Low pH, high salinity: too much for Microbial Fuel Cells?

Twelve single chambered, air-cathode Tubular Microbial Fuel Cells (TMFCs) have been filled up with fruit and vegetable residues. The anodes were realized by means of a carbon fiber brush, while the cathodes were realized through a graphite-based porous ceramic disk with Nafion membranes (117 Dupont). The performances in terms of polarization curves and power production were assessed according to different operating conditions: percentage of solid substrate water dilution, adoption of freshwater and a 35mg/L NaCl water solution and, finally, the effect of an initial potentiostatic growth. All TMFCs operated at low pH (pH$=3.0 \pm 0.5$), as no pH amendment was carried out. Despite the harsh environmental conditions, our TMFCs showed a Power Density (PD) ranging from 20 to 55~mW/m$^2 \cdot$kg$_{\text{waste}}$ and a maximum CD of 20~mA/m$^2 \cdot$kg$_{\text{waste}}$, referred to the cathodic surface. COD removal after a $28-$day period was about $45 \%$. The remarkably low pH values as well as the fouling of Nafion membrane very likely limited TMFC performances. However, a scale-up estimation of our reactors provides interesting values in terms of power production, compared to actual anaerobic digestion plants. These results encourage further studies to characterize the graphite-based porous ceramic cathodes and to optimize the global TMFC performances, as they may provide a valid and sustainable alternative to anaerobic digestion technologies.Comment: 13 pages, 10 Figure

development and performance analysis of biowaste based microbial fuel cells fabricated employing additive manufacturing technologies

Abstract In this work two different configurations of MFCs are tested, evaluating the importance of the operative conditions on power production. All the MFCs were fabricated employing 3D printing technologies and, by using biocompatible materials as for the body as for the electrodes, are analyzed the point of strength and development needed at the state of the art for this particular application. Power productions and stability in terms of energy production are deepen investigated for both the systems in order to quantify how much power can be extracted from the bacteria when a load is fixed for long time

performance of two different types of cathodes in microbial fuel cells for power generation from renewable sources

Abstract Microbial fuel cells (MFCs) technology represents a new approach to the sustainable electric power production, thanks to the advantages of its green features. The performance and the cost efficiency of a MFC are affected by several factors, such as the reactor architecture, the microbial microflora and the "costs per power" ratio of the electrodes. For example, cathodes powered by platinum as catalyzer are really efficient, but also expensive. In this study, two materials for cathode were examined: i) an economical biochar-based material (BC), ii) an activated carbon (AC) cathode with a nickel mesh current collector and a polytetrafluoroethylene (PTFE) binder to limit oxygen diffusion to the anodic compartment. The performances were evaluated in terms of power density and current density

Hydrogen-based technologies in maritime sector: technical analysis and prospective

The maritime transportation sector is one of the main contributors to global emissions of greenhouse gases (GHGs). The International Maritime Organization (IMO) has adopted a strategy to reduce these emissions from international shipping >50% by 2050, compared to 2008’s emissions. Therefore, ship owners need to adopt solutions to bring emissions within these and other future limits by means of environmentally friendly fuels (hydrogen or hydrogen carriers) and high efficiency propulsion technologies (fuel cells). This paper focuses on the replacement of the conventional Diesel genset installed on a hybrid small-size ferry, with an innovative system based on PEMFC technology. A real case scenario is investigated: the total energy/power demand of the vessel is determined basing on a typical operational profile. Then, a preliminary redesign of its powertrain configuration is proposed along with an energy management strategy. The analysis has allowed to define the hydrogen consumption for a daily operation. Finally, different storage technologies involving both compressed and liquefied hydrogen have been considered and compared, in order to identify ship’s weight and space requirements

Power to gas plant for the production of bio-methane: Technoeconomic optimization

