From the information supplied in the following text, estimate the percentage of the total land area in the lower 48 states that would have to be used to replace all of the gasoline currently used for transportation with ethanol obtained from switchgrass. Do the same for the arable land in the lower 48 states.

Data:

- Estimated ethanol productivity \(=1,000\) gallons (gal) ethanol per hectare per year (based on switchgrass as the crop)—see, http://bioenergy.ornl.gov/paper/misc/ switgrs.

- \(1.51 \mathrm{gal}\) of ethanol is required to obtain the same energy as 1 gal of gasoline, based on their respective LHVs.

- U.S. gasoline consumption in 2008 was \(138 \times 10^{9} \mathrm{gal} /\) year (information obtained from: http://eia.doe.gov/oil_gas/petroleum/inforglance/consumption/ product_supplies/annual-thousand_barrels/finished_motor_gasoline).

- U.S. total land area (lower 48 ) \(=1.92 \times 10^{9}\) ac (information obtained from: http:// cia. gov/library/publication/the_world_fact_book).

- U.S. arable land area (suitable for crops) \(=0.45 \times 10^{9}\) ac (information obtained from: http://cia.gov/library/publication/the_world_fact_book).

- 1 ha \(=2.47\) ac.