• View
• Edit
• Page History
• All Recent Changes
• Print

Nathan Writing Assignment

Review of Ne plus ultra

The Economist, January 31st, 2008

Can ultracapacitors give electric cars the extra oomph they need to push their way into the mainstream market?

If you've ever watched the movie Who Killed The Electric Car?, you know that there are monstrous forces aligned against the entry of electric cars into the common use. The arguments used against the cars include that they're too small, they can't accelerate fast enough, they can't go far enough, and they take to long to recharge. However, a new discovery based on an old technology may help overcome many of these objections once and for all. The ultracapacitor may give the electric vehicle (EV) just the boost it needs.

Traditional capacitors have long been in existence. They work by storing a static charge between two smooth, proximate surfaces and then allowing the capacitor to discharge through a wire connecting the electrodes. This differs from batteries, which have been used in the past in electric cars, in that batteries store charge as electrochemical potential. Batteries take longer periods of time to release their charge because a chemical reaction must physically take place. In contrast, capacitors are able to discharge almost instantaneously. This property makes them ideal for use in systems that require high power over short amounts of time, such as rapid acceleration in an EV. Unfortunately, capacitors have lacked the capacity to be used feasibly in mobile units - until now.

Ultracapacitors operate on the same principle as the old fashioned capacitors, but allow the charge to be balanced by electrolytes instead of as static charge on each electrode. This allows engineers to increase the surface area of the electrodes without a corresponding increase in volume, in turn improving the storage capacity of the capacitor. What was once an unwieldy technology can now be reduced in size to fit in a standard EV. In current models, the capacitor works in concert with both a combustion engine and a battery operated electric engine to provide gas mileage of about 150 mph while delivering acceleration superior to standard cars. The designer explains that the system works much like muscles in animals, providing quick acceleration with one system and endurance with another. In addition, the capacitor requires much less to time to charge that traditional batteries. Conceivably, a motorist might be able to pull into a charging station and fill his capacitor in about the same time it currently takes to pump a tank of gas. These advantages may help make electric cars an attractive option to a much wider market share.

Unfortunately, the design still requires improvements. Currently, test models can only travel about 40 miles before the combustion engine begins to operate. However, researchers expect that capacitor capacity could be enhanced by coating electrode surfaces with carbon nanotubes, which would allow improved range and reduced fuel use. Another hurdle is the cost of current designs. AFS Trinity estimates that, even if the extra kit could be mass produced, the cost would be about $8,700 over basic hybrid systems. With luck and ingenuity (maybe spurred by ever-rising fuel prices) though, this new design could very well transform the business.

But, you may ask, why do we care whether the electric car wins or loses anyway? Well, we all know that today’s vehicles run on gasoline, which is costly to extract from the earth and ends up adding green house gasses to our atmosphere. It can be agreed that to save our planet we must convert to some other fuel source. The technology in the spotlight today is biofuels. Many make the argument that such fuels, if derived from the proper sources, may one day provide the fuel for our mobile nation. However, a recent report suggests that corn ethanol at least may contribute to twice the greenhouse gas emissions as gasoline. And we must always be concerned that burning plant matter may in fact be burning someone's food. Ultimately, it seems unlikely that biofuels will be able to take over the industry.

The next technology to consider in replacing the current carbon-based means of transportation then is the electric car. If the energy used to power an EV is derived from renewable sources, the vehicle will represent minimal environmental costs beyond its imbedded energy. It has few or no tailpipe emissions, and can be conveniently connected to any source of electricity. This perhaps makes the electric car the ideal complement for a renewables-based economy. One day, temporarily unused EVs could even be used as a distributed energy storage system, with excess wind or solar energy being stored in the cars’ batteries or capacitors. This extra service could greatly reduce the cost of owning an automobile. The development of such a system may be a long ways off. However, with the addition of emerging ultracapacitor technology, electric cars may soon be able to shock the market.