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 United States = 1.4 . 10⁶ square miles Energy density of biofuels = 100 MJ/gal
Annual biofuel production from farmland =1000 gal/acre 640 acres = 1 square mile
1 gal =3.785 L
Mass density of biofuels: 800 g/L

Question

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To meet the target of 36 billion gallons, we need to calculate the farmland required. Given 1000 gal/acre and 640 acres/square mile, we find the total square miles needed and compare it to the total U.S. farmland. The calculation shows that approximately 4% of U.S. farmland would be needed.

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