Alkaline Fuel Cells with Novel Gortex‐Based Electrodes are Powered Remarkably Efficiently by Methane Containing 5% Hydrogen

Abstract

hydrogen. [1] This is likely to be less than 10% by volume as this is the maximum that natural gas pipelines can accommodate without downstream engineering modifications. [1] Natural gas is primarily composed of methane (CH 4 ), but also contains quantities of ethane, propane, and heavier hydrocarbons. [1] If the hydrogen-enriched natural gas streams of P2G could be used to generate electricity, then this would provide additional economic benefits. A hydrogenoxygen fuel cell capable of doing so would, however, need to be successfully and sustainably fueled by the low levels of hydrogen present. That is, the fuel cell would have to be capable of utilizing the <10% hydrogen blend as a fuel. The most widely used class of hydrogen-oxygen fuel cell at present is the proton exchange membrane (PEM) fuel cell. Studies have demonstrated that methane acts an inert gas when fed through the anode of a PEM. [2a,b] PEM fuel cells have, moreover, been shown to be capable of generating electrical power when fueled with a blend of 5% hydrogen in nitrogen (N 2 ), [2c] which also acts as an inert gas in such cells. However, at such high dilutions, PEM fuel cells are known to experience significant resistances arising from proton diffusion limitations due to the solid-state PEM electrolyte and its interface with the solid catalysts. [2d] Thus, for example, the charge transfer resistance in a PEM fuel cell increased from 330 mΩ cm 2 when fueled with pure hydrogen, to 780 mΩ cm 2 when the hydrogen was diluted to 5% by volume with nitrogen-a 240% increase (all feedstock gases humidified to 91%). [2c] It is perhaps for this reason that PEM fuel cells capable of operating with 5-10% hydrogen in methane do not appear to have ever been proposed or studied.Another reason may involve the need to humidify feedstock gases in PEM fuel cells in order to maintain the conductivity of the proton exchange membrane. Natural gas transported by pipeline is routinely extremely dry. [1] If a PEM fuel cell were used to extract electricity from hydrogen-enriched natural gas, then the gas would first have to be humidified before entering the cell. It may then also have to be dehumidified after leaving the cell and before re-entering the natural gas pipeline.An alternative class of hydrogen-oxygen fuel cell is the alkaline fuel cell (AFC). AFCs were one of the first fuel cell technologies applied to practical power generation, with applications in Numerous electric and gas utilities are actively pursuing "power-to-gas" technology, which involves using unwanted, excess renewable energy to manufacture hydrogen gas (H 2 ) that is then injected into the existing natural gas pipeline network in 5-10% by volume. This work reports an alkaline fuel cell that has the potential to harness such gas mixtures for downstream generation of electric power. The fuel cell, which employs novel Gortex-based electrodes layered with Pd/Pt catalysts, generates electricity remarkably efficiently when fuelled with methane (CH 4 ) containing 5% hydrogen. Methane constitutes ...

Gortex-Based Gas Diffusion Electrodes with Unprecedented Resistance to Flooding and Leaking

“…Clearly, there was no significant hindrance to gas transport into or out of the Gortex GDEs. This confirmed previous findings in this respect. , …”

“…Other than the present series of studies [14][15] and several recent reports in which Gortex membranes were coated with weakly-catalytic conducting polymers and sputtered metals or used in microbial fuel cells, [16][17][18][19][20] Gortex does not appear to have been formally considered as an electrode substrate in its own right. Moreover, no attempt has been made to select (based on a commercially-available engineering specification) or study the physical properties of a coated Gortex-based gas diffusion electrode.…”

“…This work forms part of a series of studies in our laboratory in which Gortex-based GDEs have been shown to display extraordinary interfacial properties. 14,15 2. RESULTS AND DISCUSSION 2.1.…”

Tuning the Product Selectivity of the Cu Hollow Fiber Gas Diffusion Electrode for Efficient CO2 Reduction to Formate by Controlled Surface Sn Electrodeposition

“…Here, electrodes are simply immersed in the electrolyte, resulting in a poor mass transport of CO 2 toward the electrode with limited feasibility for real applications. In recent years, gas diffusion electrodes (GDEs) have been successfully employed in applications such as fuel cells, , bioelectrochemical systems, and various gas-fed electroreduction processes (O 2 , CO, and CO 2 reduction). , With GDEs, CO 2 is fed to the reactor through the GDE, and it contacts the catalyst and electrolyte on the surface of the GDE. This is in contrast to the conventional reactor, where CO 2 is sparged to the electrolyte to saturate it .…”

Mg‐Based System for H2 Sorption from CH4/H2 Gas Mixture

“…The best-known techniques for separation of hydrogen from a gas mixture are: adsorption techniques (e.g., pressure swing adsorption-PSA); [2,3] low temperature process (temperatures <À180 C); [4] membrane techniques (diffusion separation, electrochemical separation processes); [5][6][7][8][9] combination of both membrane and PSA; [10] selective absorption (metal hydrides storage). Unfortunately, PSA methods are generally used at relatively high hydrogen concentrations (58% [11] or between 75% and 90% [12] ), whereas the low-temperature processes are considered costly while the purity grades of H 2 does not exceed 98%.…”