A new fuel cell for laptops, more compact and powerful than competing technologies, could be on the market in early 2006 for just $90, its Japanese inventors have claimed.

Materials and Energy Research Institute Tokyo (Merit) is betting on direct borohydride fuel cell (DBFC) technology, which it sees as cheaper and more compact than the direct methanol fuel cell (DMFC) technology other Japanese companies are developing.

Fuel cells generate an electrical current from a chemical reaction between a hydrogen-containing fuel and oxygen. How much current a cell produces depends on a number of factors including the exact chemical reaction involved and the area of the membrane which separates the fuel from the oxygen. The length of time which the cell can produce power varies with the nature of the particular reaction and the amount of fuel stored in a reservoir.

The technology developed by Merit is similar to the DMFC types, but has several significant advantages, said Seiji Suda, president of Merit.

As with DMFCs, Merit's fuel cell has an anode, a cathode and a membrane, but instead of using methanol as fuel, it uses a solution of sodium borohydride. Merit's fuel cells develop about four times more power for the same area of membrane than DMFCs, Suda said. "With DBFC, the anode is nickel alloy, which is very cheap, and the membrane is a conventional one. It's all very compact," he said.

The fuel cell will measure 80mm by 84.6 mm by about 3 mm, and will be able to produce 20 watts of power, enough for a notebook PC, Suda said. "We also intend to stack five of the cells together and connect them in series so that they produce 100 watts. We'll have a working prototype that is suitable to demonstrate mass production for industry in the best case in four months," he said.

Commercial versions should be available in the first few months of 2006, and will cost around $90, he said.

However, earlier this month, another main contender in the fuel cell race, NEC, said that while its technology will be ready a year earlier than that - 2005 - the whole fuel cell setup would not become commercially viable until 2007 because of legal hurdles.

These include regulations on the carriage and use of fuel cells on airplanes and other forms of public transport. NEC had been hoping that such legal hurdles would have been cleared by this year but it now expects this to happen around 2007.

There are other issues that need to be solved including standardisation of fuel cell cartridges and establishment of a sales network were new cartridges or fuel can be purchased.

Several of Japan's largest consumer electronics companies have shown prototype DMFCs for laptops and mobile phone chargers, but they have not announced prices for future commercial versions of their fuel cells.