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Hydrogen for clean urban transport in Europe

Exploitable results

Fuel cell buses and some aspects of the hydrogen infrastructure gave surprisingly high levels of availability. The project also demonstrated that the vision of a future transport system based on fuel cells and hydrogen can become a reality when all the optimisation potentials identified in 'Clean urban transport for Europe' (CUTE) are realised and transferred into series production. More than 4 million passengers were transported and directly experienced travel powered by fuel cells. This extraordinary level of exposure is far greater than all other fuel cell projects currently running added together. The distance driven and the number of operating hours of the bus fleet are perhaps the most impressive figures from this project. They document a huge step forward with regard to the lifetime and durability of the fuel cell system. Never before has a hydrogen technology project demonstrated such an outstanding operating success. Buses driven by regular bus drivers in normal traffic under standard operating conditions completed a distance of more than 20 times around the globe, producing a wealth of data and building a vast pool of experience. Fuel cell buses Over the two years of operation (the project finished in December 2005) the 27 CUTE buses travelled a distance of almost 865 000 km in the nine partner cities and were operated for over 64 000 hours, demonstrating their reliability. This also enabled a vast amount of data collection and experience of travel in and operation of fuel cell buses The distance driven in each city ranged from some 40 000 km up to more than 140 000 km, depending on the conditions in the particular city, while the operating hours ranged from about 3 300 hours up to close to 10 000 hours. The longest lifetime of a single fuel cell stack was more than 3 200 operating hours, which greatly exceeded all expectations. The buses performed with a better than expected reliability and availability. The data obtained also showed the optimisation potential of this prototype bus with regard to fuel consumption. Simulations showed that fuel consumption could be reduced by up to 50 % using hybridisation and more electric drive train-related technology. The fuel cell technology itself and the hydrogen components did not show any significant weak point, but other electrical components such as the inverter need to be improved. Hydrogen infrastructure All filling stations except one were operational (available) for more than 80 % of the time over the 2 years of operation. The majority had an availability of more than 90 %. Reliability in terms of successfully completed filling was generally somewhat lower. Critical components needing further development were the compressors and the refuelling interface. While electrolysers were generally reliable, the small-scale steam reformers need to be improved if the concept of an on-site hydrogen supply system is to be realised. The off-site large scale steam-reformer, often the source for trucked-in hydrogen, worked extremely well. The hydrogen filling stations supplied the fuel cell buses with more than 192 000 kg hydrogen in more than 8 900 fillings. This is far more than any previous trial of hydrogen-powered vehicles. The amount of refuelled hydrogen per site ranged from some 10 000 kg to 29 000 kg. More than 40 % of the energy for the hydrogen supply structure within CUTE came from renewable resources. Key findings of the accompanying studies are: The energy efficiency of the hydrogen production and dispensing infrastructure was generally poor. This meant that the overall environmental impact of the fuel cell bus system (vehicle and fuel supply) was highly dependant on its own efficiency and on the hydrogen supply route chosen, particularly the source of energy input. This demonstrates yet again the importance of increasing the level of renewable inputs to stationary energy production. There is a need for a significant cost reduction in hydrogen production and of hydrogen refuelling stations, as well as in the fuel cell vehicles. Target cost of EUR 2.5 to EUR 3 / kg of refuelled hydrogen cannot be realised with today's technology.