Is EROEI the Same Thing as the Process Efficiency?
No, and this is a big source of confusion. The process efficiency refers to the percentage of net energy yielded in the process. In the above example, 1 BTU was expended to produce 5 BTUs. The net energy is then 4 BTUs, and the efficiency of the process is (4/5), which is 0.8 or 80%. An EROEI can be greater than or less than 1. A process efficiency is always going to be less than 1 (i.e., you are always going to use up some of the energy value in the process).
