With the inexorable rise to $100-a-barrel pricing, alternative-fueled transportation once again will rise up the agenda. The recently completed trials of hydrogen-based buses across Europe provided some salutary information on how transportation based upon this energy carrier could survive as a viable transportation fuel. The data are in and the conclusions are far from convincing. While most of the European trials—the CUTE project—were extended beyond their two-year lifespan (two of the nine city fleets were not renewed) the Australian trials—the STEP project—was completely scrapped. A fleet introduction in China has just concluded, although the results are not yet available.
In terms of public perception of the safety of hydrogen-fueled buses, of those surveyed in Europe, people were generally well-disposed to the technology and felt safe with it. It was the over-40s demographic group that was interested in knowing more about the technology. The drivers themselves were more positive (than the public as a whole) to the technology, and although the environment was rated as a big factor in influencing purchasing decisions, 64 percent of the passengers surveyed were not willing to pay more for a journey taken on a fuel-cell bus compared to a regular diesel-powered vehicle.
System Infrastructure Failures
The CUTE project, like any major technology introduction, experienced its share of technical problems. Analysis of the data for all the cities included within the CUTE initiative (and the complementary ECTOS program in Iceland and STEP program in Australia) supports the idea of most reported system failures being due to the refueling infrastructure rather than the buses themselves. Despite some rigorous documentation, the majority of failures were attributable to ‘unspecified incidents.’ The hydrogen dispensing system (and the unavailability of hydrogen) and compressor failure collectively accounted for more than 70 percent of all reported failures. By comparison, there were only 10 bus-related failures across the entire fleet of more than 30 vehicles throughout the trial period.
Of the nine European Union (EU) cities included within the trial, only two—Porto and Barcelona—significantly came in below the average of 100,000 kilometers of travel. In the case of Porto there were above-average problems with the bus itself due to modifications to the hydrogen supply. In Barcelona’s case, there was a serious case of graphite contamination within the hydrogen line that affected purity of the supply. At the other end of the success scale, the three buses operating in Luxembourg totaled more than 140,000 kilometers of travel.
Averaged out for all cities, the monthly totals of distances covered increased from under 3,000 to more than 5,000 kilometers over the trial period. Likewise, hydrogen consumption increased from around 700 kg per city to almost 1,200 kg as the trials reached their conclusion. For the project as an entirety, the on-site production of hydrogen in general remained steady, in terms of volume, throughout the project lifetime. Whereas the consumption of electricity for electrolysis of water to produce hydrogen was steady, the other source of on-site hydrogen generation (steam reforming from natural gas) was highly variable, reflecting the difficulties in adapting the reformation technology to the required volumes of hydrogen production.
Throughout the trials, unexpected vehicle stops were mostly attributed to compressor failure at the station, with failure of the electrolyser and the filling nozzles accounting for the bulk of other vehicle stops. The filling nozzles had to be retrofitted in all the filling stations. Failures in the hose and breakaway were recorded in three of the cities (London, Stockholm and Perth).