Power generation via glycerol in Pseudomonas aeruginosa fuel cells was evaluated under improved culture conditions using two different electrochemical systems. One used Pt-black carbon felt air cathodes and proton exchange membranes. The other used ammonia pre-treated carbon felt electrodes immersed in ferricyanide as cathode and saline bridges as a cation exchange system. In all cases, ammonium pre-treated carbon felts were used as anodes. Experiments were conducted during 120 h at 37°C. Biochemical parameters such as microbial growth, substrate consumption and pyocyanin production were evaluated. Electrochemical studies of chronoamperometry, power output generation and coulombic efficiency (CE) were also performed. Initial concentrations of 25 g L−1 of pure glycerol were used. Small differences between systems, in terms of PCN production, glycerol consumption or microbial growth were observed. Also, good results in terms of current densities (Idmax) of 42 ± 2.1 μA cm−2, CE of 48 ± 2.4% and power output densities (Pdmax) of 350 ± 17.5 mW m−2, were achieved. The power output densities were at least 4 times higher than other previously reported MFCs based also on PCN production from pure glycerol or glucose. In contrast, when both systems were supplemented with raw glycerol obtained as by-product from biodiesel industry, lower values for Idmax, CE and Pdmax ranging 23 ± 1.15 μA cm−2, 36 ± 1.18% and 240 ± 12.0 mW m−2, were respectively achieved, depending on the electrochemical system used.

No abstract

The catalytic indirectly heated gasification of bagasse was investigated in this study. The quality of the gaseous fuel was assessed using the total energy analysis of the gas, in which both heat content and total yields of the gas produced from the gasification of bagasse are analyzed at temperatures ranging from 700 to 1000°C. Untreated bagasse gasification was used as a baseline for the investigation of the effect of catalysts on the gasification process. The total energy analysis showed a significant improvement of gas quality due to increase of temperature and due to the use of alumina-zinc based catalysts at temperatures below 900°C. The presence of these catalysts in the gasification process affected the quality of the gases formed, mainly by increasing the hydrogen production, reduction of the gas dilution by carbon dioxide and a slightly higher production of carbon monoxide. Above 900°C, temperature dominates the gasification reaction mechanisms causing the catalysts to have little or no significant effect. Thermal cracking of tar is of major importance on the gasification process, as the tar yields reduce from 42.1 to 24.7% of the bagasse original weight with the increase of the gasifier temperature from 700 to 1000°C. However, the solid residue reduced only from 16 to 13.3%. Hence, the increase in the gaseous yields at high temperature appeared to be due to the gasification of tar with some contribution from secondary reactions involving char. The result was the production of a medium heat content gaseous fuel.

O presente trabalho teve como objetivo avaliar o rendimento volumétrico e energético produzido por três diferentes clones de híbridos de Eucalyptus sp.: C39 Híbrido de Eucalyptus urophylla (cruzamento natural); C41 Híbrido de Eucalyptus urophylla (cruzamento natural) e C11 Híbrido de Eucalyptus brassiana (cruzamento natural). Para a quantificação do volume de madeira foi utilizado o processo de cubagem rigorosa pelo método de Smalian. A densidade básica da madeira e o poder calorífico foram determinados, respectivamente pelas normas ABNT (1984 e 2003). O consumo de lenha foi obtido por meio do acompanhamento da calcinação da gipsita. O delineamento utilizado no experimento foi o inteiramente aleatório. As produtividades volumétricas de tais clones foram, respectivamente, 158,46, 132,20 e 164,89 m³/ha aos 7,5 anos de idade, apresentando rendimentos durante a calcinação da gipsita de 0,16, 0,10 e 0,13 metros cúbicos de lenha por tonelada de gesso produzida, quando a lenha foi utilizada em forma de toras. Para a lenha em cavacos os rendimentos foram de 0,11, 0,08 e 0,09 metros cúbicos por tonelada de gesso, resultados bem acima dos melhores rendimentos da lenha de vegetação nativa, que são de 0,16 metros cúbicos por tonelada. Palavras-chave: Polo Gesseiro do Araripe; eucaliptocultura; demanda energética.

Due to climate change problems caused by greenhouse gas emissions generated by fossil fuels and from waste disposition, fuel alternatives for power generation are being extensively researched. Currently, in Brazil and in many countries, wood waste is disposed in landfills. However, due to lignin, one of the major constituents of biomass, which prevents wood waste from suffering microbial degradation, there is no significant mass degradation, even over decades, when landfilled. Hence, landfilling is not a solution to discard wood waste. Hence, one of the solutions to get rid of the great amount of wood waste is to use it as feedstock in waste-to-electricity (WTE) projects. WTE projects are in high demand in the world, as they can replace fossil fuels and they reduce two major environmental problems (greenhouse gas emissions due to the use of fossil fuels and the accumulation of waste in landfills), while generating biofuels and/or electricity. One of the residues that can be used in WTE projects is biomass residue from construction sites (CCbiowaste). CCbiowaste could be converted into gaseous biofuels through pyrolysis or gasification. These gaseous biofuels can be used in Otto engines connected to an electricity generator (gensets) to produce electricity and/or heat (cogeneration applications). Hence, the objective of this research was to characterize (physically, chemically, and energetically) civil construction biomass wastes (CCbiowaste), produced in a residential building construction site in Recife, Brazil, and to use these wastes in a bench-scale gasifier to produce gaseous biofuels at the temperatures of 700 °C, 800 °C, and 900 °C. The gaseous fuels were collected in the gasifier and analyzed in a gas chromatograph equipped with a thermal conductivity detector (TCD) to determine their composition and heating values. The lower heating value (LHV) results varied from 8.07 MJ∙m−3 to 10.74 MJ∙m−3 for 700 °C to 900 °C gasification temperature. These gaseous fuels were tested in an adapted Otto cycle engine connected to an electricity generator to prove the feasibility of this application. The highest total energy per ton of biomass was obtained for mixed wood and Pinus at 900 °C, with approximately 13 GJ∙ton−1. Hence, the use of CCbiowaste can become an option for the reuse of wasted wood instead of simply dumping in a landfill.