In today’s world, energy is generated mainly by fossil fuels. Motor vehicles are driven almost exclusively by gasoline and diesel fuels.
The supply of fossil fuels is limited and their exploitation is becoming an increasingly risky venture along with threats of massive burdens on the environment (oil disaster in the Gulf of Mexico, CO2-climate debate, etc.). A change of energy supply in favor of sustainable available energies therefore over the coming decades has to inevitably take place.
These so-called “renewable energies” are always due to the influence of sun and moon (weather patterns for wind and hydro, solar and tidal energy and renewable resources) and are therefore available from a human perspective virtually endless. The core question for the availability of energy should therefore be defined more precisely to a) how can we collect this energy in abundance, b) how can we store and c) how we can transport this energy.
For our mobility while the main challenges refer to storage and transportation, thus in the mobile-availability of the energy of tomorrow.
Due to the comparatively also endless availability of hydrogen at any place on Earth, its very high energy density (by weight e. g. 3 times higher than gasoline) as well as of the possibility of a zero-emission combustion (electrochemical oxidation) particularly in fuel cells, hydrogen, the smallest and lightest atom in our periodic table of elements represents the undisputed candidate among experts.
The storage of hydrogen basically can be achieved by three methods. The method to compressing as much hydrogen in a pressure vessel (e. g. gas bottle, currently possible up to about 900 bar) as well as the “liquid storage” of hydrogen at extremely low temperatures (cryo-tanks at -253° C) do require highly complex tank systems that either fail uneconomically expensive or will not find acceptance among consumers (“gas bomb”) – or both.
The third and “proper” method is to store large amounts of hydrogen at very low pressure in a so-called solid state storage (solid state absorber). For this purpose, the material class of metal hydrides is particularly suitable. These are materials that can absorb hydrogen “like a sponge.” It only requires a certain heat input to back the hydrogen out of the solid storage material (reversible absorption / desorption).
The advantages of hydrogen storage in metal hydrides (in this case so-called low-temperature hydrides) are the inexpensive and safe storage of hydrogen (average working pressure <10 bar) and the handling at room temperature. By the alternating loading and discharging, the storage material is not consumed and therefore does not create any waste products and such tank can be operated for a long time.
For that, at Zoz GmbH in Wenden/Germany, hydrogen-tank systems (H2Tank2Go®) are developed and manufactured that in medium term will be incorporated into the electric vehicles of the therefore specially founded company Zoz Mobility (prototypes already semi-commercially available). As the metal hydride storage material inside the tank cartridges, the Zoz powder material called Hydrolium® is utilized. Particular attention is given to the manufacturing cost since as well as in electrical mobility itself, they represent the major barrier to successful market introduction. Zoz thereby wants to reduce the storage costs to one-eighth of the previous usual.
For easy handling, the H2Tank2Go® tank-cartridges are delivered to the customer already fully loaded with hydrogen, which he can connect via a quick coupling system (Click ‘n-go system) quickly and easily to the fuel cell of the electric vehicle. After consumption of the tank load, the empty cartridges can be exchanged in circulation against full tanks.
The volume of the fuel cartridges for strategic reasons is fixed to marginally less than one liter. At present about 50 g of hydrogen (> 500 NL) are stored in each tank. Improvements at the nanostructured storage material through further R&D shall cause to double this amount in the future. This would mean that about 23 tank-cartridges with an energy capacity of then 75 kWh would be enough to move a small passenger vehicle at a weight of 1 ton in a range of 300 km, where the refueling time will be about 2 minutes..
Consequently in the future, refueling will be done by simple cartridge exchange at any Zoz-Mobility-Store or home depots or at modified vending machines. And of course such machines can be installed at each conventional gas station.
In cooperation with TÜV, the tanks shall receive the on-road approval (MOT) within year. As the first vehicle, the isigo® H2.0 shall be approved on road within the second quarter of next year and then come onto the market. Prototypes are already available at prescribed requirements without any admission or approval.