Should we use net energy to measure global energy reserves?

Net energy is a simple concept really. Once you understand that it takes energy to get energy, the basic math is clear. To calculate the net energy available from an energy resource, you add up the energy used to find, extract, process and deliver that resource and then subtract that amount from the amount of energy the resource contains. But global reserves for finite energy resources such as coal, oil, natural gas and uranium are estimated using measures such as tons, barrels, cubic feet and pounds. These measures tell us little about the ultimate usable energy content of each type of resource.

Nor is it of much use to compare the relative gross energy values of these resources, though such comparisons are readily available. To see some examples, check out this one showing the oil equivalence of nuclear fuel, this one for oil and natural gas, and this table containing a variety of equivalences including two comparing coal and oil. Even conversions into British Thermal Units, or BTUs, don’t really help us.

As the world moves ever closer to the time when vital, finite energy resources begin to decline, we need to know not how much oil, natural gas, coal or uranium is left; rather, we need to know how much usable energy is left in these resources. A recent illustration of the problem we face in understanding usable energy supplies came in the form of a 60 Minutes story on the Canadian oil sands. The program reported that “the reserves are so vast in the province of Alberta that they will help solve America