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Mérida, Mexico

Yazdi H.,University of Colorado at Boulder | Alzate-Gaviria L.,Renewable Energy Unit | Ren Z.J.,University of Colorado at Boulder
Bioresource Technology | Year: 2015

Septic tanks and other decentralized wastewater treatment systems play an important role in protecting public health and water resource for remote or developing communities. Current septic systems do not have energy production capability, yet such feature can be very valuable for areas lack access to electricity. Here we present an easy-to-operate microbial fuel cell (MFC) stack that consists a common base and multiple pluggable units, which can be connected in either series or parallel for electricity generation during waste treatment in septic tanks. Lab studies showed such easy configuration obtained a power density of 142 ± 6.71 mWm-2 when 3 units are connected in parallel, and preliminary calculation indicates that a system that costs approximately US $25 can power a 6-watt LED light for 4h per day with great improvement potential. Detailed electrochemical characterizations provide insights on system internal loss and technology advancement needed. © 2015 Elsevier Ltd.

Sanchez-Herrera D.,P-Com | Pacheco-Catalan D.,Renewable Energy Unit | Valdez-Ojeda R.,Renewable Energy Unit | Canto-Canche B.,Biotechnology Unit | And 3 more authors.
BMC biotechnology | Year: 2014

BACKGROUND: A laboratory-scale two-chamber microbial fuel cell employing an aerated cathode with no catalyst was inoculated with mixed inoculum and acetate as the carbon source. Electrochemical impedance spectroscopy (EIS) was used to study the behavior of the MFC during initial biofilm (week 1) and maximum power density (week 20). EIS were performed on the anode chamber, biofilm (without anolyte) and anolyte (without biofilm). Nyquist plots of the EIS data were fitted with two equivalent electrical circuits to estimate the contributions of intrinsic resistances to the overall internal MFC impedance at weeks 1 and 20, respectively.RESULTS: The results showed that the system tended to increase power density from 15 ± 3 (week 1) to 100 ± 15 mW/m(2) (week 20) and current density 211 ± 7 (week 1) to 347 ± 29 mA/m(2) (week 20). The Samples were identified by pyrosequencing of the 16S rRNA gene and showed that initial inoculum (week 1) was constituted by Proteobacteria (40%), Bacteroidetes (22%) and Firmicutes (18%). At week 20, Proteobacterial species were predominant (60%) for electricity generation in the anode biofilm, being 51% Rhodopseudomonas palustris. Meanwhile on anolyte, Firmicutes phylum was predominant with Bacillus sp. This study proved that under the experimental conditions used there is an important contribution from the interaction of the biofilm and the anolyte on cell performance. Table 1 presents a summary of the specific influence of each element of the system under study.CONCLUSIONS: The results showed certain members of the bacterial electrode community increased in relative abundance from the initial inoculum. For example, Proteobacterial species are important for electricity generation in the anode biofilms and Firmicutes phylum was predominant on anolyte to transfer electron. R1 is the same in the three systems and no variation is observed over time. The biofilm makes a significant contribution to the charge transfer processes at the electrode (R2 and Cdl) and, consequently, on the performance of the anode chamber. The biofilm can act as a barrier which reduces diffusion of the anolyte towards the electrode, all the while behaving like a porous material. The anolyte and its interaction with the biofilm exert a considerable influence on diffusion processes, given that it presents the highest values for Rd which increased at week 20.

Gutierrez-Dominguez D.E.,Renewable Energy Unit | Pacheco-Catalan D.E.,Renewable Energy Unit | Patino-Diaz R.,CINVESTAV | Canto-Canche B.,Biotechnology Unit | Smit M.A.,Renewable Energy Unit
International Journal of Hydrogen Energy | Year: 2013

Enzymatic-polymeric electrodes are prepared by immobilizing the enzyme alcohol dehydrogenase from Saccharomyces cerevisiae in polypyrrole, potentiostatically electrodeposited onto carbon paper. The applied enzymatic immobilization procedures are direct adsorption and crosslinking with glutaraldehyde. Electrodes are characterized by cyclic voltammetry, showing that ethanol oxidation occurs at around 0 V (versus calomel) for the enzymatic electrodes. Recorded current values due to ethanol oxidation in enzymatic polymeric electrodes are higher by two orders of magnitude, than those recorded for ethanol oxidation in carbon enzyme electrodes. The polymeric enzymatic electrodes crosslinked with glutaraldehyde show higher current values than those with adsorbed enzyme, reflecting a better retention of the protein in the electrode, and preserve catalytic activity for longer times. Spectrophotometric measurements are performed in order to determinate enzymatic activity. Fuel cell test show better performance for the crosslinked enzymatic electrode. Copyright © 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

Soler-Bientz R.,Autonomous University of Yucatan | Ricalde-Cab L.,Autonomous University of Yucatan | Ricalde-Cab L.,Renewable Energy Unit | Perez L.F.B.,Renewable Energy Unit | Baeza J.G.C.,Renewable Energy Unit
Conference Record of the IEEE Photovoltaic Specialists Conference | Year: 2011

A PV-Wind hybrid system has been developed at the energy Laboratory of the Autonomous university of Yucatan in order to evaluate the performance of this kind of generators in the tropical conditions of the North of the Yucatan Peninsula. The systems comprise a PV array, a wind generator, a battery bank and a set of electric regulators, converters and an inverter. The voltage and the electric current of the main components of the system have been studied monthly along with their corresponding diurnal cycles. This paper presents an outline of the PV-Wind hybrid energy generator and its main characteristics which will allow to evaluate strategies to improve the performance of independent energy generation systems from renewable resources in the study region. © 2011 IEEE.

Galleano R.,Renewable Energy Unit | Zaaiman W.,Renewable Energy Unit | Virtuani A.,University of Applied Sciences and Arts Southern Switzerland | Pavanello D.,Renewable Energy Unit | And 9 more authors.
Progress in Photovoltaics: Research and Applications | Year: 2014

This paper describes the results of an intercomparison of spectroradiometers for global and direct normal incidence irradiance in the visible and near-infrared spectral regions together with an assessment of the impact these results may have on the estimation of the short-circuit current (ISC) calibration of photovoltaic devices and on the spectral mismatch calculation. The intercomparison was conducted in the framework of the European project Apollon with the additional participation of external partners from the Italian project for the long-term monitoring of solar radiation for photovoltaics. Six institutions and six spectroradiometer systems, representing different technologies and manufacturers, were involved. Prior to the intercomparison, all participating partners calibrated their own instrument(s) according to their usual procedures in order to verify the entire measuring and traceability chain. The difference in measured spectra shape and amplitude showed to have an impact on ISC calculation of less than 3% and less than 6% for single-junction and multi-junction devices, respectively. When only the shape of the spectra is considered, the spectral mismatch ranges from 1.7% to 4.7% depending on the spectral response of the device. Copyright © 2013 John Wiley & Sons, Ltd.

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