In a Reuters News Report Dated February 3, 2010, President

Multiple Choice

In a Reuters news report dated February 3, 2010, President Obama is quoted as saying, "By 2022 we will more than double the amount of biofuels we produce to 36 billion gallons, which will decrease our dependence on foreign oil by hundreds of millions of barrels per year." Use the following information to estimate the fraction of farmland in the United States that will be needed to meet this target in order to assess the impact on other uses of farmland, such as the production of food. (M  mega  10⁶)
Farmland in the U.S.  1.4 square miles
Energy density of biofuels  100 MJ/gal
Annual biofuel production from farmland  1,000 gal/acre
640 acres  1 square mile
1 gal  3.785 L
Mass density of biofuels: 800 g/L

A) 0.4%
B) 1.0%
C) 4.0%
D) 10%
E) 40%