The Changing Meaning of Energy Return on Investment and the Implications for the Prospects of Post-fossil Civilization

Abstract

Energy return on investment (EROI) is a useful physical metric to compare the utility of energy production processes and their development over time. The concept has been extended from its physical, process-based origin to one that describes the societal metabolism. As such, EROI has been used to speculate about the prospects of humanity in a late-fossil and post-fossil civilization. Often, the narrative to emerge around EROI is that in the (near) future, prosperity will be compromised. Here, we take a fresh look at EROI, with a distinction between a physical EROI, which is useful at energy project level, and a societal, or economic, EROI-appropriate at the level of the whole economy. This distinction leads us to conclude that a renewable future is possible. Such a future is essentially unconstrained by the physical EROI and will have an acceptable economic EROI-not much different from that of the past century.

Assessing Global Long-Term EROI of Gas: A Net-Energy Perspective on the Energy Transition

“…If several controversies remain [27], EROI has proved itself to be a powerful indicator when correctly applied. It also attracted a great deal of attention starting from the 2010s, as the energy transition from high-energy-yield fossil-fuels to low-energy-yield renewables might put pressure on the energy production system [9,28,29]. Another relevant area of study in the recent literature is the difference between energy return on investment and power return on investment.…”

Natural Capital-Based Societies in the Tropics

“…The boundaries used to calculate EROI depend on the researchers (Murphy and Hall 2010). The use of different boundaries leads to "apples to oranges" comparisons (White and Kramer 2019;Raugei 2019). However, it is certain that the EROI values of fossil energies decrease and that those of renewable energies are also low.…”

“…In the pursuit of economic growth, Murphy (2014) expects that an energy source with a higher EROI will appear. White and Kramer (2019) stated that the evaluation of energy will move from a physical evaluation (i.e., EROI) to an economic evaluation (e.g., the economic cost for deriving energy) because solar and wind power, for example, will never deplete the sun's energy. These authors expect the prices of solar and wind energy to be low, depending on technological development.…”

Economic Issues in Deep Low-Carbon Energy Systems

“…For this assertion to stand, nevertheless, the energy required to produce the required capital, e.g., solar PV modules, onshore wind turbines, and biomass boilers, would have to come from renewable sources as well: in other words, only in a fully RE system that argumentation would strictly stand. Despite that, and while the conclusion of [45] may carry considerable weight-although some authors might question it [46]-the previous model and argumentation, laid down in (A7)-(A11) and Figures 1-3, can be applied more generally to any exhaustible resource, and therefore, the essence of the model holds its validity.…”

“…The EROI concept was developed in the early 1980s to analyze several issues related to fossil energies, and some authors point out that it does not apply to renewable sources and a fortiori to renewable energies [45]. For this assertion to stand, nevertheless, the energy required to produce the required capital, e.g., solar PV modules, onshore wind turbines, and biomass boilers, would have to come from renewable sources as well: in other words, only in a fully RE system that argumentation would strictly stand.…”