I love my three-year-old MacBook Pro, but it does run through the batteries, no matter how regularly I calibrate the darn things. I'm on the third replacement battery, and it's barely holding a charge anymore, lasting for, oh, 30 minutes at most. I expect it will give up the ghost any day now. The question now becomes, do I replace the battery one more time, or upgrade to a new MacBook Pro? The new version supposedly comes with batteries that last up to 8 hours, which would be pretty darned handy on a long flight.
The explosion of portable computers (laptops, smart phones, etc) has brought the problem of battery power to the forefront of technological concerns for those in the business of selling such devices. Computers keep getting smaller thanks to continued shrinking of chips and other microcomponents, but batteries necessary to operate them remain pretty clunky in comparison, and thus they add considerable weight to any product — the largest portion of my laptop's weight is due to the battery. It's just the latest chapter in mankind's quest for the perfect power source.
Some historians believe primitive batteries were used in Iraq and Egypt as early as 200 B.C. for electroplating and precious metal gilding. Around the 1790s, through numerous observations and experiments, Luigi Galvani, an Italian professor of anatomy, caused muscular contraction in a frog by touching its nerves with electrostatically charged metal. Later, he was able to cause muscular contraction by touching the nerve with different metals without a source of electrostatic charge. He concluded that animal tissue contained an innate vital force, which he termed "animal electricity."
One person didn't think Galvani was right. Count Allessandro Guiseppe Antonio Anastasio Volta was born in Como, Italy, in 1745, and eventually grew up to be a professor at the Royal School, where he studied the chemistry of gases. In 1776 he discovered methane by collecting the gas from marshes, and experimented with igniting the gas in a closed container. And he devised an intriguing method for remotely operating a pistol: he used a Leyden jar to send an electric current all the way from Como to Milan via a wire insulated from the ground by wooden boards. Once the current reached its destination, it set off the pistol. One might think this was just an exercise in futility — unless Volta had plans to become Dr. Evil and this was his way of killing a captive Austin Powers from a distance — but in fact the experiment was one of many that laid the groundwork for the invention of the telegraph.
Volta also studied electrical capacitance, although at the time that term wasn't known. He set out to prove that Galvani had drawn the wrong conclusions from his frog experiments. Specifically, he wanted to prove that electricity did not come from the animal tissue but was generated by the contact of different metals in a moist environment. So in 1800 he replaced the frog's legs with alternating layers of brine-soaked paper and two metals, zinc and silver, and also detected the flow of electricity. This was the first voltaic pile, and the first electrochemical cell. It inspired a slew of similar devices, including the so-called "wet cell" or Daniell cell, which became the workhorse for operating telegraphs and doorbells. It's called a wet cell because it relies on liquids rather than dry solids for electrolytes.
To make a Daniell cell, a copper plate is placed on the bottom of a glass jar and then covered with a copper sulfate solution until the jar is half full. Then you hang a zinc plate and add a zinc sulfate solution to the jar. Since copper sulfate is denser than the zinc sulfate, the latter "floats" on top — much like certain specialty cocktails require "layering" of liqueurs of varying density. The downside to the Daniell cell is that it has to be kept stationary: it's not good for powering portable devices, such as flashlights.
Nowadays, we use the common household battery for our portable devices. It's still the same fundamental concept. There is a positive and negative terminal; electrons are produced by chemical reactions inside the battery, and collect on the negative terminal because they are negatively charged. Connect a wire between the two terminals, and the electrons will flow to the positive terminal. This wouldn't be helpful all by itself, but the wire usually also connects a "load" — a light bulb, a motor, a radio circuit — and the energy is used to power said device(s).
So that's the old-school technology, which hasn't changed all that much since Volta's day. There's all kinds of interesting new twists on conventional batteries, mostly based on unusual fuel sources. Back in 2006, a team of MIT researchers led by Angela Belcher created a new battery technology based on a genetically engineered M13 virus — fortunately harmless to humans. Their battery is flexible and small enough it could be used to power tiny sensors, useful as detectors for cancer or heart disease, among other implantable devices, not to mention existing lab-on-a-chip technology.For instance, implant a small device under the skin, powered by the virus, and it could light up a small visible LED if cancer proteins were present.
Among the many challenges is devising a cheap means of mass production of these microscopic batteries. Last year Belcher and her colleagues published a refined version of their viral battery, which involves stamping silicon film in such a way that the negatively charged 13 virus and a positively charged cobalt strip will self-assemble based on their charges and how the stamp is patterned. Now they've got a device that could potentially be woven into fabrics, for instance — turning almost any surface into an energy-storing device. "We provide the surface and the ions, and the batteries build themselves," Belcher told Discovery News.
If viruses don't float your boat, Sony has a prototype biotech battery (technically a fuel cell) with a sweet tooth: it needs a sugar fix to operate the four-cell array, which is capable of producing up to 50 mW of power — sufficient to power a desk fan, or speakers, or other small devices. And where does that glucose come from? Why, sugary sweet fruit drinks of course. That includes an unusual Japanese beverage called Pocari Sweat, which seems to bear a close resemblance to Gatorade: its ingredients include water, sugar, citric acid, sodium citrate, sodium chloride, potassium chloride, calcium lactate, magnesium carbonate, and "flavor." (According to Wikipedia, the name derives "from the notion of what it is intended to supply to the drinker: all of the nutrients and electrolytes lost when sweating." In other words, Gatorade.)
