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Fuel Cell and Battery are a team
DWV: do not create artificial conflicts where there aren't any!
There is a broad agreement between car makers, governments and fuel companies: the long term change of road transport has started. Slowly at first, but certainly the electric vehicle will conquer the roads, at first and mainly the private car. The German federal government supports this development towards more sustainable drives in the National Innovation Program „Hydrogen and Fuel Cells“ and in the Initiative for Electromobility.
There have been comments in this context going so far as to say that this means the end for the fuel cell as energy source for vehicles. They say that the requirements could be met with batteries as well, and nothing else were necessary.
DWV disagrees sharply with this opinion and points out that there is no contradiction at all between the battery, an electrical storage device, and the fuel cell, an energy converter. They rather complement each other. The pure battery car will not be the general solution for our future mobility needs, but the fuel cell on the other hand can not perform well without a battery.
Even modern batteries still suffer from the classical disadvantages which set a limit to their use in cars.
- Batteries are heavy:
- A ride of 500 km requires a lithium ion battery with a cell weight of 540 kg, and even 830 kg for the whole battery system.
- The corresponding values for pressurized hydrogen are 6 kg for the fuel (H2) and 125 kg for the full storage.
- Batteries are large:
- A ride of 500 km requires a lithium ion battery with cells demanding a space of 360 l and 670 l for the battery system.
- The corresponding values for pressurized hydrogen are 170 l (fuel) and 260 l (filled storage).
- Charging batteries takes much time:
- Eight hours for a full charge are common, two or three hours for 60 km are standard today; systems doing it much faster demand a technical effort far beyond the possibilities of a private home.
- Filling up a fuel cell car with a technical effort comparable to that of fast charging a battery requires three to five minutes for a range of 400 or 500 km.
- Battery cars offer only a short range:
- There is hardly a battery car which goes farther than 200 km with one charge.
- The Honda FCX Clarity, the most advanced fuel cell hybrid existing today, goes 450 km with one filling under a pressure of 35 MPa (350 bar).
Intensive research and development will certainly improve the situation of the battery, but real breakthroughs in terms of energy density etc. are not in sight for the next 15 or 20 years. Of course we can not wait that long to start reducing the greenhouse gas emissions from road traffic by means of zero emission engines. And at the same time the position of hydrogen and fuel cells will improve as well.
The pure battery car will certainly play a role in future transport, but rather in the domain of short rides in a limited time. This might be the case for pure city cars like the fleets of communal companies, utilities, or authorities. This can not be the all-purpose car for the private customer or for commercial service outside the cities. Nobody who goes from Berlin to holiday in Bavaria will like the idea to make three breaks of several hours each.
So the battery alone is not the solution, but neither is it the fuel cell alone. All fuel cell cars operating or being developed now have a buffer battery to adjust the fuel cell, which should be operated as steadily as possible, to the electric motor, which has a dramatically varying power demand (hybridisation). Another option are plug-in hybrids with fuel cell. No car maker today pretends to be able to do without any type of hybridisation.
The total ecological balance of a fuel cell car depends mainly on which primary energy is used to generate the hydrogen. Of course the same is true for the electrical power used to charge the battery. While there is general agreement on the first statement, the second one is frequently withheld from the public. Another fact is that hydrogen has to be generated using primary energy, thereby reducing the efficiency of the fuel cell. While this is true it is also a fact that electricity as well has to be produced in processes which incur losses. A clean comparison should be based on the same generation process for both technologies; the problem arising here is that electricity is by no means the only path to generate hydrogen.
For all these reasons DWV disagrees with the attempts to create an artificial conflict between fuel cells and batteries. They are a team and belong together, and there are enormous synergy effects in the development of both types of electric propulsion. We welcome the support of research and development in the field of batteries because the fuel cell engine will also benefit from the progress of the battery.
In a nutshell: The car of tomorrow will have an electric motor and a battery. And many, probably even most of the cars of tomorrow will also have a hydrogen tank and a fuel cell.
Published by the German Hydrogen and Fuel Cell Association (DWV), Berlin
Editor: Dr. Ulrich Schmidtchen, Berlin
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