High efficiency power generation with water as the only emission.
A fuel cell converts chemical energy directly into electrical energy. Fuel cells have a broader field of application than any other available source of energy and can be manufactured for small units that produce only a few watts, right up to major power stations generating megawatts.
A fuel cell generates electrical energy via an electrochemical reaction. The process is similar to a battery, with the difference that a battery consumes its electrodes when they produce electricity and must therefore be discarded or recharged. Fuel cells, on the other hand, produce electrical energy as long as fuel is added in the form of hydrogen and oxygen.
The fuel cell
Compared to a combustion engine, which is also powered by a reaction between fuel and oxygen, higher power efficiency is achieved. While the combustion engine’s thermomechanical process means that a large part of the energy is always consumed as heat, the fuel cell’s reaction takes place at a significantly lower temperature. In contrast to the combustion engine, water and heat are the only emissions generated by a fuel cell.
The fuel cell’s key components are an anode, cathode and electrolyte. The electrolyte largely determines the properties of the fuel cell. We use Proton Exchange Membrane (PEM), with ion-conducting polymer membrane as the electrolyte. PEM fuel cells operate at a relatively low temperature (<100°C) and therefore have valuable rapid start-up and response times. They have the highest power density of all fuel cell types and are thereby significantly smaller and lighter than other versions.
When in operation, the anode is fed with fuel in the form of hydrogen (H2), while the cathode is continuously fed with air (O2). The hydrogen molecules are oxidised at the anode, forming hydrogen ions and electrons. The electrons wander through the external electrical circuit, which connects the anode and cathode, to generate electricity. Meanwhile, the hydrogen ions are transported via the electrolyte to the cathode, where they combine with the oxygen molecules to form water and heat. The result is electricity, water and the heat generated by the reaction. Since the fuel cells are liquid cooled, the heat can e.g. be used to heat buildings.
Fuel cell stacks and systems
A single fuel cell produces less than 1 V, which is insufficient for most applications. Therefore, individual fuel cells are typically combined in series into a fuel cell stack. It generates electricity in the form of direct current from the electro-chemical reactions that take place in the fuel cell. A typical fuel cell stack may consist of hundreds of fuel cells. The stack’s voltage and output can be varied by increasing or reducing the number of cells in the stack. The fuel cell stack is the heart of a fuel cell power system.