Angelo Moreno

Nonconventional Fuels for High-Temperature Fuel Cells: Status and Issues

The pressing environmental and political necessities of modern international society call for a suitable array of contingency solutions to the energy question. One valid alternative to fossil fuels, for example, is the use of alternative or nonconventional fuels, derived from waste or biomass. Combining these resources with fuel cell applications would provide a significant contribution to environmentally friendly and efficient energy use. Through a comprehensive literature survey and the collection of practical case studies and operational experience, an assessment of the potential for coupling with high-temperature fuel cells of three technologies of alternative fuel production-landfill, anaerobic digestion, and gasification-has been attempted. Though landfill is the easiest technology, anaerobic digestion produces superior quality gas and has the benefit of yielding extra fertilizer, in the form ofdigestate. Gasification is the most demanding of the technologies but is very flexible in its feedstock. Furthermore, using steam as a gasifying agent produces high quality syngas. However, the main issue with all three technologies is the removal of contaminants, in particular, sulfur. The application of high-temperature gas cleanup is demonstrated to bring considerable advantages on system level when gasification of nonconventional fuels is considered. Ultimately, the reforming step is a key aspect for optimal cost-effective integration of these alternative systems. The review provided establishes the key characteristics of alternative fuel conversion by landfill, anaerobic digestion, and gasification, and exposes the major points of attention for their subsequent application in high-temperature fuel cells. Indications of the measures required and the developments in the field of basic research and system integration are given to provide clear paths of activity, which should bring about the wide-scale implementation of a truly promising application of fuel cell systems.

Cogeneration of Heat and Electricity: A Comparison of Gas Turbine, Internal Combustion Engine, and MCFC/GT Hybrid System Alternatives

The purpose of this paper is to present the results of a feasibility study of the supply of electricity and heat to a large user (i.e., a public hospital in Northern Italy) by means of a molten carbonate fuel cell (MCFC) hybrid system in comparison with other technologies. The study investigated three alternative options in order to meet the users demand: internal combustion engine, gas turbine, and a hybrid system (molten carbonate fuel cells and gas turbine, MCFC-HS), which is currently under development by Ansaldo Fuel Cell Ltd. and ENEA. The user requirement was the yearly supplies of 6.65 GWh e /year and 21.64 GWh th /year. Due to demand fluctuations over the year, integration by electric grid and/or additional thermal boilers was also required and investigated. The approach integrates the usual mass balance with large scale material flow accounting, embodied energy analysis, exergy efficiency, and emergy synthesis, within a LCA perspective. Results show that the best performance from the point of view of energy and exergy efficiency is shown by the MCFC-hybrid system. The latter is also characterized by the lowest embodied energy demand and cumulative material demand as well as by the lowest requirement for direct and indirect environmental support (emergy method). However, the small thermal energy supply of the MCFC-HS compared with the large thermal needs of the hospital calls for a larger use of the additional boiler. The latter device worsens the local-scale emissions of the system, compared with the other alternatives investigated. Results point out that a proper choice cannot only be based on the individual performance of an even well performing technological device, but also needs to be tailored on the systems characteristics and dynamics, in order to adequately match supply and demand.

Fuel Cells in the Waste-to-Energy Chain

Abundance of Waste and Energy Scarcity.- Biomass and Waste as Sustainable Resources.- Anaerobic Digestion.- Biomass and Waste Gasification.- Digesters, Gasifiers and Biorefineries: Plants and Field Demonstration.- Molten Carbonate Fuel Cells.- Solid Oxide Fuel Cells.- Fuel Gas Clean-up and Conditioning.- High-Temperature Fuel Cell Plants and Applications.- Biomethane and Natural Gas.- Electricity and the Grid.- Prospects of Hydrogen as a Future Energy Carrier.- Market and Feasibility Analysis of Non-conventional Technologies.- Concluding Remarks.

Solutions for Material Corrosion Problems in MCFC

It is widely recognized that metallic corrosion of the cathode current collector is a key technological problem that must be fully resolved before Molten Carbonate Fuel Cells can be commercialized on a more competitive basis. This paper presents a short overview on the corrosion mitigation strategies that appear more appropriate for MCFC current collectors. As alternative to the current use of the 300-series austenitic stainless steels, specialty high-Mn stainless steels, corrosion-resistant Ni-based alloys and sol-gel coatings of thin conductive spinel or perovskite ceramic layers are seen as the most promising corrosion solutions for the cathode-side environment. The use of basic additives into electrolyte for inhibiting molten carbonate corrosion is a further mitigation option yet with less practical perspectives due to the high constraints on the electrolyte properties. Recent and current studies conducted at ENEA on MCFC corrosion solutions are also mentioned.

Energy Recovery From Wastewater Treatment Biogas: Integration of an Anaerobic Digester With a High Temperature Fuel Cell

Wastewater treatment facilities operating with anaerobic digesters produce a methane-rich gas as by-product of the process. In most cases, this gas is released into the atmosphere, thus increasing the greenhouse effect, due to the presence of methane. At the same time, the methane content makes the biogas an interesting source of energy. An efficient energy recovery presents the dual benefits of reducing greenhouse gas emissions and of producing a usable form of energy (typically electric current or heat), using a renewable source of energy, thus diminishing fossil fuel consumption. Due to the high operating temperature, Molten Carbonate Fuel Cells (MCFCs) and Solid Oxide Fuel Cells (SOFCs) present the advantage of being able to operate with a wide variety of fuels, of achieving high energy efficiency and of releasing near-zero emissions. In the present study, the possibility of integrating an anaerobic digester with a high temperature fuel cell is presented. The result of the study illustrates the options, opportunities and the relative benefits and disadvantages related to this energy recovery option.Copyright