Lowering Energy Spending Together With Compression, Storage, and Transportation Costs for Hydrogen Distribution in the Early Market

Abstract

This present paper is dedicated to the optimization of cost and energy consumption for compression, transportation and storage of hydrogen for vehicle refueling in the current hydrogen emerging market. So it considers only small refueling stations (20 to 200 kg/day) and currents costs. It considers 2 cases: the case of a refueling station on the site of the hydrogen production and the case of a production unit supplying hydrogen to several distant refueling stations. In the case of production and distribution located on the same site, no transportation has to be considered and the energy consumption is mainly due to hydrogen compression and cooling. In a reference case corresponding to good current practices, the study calculates an energy need at 3.5 or 4.4 kWh per kg of hydrogen transferred to car tank at respectively 35 or 70 MPa. It then shows that this need can be reduced by more than 25 % when judiciously using 4 or 5 stages of buffers organized in a pressure cascade for the filling of a tank at 70 MPa. Whereas the total volume of the staged buffers is higher than the volume of an only very high pressure buffer (VHPB), the investment cost is only slightly higher; then the energy saving results in short payback times for the extra investments in staged buffers. In the case of a production unit supplies hydrogen to several distant hydrogen refueling stations, energy for transportation by truck and for re-compression on the distribution site must be added. Current offsite distribution practices are used as a reference case: it considers the transportation of hydrogen in 20 MPa steel bottle bundles or trailer tubes and the recompression of all the hydrogen to the VHPB. To lower the energy spending, solutions are proposed and quantified, such as using small transportable containers of higher pressure light composite bottles and by-passing of the compressor as much as possible. Energy needs and CO2 emissions are estimated and compared for the reference case and the innovative cases. The study shows that, even if the investment in composite bottles is high, the resulting overall cost is definitely lower and CO2 emissions can largely be decreased. The size effect appears very important: cost decreases by 60% from 20 to 200kg/day. words ________________________________________________________________________________________1 Acknowledgement: This work is a part of the VABHYOGAZ3 project supported by the French "Programme d'Investissements d'Avenir'' under supervision of ADEME, the French Energy and Environment Agency. The project is conducted by HERA France office ALBHYON, in partnership with TRIFYL, HP Systems, EMTA (VEOLIA group) and the IMT Mines-Albi RAPSODEE Research Center. The VABHYOGAZ3 project considers hydrogen production from biogas with production units ranging from 100 to 800 kg/day to deliver hydrogen to several distribution units of 20 to 200 kg/day located within a distance less than 100 km from the production unit. The authors are grateful towards the ADEME for its support to this project. 2 Corresp...

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