Know what else contains glucose? Blood! So it was only a matter of time before scientists started investigating blood as a possible fuel source. A few years ago, other Japanese researchers built a fuel cell that runs on blood, drawing electrons from glucose (blood sugar) to generate about 0.2 milliwatts of electricity. The feat has also been done by scientists at Rensselaer Polytechnic Institute, drawing on the naturally occurring electrolytes in bodily fluids — not just blood, but tears or even urine. The RPI version is thin as paper– in fact, it pretty much is paper, being made of 90% cellulose and 10% carbon nanotubes to make it conductive. You can imprint the nanotubes directly onto nanocomposite paper, and like the virus-based battery, the RPI device is flexible, thin enough to fit under the skin, with the potential for cheap mass production. It even has similar potential applications: it can be used to power medical implants such as pacemakers, artificial hearts, or prosthetics.
Most recently, a team of researchers at the University of British Columbia in Vancouver created yet another tiny battery that runs on human blood — also useful for things like pacemakers. (Hey, it's an important energy application, and one for which we need biologically compatible and renewable battery sources — hence the strong academic interest.) The core of this particular version of the blood battery relies on a small colony of yeast — Saccharomyces cereyisiae, commonly used in brewing and baking — that sets up shop inside the core, drawing energy from the glucose in blood flowing around it.
Energy is produced as the cells start to break down food, and a chemical called methyl blue (used to stain biological samples) serves as an electron mediator, stealing some of the electrons produced during the metabolization process and delivering them to the anode, thereby creating a small current. So now we've got an actual living source of power that can regenerate itself — although it also produces waste products that must be removed before they leach into the bloodstream. So we won't be seeing this device hit the clinical market any time soon.
What might blood-based fuel cells be good for? How about a novel nightlight? An English designer named Mike Thompson was studying for his master's degree in the Netherlands, researching chemical energy, and was intrigued by luminol — the chemical forensic scientists use to detect traces of blood at crime scenes. Basically, luminol reacts with the iron in red blood cells, producing a bright blue glow. That set Thompson to thinking that perhaps folks would appreciate the energy they consume a bit more if it cost them their own life blood.
And so he built a simple lamp that uses blood to create light as it reacts with luminol. For the strong of stomach, there is a video showing how to use the lamp. You mix in an activating powder, then break the glass, cut your finger on the edge, and let the blood drip into the opening. The result is a soft blue glow — and it can only be used once. "You have to really decide when to use this lamp because it's only going to work once," Thompson told LiveScience, adding his project was intended "to challenge people's preconceived notions about where our energy comes from," forcing users "to rethink how wasteful they are with energy, and how precious it is."
All this cutting-edge research on glucose and blood-based fuel cells inspired a couple of other British designers — those Brits are a morbid bunch — to create a prototype flesh-eating clock. I kid you not. Fortunately, it eats the flesh of insects, but it's only a matter of time before it starts craving human flesh (fresh braaiiins). It's pretty ingenious, actually. James Auger and Jimmy Loizeau stretched some flypaper across a roller system; as flies are caught, the roller dumps them into a vat of bacteria that "digest" the bugs, and the resulting chemical reactions are used to power an LCD clock. There's another version that feeds on mice, and also an insect-powered lamp — the creatures are lured to their doom by ultraviolet LEDs.
*Le sigh* Whatever happened to conventional alternative energy sources, like wind, solar, or even nuclear power? Heck, even Mother Nature has built her own nuclear reactors; there are about 16 of them, two billion or more years old, buried in the rocks beneath Gabon, according to Australia's Curtin University of Technology. (h/t: Geoff Manaugh of BldgBlog) The phenomenon was first predicted in 1956 by physicist Paul Kazuo Kuroda, who argued that a chain reaction could be set off in natural uranium deposits, thereby generating heat in much the same manner as a nuclear power plant.
In 1972, scientists discovered exactly that type of natural nuclear reactor in the middle of the Oklo uranium mines in Gabon. One even pulsed in a three-hour regular cycle, "running" for 30 minutes, then shutting down for two-and-a-half hours before running another 30 minutes, and so on for over 100,000 years. Who needs batteries with that kind of energy source? Well, (a) the "reactors" no longer operate, ad (b) the conditions necessary to produce them turn out to be pretty rare. According to Wikipedia, these are "the only known sites in which natural nuclear reactions existed. Other rich uranium ore bodies would also have had sufficient uranium to support nuclear reactions at that time, but the combination of uranium, water and physical conditions needed to support the chain reaction was unique to the Oklo ore bodies."
And yes, there would have been nuclear waste products, including plutonium. Fortunately, the radioactivity has long since decayed away. Even more interesting, the deposits of (formerly radioactive) waste products haven't shifted much in location — the plutonium hasn't even moved 10 feet from the spot where it was first formed almost two billion years ago. So naturally the Department of Energy is studying the rocks at Oklo to figure out how Nature managed to contain her nuclear waste. It should help us figure out how to better contain our own nuclear waste products.
Jen-Luc Piquant, meanwhile, is far more intrigued by the notion of hooking up hamsters and other small rodents to power small generators. It's the sort of thing we used to joke about in college (my car was notoriously slow to accelerate, especially uphill), but Jen-Luc found the following YouTube video (via io9) by scientists at Georgia Tech showing a hamster running on its little wheel while connected to a generator via tiny nanowires. Okay, you'd need four nanowires to generate a measly 200 millivolts; that won't solve the global energy crisis. But it can power a tiny nanobot of the future. I say, let the Rodent Green Energy Nano-Revolution begin!