Major automakers such as DaimlerChrysler want to extend the mileage of fuel cell buses by increasing vehicle tank pressure. Instead of 200 bar today (2860 psi) the future standard will be 350 bar (5000 psi). This requires compressors that can consolidate hydrogen gas in the filling station storage up to 550 bar (7860 psi).

The development of a cost-efficient and performance-optimised piston compressor which meets the above specification has started at Bauer Kompressoren and is estimated to be completed in early 2003. The projected characteristics of the new compressor are:

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In 2001 a detailed study of hydrogen fuel supply to buses in public transport was completed at PLANET. The investigation followed the rules for life cycle assessments as laid down in the series of standards EN ISO 14040 – 14043. Seven scenarios were compared which rely on different primary energy sources (e.g. coal, natural gas, wind and water power) as well as various ways of energy conversion (electricity generation, synthesis of methanol, liquefaction of hydrogen...).

Compared to previous works in this field, the data basis could be extended substantially. It enabled the supply paths to be analysed stepby- step and in detail from primary energy to the vehicle ("from well to wheel").

The crucial question was, which of the scenarios would come off well in comparison to diesel, the standard fuel for buses today. The consumption of fossil resources and, closely linked to this, the emission of greenhouse gases belonged to the prime criteria. In this context, the "ecological rucksack" had to be considered, i.e. the effort of energy and materials to build the necessary infrastructure like chemical production facilities, wind turbines, pipelines for transportation etc.

The figure below shows that hydrogen derived from wind power has a significant ecological advantage over diesel. Other renewable energy sources yielded similar results (not displayed here). Only the renewables therefore legitimate the massive investment that will be required to convert the fuel supply infrastructure to hydrogen use.

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