Table 1: Comparison of biofuel feedstock environmental impacts for transportation fuels.

Crop typeUsed to produceGHG emissions* (Kg of CO2 created per mega joule of energy produced)Use of resources during growing, Pros and Cons
harvesting, and refining of fuel

CornEthanol81–85HighHighHighHighTechnology ready and relatively cheap; reducing food supply.
Sugar caneEthanol4–12HighHighMedMedTechnology ready; limited as to where it will grow; reducing food supply.
Switch grassEthanol−24Med-lowLowLowLowIt will not compete with food crops; technology not ready.
Wood residueEthanol, biodieselN/AMedLowLowLowTechnology ready; reducing food supply.
SoybeansBiodiesel49HighLow-medMedMed-lowTechnology ready; reducing food supply.
Rapeseed, canolaBiodiesel37HighMedMedMed-lowTechnology ready; reducing food supply.
AlgaeBiodiesel−183MedLowLowHighPotential for huge production levels; technology not fully ready for scale up.

*Emissions produced during the growing, harvesting, refining and burning. Gasoline is 94, diesel is 83.
Data source: Adapted from [2].