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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

Resumen La biomasa proveniente de Jatropha curcas ha sido estudiada como materia prima para la obtención de energía renovable, debido a que es un cultivo no alimentario. Uno de los procesos más prometedores para producir etanol a partir de biomasa lignocelulósica es la sacarificación y fermentación simultáneas (SSF). En otros estudios realizados, con experimentos SSF, se ha evaluado la conversión de glucano en etanol a partir de la cáscara de Jatropha pretratada en medio ácido o alcalino, pero no a través de procesos hidrotérmicos. En el presente estudio, la cáscara de Jatropha curcas fue pretratada hidrotérmicamente con agua caliente a 200 °C por 15 min y ensayada en experimentos de SSF con un coctel enzimático (Cellic CTec2) y levadura comercial (Saccharomyces cerevisiae). Diferentes cargas enzimáticas, medios estériles y tamaños de ensayo fueron usados para determinar su influencia en el rendimiento de etanol. Los resultados mostraron que, con 5 % p/p de sólidos, 15 UPF/g biomasa seca y 1 mg/ml de levadura se alcanza el máximo rendimiento de etanol (0,160 - 0,177 g etanol/ g biomasa seca) y conversión de celulosa (57,71 - 63,90 %). A través de esta investigación se propone una alternativa para el uso integral del cultivo de Jatropha curcas dentro de una economía circular. Abstract Biomass from Jatropha curcas has been studied as a raw material for obtaining renewable energy, due to its non-food crop characteristics. One of the most promising processes to produce ethanol from lignocellulosic biomass is simultaneous saccharification and fermentation (SSF). In other studies carried out through SSF experiments, the conversion of glucan to ethanol from Jatropha shell pretreated with acid or alkaline medium was evaluated but not through hydrothermal processes. In the present study, the Jatropha curcas shell was hydrothermally pretreated with liquid hot water at 200 °C for 15 min, and tested in SSF experiments with an enzyme cocktail (Cellic CTec2) and commercial yeast (Saccharomyces cerevisiae). Different enzyme loadings, sterile media and sizes test were used to assess their impact on ethanol yield. The results showed that the maximum ethanol yield (0.160 - 0.177 g ethanol / g dry biomass) and the conversion of cellulose (57.71 - 63.90 %) were achieved with 5 % w/w of solids, 15 FPU/g dry biomass, and 1 mg/ml of yeast. Through this research, an alternative is proposed for integral using of the Jatropha curcas crop for a circular economy.