In this work, a power to bio-methane plant in which the biogas is produced from an anaerobic digester plant and the hydrogen is generated by using an electrolysis unit powered by a renewable plant (photovoltaic or wind-based), is designed and sized. The plant sizing is carried out by applying a techno-economic multi-objective black box optimization approach. A numerical code, built by using the Matlab software package, is used to evaluate components sizes and to assess plant costs. This code is implemented in an optimization workflow developed in the modeFRONTIER environment. This approach allows to identify the optimal size of the plants components with the aim of maximizing the annual bio-methane producibility and minimizing its levelized cost. The results show that for a low-price electricity scenario (45 €/MWh) the minimum levelized cost of bio-methane (LCOBM), equal to 84.6 €/MWh, is obtained adopting the PV-based configuration. On the contrary, considering an high-price scenario (135 €/MWh), the minimum LCOBM is obtained for the Wind-based plant and is equal to 34.9 €/MWh

Coupling of Biomass Gasification and SOFC – Gas Turbine Hybrid System for Small Scale Cogeneration Applications☆

Abstract In this study the performances of small cogeneration power plants fed by biomass and based on conventional and advanced technologies are presented. Three system configurations have been considered and analyzed. They are characterized by: a) a biomass gasification (G) unit, based on down-draft technology; b) a power unit, based on the SOFC technology or on the micro gas turbine (MGT) technology or on a hybrid configuration SOFC-MGT; c) a thermal recovery unit. The energy analysis of the proposed power plants has been conducted by using thermochemical/thermodynamic models able to study the integrated systems and each unit in terms of operating and performance parameters

Performance Evaluation of Microbial Fuel Cells Fed by Solid Organic Waste: Parametric Comparison between Three Generations

Abstract In this paper, the results of three generations of reactors for the direct conversion of the Organic Fraction of Municipal Solid Waste (OFMSW) in electrical energy are presented. The different generations corresponds to the prototype realized in the Energy Lab of the University of Naples "Parthenope" and have been monitored along a period of over three years in terms of polarization and power curves, in order to assess the feasibility of Microbial Fuel Cell as a promising source for future, sustainable energy generation

A renewable energy and hydrogen storage system for residential electricity supply

Because of the intermittent behavior of renewable sources, efficient, reliable and clean energy storage technologies are needed to achieve a more stable and secure energy supply. In this context, hydrogen technologies play a key role because they can store large amount of energy for long time. In this study, a hydrogen-based electrical energy storage system, integrated with a solar power plant, is designed and analyzed from the energy perspective. The system consists of a photovoltaic power plant, an alkaline electrolysis unit, metal hydride tanks for hydrogen storage, a Li-ion battery unit and a polymer electrolyte membrane fuel cell module. The system is conceived for supplying a residential user. A numerical model is developed for sizing the system’s components and for evaluating their behaviors in terms of produced/stored electricity and hydrogen production. In this purpose, a sensitivity analysis varying PV plant size as well as the Li-ion battery capacity is performed for achieving the best compromise in terms of energy supply among all the considered power sources

On the Emergy accounting for the evaluation of road transport systems: an Italian case study

Road transportation is one of the most polluting as well as energy-intensive sectors, and requires planning policies capable to address at the same time several different environmental, social, and economic issues. Cost-benefit analyses are generally carried out with a major focus on fuelling and driving efficiency, whereas a systemic approach appears to be needed for a more comprehensive evaluation of the alternatives that may become available to address any issue, be it intended for either short-term or long-term spans. For instance, building up a new infrastructure might allow for savings in time or fuel per km, but this may require an equivalent or even higher socio-environmental investment. In this work, a short review is presented of some systemic studies on transportation that use the emergy synthesis methodology. A case study is also addressed, concerning recent important expansion works on the Apennine Mountains section of the Italian major highway A1. In particular, the analysis points out the role of time saving, since for a new or renewed transport infrastructure (and when comparing for example road to rail transport) saved time is likely to become crucial in justifying civil enterprises. Nevertheless, the present emergy synthesis and the teaching of H.T. Odum (Odum & Odum, 2001) warn us that such “luxury” highly depends on the abundance of available energy, which is less and less given for granted, whereas a systemic analysis approach may indicate different levels of criticality when oriented towards environmental and well-being issues