Coir Fibers as Valuable Raw Material for Biofuel Pellet Production

Coir is a natural, lignin rich, fiber that can be found between the hard internal shell and the outer coat of a coconut. There are multiple products made from coir fibers but a significant amount of fibers accumulating from coconut processing remains unutilized. Coir fibers obtained from ripe (brown fibers) and unripe (white fibers) have a high lignin content about 41–42 wt%, a low ash content < 15 wt% and a high heating value of about 18.5–19 MJ kg−1. The pelletizing properties were studied in a laboratory scale, single pellet press, and produced pellets were of high mechanical properties. Dynamic mechanical thermal analysis was used to identify the glass transition temperature of coir lignin and indicated that at the applied conditions the softening of coir lignin occurs at about 120–130 °C, which is the usual temperature reached in an industrial scale pellet mill. These properties make coir a suitable raw material for fuel pellet production. Its high availability makes coir fibers a potential replacement for firewood and charcoal in developing countries, and thereby contributes to reduce deforestation.