The energy efficiency ratio of Ethanol is 1.06 without byproduct credits and 1.67 with byproduct credits. (Ethanol.org). In other words, ethanol generates 6% more energy than is required for production. If you were to allocate 34% of the required energy to the production of the byproduct, then it produces 67% more energy than it consumes.It took a while to comprehend this statement, because it is physically impossible. The energy efficiency ratio is defined as a value between 0 and 1.
In physics and engineering, including mechanical and electrical engineering, energy efficiency is a dimensionless number, with a value between 0 and 1 or, when multiplied by 100, is given as a percentage. The energy efficiency of a process, denoted by eta, is defined asIn mechanical engineering terminology, the ethanol proponents are making a claim that violates the First Law of Thermodynamics.
where output is the amount of mechanical work (in watts) or energy released by the process (in joules), and input is the quantity of work or energy used as input to run the process. Due to the principle of conservation of energy, energy efficiency within a closed system can never exceed 100%.
The change in the internal energy of a closed thermodynamic system is equal to the sum of the amount of heat energy supplied to the system and the work done on the system.I think what these alchemists really mean is that for every one human supplied energy unit used in producing ethanol, 1.06 energy units of ethanol are produced. Fair enough and with a scientifically researched basis. But this calculus ignores the huge amount of solar energy converted to potential energy as the corn grows.
- The misstatement of energy efficiency is made by the ethanol hucksters to put their product in an impossibly good light. This can be used to fool a scientifically ignorant audience, the Wisconsin State Legislature, for example.
Same goes for the Milorganite produced from last Friday's burrito and the waste byproducts from ethanol production. The Milorganite has no nutritional value and distillers grains have no use as motor fuels. Therefore, these byproducts do not get considered in determining the efficiency of the process, be it digestive or ethanol distillation.
The implications to the analysis in The Futility of Ethanol of disregarding byproduct production will be addressed in a later post.
I have reviewed the Net Energy Balance of Ethanol Production issue brief from Ethanol.com and found that they use the term "Energy Ratio" not "Energy Efficiency." Therefore, my above rant misses the mark.