Collaborative Research in Energy with South Africa. Intermediate Temperature Proton Conducting Membrane Systems for the Hydrogen Economy

基于质子交换膜(PEM)或固体聚合物电解质(SPE)的商用电解水器可以从纯净(脱钙)水和电力中生产氢气。与碱性电解槽技术相比，它们具有更高的能效、更高的生产率(单位电极面积)和更紧凑的设计。这些系统的制约因素是材料的高成本，如电解液膜和贵金属基电催化剂以及电能的投入。以质子交换膜为基础的水电解槽在&lt；80oC的温度下运行，并具有由平衡槽电位(标准电位)确定的最低能量需求。由于电极极化和欧姆电压损失，实用电池需要更高的电压；这既增加了能源成本，也增加了经济成本。通过在更高的温度下操作电池，电池反应的自由能下降，从而平衡电势下降。因此，在高温(&gt；800℃)下运行的固体氧化物蒸汽电解器(SOSE)正在开发中，但需要在高温下提供热能；而这种热能往往无法获得或供应昂贵。在较低温度(150-350摄氏度)下操作可以减少能源需求(热力学潜力约为1.12V)，在耦合为电池提供蒸汽的热能需求和减少对极高温度所需材料的限制方面可能是更实用的解决方案。在较低温度(150-350摄氏度)下操作还可以减少铂催化剂和/或电极用非铂催化剂的使用，以及降低质子导电膜成本。通过这些方法，PEM电解氢装置的投资和运行成本都可以降低。该项目的目的是启动英国和南非两个互助性团体之间的合作计划，重点是开发中温范围(~200℃)的氢电解器，这也将对其姊妹技术PEM燃料电池产生溢出效应。因此，该方案将重点放在一种新技术上，以与两种较成熟的电解技术竞争。标准的PEM电解槽已经可用(低风险)，但其电气效率较低。中温PEM电解槽虽然更具投机性，但如果可再生能源发电量增加，它可能会被证明是有价值的。这项技术的发展需要在电解液研究上投入大量资金。纽卡斯尔现有的关于这一主题的探索性研究有助于降低与新电解液开发相关的风险。该项目的目标是通过使用质子导电膜、无机和复合电解液来提高PEM电解槽的运行温度，从而降低电压要求(了解到标准热力学电池电位降低，而电催化剂的活性增加)。虽然使用氧化物陶瓷质子导体的高温电解槽(&gt；600C)已经被研究过，但还没有关于大约150-300℃之间的中间温度范围的重要研究。

Commercial water electrolysers based on proton exchange membrane (PEM) or solid polymer electrolytes (SPE) enable hydrogen production from pure (demineralised) water and electricity. They offer advantages over alkaline electrolyuser technologies; greater energy efficiency, higher production rates (per unit electrode area), and more compact design. The restricting aspects of these systems are the high cost of the materials; such as the electrolyte membrane and noble metal-based electrocatalysts and the electrical energy input. PEM based water electrolysers operate at temperatures of < 80 oC and have a minimum energy requirement, determined by the equilibrium cell potential (standard potential). Practical cells require higher voltages due to polarisation at electrodes and ohmic voltage losses; raising both energy and economic cost. By operating cells at higher temperatures the free energy of the cell reaction and thus the equilibrium potential falls. Thus solid oxide steam electrolysers (SOSE) operating at high temperatures (>800C) are under development but require a source of thermal energy at high temperatures; which is frequently not available or is expensive to supply. Operating at lower temperatures (150-350 C) gives benefits of reduced energy requirements (thermodynamic potential around 1.12V) and potentially a more practical solution in terms of coupling the thermal energy requirements to provide steam for the cell and reducing the constraints on materials required for very high temperatures.Operating at lower temperatures (150-350C) can also give benefits of reduction in Pt catalyst use and/or use of non-Pt catalysts for electrodes as well as reduced proton conducting membrane costs. In these ways capital and operating costs of PEM hydrogen electrolysers can both be reduced. The aim of this project is to start a collaborative programme between two complimentary groups in the UK and South Africa, that focuses on the development of hydrogen electrolysers in the intermediate temperature range (~200C) that will also have spillover benefits on its sister technology, PEM fuel cells. This programme thereby focuses on a new technology to compete with the two more established electrolysis technologies. The standard PEM electrolyser is already available (low risk) but its electrical efficiency is low. The intermediate temperature PEM electrolyser, although more speculative, could prove valuable if renewable electricity generation increases. Development of this technology requires significant investment into electrolyte research. Existing exploratory research on this topic at Newcastle helps to reduce the risk associated with new electrolyte development.An aim of this project is to increase the operating temperatures of PEM electrolysers through the use of proton conducting membranes; with inorganic and composite electrolytes; thereby reducing voltage requirements (knowing that the standard thermodynamic cell potential falls whilst the activity of electrocatalysts increases). Although high temperature electrolysers (>600C) using oxide ceramic proton conductors have been researched there has been no significant research of the intermediate temperature range between approximately 150-300 C.