Hydrogen-based Fuel Cells (FCs) hold significant potential as energy conversion technologies. In a previous study, we presented a pump-based hydrogen generator (PHG) that utilizes a catalytic reaction between sodium borohydride (NaBH4) powder and water. The pump circulates the water solution through the powder chamber in a closed-loop reaction. The PHG demonstrated clear advantages over alternative hydrogen sources in terms of both safety and energy density. However, as operating time increases, the solution in the closed-loop PHG becomes saturated, causing the reaction rate to decline. This limitation can be overcome in cases where an external water source is available, such as marine vehicles, drones equipped with water recovery systems from their fuel cells, or systems located near pipelines. In such scenarios, introducing freshwater feeding and product emission offers intriguing possibilities for significantly enhancing the fuel's energy density and extending its effective operation time. Our current research introduces an innovative concept: a dual-cycle generator (DCG) that effectively overcomes the issue of solution saturation over time. It achieves this by combining solution circulation with freshwater feeding and product emission. Our study employed a DCG prototype to examine various operating modes and to demonstrate the effectiveness of this approach. The DCG achieved a calculated energy density for the fuel of 3868 Wh/kg, with 93% H2 extraction yield from the powder. Our findings reveal substantial improvements in terms of extended operation duration (81%), increased hydrogen flow rate (36%), enhanced energy density (33%), and improved H2 yield extraction from the powder (39%). This methodology holds promise for mobile applications or off-grid systems situated in proximity to a water source.
Keywords: Fuel cell; Hydrogen generator; Mobility; Off-grid; On demand; Power pack; Solid sodium borohydride; Storage.
© 2024 The Authors.