NH2 GO WITH NEW TOOL

fcFOCUS profiles an interesting new hydrogen generator
for PEM fuel cells, used in mobile electronic devices

ALVATEC is a high-tech metallurgical start-up company based in Althofen, Austria. It specialises in the processing of alkali and alkali earth metals, vacuum and hydrogen technology. After reading an article about the problems of supplying Hydrogen for fuel cells, the company decided to design a generator which produces hydrogen in a simple and controllable way. Sebastian Schebesta takes up the story.

New hydrogen generator

After several years working with chemically- active alkali materials, Alvatec understood completely the need to avoid bringing alkali metals and alloys into contact with water as the resultant reaction would produce unwanted gas, namely hydrogen.

However, in 2006 one of its scientists read an article about fuel cells and the big problems they faced with regard to hydrogen supply.

Pure alkali metals have a strong exothermal reaction with water, sometimes even an explosive ignition of the developed
hydrogen or of the alkali metal. Alvatec tested this on its products and found, much to its surprise, that most of the
alkali and alkaline earth metal alloys have a less explosive, more moderate reaction with water.

As a result Alvatec started a project to design special alkali metal alloys with a controllable reaction with water, acids and other protic compounds. It now uses these in the Alvatec hydrogen generator for proton exchange membrane (PEM) fuel cells, still under development. First patents are pending.

Technology

The goal of the project was to design a generator that produces hydrogen in a simple and controllable way. The produced hydrogen had to be pure and wet to feed the PEM
fuel cells on demand.

To do this Alvatec developed alloys that contain at least one alkali metal. The generated hydrogen comes from the chemical
reaction of water with these alloys.

The formed alkali base guarantees that the whole alloy reacts with water to liberate hydrogen with a high yield. The exothermal reactions need no extra catalyst or heating and have high rates of production. The results of this reaction form the generated hydrogen, and a base as a solid by-product.

This hydrogen generator system uses a replaceable cartridge system. The reactive material is in the tank. The hydrogen
generation process starts by adding water in a controlled manner directly to the cartridge.

The high reaction rates mean that the liberation of hydrogen stops as soon as water ceases to be added. When the material is completely consumed the solid byproduct stays in the tank. The cartridge is designed to be sealed tightly before and after mounting it to the rest of system.

A basic schematic is shown in figure 1. Table 1 compares Alvatec hydrogen generator alloys (highlighted in green) with
other interesting candidates of a chemical hydrogen source. Energy densities were calculated taking into account the amount of alloy, water (and acid). Fuel cell efficiency is 50%.

Market potential

Alvatec believes the availability of a high energy density and wet hydrogen supply opens the door for an economic redesign, and market success of PEM fuel cells.

Typical applications for the new hydrogen generator will be portable fuel cell chargers for cell phones and laptops, micro-batteries and sensors, medical pumps, and military applications, for example.

Alvatec hydrogen generators are suitable for PEM fuel cell systems in the range from 0.1 w to 100 w.

Large scale production

Manufacture of the Alvatec hydrogen generator and the cartridges can be scaled up to meet consumer demand. There is sufficient capacity in the alloy industry as well as among system integrators and contract manufacturers.

Cooperative ventures

Alvatec has started cooperative ventures with fuel cell companies and research institutes to develop fuel cell-based platforms for different applications.

A partnership with myFC AB from Sweden focuses on the development of a micro fuel cell charger for mobile phones and
other portable electronic devices. myFC has developed an effective way to produce small fuel cells in an output range around 2 w. Combined with the Alvatec hydrogen generator, this venture is delivering promising results.

As part of a long term partnership with a Fraunhofer Institute in Berlin, Alvatec is investigating the qualities of its alloys in more detail. As a result of this venture it is working on a fuel cell system for sensors. Other partnerships for larger applications are in preparation.

Further information:
Alvatec
Tel: +43-4262-2644-1321
Email: sales@alvatec.com
Web: www.alvatec.com

Note: Alvatec will show its first prototype hydrogen generators, first fuel cell platforms and portable chargers at the industrial trade fair in Hannover from 16-20 April 2007 at Hall/Floor/Stand No. 013 F40/5.