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The Jatropha curcas fruit shells (JCFS) and Jatropha curcas seed cake (JCSC) have drawbacks when used as fuel, namely flame front instabilities and short combustion periods. In this work, a blend of 25 wt% Jatropha curcas pellets with 75 wt% of pruning residues (PR) resulted in a fuel mixture that promote a stable flame front and the combustion process could be sustained for periods larger than 60 min. The improvement in the combustion of the blend composed of Jatropha curcas pellets and PR, when compared to mono-combustion of Jatropha curcas pellets, can be explained in result of the better fuel properties given by PR to the fuel blend. It was observed that PR combustion is associated to higher temperatures in the flame gases and the CO concentration in the flue gas is less than 1500 mg/Nm3 (dry gases, 13% vol. O2), thus in accordance to the European standards for solid fuel stoves. Although the PR fraction in the biomass mixtures is high (75 wt%), the observed CO concentration in the flue gas during combustion of the fuel blends was higher than 1500 mg/Nm3 (dry gases, 13% vol. O2) especially in the fuel mixtures that incorporate JCFS in their composition.

The aim of this work was to evaluate the bioenergy potential of cocoa residue via anaerobic digestion. Batch and fed-batch lab-scale reactors were operated under low and high solids conditions. In the batch tests, 59 ± 4% of Chemical Oxygen Demand (COD) was recovered as methane. This corresponded with an average methane yield of 174 (wet) and 193 (dry) L kg-1 volatile solids fed, whereas a series of fed-batch reactors produced 70 ± 24 (wet) and 107 ± 39 (dry) L CH4 kg-1 volatile solids fed during stable conditions. A case study was developed for canton Balao (Ecuador) based on our experimental data, operational estimates and available cocoa waste in the area. Annually, 8341 MWh could be produced, meeting 88% of the current electricity demand in Balao. This case study proves the potential for cocoa waste as a source of renewable energy in rural areas. ispartof: BIORESOURCE TECHNOLOGY vol:265 pages:568-572 ispartof: location:England status: published