The land footprint of biofuels You are attempting to create transportation fuel in Tempe, AZ on one acre (4,047 m2) of land. You have the option to grow corn, safflower (an oilseed crop that can be dry farmed), or switchgrass. The corn can be used to produce ethanol, the safflower to produce biodiesel and the switchgrass could be used to produce ethanol, diesel or electricity. The yields for the crops and each conversion process is given in the table below

Crop	Yield	Ethanol Yield	Diesel Yield	Electricity Yield
Corn	202 bu/acre	2.85 gal/bu	-	-
Sunflower	1.2 tons/acre	-	107 gal/ton	-
Switchgrass	9 tons/acre	76 gal/ton	55 gal/ton	2,200 kWh/ton

Drivetrain	Fuel Economy
Gasoline/Ethanol	20.4 miles/gallon ethanol
Diesel	38.3 miles/gallon diesel
Electric	3.59 miles/kWh

(c) Photovoltaic option: A different option is to produce electricity using photovoltaics and use that electricity in a battery electric vehicle. Assume a PV system with 20% efficiency for the production of electricity, 10% loss in the transmission of electricity to the charger and that the average insolation in Phoenix is 5.38 kWh/m2/day. How many vehicle miles can be produced using photovoltaic electricity in an electric drivetrain from one acre of land over the course of a year? (d) Synthetic fuel option: Yet another option is to use the electricity from photovoltaics to produce synthetic fuel via electrolysis, carbon capture, and synthesis of a diesel- like fuel. Once again, assume a PV system with 20% efficiency for the production of electricity, 10% loss in the transmission of electricity to the synthetic fuel production facility and that the average insolation in Phoenix is 5.38 kWh/m2/day. In addition, assume a 50% efficiency in converting the renewable electricity into the synthetic fuel has a higher heating value of 39 kWh/gallon and that a diesel VW Golf would have the same fuel economy operating on the synthetic fuel as diesel. How many miles of travel can be supported with one acre of photovoltaic-based synthetic fuels over the course of one year?