Table 5 A comparison of candidate biofuel feedstock plant species across several parameters.
Crop | Harvestable biomass (tons/ha/yr) | Ethanol (L/ha) | Ha needed for 132.5 billion L ethanol (millions) | % of 2006 harvested US cropland: 165 million Ha (2007) | Energy output/ input ratio |
|---|---|---|---|---|---|
Maize grain | 3.1–6.4 a | 4266 | 31 | 19 b | – |
Maize stover | 3.1–6.4 a | 2805 | 47 | 29 b | – |
Maize total | 6.2–12.8 c | 3500–5400 d | 25–38 d | 15–23 b | 10.7 c |
Switchgrass | 5.2–11.1 e | 2000–2900 d | 46–66 | 28–40 b | – |
Miscanthus | 20.9–34.6 e | 8600 d | 15 | 9 b | – |
Prairie | 3.8 | 1439 | 92.1 | 56 b | – |
Willow | 6.2–12.8 c | – | – | – | 24.0 c |
Wheat total | 7–14.4 c | – | – | – | 11.3 c |
