High Temperature Fuel Cell

Volkswagen Research has developed a type of high temperature fuel cell (HTFC) that is one of a kind in the world. It eliminates numerous disadvantages of low temperature fuel cells (LTFC) previously known and used in virtually every type of vehicle with this propulsion system in the world. "The high temperature fuel cell independently developed by Volkswagen in seven years of research work will make the overall system in the car lighter, more compact, stable and cheaper. And those are the decisive criteria for putting fuel cells on the path towards mass series production", comments Prof. Jürgen Leohold, head of Volkswagen corporate research.

In detail, Volkswagen Research specially developed a new membrane and new electrodes for the fuel cell. Membrane, electrodes, cells – these conceal the exceptionally complex process of extracting electrical energy from chemical energy to power the electrical engine of future fuel cell cars. Compared to the low temperature fuel cell the Volkswagen system with the newly developed parts membrane and electrodes provides the following advantages: For the high temperature fuel cell a significantly simpler cooling system and water management is sufficient. And this significantly reduces the weight and costs. The space required for the fuel cell system is also lowered by more than 30 percent. In contrast vehicle prototypes with low temperature fuel cells have an extremely sophisticated and expensive cooling system. The cooling surface alone is approximately three times as large as for diesel engines.

The high temperature membrane developed by Volkswagen can in combination with newly designed electrodes be "driven" at temperatures of up to 120 degrees Celsius with no loss in performance. And this without humidification. Novelty and background: In the high temperature fuel cell protons are exchanged via phosphoric acid. This acid has good electrolytic properties similar to water, yet demonstrates a higher boiling point. Low temperature fuel cells in contrast are operated at a membrane temperature of approximately 80 degrees Celsius. If the temperature greatly exceeds this value fuel cell performance breaks down and irreparable damage is done to the fuel cell. In addition, in a low temperature system the supply of hydrogen gas and air must be continuously humidified, because otherwise the production of energy will also break down, permanently damaging the fuel cell.

Volkswagen has for decades been involved in the area of fuel cell research. In doing so, the potential of low temperature fuel cells was also extensively researched. The research results on the topic of low temperature fuel cells were in the end crucial towards investing concentrated energy in the development of high temperature fuel cell systems that are more suitable for everyday use, more compact and cheaper. High temperature technology is thus ready for the next research step. A peek into the future could look like this: More higher performance high temperature fuel cell systems come about that are perfected step by step and are expected to power the first research vehicles in 2010. In about 2020 the first Volkswagens with a fuel cell drive that is affordable and suitable for everyday use – the decisive factors – could appear. "We believe that the high temperature fuel cell is part of the future. In contrast, we no longer give much chance to low temperature fuel cells going into series production”, says Prof. Leohold.