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Energy return on investment and economic stimulus spending

There is much discussion today in the US regarding how much the government should spend, and go further into debt, to help get the economy growing and increase employment such that we can later pay back this debt when economic growth is good (i.e. positive) again. For those who do not believe in the general capitalism arrangement that assumes economic growth (as we define it today) can and must continue indefinitely, the logic of spending more so we can pay it back later can seem like putting off the inevitable final economic bust.

Persons such as Robert Reich, former Labor Secretary under the President Bill Clinton, are calling for more stimulus spending (see, and for an entry on his normal calling for more stimulus spending, visit Reich correctly says that the latest increase in US GDP growth, of a reported 3.6% in the 3rd quarter of this year, is mostly related to a shift in capital assets at the expense of labor. This is supported by research by Robert Ayres and Benjamin Warr indicating that investments in providing “useful work” and capital are responsible for roughly 50% of US economic growth whereas additional labor investments are only responsible for some amount of less than a few percent. Useful work is roughly equivalent to primary energy consumption divided by efficiency of conversion into mechanical motion – but think of essentially as how energy impacts our economy. In 1900 their research shows that investments in labor were the most influential factor (55%) in US economic growth with useful work responsible for nearly 40%.

What all of this means is that over the last 100 years our industrialized economy has replaced physical labor (working in factories and farms) with machinery run on fossil fuels. Therefore as long as cheap energy is available to operate this machinery and make more of it, human labor is simply not necessary. We pay people to think of ways to not need as may people to make a product, and then we act surprised when we succeed. We now pay people to think, not use their muscles, and we translate this to a need for better education. We also translate this to other areas of life, such as health care, where investments in capital (knowledge and machinery) have enabled incredible tools and techniques to cure disease and injuries.

What all of these advancements depend upon is excess energy such that people CAN be paid to spend time and think of new inventions. This excess energy is a function of the resource (renewable or fossil) and our ability to exploit it. This ability can be measured as energy return on investment (EROI). If US oil had an approximate EROI of 100 in the first decade of the century and today has an EROI of 10–20, then each barrel of oil in 1900 had approximately six times more capability of growing the economy than today. This estimate is calculated as follows:

˜ ((EROI-1)“useful work” productivity factor in 1900) / ((EROI-1)“useful work” productivity factor in 2000)

˜ ((100-1)40%) / ((15-1)50%)

˜ 40/7 = 5.6

So when we look to the past and assume we can invest in various economic stimulus packages with the thought that we have always had the ability to repay the debt in the future, I believe understanding this tie energy (EROI, useful work) and economic growth is important. So we can say:

1. The US has a large national debt load (the highest ever) and now the annual budget deficit is reaching the highest levels ever reached. Thus, we seem not to be paying back the debt over time, except interestingly the US did that during the time Robert Reich was serving in the 1990s under the Clinton administration; and

2. The total system-wide conversion of energy resources into useful work is becoming less productive over time yet more influential on the economy.

The conclusion is that we are increasing our debt load at the same time we are having less ability to pay it back. This basic conundrum will define this current century.

About Carey King

Dr. Carey W King performs interdisciplinary research related to how energy systems interact within the economy and environment as well as how our policy and social systems can make decisions and tradeoffs among these often competing factors. The past performance of our energy systems is no guarantee of future returns, yet we must understand the development of past energy systems. Carey’s research goals center on rigorous interpretations of the past to determine the most probable future energy pathways. Carey is a Research Scientist and Assistant Director at the Energy Institute at The University of Texas at Austin, and appointed also at the the Center for International Energy and Environmental Policy within the Jackson School of Geosciences and Business, Government, and Society Department of the McCombs School of Business. Visit his website at: and follow on Twitter @CareyWKing
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