The traditional battery's days may be numbered. Thanks to recent advances in fuel-cell technology, your next notebook (or maybe the one after that) could run for days on a single charge. These next-generation batteries, which contain chemicals such as methanol stored in small tanks, certainly aren't your average power source. More like tiny chemical plants, different types of fuel cells are currently used in space shuttles, experimental eco-friendly cars and small power plants. NEC is developing a fuel cell for a notebook that could provide a mind-boggling 40 hours of battery life.
NEC is developing a fuel-cell notebook. This is a prototype, but the company expects to bring a product to market by the end of 2004.
So how does a fuel cell work? "The fuel cell is based on the reverse principle of water electrolysis...[Fuel cells] work by having hydrogen and oxygen react to generate electricity", said Yoshimi Kubo, senior research manager overseeing NEC's project to create a fuel cell-powered notebook (prototype pictured above).
Methanol, or methyl alcohol, is NEC's fuel of choice, and Kubo has created a prototype notebook that can run for five hours on about a pint of 10 percent fuel. When the tank is dry, forget about a power cable, because the fuel cell wants more methanol. Just pour in a small bottle of fuel, and it's ready to go. Rather than carrying a bagful of batteries on a long flight, all you'd need is a bottle of methanol -- but be careful: methanol is a poison.
For now, packaging is the biggest obstacle that fuel cells face. "Currently, the fuel cell cannot fit into a standard battery location", Kubo said. "It will need further development in order to fit into a notebook, and miniaturisation is a challenge we're facing". If all goes well, by the end of 2004 NEC may have a 2kg commercial notebook that runs for up to 40 hours on one tank of fuel. According to Kubo, NEC is attacking this problem from three directions: upping the concentration of methanol; using a low-power processor; and increasing the tank size.
Fuel-cell-powered handheld
By contrast, Hitachi is thinking smaller. Along with Tokai, a Japanese maker of cigarette lighters, Hitachi is working on a fuel cell-powered handheld. About the size of a AA battery, the fuel cell contains 57g of 20 percent methanol fuel, and it powers a handheld computer for 6 to 8 hours. Before its planned launch next year, the companies will try to boost runtime by using 30 percent methanol fuel, making a 12-hour handheld a distinct possibility.
All this adds up to big business over the next decade, according to Daniel Benjamin, a marketing analyst at Allied Business Intelligence, based in Oyster Bay, New York. "Fuel cells will provide a clean source of energy, but cost and technical issues will pose significant barriers". He has forecast the fuel-cell industry to be powering up with sales of only 5,000 units this year. But by 2011, there could be 200 million fuel cells of all sizes and capacities sold, powering everything from MP3 players to notebooks.
By then, we may be able to kiss our batteries goodbye, along with the eternal search for a power outlet to charge them -- although finding fuel may create another problem.
Dear reader,
Don't get confused by the descriptions above about the flow of electrons to and from the positive and negative electrodes.
A negative electrode is negative because it carries a surplus of negative charge. As electrons are negatively charged, this means that the negative electrode has an excess of electrons.
Similarly, the positive electrode is positive because it has a lack of electrons - and it is the tendancy of the electrons to move in such a way as to balance this out that causes electric current.
In other words, electrons will flow out of the negative electrode into the external circuit (in this case, the laptop's electonics), through this circuit and into the positive electrode.
The place to which the description refers is from the electrode into the electrolyte - the conductive paste that is between the electrodes inside the battery. Electrons move from the electrolyte onto the negative electrode, and from the positive electrode into the electrolyte.
The direction of flow (from the negative to the positive) is called electron current.
However, because our brains like to think in terms of positives, and because the early experimenters with electricity did not realise that the current was being carried by negatively charged particles, they defined current in terms of flow of positively charged particles from the positive to the negative. This is called conventional current.
A way of visualising this in electron flow is the opposing flow of "holes" into which an electron can move. As an electron moves forwards in the direction of electron current, the (effectively positively charged) hole moves backwards - in the direction of conventional current.
The effect is identical - charge is carried around a circuit through charged particles.