4.4. Sensitivity Analysis
While increasing seed yield improves the useful energy of the
Jatropha system, the increases do not exceed the useful energy of the
Prosopis system even under the most aggressive yield assumptions
(5 t/ha/yr) (Fig. 5). The useful energy of the Jatropha system under
the most aggressive yield assumptions and full by-product use is
500.2 TJ/yr, which is approximately 40% of the useful energy delivered
by the Prosopis system (825.1 TJ/yr). Holding all yield-independent variables
constant, a seed yield of 17.7 t/ha/yrwould be required to provide
the same quantity of useful energy as the Prosopis system (authors' calculations),
which is far beyond any conceivable yield. Indeed, the most
optimistic projections for Jatropha are a doubling of yields anticipated
by SG Biofuels, one of the main companies developing hybrid Jatropha
seeds (SG Biofuels, 2010