One of the main drivers to the introduction of hydrogen is the possibility to have a local as well as global C02 free system. For that purpose, a renewable energy source must be used, and that is the case when using hydro or geothermal power. However, cost and availability issues bring the possibility of using conventional fossil fuels as primary energy sources. At the present stage, steam reforming of natural gas is the most probable route to produce hydrogen on a large scale (needed if it is to be introduced in widespread use as transportation fuel). For the CUTE project, given its demonstration status, it was been decided to cover a broad range of alternatives, not only in what refers to primary energy source but also if the production is centralized or on-site. The routes taken are summarized in Table 2.
Different filling stations were used in each city, and the hydrogen is either stored at a high pressure (~450bar) prior to refueling or is compressed to a suitable pressure during filling. In any case, the filling time is not expected to exceed 10 minutes. The use of different filling station technologies allowed drawing conclusions to what is the best way to provide hydrogen at such high pressures, regarding not only the energy consumed for compressing the hydrogen, but also the availability of the filling station.
Table 2. Hydrogen supply routes used in the CUTE project.