Moringa oleifera Lam. as an energy crop for biogas production in developing countries

Moringa oleifera Lam. (moringa) is a typical plant of tropical climates used as food, feed, and natural medication. This plant, rich in oil, could be valorized in the bioenergy sector, as infeed to produce biofuel, useful to save fossil sources, and to limit GHG emissions. This paper has evaluated its potential methane production by the anaerobic digestion process, in comparison to corn and giant cane, two typical food and non-food energy crops. Biogas production has been correlated to the content of fats, waxes, resins, cellulose, hemicellulose, proteins, and lignin in the three plants and to the different carbon types detected by solid-state nuclear magnetic resonance (NMR) technique. Chemical and spectroscopic analysis showed that organic matter of moringa contains more than 40% of fats having high potential to produce biogas. Although the quantity of biogas produced from corn was higher, among the three samples, the content in methane for corn and moringa was not statistically different. In particular, the methane yields for the giant cane, moringa, and corn were 363 ± 11, 442 ± 9, and 452 ± 12 m3 Mg DM−1 respectively: moringa produced less biogas but it was richer in methane. Methane concentration was positively correlated to the sum of fats, waxes, resins, hemicellulose, and proteins (R2 = 0.97; n = 3; p < 0.05). All these results seem to indicate that effectively moringa can be used as substrate to produce biogas by anaerobic digestion. When combined with small-scale low-tech digesters, this can represent a good opportunity for bioenergy production in developing countries.