Charlie Hall’s Balloon Graph

Energy researcher Charlie Hall’s balloon graph challenges the notion that alternative energy sources will provide a smooth transition to a post-fossil fuel society. Scale and energy return remain huge obstacles.

Charlie Hall is one the best-known energy researchers you’ve never heard of. That’s because he puts his effort into understanding whole energy systems such as human civilization rather than perfecting headline-grabbing energy panaceas such as corn ethanol. From the early 1980s onward Hall and his colleagues–some of them former students–have been warning that a society hooked on fossil fuels would find itself up against limits not easily breached–probably sooner rather than later.


With the current boom in biofuels, wind, and solar, and even a revival in nuclear power, many people believe that a smooth transition to a post-fossil fuel economy is already a foregone conclusion. But a careful look at Charlie Hall’s balloon graph tells a different and much more disconcerting story (1). (To view a larger version of the graph, click here or on the graph itself.)

First, let’s look at the components of the chart. On the vertical axis we have energy return on investment (EROI) expressed as the ratio of energy output versus energy input for each energy source. (Hall, an ecologist by training, appears to have coined the term by adapting “yield per effort” concepts from fisheries.) It is not always obvious to modern industrial people that it takes energy to get energy. The more energy we spend on finding, extracting, refining, and transporting energy resources, the less we have for all the other activities of society. The horizontal axis of the graph represents quads or more precisely, quadrillion BTUs (British Thermal Units). The graph depicts energy use in the United States. But the principles it demonstrates apply to the world as a whole.

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