EROI and the limits of conventional feasibility assessment—Part 3: Intermittency & seasonal variation

In the previous post in this sequence, I developed the concept of power return on investment as a complementary indicator to energy return on investment (EROI) for assessing the viability of wind and solar PV as alternatives to thermal electricity generation. I used as my departure point for this an article in which Ioannis Kessides and David Wade introduce a dynamic approach to EROI analysis.[1] Specifically, I drew on an illustrative example that they present, based on IEA data for coal-fired thermal and wind electricity generation in Japan, showing how the time required for coal and wind installations to provide sufficient energy to emplace additional generating capacity equal to their own can differ by an order of magnitude even where the EROI for coal and wind is identical. Given that the data on which this example was based was from prior to 2002, both the doubling time in Kessides & Wade’s example and the power return on investment in the extended analysis would likely be improved if up-to-date figures for emplacement energy and capacity factor were substituted for those from the IEA study. Unfortunately, this goes only a limited way to mitigating the central issue in terms of “real world” considerations. Continue reading

EROI and the limits of conventional feasibility assessment—Part 2: Stocks, flows and power return on investment

Update, 24 July 2015: while doing some background work for a forthcoming post that draws on data presented here, I reconsidered the best basis to use for the PV comparison. The post has now been revised to reflect my updated thinking, specifically using a higher EROI for PV of 4.17:1, rather than the original of 2.45:1, by considering only a subset of Prieto and Hall’s energy costs. In the course of making this change, I also discovered an error in the original calculation, in the ratio of emplacement energy to operating & maintenance energy for PV (relatively minor impact only, from 0.59 to 0.55). This is also corrected here.


 

An important principle to bear in mind for inquiring into the ways that energy-related considerations influence human societies is that, by and large, economies are dependent for their present functioning not on the total stocks of energy sources they might have at their disposal, but on the current rate at which energy sources are supplied and utilised. This is a key distinction in understanding the phenomenon of peak oil. “Peak oil” for a given field or territory is taken to have occurred at the point in time for which the production rate for petroleum—appropriately defined, i.e. by grade or composition—reaches a maximum, and thereafter declines. But at such a time, as much as half of the ultimate resource may still be available. Peak oil doesn’t imply that we’re on the brink of “running out of oil”. What it means is that the production rate is at the highest level that will ever be achieved. It is the change in rate that is central for understanding the implications of the phenomenon for future social prospects, as a declining aggregate oil production rate (i.e. where a shortfall from one region cannot be compensated by increased production from others) implies greatly foreshortened prospects for further growth in the non-energy related economic activity enabled by that production, and in fact very likely implies commensurate economic contraction. The same principle applies to any resource that is ultimately stock-limited, but for which it is the supply rate upon which the present nature of the economic activity enabled by that resource depends. Continue reading

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: rebound and backfire—Jevons’ legacy

As I stoke the boilers here at Beyond this Brief Anomaly after another (much) longer-than-anticipated intermission, it’s worth checking in on what this project has been all about to date. In a nutshell: I’ve attempted to make some modest in-roads into improving how we make sense of energy-related concepts, given the central role that I see for these in coordinating social action as we seek ways of living well together in the face of the increasingly urgent socio-ecological dilemmas confronting humanity. And in doing this, I’m drawing on principles from the field of inquiry known as systems thinking, or simply systems. If I were to try capturing what this means in essence, it would be along the lines of “considering the situations in which we’re interested as comprehensively as we’re able, by paying attention to their encompassing contexts.” The approach I’m taking extends this question of context to include considerations around cognition, language and meaning. Put simply, this implies treating the energy-related concepts that the inquiry deals with as sense-making “tools” and “artefacts” constructed by us. As such, they constitute important and influential parts of our shared culture. With them and through them, we bring our circumstances into being. What this implies is that the quality and coherence of our conceptual spaces “in here” affects the nature of our physical, social, economic, political etc. conditions “out there”. Attending to this “interior dimension” can have profound implications for the quality of the worlds that we bring about through the actions we engage in together. 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

Post Carbon Institute’s ‘This is Our Energy Reality’: visualising this Brief Anomaly

I’m a little slow on the uptake with this one. The promotional slide show ‘This is Our Energy Reality’ was released on publication of the Post Carbon Institute’s book Energy: Overdevelopment and the Delusion of Endless Growth in October last year. I’d seen the book (and the accompanying Energy Reader), but only just discovered the slide show when I went hunting for a reference for the next post in the energy efficiency series, that will take a closer look at energy return on investment.

It’s a powerful addition to the occasional visualisation series that I started last year—and certainly no less relevant now than eight months back:

 

From the website accompanying the books, energy-reality.org:

Energy is at the heart of the human predicament in the twenty-first century, and we now face a transformational moment in our energy story. As we leave the age of seemingly cheap and plentiful fossil fuels and enter an era of extreme energy, the ever-rising financial, social, and environmental costs of fossil fuels can no longer be ignored.

How we embrace this moment may well dictate the very future of our species — and millions of others.  

Please join Post Carbon Institute in a national campaign to increase energy literacy, with the ultimate goal of remaking the energy economy as if nature, people, and the future mattered.

Fostering increased energy literacy lies at the heart of Beyond this Brief Anomaly, and the course ‘Energy for the Future’ from which it evolved. Seems like a very worthwhile connection to make here.

The engineering view of systemic efficiency: available energy

So far in looking at the broad topic of efficiency, we’ve focused on what I described in the introductory post as the analytic perspective. In this post I’ll start to consider the systemic view of efficiency in more detail, by taking a closer look at the concept of available energy: the maximum work output achievable when a system is brought into equilibrium with its environment (or, as the corollary of this, the minimum work input required to bring about a given change in a system’s state). Continue reading