There is a well-established data set for corn-ethanol production in the US, without major differences in the physical assessment of biophysical inputs and outputs among different studies. The differences found in the overall assessment of the output/input energy ratio are basically generated by different choices about how to convert the various inputs and outputs into energy equivalents, but not by the initial accounting of the quantities of biophysical inputs and outputs.
Gross output (per hectare of crop production)
Corn production: 8000kg/ha
Ethanol production: 3076L/ha (2.69kg of corn to produce 1L of ethanol)
Gross supply of energy carriers: 66.13GJ of ethanol/ha (1L of ethanol = 21.5MJ)
From this data set above we could obtain two benchmarks:
1 net supply of ethanol per hour of labor in the corn-ethanol production system: 224MJ/h;
2 net supply of ethanol per unit of land in the corn-ethanol production system: 6GJ/ha/year or 0.6MJ/m2/year or 0.02W/m2.
Please note that when considering the requirement of fossil energy for a two step process the agricultural production of corn, and the conversion of the corn into ethanol, we assumed as valid the pro-ethanol claim that the by-products of agricultural production provide the entire heat energy consumption of the step of distillation.
This is not always the case, but again we went for the most favorable assumption. Therefore, the requirement of fossil energy refers only to the consumption of energy carriers both for the phase of agricultural production (transportation, production of fertilizers, pesticides, irrigation, the making of steels and technical infrastructures) and only transportation and technical infrastructures for the phase of fermentation-distillation.