Potential of by-products from primary coffee processing as source of biofuels

Publikations-Art

Poster

Autoren

Chala, B.; Latif, S.; Müller, J.

Erscheinungsjahr

2015

Veröffentlicht in

Book of Abstracts

Seite (von - bis)

641

Tagungsname

Tropentag 2015 "Plant 2030"

Tagungsort

Potsdam, Germany

Tagungsdatum

4 - 6 March 2015

Schlagworte

Biofuel, fibre, heating value, husk, Kaffee / coffee, mucilage, parchment, pulp

Coffee is second most traded legal commodity next to petroleum. Millions of people particularly from developing countries rely their livelihood on coffee production. Primary coffee processing is conversion of fresh cherries to green bean by following the dry or wet methods. Both processing methods generate almost half the weight of the coffee cherries as by-products, mostly seen as waste and dumped, which causes environmental problems. The main process by-products from wet method are pulp (43 % w/w), mucilage (11.8 % w/w) and parchment (6.1 % w/w); while the dry method generates the husk, which is 44 % of the dry cherry. In the present study, physical and chemical properties of the coffee processing by-products were made on dry weight basis. Sample by-products were obtained from coffee processing farm in Jimma, (Ethiopia) and sundried before transported to Germany. The parchment had highest cellulose (44.7%), hemicellulose (19.9%) and lignin (32.2%) content of the by-products fraction, while the pulp and husk exhibited 31.6% & 32.0% cellulose, 8.5% & 14.5% hemicellulose and 15.5% & 17.5% lignin respectively. The high lignin and lower ash content in the parchment makes it attractive for different biomass pressing, and thermochemical conversions; however it is less suitable for anaerobic conversion. The pulp, husk and the mucilage have promising properties for bio-chemical and thermo-chemical energy conversion technologies. The calorific value of parchment, husk and pulp was 19.7MJ/kg, 18.8MJ/kg and 17.4MJ/kg respectively; which is comparable to most common fuel woods. The characterization of the by-products indicated promising potential source for renewable energy production particularly biogas and briquette/pellets.