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）的商用水电解器可以从纯（脱盐）水和电中制氢。与碱性电解技术相比，它们具有优势；更高的能源效率，更高的生产率（每单位电极面积），更紧凑的设计。这些系统的限制方面是材料的高成本；如电解液膜和贵金属基电催化剂以及电能的输入。基于PEM的水电解槽在< 80℃的温度下工作，并具有由平衡电池电位（标准电位）决定的最低能量需求。由于电极极化和欧姆电压损失，实用电池需要更高的电压；提高能源和经济成本。通过在较高的温度下操作电池，电池反应的自由能因而降低了平衡电位。因此，在高温下工作的固体氧化物蒸汽电解槽（soe）正在开发中，但需要高温热源；这通常是不可用的或昂贵的供应。在较低温度（150-350℃）下运行，可以减少能量需求（热力学势约为1.12V），并且在耦合热能需求以为电池提供蒸汽方面可能是更实用的解决方案，并减少了对高温所需材料的限制。在较低的温度（150-350℃）下操作也可以减少Pt催化剂的使用和/或使用非Pt催化剂的电极，以及降低质子导电膜的成本。通过这些方式，质子交换膜氢电解槽的资本和运营成本都可以降低。该项目的目的是在英国和南非的两个互补小组之间启动一个合作计划，重点是在中温范围（~200℃）内开发氢电解槽，这也将对其姊妹技术PEM燃料电池产生溢出效益。因此，该计划侧重于一种新技术，以与两种更成熟的电解技术竞争。标准PEM电解槽已经可用（低风险），但其电效率低。中温PEM电解槽虽然更具有推测性，但如果可再生能源发电量增加，它将被证明是有价值的。该技术的发展需要对电解质研究进行大量投资。纽卡斯尔大学对这一主题的现有探索性研究有助于降低与新电解质开发相关的风险。该项目的目的是通过使用质子导电膜来提高PEM电解槽的工作温度；与无机和复合电解质；从而降低电压要求（知道标准热力学电池电位下降而电催化剂活性增加）。虽然已经研究了使用氧化物陶瓷质子导体的高温电解槽（> - 600C），但尚未对大约150-300 C之间的中间温度范围进行重大研究。

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.