My two previous blog posts have treated two abstracts (proposed articles) to a special issue on "Energy and the Future" in the journal Energy Research & Social Science and this blog post treats the third and last abstract I submitted, this time together with my colleague Ambjörn Naeve.
This abstract is again directed towards the special issue theme "Ways of thinking about the future of energy" and I think it's a pretty certain bet that not all three of these proposed articles will be invited to the special issue... I would be happy if one is accepted and I would be delighted but overworked if two are accepted (luckily I'm the second rather than the first author of all three proposals)... For a little more information about the special issue (and the five themes), see the previous blog post.
The background to this blog post is to some extend many long free-ranging discussions between me and Ambjörn about energy and other topics over the years, but this is our first attempt at actually writing something together. We have recently started to discussed the twin ideas of "Homo Colossus" and of "Energy Slaves" and the original plan was to write a paper that was to be based on us examining and digging deep down into those metaphor (including comparisons, calculations and graphs), but with Ambjörn as the first author, the proposed paper took a slightly different turn. Here's the result of that process:
Harnessing the work ability of energy slaves
This paper aims to disentangle the confusion between the energy of a system and its capacity/ability to perform work. It makes consistent use of the terminology of thermodynamics, which separates between the concepts energy and exergy. ’Energy’ denotes an invariant quantity of a closed system, which, when the individual parts of the system interact with each other, redistributes itself among different forms with decreased total work ability. ’Exergy’ denotes the latent ability of a system to perform work on its surroundings. The degradation of the work ability of energy, i.e., the degradation of its exergy, is a fundamentally important law of nature. In fact, it is the only law (on the macroscopic level) which is sensitive to the direction of time.
We illustrate our argument by way of Buckminster Fuller’s concept of energy slaves. From a thermodynamical perspective they ought to be called exergy slaves since they (by definition) deliver work at the same rate as (average) human beings. An ”energy slave” is defined, e.g., by Wikipedia as "that quantity of energy (ability to do work) which, when used to construct and drive non-human infrastructure replaces a unit of human labor (actual work)."
This unfortunate identification between ‘energy’ and ‘work’ restricts the concept of energy to cover only its prime quality forms (such as mechanical energy or electrical energy), which are completely convertible into work, and it excludes all other (non-prime-quality) forms of energy, such as e.g., chemical energy and heat energy, which are only partially convertible into work.
We argue that basing the future energy discourse on thermodynamics can help dispel present confusion and increase the conceptual quality of the discourse. Specifically, this perspective can help to better locate effective leverage points when it comes to harnessing the latent work ability of a given energy flow. For example, when we heat our living rooms with electricity, we turn each kilowatt hour of electrical input energy into a kilowatt hour of ”room-temperature-heat” output energy, and the latter has less than 7% of the work ability of the former. Hence, we have thrown away more than 93% of the work ability of the energy - work ability that is costly to provide and that can never be regained.
From the thermodynamical perspective, each untapped temperature difference in a process is an untapped source of work. The present confusion prevents the discovery of untapped work resources, especially those that are based on heat energy. In fact, being able to thermodynamically estimate the exergy of heat energy is crucial in order to discover the heat-based work that is wasted in such untapped temperature differences. This is especially true for industrial processes, and by redesigning their energy flows, many of them could operate from the same flow, thereby reducing their untapped work ability. Under the name of energy conservation such activities do take place today, but we argue they must be greatly increased in order to meet the strategic demands of better managing scarce energy resources in the future.