EROI and the limits of conventional feasibility assessment—Part 1: The technical potential for renewables

A fundamental requirement that any energy supply system must satisfy for economic viability is a sufficiently high energy return on energy investment (EROI) for manufacturing, installing, operating and maintaining the system over its operating life. The question of what constitutes a sufficient return depends on the nature of the economy and society that the energy supply system is intended to support—while an EROI <1 implies a net energy sink, an EROI >1 does not automatically entail viability. Consider the limiting case in which net energy supply is zero, i.e. EROI =1. This would entail an economy consisting entirely of an energy supply sector that supported itself, but allowed for no economic activity beyond this. It’s certainly possible to imagine a functional economy along such lines, but it implies that every person living in such a society must dedicate their life to and focus all of their attention and effort on providing for the subsistence energy needs of their economic system. Such an economic system would serve no purpose beyond its own perpetuation; citizens of such a society might very well consider their lives to constitute a form of slavery to their economy. Continue reading

The economic view of systemic efficiency: energy return on energy investment

The last post looked at what I’ve called the engineering view of systemic efficiency, specifically the concept of available energy, or exergy. I refer to this as systemic because it considers energy conversion processes in relation to their specific operating contexts, in order to understand the useful work that a system can provide. While energy conversion processes serve an infinite array of human purposes, in the proximate or most immediate sense, we carry out energy conversions in order to do work—to effect transformations in our material worlds—and to provide heating (and while technically it’s not necessary to further differentiate it here, to provide illumination also). The systemic view provided by exergy analysis deals directly with the question of how much utility we can derive from an energy conversion process, and so it allows us to think about energy resources and infrastructure in a more concrete way than when we conduct analysis in terms of the nominal heating value of primary sources or fuels, in isolation from the particular situations in which they are used. Differences in energy use situations—different conversion technologies, implemented in different ways, operating in different physical environments—lead to differences in the utility that can be derived from an energy source. In establishing the efficiency of an energy conversion process—the useful energy output from the process divided by the nominal energy input—a focus on conversion systems and their parts (including the particular energy sources involved) only gets us so far. For a comprehensive view of efficiency we need to consider energy conversion processes in terms of all three levels of the basic systems hierarchy of system, sub-systems and supra-system. Exergy analysis provides the means for achieving this.

My reason for identifying this approach to thinking about efficiency as the engineering view relates in part to the scale at which exergy analysis’s systemic approach is most fruitfully applied—namely the plant or equipment scale. In other words, this is most immediately useful at the micro-economic or enterprise level, where we deal with technology components that make up economic units. In macro-economic terms, exergy analysis does have particular value for understanding performance of an economy’s energy sector, and also provides especially valuable insights in relation to transport and manufacturing activities.  Coming to terms, though, with industrial societies—or, as we’ll see, any forms of social organisation for that matter—in physical- or energy-economic terms requires that we look beyond the enterprise and even sectorial levels. That is, we need a basis for thinking holistically about societies and their economic forms that relates energy supply and use at the overall macro-scale. It’s for this purpose that the concept of energy return on investment (EROI) (or energy return on energy investment—EROEI), has started, only relatively recently, to be better appreciated as so important. EROI tells us about the energy available for economic activity other than the supply of energy itself, and it is in this sense that I referred to it in the introductory post on efficiency as, roughly speaking, the economic equivalent of thermodynamic availability. Continue reading

Introducing efficiency: the energy costs of energy supply and use

In an earlier series of posts (Fueling an industrial world and Energy and the biophysical view of economic activity: from joules to fuels) I pointed out how aggregating energy sources on the basis of their nominal heating values—as is common practice for our most prominent and influential energy information agencies at national and international scale—tends to obscure the dependencies between concrete economic infrastructure and the specific forms that energy sources take in practice. The aggregation process involves taking a highly abstract view of energy sources—a view that highlights only one narrow parameter, at the expense of most of what is important for appreciating how our physical economy functions. One of the most critical areas of omission relates to the energy costs of energy supply and use. Continue reading

Worldviews and energy futures

In last week’s post I linked to an article published recently in the Journal of Futures Studies (JFS) in which I look at the relationship between the questions that we ask about energy futures, what it is that we then take into account as relevant in exploring them, and the possible avenues for action that are apparent to us in the present as a result. As I pointed out, that article acts as a pretty good overview of the inquiry here at Beyond this Brief Anomaly, and also prepares the way for the phase into which this will head shortly. Before embarking on this next phase, it occurred to me that it might be worth dusting off some earlier work on which the JFS article was based that goes a little further in sketching out the background context for the inquiry, and that will help with locating the areas covered to date within that broader context. Continue reading