Research On Risk Control Technique Of High-Pressure Hydrogen Storage

Hydrogen is seen by many as a major energy carrier for the future as energy economy based on hydrogen could resolve the major concern about security of energy supply, source diversification and reduction of greenhouse gas emissions. With the significant progress in developing fuel cell technology for vehicle applications in recent years, increasing attention has been paid to the development of hydrogen storage technology and hydrogen fueling infrastructure construction. Safe and economical hydrogen storage technique is the key for the industrialization of hydrogen energy. Among the present hydrogen storage techniques, the storage of hydrogen in a compressed gaseous form offers the simplest solution in terms of infrastructure requirements and has become the most popular and most highly developed method. In the course towards a safe future hydrogen based society, one of the tasks to be considered is the investigation of the risk control technologies on high-pressure hydrogen storage.Sponsored by 863 Hi-Tech Research and Development Program of China on the topic of Technique and Equipment of High-pressure Hydrogen Storage (No. 2006AA05Z143), Key Technique of Hydrogen Refueling Station and Hydrogen Refueling System (No. 2007AA05Z152) and U.S. Department of Transportation Project Safety Issues Related to Transport and Storage of Hydrogen Fuels in Northern Climates(No. US DoT DTOS59-06-G-00048), researches are performed on the risk control technique of high-pressure hydrogen storage method. The main research results are as follows:1) Identification of hazardous factors. After the careful investigation to the basic character of hydrogen and a comprehensive cause anlysis of hydrogen accidents, various hazardous factors are indentified systematically through five aspects- medium, equipment, environment, operation and management.2) Hydrogen embrittlement of metallic materials in high-pressure hydrogen at ambient temperature. Hydrogen embrittlement may occur to metallic materials long-term serving in high-pressure hydrogen at ambient temperature and cause brittle fracture. In order to insure the long-term safe and reliable operation of high-pressure hydrogen storage system, hydrogen embrittlement of metallic materials in high-pressure hydrogen at ambient temperature should be taken into account. On the basis of domestic and abroad literature review, this paper introduces the mechanism of hydrogen embrittlement in high-pressure hydrogen at ambient temperature, analyzes the hydrogen compatibility of several materials, and puts forward useful suggestions for the hydrogen compatibility research of pressure vessel steels in China.3) Risk assessment of hydrogen leakage, diffusion and explosion. The models for the leakage of high-pressured hydrogen due to storage tanks failure are established and corresponding numerical simulation method is put forward. By numerical simulation, the characteristics of the dispersion from different leakage locations of tank are obtained.4) Risk control policy. Based on the above identification of hazardous factors and related calculations, risk control policies including improving and optimizing vessel structure, using safety accessories; selecting hydrogen compatible materials; detecting hydrogen leakage and flame to prevent hydrogen/oxidizer mixture from forming and enhancing safety management are put forward.