Based on a study for Tennessee Valley Authority, written by Drs. Van Dyne and Raymer, the average American farm consumes fuel at the rate of 82 liters per hectare, about 8.75 US gallons per acre of land to produce one crop, although average crops of rapeseed produce oil at an average rate
of 1,029 liters per hectare, 110 US gallons per acre, and high-yield rapeseed fields produce about 1,356 liters per hectare, 145 US gallons per acre.
This means the ratio of input to output in these cases is roughly 1:12.5 and 1:16.5. Photosynthesis is known to have an efficiency rate of about 16 percent and if the entire mass of a crop is utilized for energy production, the overall efficiency of this chain is known to be about 1 percent,
which does not compare favorably to solar cells combined with an electric drive train. Biodiesel out competes solar cells in cost and ease of deployment, but these statistics by themselves are not yet enough to show that the change makes economic sense.
However, with biodiesel additional factors must be considered, including the yield of fuel from raw oil, the return on cultivating food, the fuel equivalent of the energy required for processing, and the relative cost of biodiesel versus petrodiesel. Several countries that have pondered
transitioning fully to biodiesel have found also that doing so would require immense tracts of land considering only for the use of traditional crops, and analyzing the amount of biodiesel that can be produced per acre of cultivated land.
They have concluded that it is likely that the United States does not have enough arable land to fuel all of the nation's vehicles, and currently this is the nation with the highest per capita energy demands of any other country. Probably other developed and developing countries may be
in a better situation to produce biodiesel, although many of their regions could not afford to divert land away from food production. For third world countries, biodiesel sources, such as that use marginal land would make more sense.