Hello all! I saw this article the other day on Futurity, one of many technology-related blogs that I frequent, and it got me thinking about the issue of electric vehicles. It’s pretty standard in science fiction, probably because it’s been “futuristic” for almost as long as we’ve had the electric motor, but so far there hasn’t been widespread adoption of electric vehicles to the point where we have displaced the traditional combustion engine. Now, I’m certainly not going to open the whole “global warming/climate change” can of worms in this post (or any, if I can help it…), but environmental issues aside, the combustion engine has met somewhat of a plateau, where as the electric motor has the potential to go much further as far as efficiency, performance, and practicality go:
- Fewer moving parts = fewer parts that can break
- Lighter weight (potentially) – at the moment it’s simply easier to get more power out of a combustion engine with less weight due to reasons I’ll explain below
- Better Control: electric engines don’t require the same torquing up that combustion engines do- you apply current, and it moves. No stages or timing belts or multiple pistons required. You can also easily control the speed of the motor and directly connect them to control systems
- Energy Efficient: electric vehicles on the scale of cars can typically convert about 75% of the chemical energy in batteries into power the motors, whereas gasoline powered vehicles of the same type convert about 20%
Batteries. The fuel used in combustion engines can be extremely dense with potential energy, and it is often in a form that is very durable in most climates, and is relatively cheap to get. Electric motors, on the other hand must get their electricity from somewhere. You can tether the motor to a huge supply, like the third rail on subways, but that obviously limits the vehicle’s mobility and can be a mite dangerous. You can generate electricity on board like attaching solar panels, or a nuclear reactor, but there are obvious limitations to these methods, and you can’t usually just attach the motors directly to the energy-generating system- you have to store it first so you can control the flow.
The most practical way is to use a mobile electrical storage device, like the lithium-ion batteries you see in practically all of your high-end electronics, and to recharge it when it needs more energy. This works fine on the small scale where energy demands are low, but when you’re, say, trying to run a 4-passenger car for a trip to the beach, the only batteries we have that could hold enough of a charge to get you there would be too big and heavy. In fact, there are several battery-related problems that keep electric motors from taking the place of combustion engines completely:
- Weight and Bulkiness: as described above. The energy density just isn’t where we need to be.
- Recharge Time: a full charge takes hours, whereas it only takes minutes to fill a gas tank
- Cost: Batteries are expensive, and the higher the charge and capacity, the more often it is likely to burn out, meaning larger vehicles will usually need to have a replacement at least twice in its lifetime.
- Driving Range: the effective range of a typical electric vehicle is about 100 to 200 miles on a full charge, whereas a gas-engine vehicle of the same type can get around 300 miles a tank. Add onto that the lack of charging stations, and the problem compounds.
So the battery is the main problem holding up electric motors from taking over. Until we invent a better battery, gas engines are way more practical. Well, researchers over at Stanford Univeristy have made a big step towards doing that. By coating the inside of carbon nano-fibers with sulpher atoms, the engineers led by Yi Cui have managed to multiply the storage capacity of their battery by 10 times. As Cui explains: “Without the additive you put 100 electrons into the battery and you get 85 out. With the additive, you get 99 out.”
It doesn’t sound like much, but it’s a start. The truth is, this new battery will come around some time soon- there are just too many people hugely invested in the invention for it to not happen. While necessity is the mother of invention, deep RND funding pockets and good ol’ fashioned capitalism get the job done double-time.
Until then, we’ve got our Harley’s and gas-guzzlers to ride and drive.