Toshiba's 'world first' methanol fuel cell cracks the portable PC power problem

The new prototype, announced in Tokyo this week by the Toshiba Corporation, works for about five hours on 500 ml of fuel contained in a replaceable cartridge.

It provides instant power and achieves significant advances in operating times, without having to be close to a mains power supply.

"Toshiba will continue development of DMFC technology, with the aim of commercial availability next year," said Ahmed Khalil, regional manager of Toshiba's Middle East Computer Systems Division.

"We will present the prototype at the CeBIT exhibition in Hanover, Germany from March 12 to 19," he added.

The limitations of current lithium-ion batteries have inhibited the advances made in computer portability by faster CPUs, higher resolution displays, and wireless connectivity that all depend on increased power supply.

Fuel cells are widely seen as the answer, but engineers have battled to overcome the problems of miniaturisation and fuel delivery.

Toshiba has achieved the breakthrough with its DMFC technology, generating clean energy with average output of 12W and maximum output of 20W.

Although methanol in a fuel cell delivers power most efficiently when mixed with water in a 3-6 percent methanol concentration, the compound needs a fuel tank much too large for use with portable equipment.

Toshiba overcame this by developing a system that allows a higher original concentration of methanol - achieving the correct dilution by using water arising as a by-product of the power generation process.

This technology allows methanol to be stored at a much higher concentration, enabling the fuel tank to be less than a tenth of the size.

Toshiba has also devised new technologies for miniaturisation of a high performance fuel cell. These include interface and electric circuits to assure efficient control of power supply, and sensors that monitor methanol concentration and liquid level as well as indicating when the fuel cartridge needs replaced.

All these components, and low power liquid and air transmission pumps, are controlled by a super small DC-DC converter.

For the cell itself, Toshiba developed a new material that allows smaller cells, allowing for miniaturization of the cell stacks.

Optimized operating efficiency was also a priority, ensuring that the fuel cell generates power at the required level with minimal waste of energy. To achieve this, Toshiba researched fuel density, circulation, and air supply levels.

The PC itself sends information on its operating status to the fuel cell so as to balance power demand and supply. Any unused energy is stored in the cell and can be drawn on when the PC requires extra power.

Toshiba has given the DMFC the same electrodes as lithium-ion batteries, so that it can connect directly to a PC or other portable device. It can also be used as an alternative to lithium-ion batteries.