Abstract
A medium-scale hydrogen distribution chain, 3 tpd, is investigated for distribution in compressed gaseous form or in liquid form. The evaluation is complex and depends on factors like the upstream production and conditioning, the value chain energy efficiency, costs, chain flexibility, end user needs, and safety-related aspects. The article relates primarily to energy related aspects of a medium scale distribution chain for compressed hydrogen intended for heavy vehicle transport applications. Hydrogen production is assumed based on production by electrolysis from renewable sources. Some initial considerations related to the possible integration of liquid hydrogen in parts of the chain are also made. A compressed hydrogen value chain involves compression and re-compression in several stages, as well as a possible need for pre-cooling of the hydrogen prior to fuel tank charging. The results show a power demand for compression in the range 4.6-6.2 kWh/kgH2 depending on the efficiency of the compression. An additional power demand for refrigeration in the range of 0-0.25 kWh/kgH2 will be required depending on end pressure and fueling time limitations. In conclusion, the power demand in the distribution chain may be approximately 10-13 % of the power demand for electrolysis, assumed to be 50 kWh/kgH2. Liquefied distribution might be an alternative. The power demand needed for liquefaction and cryo-pumping may be estimated to about 10 kWh/kgH2 based on literature data. Thus, the power demand may be doubled compared to compressed gaseous value chain, but not more than 20 % of the power needed for production. Cost elements such as for storage tanks and compressors, required energy storage capacity, flexibility of end-use storage, as well as operational costs and safety-related issues may thus be more important factors in design and operation of medium scale distribution chains for hydrogen if compressed is to be compared to liquified distribution.