| 학회 | 한국고분자학회 |
| 학술대회 | 2004년 가을 (10/08 ~ 10/09, 경북대학교) |
| 권호 | 29권 2호, p.123 |
| 발표분야 | 연료전지와 고분자 재료 |
| 제목 | The Present Status and Development Issue of Polymer Electrolyte Membrane Fuel Cell (PEMFC) |
| 초록 | Recently, economic development has been rapidly growing worldwide due to many R&D activities. Additionally, many experts say that the world population keeps increasing at 1.2-2% per year, so that it is expected to double by the middle of the 21st century. As a consequence global demand for energy supply is significantly expected to increase. Unfortunately, generation of such energy for producing electricity or powering transportation almost exclusively relied on refined petroleum products from a fossil fuel, which is continuously being exhausted as well as just few countries have the majority of the whole reserves. From this point of view, we are now facing up the energy-related problems to be solved in near future: (i) a whole range of environmental challenges such as the global warming situation and harmful levels of local pollutants and (ii) dependence on limited foreign energy sources. We need to give an impetus to the new development of renewable and environmentally-friendly energy technologies. It has been widely considered that fuel cells are a promising solution to the aforementioned critical need for cleaner energy technologies. A fuel cell is an energy conversion device that generates electricity and heat by electrochemically combining a fuel and an oxidant gas (oxygen from the air) through electrodes and across an ion conducting electrolyte. During this process, much higher conversion efficiencies and virtually pollution free exhausts are guaranteed, compared with any conventional thermo-mechanical systems. Among the fuel cells, proton exchange membrane fuel cells (PEMFCs) using hydrogen as a fuel are recently favored for use in portable, military, transport and stationary applications. The PEMFC system mainly consists of three types of sectors: (i) the fuel cell stack in which electrodes, electrolytes and bipolar plates are alternatively assembled for generation of electricity, (ii) the fuelling system such as pressurized storage tanks, reformers and dispensers for hydrogen supply and (iii) the balance of plant (BOP) such as power conditioning parts, pumps, compressors, etc. Until now, development of each element in the fuel cell stack, such as membrane-electrode assembly (MEA), bipolar plate, gas diffusion layer (GDL), etc., has been intensively investigated. However, the hydrogen-supply infrastructure and integration technology for PEMFCs are nowadays beginning to be highlighted for maturation of the PEMFC technology. Despite many unsolved technological problems, governments are providing driving forces for the introduction of this technology to markets by regulating the emission of pollutants and car sale policy and increasing funding for fuel cell R&D. In 1990s, transport, in particular light duty vehicles, gained much attention. On January 2002, the US government announced a new cooperative automotive research partnership called FreedomCAR for the development of fuel cell vehicle technologies. Since 2002, the large number of car companies has been dominantly being engaged in PEMFC development. In the portable sector, the market drivers for PEMFCs are under investigation as a more convenient alternative of secondary batteries to allow portable electronic devices to function for longer periods. Additionally, many Japanese developers are investigating residential-size PEMFC systems (＜1 kW) and many countries began to introduce fuel cell technologies, especially, PEMFC, for their military applications. Many technologies for PEMFCs should be further developed on the basis of practical aspects. Among them, development of polymer electrolyte membranes are one of the core challenges to meet the requirements of end-users. The most commonly used membrane, NafionTM, has several disadvantages to be used in extensive applications. They can be categorized into three aspects: its manufacturing concerns, extensive supporting equipment requirements and temperature-related limitations. First, the membrane material is so expensive as well as its manufacturing processes can be highly dangerous to workers. Second, for achieving the sufficient proton conductivities to properly operate PEMFC, the hydration system should be equipped, which causes considerable cost and complexity to the PEMFC design and manufacturing. Third, at elevated temperatures, the membrane properties, in particular the proton conductivity, abruptly degrade. Therefore, the present PEMFC system using the membrane is often operated at low temperatures. The low temperature operation (below 80 oC), however, causes several technical difficulties such as slow start-up and shut-down, the catalyst poisoning in the presence of carbon monoxide and water management. In this respect, polymer electrolyte membranes should be inexpensive and keep the sufficient electrochemical properties (i.e., proton conductivity, chemical and mechanical durability for above 5000 hrs) to function at elevated temperature above 120 oC for its extensive introduction to markets. |
| 저자 | 김창수 |
| 소속 | 한국에너지기술(연) |
| 키워드 | |
