process, i.e. a smaller energy return on investment (EROI).
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