8 LCA (5) 2003     Fuel cells as energy converters and hydrogen as a suitable energy carrier are often seen as a potential solution to problems associated with our global energy system (see the article on p. 283–289). Fuel cells are electrochemical energy converters and have been known for a long time (see William Grove's experimental set-up from 1842, below right). The principle design of a single fuel cell is simple: it consists of an anode, an electrolyte and a cathode (below left; courtesy of DLR-ITT Stuttgart, Germany). Nevertheless, used as power plants [for instance the cogeneration units by MTU Friedrichshafen, Germany (above left) or Siemens Westinghouse (above middle)], or as power suppliers for electric vehicles, a number of technical, environmental and economic questions have to be tackled. The ultimate goal of many fuel cell enthusiasts is the solar hydrogen economy where hydrogen produced from renewable energy carriers is used as a fuel for mobile and stationary applications (see filling station in Munich, above right, courtesy of BMW) and where the hydrogen circle – production of hydrogen by water electrolysis, emission of water when the hydrogen is energetically used – is closed. In small scale, this hydrogen cycle has been realised in the German Hysolar building (central picture, courtesy of DLR-ITT Stuttgart). Cover design: Edwin Grondinger.

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