No consumer product improves more drastically, year after year, than the computer. I buy a new laptop every two years, and when I uncrated my Dell last month, it made my old machine look like a Model T. The new processor is twice as fast, the hard drive is eight times bigger, and there's free Wi-Fi to boot. But there's one thing that hasn't kept pace with the computing revolution: the battery.
Since the early 1990s, when the lithium-ion battery was first introduced, laptop batteries haven't gotten much smaller, and worse, they don't seem to last much longer: The battery industry admits that it is improving power capacity by a measly 8 percent a year. My new battery dies after three hours, lasting barely 20 minutes longer than my old one from two years ago. I can process cutting-edge video-game graphics on the Pentium chip, but the battery will wheeze out halfway across a trans-Atlantic flight. We've got the technology of the future, but to power it we're still rubbing two sticks together.
To make your computer run faster, engineers develop elegant ways to cram more circuits onto its surface. But once they've created the chip, it's pretty inert. It just sits there, like a piece of glass. A battery, in contrast, is a bubbling cauldron of chemicals. It's practically alive. A laptop battery is composed of a few pieces of metal surrounded by an "electrolyte" that lets charged particles flow through, generating current. It's just like the batteries you built in high-school science class, where you jammed a penny in one end of a lemon and a dime in the other, and presto: It generated a tiny current.
The problem is, whether you're using coins and a lemon or whether you're using lithium—the most common substance used in laptop batteries—there are only so many ways for those chemicals to behave. The reason that laptop lithium-ion batteries aren't getting radically better these days is that we have reached, as experts in the field say, "the limits of the chemistry." We've learned all the tricks for improving their efficiency. In comparison, speeding up a computer chip is about shrinking the transistors and wires on a chip, and we've still got plenty smaller to go.
Granted, there are otherways to get more juice out of a battery. You could make the battery bigger, to allow for more lithium and electrolyte to power it.But who wants a bulkier, heavier laptop? Instead, most computer-makers focus on energy efficiency—using what little juice we have more intelligently. Intel's Centrino chip, for example, monitors what it's being asked to do and ramps down its power usage accordingly.
But we're cramming more and more gewgaws into our laptops all the time, and each one requires more electricity. Each new chip, each bigger screen, each Wi-Fi card cries out for more juice. And suppose you're one of those people who uses a laptop as your main computer? You're killing the battery even faster. The life span of a battery is determined in cycles—how many times you use and recharge it. A lithium-ion battery usually permits 300 to 500 cycles. The more you use it, the faster it burns through those cycles, like a cat going through its lives.
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 break open, several of its chemicals can react with air or water to catch fire, which also means that water or foam-based extinguishers aren't recommended for putting them out: You need sand, sodium chloride powder, or copper powder. *
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.