The Fuel Cell
High efficiency power generation with water as the only emission
A fuel cell is an energy converter that converts chemically stored energy in hydrogen to electricity by catalytically reacting it with oxygen from the air to form electricity, heat and water as products.
The principle is similar to a battery but the energy content is not limited by the container but by the sources of hydrogen. A fuel cell does not work stand alone and thus needs other surrounding components to transfer hydrogen, air and coolant in and out of the fuel cell stack. A fuel cell has a voltage of about 1V if no load is applied. When load is applied the normal operating window is 0.6 – 0.8V per cell. The area of the fuel cell determines the current and the number of cells give the operating voltage window and total power.
How does it work?
A fuel cell is made up by a thin membrane, an electrolyte, which conducts protons (H+) and is gas impermeable. On each side of the membrane is an electrode made of catalyst on a porous support. The anode (hydrogen side) is the negative pole and the cathode (air side) is the positive pole. Hydrogen is fed to the anode and catalytically separated into protons and electrons. The electrons are electrically conducted to an external circuit and the protons are conducted to the cathode by the electrolyte. Air is fed to the cathode and on the catalyst the oxygen reacts with the proton from the electrolyte and the electrons to form water and heat. To separate hydrogen air and cooling media from each other, a three fluid channel system is created in a bipolar plate. A rubber gasket separates the medias from each other and seals between the membrane and the plate.
PEM Fuel Cell
PEM is a fuel cell that uses Proton Exchange Membrane as an electrolyte. There are several different types of fuel cells classified according to the type of electrolyte they use, which largely determines the properties of the fuel cell.
PEM fuel cells operate at a relatively low temperature (<100°C) with rapid start-up and response times. They have the highest energy density of all fuel-cell types and are the most commonly used and mature fuel-cell technology. This makes them ideal for most applications, including for deployment in the automotive industry. About 95% of all fuel cells delivered are of the PEM type. The previous drawback was that PEM fuel cells were shown to be most suited for use with pure hydrogen gas, but were not suited to reformed gas. PowerCell has a reforming technology with the capacity to produce hydrogen gas of such a quality that it can be used in a PEM fuel cell from reformate based on fossil fuels. The area of use is thereby dramatically expanded.