In my last post, I referred to the work of Charles Hall on Energy Return on Investment (EROI) and biophysical economics. Following an exchange of e-mails with Professor Hall, he directed me to some of his more recent work, including a January 2014 paper titled “EROI of Different Fuels and the Implications for Society” published in Energy Policy (free access). The paper looks at the critical EROI question: “How many units of energy do you extract for each unit of energy you invest?”.
The paper is a veritable chartfest of all things EROI, but I will wet your appetitive with just three. First up, is an EROI comparison between different fossil fuel and biomass energy sources (click for larger image).
The bad news here is that coal remains the king of EROI since you get around 40 times as much energy out for each unit of energy you put in. Hardly good for CO2 emissions trajectories and climate change.
Next up is the decline in global oil and gas EROIs (click for larger image):
The decline is unsurprising since we are trying to exploit ever more geologically marginal sources of oil and gas in ever more unconventional forms.
Finally, a chart showing fossil fuels up against renewables (click for larger image):
I was genuinely surprised at this one because both wind and photovoltaic (PV) came in higher than I expected. Hall flags all the major problems with wind and PV (need for base load and so on) and also points to disputes over PV EROI methodology. Nonetheless, I have heard arguments in the past that PV is almost break-even in EROI terms; this does not appear to be the case.
There is a lot more in the paper, including numerous interesting references. When I get time, I will come back to the EROI of renewables as it seems such an important topic.
Risk and Well-Being 
Great post once again. Thanks for the link to the Hall, et al paper. It was very informative. I found this paragraph from the paper to be supportive of my belief that we need to be ready to get substantially poorer.
“Any transition to solar energies would require massive investments of fossil fuels. Despite many claims to the contrary—from oil and gas advocates on the one hand and solar advocates on the other—we see no easy solution to these issues when EROI is considered. If any resolution to these problems is possible it is probable that it would have to come at least as much from an adjustment of society’s aspirations for increased material affluence and an increase in willingness to share as from technology. Unfortunately recent political events do not leave us with great optimism that such changes in societal values will be forthcoming.”
I doubt that “willingness to share” (redistribution) will come easily. I also doubt that the financial sector of the global market economy will be able to tolerate continuous “adjustment of society’s aspirations for increased material affluence” (recession).
It’s not that surprising..
One of the problems I’ve seen with the more committed Peak Oil people is a tendency to under-estimate EROEI; it’s a genuinely tricky number to pin down, with ample scope for double counting; and of course if you add up the entire economy (all of which is linked to energy in some way) you get an EROEI summing to 1. Unless you count environmental degredation, in which case you get a ‘global’ EROEI of < 1.
Andrew. I see where you are coming from. Well, I guess also from the First Law of Thermodynamics the ultimate EROEI < 1 by definition since we always have some lost heat somewhere. EROEI also doesn't take into account the form of the energy produced. Oil has some unique attributes in terms of energy density and transportability, and EROEI doesn't really tackle this issue.
But EROI is generally applied to the study of primary energy. Accordingly, I see EROEI as mostly a pointer to where cost and, ultimately, price is going, although you could set up theoretical cases where EROEI is falling and cost of production is also falling due to feedstock price and availability, technology and so on.