Cleaner hydrogen production by microwaves: Experimental investigation and comparative assessment

Abstract

Sustainable development goals of the United Nations require cleaner energy solutions and carbon-free fuels. Hydrogen, in this regard, appears to be a unique candidate for all, and its production in a cleaner manner is critically important, which is the prime focus in the present paper. This study focuses on the newly designed experimental investigations into microwave-driven water dissociation for cleaner hydrogen production, specifically exploring the effect of various tungsten-based electrode materials and steam inlet conditions on hydrogen production. The evaluation is conducted in two main sections, assessing hydrogen production at the water dissociation level and the overall system. Some of the key observations include a positive correlation between steam inlet temperature and hydrogen production for all electrode materials, with lanthanated tungsten demonstrating superior performance. When only the water dissociation is considered, lanthanated tungsten electrodes exhibit the most favorable energy consumption, showcasing the minimum energy requirement for hydrogen production. Incorporating the overall energy and exergy efficiencies, the lanthanated tungsten emerges as the top performer, followed by ceriated tungsten, attributed to their superior arc stability. The energy requirement per kg of hydrogen varies from 51.98 kWh/kg to 56.66 kWh/kg for varying steam inlet temperatures from 104 degrees C to 120 degrees C. The highest energy and exergy efficiencies are recorded to be 64.1 % and 62.3 %, respectively, for lanthanated tungsten electrodes at 120 degrees C steam inlet temperature. When all energy inputs (steam generation, preheating, condenser pump, and microwave generator) are considered, the overall energy and exergy efficiencies are found to be 35.1 % and 34.2 %, respectively. The energy needed for 1 kg of hydrogen production is recorded to be 94.87 kWh/kg. Consequently, the lanthanated tungsten electrode stands out as a superior performer, offering valuable implications for advancing microwave hydrogen production technologies.