Direct Carbon Fuel Cell System Development Study

虽然欧洲在增加低碳和可再生能源发电方面取得了长足的进步，但由于新兴能源经济体的能源需求迅速增长，这不太可能对全球二氧化碳排放产生足够的影响。由于煤炭在中国等国家的重要性，煤炭似乎肯定会成为全球主要的能源。这意味着开发尽可能有效地利用碳燃料发电的技术是绝对必要的。人们已经对利用碳固存进行发电的清洁碳技术产生了相当大的兴趣;然而，仍有一些重大障碍有待克服。首先，封存存在显著的能源和成本惩罚，其次，封存仅在大规模下有效，限制了分散化的任何可能的好处。这些都是对系统效率的巨大惩罚，这表明显然需要替代或补充清洁碳技术。大多数燃料电池概念涉及利用诸如氢气或液体甲醇的流体燃料的固体电化学系统。特别是在高温燃料电池中，经常发现从烃源形成碳会破坏活性，因此考虑在燃料系统中直接利用碳是令人惊讶的，但通过适当选择系统可以实现这一点。在这里，我们寻求开发直接碳燃料电池技术，以期在分散式（兆瓦级）发电中实施这一技术。这种技术可以使煤炭或可再生碳的能源转换效率比集中式火力发电高出2-3倍。一种基于混合燃料电池技术的用于直接碳转化的新型燃料电池系统正在开发中，该燃料电池系统利用具有结合MCFC和SOFC功能的扩展阳极的SOFC基底。目前正在评估从煤和生物质/废物流中加工碳燃料的方法，以产生最适当的碳形式，实现高效率。最近的研究结果表明，在煤炭，甚至高硫煤以及可持续或废物衍生的木炭中具有良好的性能。整个系统的设计将选择最佳的几何形状和特性，以实现最佳性能。成功的关键是将燃料电池开发、燃料处理和系统设计联系起来。这项可行性研究的主要重点是指定，建立和评估一个短的碳空气燃料电池测试堆栈，从而探索扩大这一重要技术所涉及的技术问题。这些问题主要涉及互连的电流收集和腐蚀。到目前为止，性能在很大程度上受到有限的电流收集的限制，这需要通过优化互连材料和选择/处理碳形式（碳充当燃料和二次集电器）来改善。腐蚀当然是一个关键问题，因为目前的概念是基于熔融碳酸盐阳极，而从熔融碳酸盐燃料电池研究中获得的经验是一个有用的指导，我们的概念中的条件与所需的更高的碳酸盐含量有显着不同。

Whilst Europe is making excellent strides to increase low carbon and renewable electricity generation, this is unlikely to have sufficient impact on global CO2 emissions due to the rapidly increasing energy demands from the emerging energy economies. It seems certain that coal will become the dominant global energy source due to its importance in countries such as China. This means that it is absolutely essential to develop technologies to utilise carbon fuels as efficiently as possible in generating electricity. There is already considerable interest in clean carbon technologies for electricity production with carbon sequestration; however, there are some major obstacles to be overcome. Firstly, there are significant energy and cost penalties to sequestration and secondly, sequestration is only effective at large scale limiting any possible benefits from decentralisation. These are huge penalties on system efficiency, which suggests a clear need for alternative or complementary clean carbon technologies. Most fuel cell concepts involve a solid electrochemical system utilising a fluid fuel such as hydrogen gas or liquid methanol. In high temperature fuel cells, in particular, formation of carbon from hydrocarbon sources is often found to destroy activity, so it is surprising to consider direct utilisation of carbon in a fuel system, but it is possible to achieve this by appropriate choice of system. Here we seek to develop Direct Carbon Fuel Cell technology with a view to implementing this in decentralised (megawatt scale) generation. Such technology could achieve 2-3 times higher efficiency of energy conversion from coal or renewable carbon than centralised thermal generation. A novel fuel cell system for direct carbon conversion based upon a hybrid fuel cell technology is being developed utilising an SOFC base with an extended anode combining MCFC and SOFC functions. Carbon fuel processing from both coal and biomass/waste streams are being evaluated to yield the most appropriate carbon forms for high efficiency. Recent results show considerable promise with good performance in coal, even high sulphur coal as well as sustainable or waste derived charcoals. The overall system will be designed to select optimal geometry and characteristics for optimum performance. Critical to success is to link fuel cell development, fuel processing and systems design. The main focus of this feasibility study is to specify, build and evaluate a short Carbon Air Fuel Cell test stack and hence to explore the technical issues involved in scale up of this important technology. Primarily these issues relate to current collection and corrosion of interconnects. So far performance has largely been limited by limited current collection and this needs to be improved through optimisation of interconnect material and choice/processing of carbon form (carbon acts as both fuel and secondary current collector). Corrosion is certainly a key concern as the concept at present is based on a molten carbonate anode and whilst experience gained from molten carbonate fuel cell research is a useful guide, conditions in our concept are significantly different with a higher carbonate content being required.