... at least two major mobile companies were set to release fuel cell-powered handsets in 2005. Fuel cells turn the chemical energy stored in hydrogen into electrical energy to power devices. Unlike traditional lithium ion batteries, they can be made in a variety of shapes and form. They are also refillable, as opposed to rechargeable via electricity and last for days rather than hours. "The form factor of early fuel cells will be significantly larger than current battery technology, but the power capacity will be significantly greater," he said. "Whether they are bundled with handsets or not remains to be seen." They are likely to be an option for those who need lasting power - such as emergency workers or business people- rather than mobiles that make fashion statements.