Obtaining bioproducts by slow pyrolysis of coffee and cocoa husks as suitable candidates for being used as soil amendment and source of energy

Abstract

The agricultural economic policy of Cuba pretends to triplicate the crops of coffee and cocoa by 2021, a measure which will bring about both an increase in biomass waste and the need to find a proper method for its disposal. Slow pyrolysis process can transform lignocellulosic waste into added value products as biochar, bio-oil and gas. The present research evaluated the yield and the theoretical potential energy of co-products (biochar, bio-oil, and gas) from coffee and cocoa seed husks using the pyrolysis process as a source of friendly and renewable energy. Results indicated that coffee husks are more suitable for the production of gas with a yield of 40.4%, while cocoa seed husks are better suited for the production of bio-oil, with a yield of 37.4%. For 2021 the theoretical energy potential estimated is 8291 MWh, equivalent to 716000 kg for the coffee husks, and 1384 MWh equivalent to 121000 kg for the cocoa seed husks. The bio-char characterization indicated high contents of carbon, calcium, potassium, nitrogen, and oxygen, which makes it a suitable candidate for being used as a soil amendment.  The conversion of coffee and cocoa seed husks into added value products through slow pyrolysis process will help clean the environment, decrease the greenhouse effect, and will aid farmers in the rural populations by providing them with an additional source of income.