Background
The authors write that "the cultivation of energy crops dedicated to the production of biofuels presents some potential problems, e.g., competitiveness with food crops, water needs, use of fertilizers, etc.," and they note that "the economic, energy, and environmental convenience of such activity depends on accurate evaluations about the global efficiency of the production system."

What was done
In light of the above observations, Marta et al. analyzed the processes involved in the cultivation of energy crops in the Tuscany region of Italy from the perspective of energy and water costs, focusing on maize (Zea mays) and sunflower (Helianthus annuus) because of their different water requirements and methods of cultivation. This work was done using a 50-year climatic series of meteorological data from 19 weather stations scattered across the Tuscany region to feed the crop model CropSyst for the simulation of crop production, water requirements and cultivation techniques, with the final results being used to define the real costs of energy crop cultivation.

What was learned
The six scientists state that, first, "the energy balance is positive only considering the more efficient system of irrigation, whereas in the rest of the cases the energy invested is greater than the energy returned." Second, they report that "the water need for bioethanol production is too high considering the trend and the distribution of precipitation in the region in addition to water requirements of the other productivity sectors," noting that "more than 1,000 liters of water are required for producing one liter of bioethanol," which implies that "the cultivation of energy crops in the reserved areas of the region will almost double the actual requirement of the agricultural sector in Tuscany."

What it means
The Italian researchers from the University of Firenze conclude that "the cultivation of maize and sunflower for energy production cannot be considered a sustainable choice in Tuscany," even at the present time. And we hasten to add that demands upon energy, land and water resources will only grow larger, as the world's population grows by a couple billion people on its temporal trek towards AD 2050.