Why your laptop is always running out of power:

“Another way to provide more power would be to invent a “new chemistry”—a new set of materials with which to build batteries—or to develop a technique for more heavily charging an existing chemistry. But there’s a tradeoff: Generally, the more electricity a battery can store, the more dangerous and toxic it is. Even the lithium-ion battery, a traditionally safe technology, has its own risks. If it were to somehow catch fire, it becomes “exothermic”—it doesn’t need oxygen to burn, so it can’t be smothered. It’ll just burn and burn and burn until there’s nothing left.

This hair-raising prospect means that anyone who wants to build a stronger battery has to deal with federal regulators, most notably the Federal Aviation Administration. If a super-potent battery caught fire on a plane, it could do serious damage to the aircraft. And if it’s a choice between having my laptop conk out after three hours and having a nice powerful battery that knocks the entire plane out of the sky, I’m siding with the FAA. The lithium-ion battery, lame as it can sometimes be, hits the sweet spot between stability and usability. (Computer chips don’t face these problems. When you make them faster, they get hotter, but that isn’t as scary a proposition. You can deal with hot chips by installing better fans, which, of course, require ever more battery power.)

The great hope for the future lies with fuel cells, which are a whole new paradigm for laptop power. When they run out, you don’t recharge them. You just buy new cells and shove ’em in, the same way you put double-As into a portable radio. This year, some companies promise to introduce the first cells. In the long run, they aim to have them widely available for two or three dollars a pop, with each one promising perhaps 15 hours of power.

But fuel cells have their own downside. If they’re made with hydrogen, they produce water as a byproduct, so you’d have to cope with your laptop urinating. And the airlines aren’t too keen about letting people carry hydrogen onboard either, since it can be explosive, too. Manufacturers are looking at making fuel cells safer by using less-potent fuels like ethanol and methanol instead of hydrogen, but they deliver less energy—and the FAA claims they can be a fire hazard, too. In this quest for infinite life there is, as it turns out, no holy grail.” Slate