High efficiency reversible solid oxide cells for the integration of offshore renewable energy using hydrogen

氢的生产、储存、分配和转化是帮助经济脱碳的一个迅速崛起的候选领域。在这里，我们重点关注其在支持海上可再生能源（ORE）整合方面的作用，鉴于海上风力发电成本下降（预计到2023年价格将降至2017年的25%）和政府的雄心，这一主题对英国越来越重要。事实上，最新的BEIS方案包括超过120吉瓦的海上风电，在某些方案中甚至高达233吉瓦。这给电力基础设施带来了巨大的挑战，因为我们在岸上整合这些可变能源流的能力，时间跨度很大。目前由固定的海上风力结构组成的ORE工厂位于相对靠近陆地的浅水中，使用海上电缆和变电站系统将产生的电力转换，传输到岸上并连接到电网。然而，为了充分利用可再生能源的潜力和2050年净零目标的要求，海上风力发电场将需要建在更远的近海和更深的水域。这就考虑到通过氢等替代载体将能源输送到岸上可能成为最具吸引力的途径的可能性。因此，我们考虑陆上和海上制氢。氢不仅可以成为整合海上风电的有效手段，而且还日益成为一种有吸引力的低碳能源载体，以支持工业供热、化工、卡车、重型车辆、航运和火车等难以解决的行业的脱碳。这一点在全球范围内得到了越来越多的认可，仅在过去三年中，法国、中国、加拿大、日本、韩国、德国、葡萄牙、澳大利亚和西班牙就对氢能源做出了重大的国家承诺，最近还启动了欧洲氢能源战略，并将氢能源大规模纳入了2020年11月的英国政府绿色计划。这些国家战略的大部分重点是在可再生电力的驱动下，利用电解生产“绿色”氢。然而，一些国家仍然对“蓝色”氢感兴趣，英国就是一个例子，这是一种由化石燃料制成的氢，加上碳捕获和储存，因此是低碳而不是零碳的氢。如今，全球96%的氢气来自未减排量的化石燃料，其中6%的天然气和2%的煤炭消费用于生产氢气，主要用于石化产品，每年排放约8.3亿吨二氧化碳。目前绿色氢是最昂贵的氢形式，大约60-80%的成本来自电力输入的成本。影响这一点的一个关键因素是电解槽本身的效率，以及在需要时用于将绿色氢转换回电力的发电机的效率。在这项工作中，我们专注于可逆电解槽的概念，这是一台既可以在燃料电池模式下产生电力，又可以在电解槽模式下产生氢气的机器。电解槽和燃料电池分为两类：低温（70-120℃）和高温（600-850℃）。虽然低温电解槽和燃料电池系统已经商业化，但它们相对较低的组合往返效率（约40%）意味着可在高温（600-900℃）下工作的可逆固体氧化物电池（rSOC）越来越受到关注。它可以实现高达95%的电解槽效率，高达65%的发电效率，因此在环境压力下，使用目前接近商业化的产品，往返效率约为60%。本项目将该新技术的开发和应用考虑到使用氢气的ORE集成的情况。

The production, storage, distribution and conversion of hydrogen is a rapidly emerging candidate to help decarbonise the economy. Here we focus on its role to support the integration of offshore renewable energy (ORE), a topic of increasing importance to the UK given the falling costs of offshore wind generation (with prices expected to drop to 25% of 2017 by 2023) and Government ambition. Indeed, the latest BEIS scenarios include more than 120 GW of offshore wind, and even up to 233GW in some scenarios. This brings with it significant challenges to the electricity infrastructure in terms of our ability to on-shore and integrate these variable energy flows, across a wide range of timeframes. Current ORE plants composed of fixed offshore wind structures are sited relatively close to land in shallow water and use systems of offshore cables and substations to transform the electricity produced, transmit it to the shore and connect to the grid. However, in order to exploit the full renewable energy potential and requirements for the 2050 net zero target, offshore wind farms will need to be sited further offshore and in deeper waters. This brings possibilities into consideration in which transporting the energy to shore via an alternative vector such as hydrogen could become the most attractive route. Hence we consider both on-shore and off-shore hydrogen generation.Not only can hydrogen be an effective means to integrate offshore wind, but it is also increasingly emerging as an attractive low carbon energy carrier to support the de-carbonisation of hard to address sectors such as industrial heat, chemicals, trucks, heavy duty vehicles, shipping, and trains. This is increasingly recognised globally, with significant national commitments to hydrogen in France, China, Canada, Japan, South Korea, Germany, Portugal, Australia and Spain in the last three years alone, along with the recent launch of a European hydrogen strategy, and the inclusion of hydrogen at scale in the November 2020 UK Government Green plan. Most of the focus of these national strategies is on the production of 'green' hydrogen using electrolysis, driven by renewable electricity. However, there remains interest in some countries, the UK being one example, in 'blue' hydrogen, which is hydrogen made from fossil fuels coupled with carbon capture and storage and hence a low carbon rather than zero carbon hydrogen. Today, 96% of hydrogen globally is produced from unabated fossil fuels, with 6% of global natural gas, and 2% of coal, consumption going to hydrogen production, primarily for petrochemicals, contributing around 830 million tonnes of carbon dioxide emissions per year. Currently green hydrogen is the most expensive form of hydrogen, with around 60-80% of the cost coming from the cost of the electrical power input. A critical factor that influences this is the efficiency of the electrolyser itself, and in turn the generator used to convert the green hydrogen back into power when needed. In this work we focus on the concept of a reversible electrolyser, which is a single machine that can both produce power in fuel cell mode, and produce hydrogen in electrolyser mode. Electrolysers and fuel cells fall into one of two categories: low-temperature (70-120C) and high temperature (600-850C). While low temperature electrolyser and fuel cell systems are already commercially available, their relatively low combined round-trip efficiency (around 40%) means that the reversible solid oxide cell (rSOC), which can operate at high temperatures (600-900C) is of growing interest. It can achieve an electrolyser efficiency of up to 95%, power generation efficiency of up to 65%, and hence a round-trip efficiency of around 60% at ambient pressure using products now approaching commercial availability. This project considers the development and application of this new technology to the case of ORE integration using hydrogen.