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Useful information about fuel cells
Fuel cell systems generate electrical energy from hydrogen and oxygen. They are used both stationary and mobile for the power supply of diverser electrical consumers. In the private sector, fuel cells are of interest for the use of electrical devices while traveling, for example, in mobile homes, on boats, in garden houses or on camping sites.
The fuel cell is regarded as a technology of the future. Other applications include heating systems and power drives for vehicles, ships, aircraft and space rockets.
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How do fuel cells work?
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What are fuel cells used for?
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What fuel cells are available in the shop?
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Technological progress: The future belongs to fuel cells!
How do fuel cells work?
Fuel cells generate electrical energy from hydrogen. They are maintenance-free and can be used all year round.
Unlike batteries and accumulators, fuel cells are not energy storage, but energy converters. In other words, they generate electricity on site only when it is needed. This results in high efficiency.
Fuel cells are a forward-looking and efficient form of energy production, as they can generate electricity anywhere. The on-site production eliminates the effects of batteries and accumulators which are inevitably caused by the double conversion of electrical to chemical energy and back. In addition, the use of fuel cells eliminates the energy losses caused by longer storage and the associated self-discharge of battery cells.
Fuel cells are also environmentally friendly. The conversion of hydrogen and oxygen into electrical energy takes place without emission. As residual products, the hydrogen fuel cell generates only water and heat. The chemical conversion process is cold combustion. For safety reasons, this low heat development is of interest for many applications.
The construction of a fuel cell is relatively simple:
- Two electrodes, the anode and the cathode, are separated by a membrane (electrolyte).
- On one side hydrogen flows in, on the other oxygen flows in.
- Hydrogen consists of two electrons and two protons as a chemical element. These are separated and go different ways in the fuel cell:
- The protons pass through the membrane directly to the side with the incoming oxygen.
- The electrons take the detour via the connected circuit. As a result, current flows and the fuel cell passes on electrical energy to electrical consumers (for example, the light bulb in Figure 1).
- When the electrons finally arrive at the protons on the oxygen side, hydrogen protons together with the electrons and the oxygen produce harmless water.
Info: The total chemical equation for the reactions in the original hydrogen fuel cell* is:
2 H2 + O2 -> 2 H2O
* For various types of fuel cells, the basic equation is partly modified by additives. For example, for a direct methanol fuel cell, the equation is 2 CH3OH + 3 O2 -> 4 H2O + 2 CO2, so some carbon dioxide is produced.
The voltage in the circuit is approximately 1.2 volts for a pure hydrogen-oxygen fuel cell. Higher voltages can be generated by series connection of the cells. To do this, the fuel cells are "stacked". The powerful formation of several fuel cells connected in series is called stack. Stack comes from English and means stack or stack.
Practical knowledge:
A fuel cell stack consists of several individual fuel cells, which together can provide more electrical power and enable a higher electrical voltage. In terms of language, one often speaks of a fuel cell, but actually means a functional unit consisting of several, small energy converters.
What are fuel cells used for?
For private users, there are currently fuel cells with a nominal voltage of 12 or 24 V. This is sufficient for charging a car battery or for supplying electronic consumers directly on board a camper van, a ship and other mobile applications.
Tip: Fuel cells also provide good services in small garden colonies, because they can be used all year round and thus bridge possible power interruptions in the winter months.
What fuel cells are available in the shop?
In our shop you will find membrane fuel cells as well as direct methanol fuel cells.
Nowadays freely available fuel cells for mobile operation generate electrical current for consumers with low voltage between 12 and 24 V. For example, you can charge mobile phones and laptops with a fuel cell, operate TV sets and radios or supply a floodlight with power. Both the voltage and the electrical power of the connected devices must be compatible with the electrical parameters of the fuel cell. This power is currently around 40 to 380 watts for low-voltage fuel cells, which was also possible for a wide range of electrical applications in view of the trend toward energy-saving small appliances.
By the way: The charge quantity of fuel cells is indicated in ampere hours (Ah). The charging capacity per day can be converted into the available current according to the quotient 24.
Membrane Fuel Cell (PEMFC)
Diaphragm fuel cells generate electrical energy CO2-neutral. In operation, these fuel cells are very quiet compared to diesel engines and similar alternatives for power generation independant of the location.
To operate a diaphragm fuel cell, you need only one hydrogen bottle.
The hydrogen fuel cell can be integrated into existing energy systems. By the optional connection of lead accumulators, such as a vehicle battery, you have the possibility to store the electrical energy generated by the fuel cell for later use between.
Figure: Functional diagram of a diaphragm fuel cell (PEMFC)
Direct Methanol Fuel Cell (DMFC)
Direct methanol fuel cells convert methanol and oxygen into the basic products of water and carbon dioxide in the production of electrical energy. The chemical equation for the reaction in the direct methanol fuel cell is:
2 CH3OH + 3 O2 -> 4 H2O + 2 CO2
The proportion of CO2 produced is not very high, but rooms should be ventilated more frequently when the methanol fuel cell is working. These fuel cells are also quiet in operation and can be used to save space.
For the operation of a direct methanol fuel cell you need methanol and occasionally some service fluid.
Note: The required methanol may not be sent online. However, you can get it in our local Conrad branches. Methanol may only be delivered to adult customers.
Figure: Functional diagram of a direct methanol fuel cell
Technological progress: The future belongs to fuel cells!
The advantages of the fuel cell are:
- Simple construction
- Zero-emission, quiet operation
- Conversion capability of the generated electrical energy for charging batteries
- Location-independant application possibilities.
These advantages suggest that this technology will prevail in the future over conventional forms of electricity generation and, in particular, mobility applications.
Apart from diaphragm fuel cells (PEMFC = Proton Exchange Membrane Fuel Cell) and direct methanol fuel cells (DMFC = Direct Methanol Fuel Cell), there are other types of fuel cells:
- Solid Oxide Fuel Cell (SOFC)
- Alkaline Fuel Cell (AFC)
- Phosphoric acid fuel cell (PAFC = Phosphorous Acid Fuel Cell)
- Fusible carbonate fuel cell (MCFC = Molten Carbonate Fuel Cell)
In some of these fuel cells, the chemical reactions are associated with high temperatures.
Areas of application that have already been tested are:
- Cars as hybrid with fuel cell drive
- Renewable energies in the form of solar modules and fuel cell heating devices with heat recovery
- All types of propulsion, for ground vehicles, ships, aircraft and, among other things, for space rockets
Today, these are niche products, but the trend for fuel cells is upward.
The shortcomings where the spread of fuel cell technology (currently still) is haunted:
- For a large-scale application, it would be necessary to find ways to produce hydrogen in large quantities. There are already some interesting approaches here, some of which work with recovered energies from other drive technologies.
- Today's fuel cells are still too expensive for the mass market, compared to lithium-ion batteries, for example.
Overall, there is still a need for some research in this area. However, this technology is clearly ahead was the environmental footprint and the environmental friendliness. It is therefore worth watching closely the interesting topic of fuel cells and their continuing development.