Hydrogen_na-acha_akwụkwọ_ndụ_akwụkwọ_ndụ
Mmepụta hydrogen na-acha akwụkwọ ndụ akwụkwọ ndụ site na mmiri oké osimiri
As part of an interest in examining sustainable hydrogen fuel for maritime shipping and in response to concerns of freshwater scarcity, a 2020 study into the various means of electrolysis for green hydrogen from seawater as a source of water have been conducted. Four such methods, direct electrolysis of seawater, alkaline electrolysis, proton-exchange membrane electrolysis, and solid oxide electrolysis, are briefly summarized. Direct electrolysis of seawater follows known processes, forming an electrolysis cell in which the seawater acts as the electrolyte to allow for the reaction at the anode, and the reaction at the cathode,. The inclusion of magnesium and calcium ions in the seawater makes the production of alkali hydroxides possible that could form scales in the electrolyzer cell, cutting down on lifespan and increasing the need for maintenance. The alkaline electrolyzers operate with the following reactions at the anode, and cathode,, and use high base solutions as electrolytes, operating at 60-90 C and need additional separators to ensure the gas phase hydrogen and oxygen remain separate. The electrolyte can easily get contaminated, but the alkaline electrolyzer can operate under pressure to improve energy consumption. The electrodes can be made of inexpensive materials and there's no requirement for an expensive catalyst in the design. Proton-exchange membrane electrolyzers operate with the reactions at the anode, and cathode,, at temperatures of 60-80 C, using a solid polymer electrolyte and requiring higher costs of processing to allow the solid electrolyte to touch uniformly to the electrodes. Similar to the alkaline electrolyzer, the proton exchange membrane electrolyzer can operate at higher pressures, reducing the energy costs required to compress the hydrogen gas afterwards, but the proton exchange membrane electrolyzer also benefits from rapid response times to changes in power requirements or demands and not needing maintenance, at the cost of having a faster inherent degradation rate and being the most vulnerable to impurities in the water. Solid oxide electrolyzers run the reactions at the anode and at the cathode.The solid oxide electrolyzers require high temperatures (700-1000 C) to operate, generating superheated steam. They suffer from degradation when turned off, making it a more inflexible hydrogen generation technology. In a selected series of multiple-criteria decision-analysis comparisons in which highest priority was placed on economic operation costs followed equally by environmental and social criteria, it was found that the proton exchange membrane electrolyzer offered the most suitable combination of values (e.g., investment cost, maintenance and operation cost, resistance to impurities, specific energy for hydrogen production at sea, risk of environmental impact, etc.), followed by the alkaline electrolyzer, with the alkaline electrolyzer being the most economically feasible, but more hazardous in terms of safety and environmental concerns due to the need for basic electrolyte solutions as opposed to the solid polymers used in proton-exchange membranes. Due to the methods conducted in multiple-criteria decision analysis, non-objective weights are applied to the various factors, and so multiple methods of decision analysis were performed simultaneously to examine the electrolyzers in a way that minimizes the effects of bias on the performance conclusions.