Thursday, August 22, 2013

Striving for the Ideal Battery Technology

Electrical energy is the “juice” that powers any number of technologies today, from electronic gadgets like smartphones to electric vehicles and on and on. Energy, however, is something that’s difficult to “grasp”: we can’t just roll it up like a blanket and set it aside for later use. Yet if we don’t use it when it’s available, it disappears (at least in its usable form). Batteries are a way around this problem: they store electrical energy in another form that can be accessed later. But the state of battery technology seems to be a limiting factor for progress in many areas. So what’s the story?
Key Battery Uses
Chemical batteries serve in smartphones, notebooks, tablets and other mobile electronics; you’re probably all too keenly aware of this fact when your device is running out of “time.” Batteries also power electric cars and other machines, such as robots. In the data center, they allow uninterruptible power supplies (UPSs) to maintain a clean energy flow to the facility, limiting the effects of short-term power spikes and dips.
Unlike, say, an engine powered by gasoline, batteries are quiet and produce no emissions. As long as they stay contained in their encasements, they are also fairly safe, producing no excessive heat (although certain situations can be problematic). Unfortunately, however, chemical batteries struggle to keep up with the demands placed on them. The electric-car market is floundering because current battery technology limits these vehicles to about 250 miles maximum—assuming ideal conditions and a full charge.
In a data center, a UPS system can cover for a power dip, but only for a short duration. Diesel generators must pick up the slack for any long-term outage. On a larger scale, electrical energy generated by, say, a wind turbine or solar panel is lost if not used immediately; but storage of large amounts of energy in this context is limited by the cost and capacity of batteries. In other words, batteries are not cheap and capacious enough to enable the kind of massive energy storage that could really benefit the power generation and distribution system.
But have any battery technologies that can offer such benefits appeared on the horizon?
The Ideal Battery
What would an ideal battery look like? It would have several important characteristics:
Safety: The battery would be able to handle a little abuse without causing grievous harm to people or equipment.
Capacity: It would be able to hold a lot of energy—the more, the better.
Size: An ideal batter would be small. Of course, you can’t have everything, but the size of the battery should be appropriate for the application. A battery the size of a desktop computer is not problematic for a car, for instance, particularly if it consistently enabled some 400 to 500 miles of travel on a single charge.
Recharging time: Realistically, every battery will run dry eventually. But even if it is otherwise a fantastic design, it loses much of its value if takes too long to recharge. Instantaneous recharging may be out of the question, but fast charging (or refueling) is critical to making a particular battery useful.
Cost: The best battery technology in the world does little good if no one can afford it. Thus, a battery must have a price tag commensurate with its application. A $20,000 car that costs $50,000 when the battery is added is a tough sell.
Service life: Ideally, a long life (based on the number of recharges, amount of degradation over time and so on) is necessary for a good battery.
Environmental impact: Many industries and the public have increasingly focused on the environmental effects of their actions. Thus, the manufacture, use and disposal/recycling of batteries should have a minimal effect on the environment and should be sustainable.
The reigning battery technology is lithium-ion, although other technologies are in use to convert chemical energy into electrical energy. Progress in chemical-cell technology has lagged that in other areas, such as electronic devices. Furthermore, lithium-ion batteries probably lack the capability to store power-grid-scale amounts of energy. So what might be some far-out possibilities for batteries that could drive a car many hundreds of miles, make your laptop run for a week straight and store enough energy to run the local power grid for a day or two without breaking a sweat?
A Fun Look at the (Possible) Future
If one thing is certain about innovation, it’s that today’s headline about a promising new technology is probably the last you’ll ever hear about it. But every now and then, some development gains enough momentum to break into the market as a product. Here are a few sci-fi (and not-so-sci-fi) battery technologies and their pros and cons.
Nuclear: Nuclear power is a reality, but the infrastructure surrounding it is so huge that compacting it into a battery—even on the scale appropriate for a large vehicle—is extremely challenging. Furthermore, the fuel, although packed with energy, is dangerous owing to its radioactivity. But could a controlled fission (or fusion) reaction be safely created in a small enough space to enable such a technology? There’s also the matter of how exactly to turn the energy output into a voltage. Furthermore, such a battery would likely not be rechargeable in the standard way (plugging it into your wall).
Hydrogen: Hydrogen fuel-cell technology is already in use. Apple’s Maiden, NC, data center, for instance, relies in part on this technology. Here, again, recharging is probably out apart from adding more fuel, and hydrogen—although not radioactive like nuclear fuel—is highly flammable, posing a significant danger.
Antimatter: Now on to a Star Trek–level technology. Matter and antimatter annihilate to create large amounts of energy, so small amounts of antimatter (matter is already plentiful) could pack a tremendous punch in a small battery. The problem, however, is containment (yes, Star Trek had this right). The antimatter must interact with matter in a controlled manner and only at the right times; unfortunately, the energy input needed to separate the antimatter may make this approach self-defeating. Either way, it probably won’t work in your laptop.
Other chemical cells: Lithium-ion batteries are currently the leading technology, but other chemical processes (whether involving lithium or other elements) could pack more punch into a smaller cell. These approaches may or may not allow recharging and a long service life, depending on the dynamics of the reaction; their safety and environmental impact also depend on these details.
Something we haven’t thought of: A battery is basically two electrodes (electrical conductors) with a potential difference (voltage) across them. In the case of chemical cells, a chemical reaction inside the battery creates the voltage, but other processes could conceivably do the same thing. The key (and here’s your homework) is to identify such a process that’s safe, inexpensive, rechargeable, capacious, small, long-lasting and environmentally friendly. Many researchers are working on this problem.
An ideal (or at least superior) battery technology could allow, for instance, power-generation plants to produce electrical energy at whatever rate is most efficient (regardless of whether that power will be used at the time) and store the excess for later (such as maintenance times) or for other uses. Data centers could save up energy for backup purposes without relying on diesel fuel. Electric cars could run for normal distances with less worry. Robots could function longer without power cables, and so on. What stands in the way is battery technology that lags development in other areas. Energy storage may simply be a perennial problem—or it may just be one for which we’ll need to work a lot harder and longer to solve. Time will tell.