Biomass estimates, characteristics, biochemical methane potential, kinetics and energy flow from Jatropha curcus on dry lands

In this study, we examined the production of Jatropha curcus plants on 1 ha of rain fed dry lands. All of the plant components that would result from plantation tending, fruit harvesting and processing were sampled for their yield and chemical composition, and then subjected to the biochemical methane potential (BMP) assay. The component parts exhibited significant variation in BMP which was reflected in their ultimate methane yield which ranged from 0.08 to 0.97 L g−1 VS added, and their first order kinetics which ranged from 0.07 to 0.14 d−1. We examined two integrated utilization schemes: the first which converted plant prunings, fruit hulls and de-oiled seed cake to methane, and the oil to fatty acid methyl-ester (FAME); the second was to convert the seeds, plant prunings and fruit hulls entirely to methane. The basis for the plantation was, a density of 4444 plant ha−1 (1.5 m × 1.5 m spacing), with a seed yield of 0.911 kg TS plant−1 (1 kg total weight) with an oil content of 35% providing an annual oil yield of 1.42 t y−1. The corresponding yields of pruned leaves, fruit hulls and de-oiled cake are 0.97, 1.0, and 2.35 t VS ha y−1, respectively. An integrated scheme of producing biogas by means of anaerobic digestion of the latter components and oil for biodiesel would produce 90 GJ ha−1 y−1 in total with the oil being 54 GJ. The alternative biogas only option which would convert the seed oil into methane instead of biodiesel would produce 97 GJ ha−1 y−1.