Reply to Cobb’s article on net energy

I am not sure what audience Kurt Cobb was writing his article for, but I think most Energy Bulletin readers would have found little difficulty in accepting the critical importance of what Cobb calls “net energy” to the world’s energy future. However it should be noted that net energy is a notoriously difficult figure to pin down in many cases, and when it is pinned down, the interpretation of the information is not always so straightforward.

Strictly speaking “net energy” is the difference between the energy input into a system (for example, an energy producing project like a power station and all the associated resources and infrastructure) and the energy output by the system over its lifetime. However the only way to properly compare projects of different sizes is to use the ratio of Energy Returned (ER) to Energy Input (EI), or ERoEI, instead of net energy. An ERoEI for an energy project is 1.00 when the process is at the break-even point, that corresponds to the net energy being zero.

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