Which technology combines best mobility with protection of the environment?
Already several years ago Toyota and Hyundai have started to put their first commercial models with fuel cells on the market, a mature technology considered by now. The cars are equipped with an on-board electric motor. However the energy is not provided from a battery, but is generated on board in a fuel cell, where compressed hydrogen from a tank reacts with oxygen from the air. This process generates electricity. As waste products mainly water vapour and heat are emitted, but no carbon dioxide and very few other pollutants. However there still exists a considerable lack of the required hydrogen infrastructure. A consortium of the companies Linde and Shell had planned to establish in total 400 hydrogen refuelling stations in Germany up to the year 2023.
Compared to pure battery electric cars hydrogen vehicles have several advantages: fuel cell electric vehicles can be fully refuelled within three minutes with the gas and allow also heavy vehicles a travel range over long distances with more than 500 kilometres. This makes them as versatile as vehicles with conventional combustion engines. Additionally, hydrogen is an excellent storage for electricity generated from renewable sources. Disadvantages are the still very high costs for the vehicles and the necessary investments in hydrogen refuelling stations, which are at a cost of one million Euros per location still very expensive. But compared to electric charging stations much less will be needed – with 2,000 hydrogen fuelling stations the whole country of Germany could be sufficiently covered. But the biggest obstacle of hydrogen cars today is their low total process conversion efficiency, because electrolysis and storage of hydrogen is much less efficient than using electricity to directly load a battery.
For the built-up of a mobility infrastructure based on hydrogen, safety and practical application issues stay at the centre of current research and development. Vehicles with hydrogen propulsion shall be as safe as conventionally powered cars and the refuelling process comparable as much as possible to today’s tanking of gasoline, although hydrogen is filled up with a pressure of around 700 bar and a temperature of approximately – 40 degrees centigrade. Therefore the use of hydrogen requires extremely high standards of technology and materials, which hydrogen vehicles and refuelling stations must comply with. A number of various technical service organizations and inspection bodies as among others the TÜV in Germany are engaged in the elaboration of common standards, in order to document their reliability through suitable procedures and with the help of e.g. crash-tests with hydrogen vehicles. Furthermore preferably a global common set of standards should be agreed to, in order to lower costs and to safeguard easy interoperability of systems.
