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One Scientist's Easily Understood Theory Offers a Radically Different Vision for How We Think About Energy

Charlie Hall champions a revolutionary idea known as "energy return on energy invested." Every plant, animal and human civilization lives by EROI, he explains.


Charlie Hall, the outspoken ecologist who charges that neoclassical economists largely write fairy tales, is having a good day in Puerto Rico. The sun is shining and girls in bikinis are walking down the beach.

But Hall, as usual, is thinking about how surplus energy makes the world go around and why the U.S. economy is faltering.

Now Hall, a 68-year-old New England born professor with a gift for plain speaking, has made a name for himself by championing a revolutionary idea known as energy return on energy invested (EROI). Every plant, animal and human civilization lives by EROI.

The law isn't rocket science. Whenever a salmon, bear, lodgepole or Dow Jones company spends more energy on an activity than they get back, death follows. Or in corporate terms, debt builds and things fall apart.

While studying migrating fish in the U.S. eastern seaboard and juvenile salmon in Nanaimo, B.C., 40 years ago, Hall derived and got obsessed with the idea.

At the time he discovered that 27 species of fish in North Carolina's New Hope Creek would spend a considerable amount of energy to migrate upstream. This great swim guaranteed their offspring a rich nursery where the young wouldn't have to spend so many calories trying to find food. In fact parents of all species behave much like these temperate fish.

The biologist then studied why tiny Pacific salmon smolts would bother migrating all the way to Alaska and the Aleutians instead of hanging around at the mouth of the Fraser River for a free meal. Energy gains once again figured in the answer. Higher densities of zooplankton that moved up the coast toward Alaska during the season just insured higher energy returns and faster growth. 


These novel fish studies convinced Hall that the world revolves around surplus energy: "Everything in life is about energy costs and energy gains." (In Hall's line of thinking, the best advice a parent can ever give a child is strictly fishy: invest your energy wisely.)

Puzzling picture of oil drilling

After his fish energy studies Hall, a student of the great ecologist Howard Odum, started thinking about energy gains in the oil patch in the early 1980s. He wondered if the industry experienced that same sort of declining returns over time that dogged the world's fisheries. As ships, nets and quantity of oil burned got larger, the protein returns per unit of energy invested shrank dramatically.

Cutler Cleveland, then a muscular undergraduate and now an energy brain in his own right, investigated and came up with a puzzling graph.

It was N shaped and showed energy gains for oil going up and down like a yo-yo. "The yield per foot of drilling would reach a minimum and then jump back up, then down even more sharply." Hall then asked Cleveland to add the number of feet drilled per year and then the graph showed a dramatic decline over time. "It was just like the fisheries."

The Wall Street Journal reported on the findings with a headline that declared "Increased Drilling for Oil May Consume More Energy Than It Gleans." Like most of the media it then forgot all about EROI.

"Politicians who say, 'Drill, baby, drill' have their head up their asses," adds Hall. "You don't get more oil by drilling more. You just get less efficient returns. You only get more oil by drilling thoughtfully."

But Hall's EROI work (and that of students and colleagues) unsettled the energy status quo. "We never got any money to do this," he reflects. "It all happened on weekends or pro bono. No government agency is interested in the information. Most science, to be honest, promises some form of candy. EROI doesn't do that and we don't do that."

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