Ultracapacitors Make City Buses Cheaper, Greener
October 21, 2009 by Lisa Zyga
Buses with ultracapacitors stop at recharging stations, which double as bus stops, to recharge in less than a minute. Image credit: Sinautec.
(PhysOrg.com) -- A fleet of 17 buses near Shanghai has been running on ultracapacitors for the past three years, and today that technology is coming to the Washington, DC, for a one-day demonstration. Chinese company Shanghai Aowei Technology Development Company, along with its US partner Sinautec Automobile Technologies, predict that this approach will provide an inexpensive and energy efficient way to power city buses in the near future.
The biggest advantage of ultracapacitors is that they can fully recharge in less than a minute, unlike lithium-ion batteries which can take several hours. The downside of ultracapacitors is that they currently have a very short range, providing a distance of only a few miles, due to the fact that ultracapacitors can store only about 5% of the energy that lithium-ion batteries can hold.
Although their short range makes ultracapacitors impractical for cars, city buses have to stop frequently anyway. By quickly recharging at bus stops, buses could take advantage of ultracapacitors' other benefits: a bus with ultracapacitors uses 40% less electricity compared to an electric bus with lithium-ion batteries, and requires just one-tenth the energy cost of a typical diesel-fueled bus, which would save about $200,000 during the life of the vehicle. Plus, the buses are environmentally friendly: "Even if you use the dirtiest coal plant on the planet, it generates a third of the carbon dioxide of diesel when used to charge an ultracapacitor," said Dan Ye of Sinautec.
Today's demonstration will take place at American University in Washington, DC, where an 11-seat minibus powered by ultracapacitors will be shuttling people around campus. At designated charging stations, which double as bus stops, the bus recharges by raising a collector on top of the bus a few feet to touch an overhead electric charging line, which recharges ultracapacitor banks stored under the bus seats.
The two companies hope that this is just the beginning for ultracapacitor buses. The company that makes the Shanghai buses, Foton America Bus Co, based in Tennessee, plans to deliver another 60 buses to the Chinese city in early 2010. The new buses will have ultracapacitors manufactured by Shanghai Aowei that supply 10-watt hours per kilogram, compared with the current ultracapacitors that have an energy density of six watt-hours per kilogram. Other US cities, including New York City, Chicago, and some towns in Florida, have also expressed interest in trialing the buses.
The companies expect that the ultracapacitors will continue to achieve higher energy densities in the future, which would allow them to hold a charge for longer. This improvement could increase the driving range from a few miles to 20 miles or more, helping to decrease the number of charging stations required on a route and make the technology practical for many more cities and bus routes.
More information: Sinautec
via: Technology Review
© 2009 PhysOrg.com
5 hours ago
Just the waste of time and money.
Railroads did this in the 1920s, using big, heavy batteries. An electric locomotive would have batteries for use where wires or third rail couldn't be used, such as in explosives factories. The Central of New Jersey had the oddest ones. They could run on third rail, battery, or diesel-generator, making them a rechargeable hybrid - with extension cord.
sounds like evangelion, especially the cord.
developments like this shouldn't be viewed in isolation. as the article admits, the source of electric power also has to be green, otherwise, they're only hiding from plain view the source of those greenhouse gases, or even accumulating them since demand for power will be centralized to the dirty coal plants to make electricity for these buses.
I'm sure they are still a great deal greener then lith-ion batteries.
The same technology and infrastructure can also be used for other short drive urban vehicles, such as delivery vans and trucks, taxis, postal delivery, police cars, and more. Physically connecting a vehicle to a charging station can also exchange information, such as vehicle identity (for billing), distance and time traveled (identify traffic jams), routes taken (identify detours), and more.
They're not talking about wireless transmission. If you read the article, you'd know there will be overhead charging stations at bus stops. Since most normal people don't stop at every bus stop, t'wouldn't work for most normal people
Good thing smart people don't share that view
How do you propose making the efficiency of an inductive charge match that of a hard-wired charge? As far as I know, it hasn't even close to been done yet. Inductive charges are currently an inefficient convenience for smaller devices. Also, charging a bus to full power in less than a minute as the article implies would require a tremendously powerful inducer, perhaps enough to fry all the electronics nearby?
How do you propose to inductively charge up a 1KW VASIMR engine?
http://www.copper...ncy.html
As a charging method it would be expected that the ultracapacitors would pull power at full capacity of the inductive unit until fully charged, so it should be able to be engineered to the exact size for the load. Granted, the aligning of the two coils for best effeciency would still need to be engineered into the system, but I'm of a mind that anything can be done if enough resources are put into the project.
I didn't mention a VASIMIR engine. I am not familiar with them nor the radiation from their plasma exhaust. Besides, unless technology has come up with some way to counter the G-forces involved - any method of getting around town in 39 seconds will be impractically messy for a mode of public transport.
They only take a minute because UC's don't hold much power. A lithium would take just a minute too to charge the same amount.
Lithium batts are 95%+ eff, not 60%.
UC's cost, weigh 100x's more/watt so just what are their advantage? Just use a small A123 lithium pack would be far less and go far more miles.
Under vehicle induction charging has been done for 80+ yrs and 90+% eff.
A combo of battery, third rail/overhead wire bus/trolley would be very flexible and cost effective and been around 110 yrs.
Golf carts on the road with street tires would get 60-100 miles. I built, drive a trike MC with a GC transaxle which with 4 12v lead batteries, 14" car tires/Rabbit fits, gets 40 mile range.
http://www.boston...rged_up/
However, they only have that small scale for now. If you tried to charge a standard Li battery as fast as a capacitor, you'd ruin it. Maybe the A123 battery will put UCs out of business?
I've never heard of under-vehicle induction charging on anything other than a tracked vehicle, where is this used?
Nissan is supposed to be looking into an inductive powering or charging system for their "Zero Emission" cars (More like relocated emissions, but that is a different topic).
There is plenty of room for electric vehicles to optimize a power-plant configuration, perhaps by using the storage capacity of plug-in batteries, or even fuel cells, to power the switching advantage of ultracapacitors.
Just look up their websites, read the specs and do the math. It's not like it's hidden. It's basic physics.
While some A123 are small, they can be series/paralleled into and rating you want. that's what Tesla did and Panasonic just came out with a 25vdc battery built that way for EV's, plug in hybrids..