It's important to know about the relationship of the ER/ EI of liquid fuel and the world economy.
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"The prosperity and stability of modern society is inextricably linked to the production and consumption of energy, especially oil (Odum, 1973, Hall et al., 1986, Hall and Klitgaard, 2012; Tverberg, 2012).
Economic production, exchange and growth requires work and consequently a steady and consistent flow of energy to do that work. Longer intervals of sustained economic growth in countries and the world have been punctuated by numerous oscillations; i.e. there are periods of economic expansion but also recession. In general, the growth of real GDP is highly correlated with rates of oil consumption (Murphy et al., 2011). Four out of the five recessions experienced since 1970 can be explained by examining oil price shocks."
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"Thus society seems to be caught in a dilemma unlike anything experienced in the last few centuries. During that time most problems (such as needs for more agricultural output, worker pay, transport, pensions, schools and social services) were solved by throwing more technology investments and energy at the problem. In many senses this approach worked, for many of these problems were resolved or at least ameliorated, although at each step populations grew so that more potential issues had to be served. In a general sense all of this was possible only because there was an abundance of cheap (i.e. high EROI) high quality energy, mostly oil, gas or electricity. We believe that the future is likely to be very different, for while there remains considerable energy in the ground it is unlikely to be exploitable cheaply, or eventually at all, because of its decreasing EROI. Alternatives such as photovoltaics and wind turbines are unlikely to be nearly as cheap energetically or economically as past oil and gas when backup costs are considered. In addition there are increasing costs everywhere pertaining to potential climate changes and other pollutants. 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."
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https://www.sciencedirect.com/scienc...13003856#bib37
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