The Genecom project consists in a portable source based on a direct methanol fuel cell for leisure and entertainment applications
In the last few years, direct methanol fuel cells (DMFC) have attracted much interest because of their application potential. One of the main reasons for that is the fuel being in the liquid state at room temperature (as opposed to hydrogen), which makes it a better choice for its introduction as an energy vector.
In spite of the aforementioned advantage, a drawback of such cells is methanol crossover: transference of methanol from the anode to the cathode, whereby catalytic material is contaminated and work capacity is reduced. Thus, lower power generation capacity is reached, and durability lessens. As a consequence, one of the main issues to tackle in order to face the problem lies in the development of new reinforced membranes that prevent fuel leakage.
The overall goal of the GENECOM project is the development of a portable energy generator based on a direct methanol fuel cell for leisure and entertainment applications.
To that end, new optimized hybrid polymer membranes have been developed, and they have been characterized and electrochemically evaluated in order to obtain their polarization curves. A stack was built with the developed MEAs, and a compact generator (along with power electronics) was obtained. Finally, environmental impact was analyzed by means of Life Cycle Assessment (LCA) of the developed energy generator to ensure it being a sustainable, market-competitive product.
New Nafion® membranes
Over the last few years, significant efforts have been devoted to the obtention of long-lasting, low-cost membranes with better properties than those that are actually in the market. In order to improve membrane performance, several steps may be taken, such as adding reinforcing polymer materials (blends or composites) or adding metal oxides as a dispersion within the global matrix, such as SiO2, TiO2 or ZrO2. By adding such reinforcing materials, shielding of methanol crossover has been reported to increase.
Within the framework of this project, hybrid Nafion® membranes were developed with both organic and inorganic (TiO2) reinforcing materials by using a casting process; final thickness was around 50 µm. Evaluations were performed on swelling capacity, ionic exchange and membrane conductivity, and single-cell yield curves were analyzed. Membranes developed contained several TiO2 loads (1-5%) and different polymer compositions (PVdF-HFP) on the Nafion® matrix.
Results for physico-chemical characterization of evaluated membranes yielded swelling capacity values around 98%, which were somewhat determined by the properties of Nafion® (the matrix). As for methanol permeability results, lower values than those for Nafion® alone are obtained when inorganic loads are added, and higher shielding values are obtained when polymer blends are used. On the contrary, membranes with low permeability values are associated to low yield values.
The MEAS polarization curves chart shows membrane power results obtained for hybrid membranes developed in the GENECOM framework. The chosen membrane to be included in the final stack was the one with the highest power values (numbers 1-4). The highest power value was obtained for low or zero values of inorganic load. On the other hand, lower yields were obtained for hybrid membranes with polymer blends, which provided higher methanol shielding. In order to reach a balance between both properties, the Nafion-TiO2 (3%) membrane was chosen as optimal.
On the other hand, a study on stack design was performed regarding weight reduction and an increased yield for the global system. Designs of bipolar plates were carefully considered and a significant reduction in the size and weight of the final stack was achieved. Design was undertaken by means of mechanization of bipolar plates made of carbonaceous material; flow distribution was highly efficient in order to prevent reduction of internal charge loss while significantly improving its final yield.
LCA development was analyzed according to the UNE-EN ISO 14040, where the scope and range of the project were defined. Focusing on stack impact, the stock of products and processes involved in its development were obtained and results were evaluated. It was shown that the higher impact was caused by the construction of the stack structural elements (bipolar plates, end plates, collectors, insulating materials…). The aforementioned impact was caused by processes used to cut and mechanize pieces, and the amount of energy used was a prevailing factor.
As an overview, in the accompanying chart the global impact of the processes involved in building the stack may be seen, as well as the flow chart of the processes involved in stack building, which shows that flow line thickness is proportional to the impact of the element in the global process. The corresponding table describes the impact of the three elements in the system in detail.
The fully assembled generator developed includes an integrated control system that is fully automated; pressing a button is the only action required. The generator output is 75 Watts, and it is possible to connect it to any device that requires a 12-V or 24-V power supply; this makes it possible to recharge batteries of recreational craft and motor homes. The power control and component management systems for the operation of the fuel cell have also been developed in the framework of the project. The systems permits keeping fuel consumption as low as possible by providing an efficient power control, controlling the minimum reagent amount for the operation of the fuel cell system and keeping consumption of any other components in the balance of plant to the minimum.
1The Project was co-funded by the Instituto Valenciano de Competitividad Empresarial (IVACE) and the European Regional Development Fund in the framework of the call for proposals for Technological Institutes 2014.
About the ITE
The Instituto Tecnológico de la Energía (ITE, Technological Institute for Energy) is a Technological Institute with an international scope. Its creation was fostered by business entities, and its development has been driven by the Generalitat Valenciana and the Universidad Politécnica de Valencia. The projects and services undertaken at ITE are aimed at companies and public organisms that belong to any field in the energy sector. The Applied Chemistry Laboratory at ITE (UQA) develops R+D+i activities focused on the development of new materials and components for energy storage, such as batteries (polymer, lithium or redox batteries), supercapacitors and PEM-like fuel cells (PEMFC, DMFC and electrolyzers).
AIJU, a technological Institute for children and leisure products, undertakes several actions in the fields of research, development and technological innovation. Besides, it offers technological services to increase competitiveness of the toy sector and related and similar industries in Spain. The strength and differential value of the Technological Insitute lie in their more than 70 professionals -who work to provide excellent services and high-value R+D+i projects for their company- as well as in more than 25 years of experience working as a consultant for hundreds of companies.
The main aim of the energy area at AIJU is doing research and development on new, high-efficiency devices for the generation and storage of energy to be used in portable applications, along with the development of new processes and equipment for the obtention of “clean fuels” such as hydrogen, along with biofuels and the development of state-of-the-art supports and catalyzers that increase energy efficiency of the processes in which they are used.
Mayte Gil-Agustí, Inés Monfort, Instituto Tecnológico de la Energia (ITE) (Technological Institute for Energy)
Rubén Beneito, Agustín Merlos, Instituto Tecnológico del Juguete (AIJU) (Technological Institute for Toys)