Packing a fuel cell

A hybrid fuel cell system capable of generating significantly more energy than standard batteries could be used in battlefield equipment.

The army’s Future Integrated Soldier Technology (FIST) programme, due to start in 2009, is designed to equip soldiers with sensors, communications equipment and information technologies. Batteries, however, will be unable to support the power requirements of all this new equipment due to their weight.

For that reason, the MoD is presently evaluating a hybrid fuel cell device developed by Qinetiq as a solution to the increasing energy needs of the infantry and Special Forces soldier.

Unlike standard fuel cells, the portable Qinetiq device, which is capable of producing up to 60W of power from a 10-cell stack, contains a microprocessor with a tiny lithium ion battery that allows it to start up instantly.

For the army, the new Qinetiq device offers several advantages over standard fuel cells, said Dr. Gary Mepsted, technology leader for Qinetiq’s environmental sciences group. ‘A fuel cell on its own is not like a battery – you cannot simply plug it in and off it goes. Our system is very user friendly: the soldier can immediately start it up, and when unplugged it will shut down straight away. We don’t want the soldier to even think that this is a fuel cell.’

Existing fuel cells are expensive to make, and the materials used are not suitable for use on the battlefield. The Qinetiq system, on the other hand, uses plastic injection-moulded parts wherever possible, making it durable and cheap to produce.

The team has also developed a hydrogen generation system that is more appropriate at smaller scales than existing storage devices such as gas cylinders. The dome-shaped device consists of layers of pellets made from a material containing 20 per cent hydrogen by weight. The pellets decompose thermally when ignited by a small wire underneath, producing hydrogen and an inert solid as a by-product.

The hybrid system can be used with professional cameras, which tend to be heavy and power hungry, and as an auxiliary power source for trains, aircraft, cars and mobile phone base stations. A 25W version is also being developed that is more suitable as a power pack for smaller devices such as laptops.

The company is also working on an even smaller fuel cell for consumer electronic devices. This will be capable of producing 200 times more energy than a standard mobile phone battery.

The device is much simpler than standard fuel cells, as it is based on a tubular shape with the electrodes on the outside and the fuel in the middle. This eliminates the need for fans to drive air over the electrodes, as they can get all the air they need from the atmosphere.The team has produced a 6W device the size of a C battery, but is hoping to reduce this further to AA battery size. The fuel cells can be used to power devices such as mobile phones, and can easily be clipped together to increase the power generation capability to the required amount.

The devices can run on hydrogen but for consumer applications such as laptops and mobile phones, where safety is critical, the team is investigating the use of a non-flammable aqueous solution. This solution produces more power than methanol, the fuel currently being considered for most other miniature fuel cells in development.

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