Will Your Notebook Soon Be Powered by Methanol?

Fujitsutoday announced the development of a new fuel-cell material technology that enables the use of 30% methanol - highly concentrated methanol - as a fuel source, as well as a prototype power unit that incorporates the technology. This technology enables much higher power capacities for passive micro fuel cells (a fuel-cell system that uses no fuel-supply pumps or circulatory fans, relying entirely on gravity and natural convection to circulate fuel and air, this is ideal for small, lightweight systems)and realizes longer runtimes for mobile devices such as notebook PCs, PDAs and mobile phones.

What's the big deal?

Is your fuel cellbattery running low?

While it's not likely that fuel cells will replace all batteries any time soon, the market it growing at an exponential pace. The fuel cell essentially converts hydrogen or methanol, combined with oxygen into energy, water and heat. Once the fuel supply runs out, you simply refill or replace the fuel source. The end result is clean energy that is easy to re-use. While the most impact might be felt on applying fuel cells to cars and other situations where there are high levels of exhaust, mobile devices certainly have a role. Fuel cells promise much longer lives than batteries and can be easily refilled with a liquid or gas fuel. While I'm not sure everyone will want to carry around a container of fuel, the technology may become so prevalent that you'll be able to pick it up at your local corner store.


Background on Notebooks andthe Need for More Energy

As notebook PCs evolve to deliver higher performance and greater functionality, they have also come to demand more electrical power. But the lithium-ion (Li-ion) batteries commonly used today have already approached the limits of their capacity, which has made the development of a higher-capacity power source a matter of greater urgency. The only way to increase power from a lithium-ion battery is to increase its size, thereby defeating the purpose of having a light and mobile computer.

Micro fuel cells, envisioned for use in mobile devices, generally use alcohol solutions as fuel. In terms of energy density, these fuel cells offer up to 5-10 times the power per unit weight of a Li-ion battery. From the user's perspective, micro fuel cells have advantages in that they offer cheap and easy means to power electronic devices by simple refueling, enabling continuous use when traveling with no access to the power grid.

Challenges

Passive systems are best suited for micro fuel cells to help keep the package compact and light, as they do not require fuel pumps or circulatory fans. Thus, in order to obtain long runtimes without such functions, the fuel cells must be able to handle concentrated methanol as its fuel.

To date, micro fuel cells mainly have employed fluorinated polymers for their solid electrolytic material. But fluorinated electrolytes are too readily permeated by the methanol molecules in the fuel, so that when concentrated fuels are used, fuel is lost in the generating process and power capacity suffers, and the sub-reaction of methanol and air drastically reduces wattage, creating a problem known as methanol crossover.

Fujitsu's Technology and Solution to this Challenge

Fujitsu has developed a new material technology for the Membrane Electrode Assembly (MEA - A composite power-generation unit consisting of an electrode catalyst layer and a film/membrane of a solid electrolytic material, which is the basic unit of a fuel-cell system). An aromatic hydrocarbon solid electrolyte material, which allows slow methanol permeation, is covered with a high density of highly active platinum-based nano-particle catalyst with methanol blocking properties. This reduces the total MEA methanol crossover effect to one-tenth that encountered with typical fluorinated polymers.

Benefits

This new material technology for MEA enables the direct use of methanol concentration of 30%, previously too high to use, resulting in greater capacity from passive fuel cells. Applying this technology in a prototype micro fuel-cell system with 300ml of 30% methanol enables a notebook PC to run for eight to ten hours. Furthermore, the prototype fuel cell has been slimmed down to a thickness of a mere 15mm, while delivering power output levels of 15 watts.