This article is insightful: All Biofuels Are ‘Nonsense’, Says Nobel-Winning Photosynthesis Expert Hartmut Michel
The Nobel laureate says: “Because of the low photosynthetic efficiency and the competition of energy plants with food plants for agricultural land, we should not grow plants for biofuel production. The growth of such energy plants will undoubtedly lead to an increase in food prices, which will predominantly hit poorer people.”
The article’s author says: “I’ve been against corn ethanol ever since I saw the studies that show just how little net energy is produced, if any at all, and even then, using arable land and food to make fuel will never be sustainable.”
My take is that farmers will grow whatever sells. If there is a strong market for biofuels, like ethanol from corn, then that is what they will grow. We need to find some way to make growing food for the hungry commercially viable.
Corn for ethanol is the primary biofuel in the U.S. In 2010 and 2011, about 5 billion bushels of corn per year were used for ethanol production. Corn produces 2.7 gallons of ethanol per bushel and a typical yield is about 150 bushels per acre (not counting the terrible yields of 2012).
56 lbs of corn per bushel, which is 25.4 kg per bushel
2.7 gallons is 10.2 liters
150 bushels of corn per acre is 9415 kg/ha
25.4 kg/10.2 liters = 2.49 kg of corn to produce 1 liter (about 2.5)
(9415 kg of corn/ha)/2.5 = 3,766 liters of ethanol per hectare from corn
By comparison, a crop like chufa (tigernut) could theoretically produce 3750 kg of oil per hectare per crop (assuming a moderate yield of 11 t/ha), which is about 4075 liters (1075 gallons) of oil. At the high end of yields (14 t/ha), chufa could produce over 5,000 liters per hectare, compared to just under 4,000 liters per hectare for corn.
Once there is enough land being used to grow oil or carbs for conversion to fuel, we might find some way to incentivize using that land to grow food for the hungry. So all is not lost if there should be an increase in land used to grow biofuel in the coming years.