Fast charger: A bus that runs entirely on ultracapacitors charges up at a bus stop in Shanghai. The buses can only travel three to five miles between charges, but the ultracapacitors allow for fast recharging at designated bus stops.
Sinautec Automobile Technologies
A U.S.-Chinese venture is out to prove the benefits of quick-charge buses.
Municipal transit agencies have tried to reduce the carbon footprint of their bus fleets using a range of options over the years, from biofuels and hydrogen to batteries and hybrid-electric diesel. Now a Chinese company and its U.S. partner say that ultracapacitors could offer the greenest and most economical way of powering inner-city buses.
There's just one catch: the best ultracapacitors can only store about 5 percent of the energy that lithium-ion batteries hold, limiting them to a couple of miles per charge. This makes them ineffective as an energy storage medium for passenger vehicles. But what ultracapacitors lack in range they make up in their ability to rapidly charge and discharge. So in vehicles that have to stop frequently and predictably as part of normal operation, energy storage based exclusively on ultracapacitors begins to make sense.
Sinautec Automobile Technologies, based in Arlington, VA, and its Chinese partner, Shanghai Aowei Technology Development Company, have spent the past three years demonstrating the approach with 17 forty-one seat municipal buses on the outskirts of Shanghai. On October 21, the two companies will offer a one-day demonstration at American University in Washington, DC, where an 11-seat minibus running on ultracapacitors will spend the day shuttling people around campus.
The trick is to turn some bus stops along the route into charge stations, says Dan Ye, executive director of Sinautec. Unlike a conventional trolley bus that has to continually touch an overhead power line, Sinautec's ultracapacitor buses take big sips of electricity every two or three miles at designated charging stations, which double as bus stops. When at these stations, a collector on the top of the bus rises a few feet and touches an overhead charging line. Within a couple of minutes, the ultracapacitor banks stored under the bus seats are fully charged.
"It's a brilliant concept," says ultracapacitor expert Joel Schindall, professor of electrical engineering and computer science at MIT. "It's not well suited for electric-only cars, but it is practical to stop a bus every few city blocks."
The buses can also capture energy from braking, and the company says that recharging stations can be equipped with solar panels (although this is mainly to further the perception that the vehicles have a lower carbon footprint). Ye says the buses use 40 percent less electricity compared to an electric trolley bus, mainly because they're lighter and have the regenerative braking benefits. They're also competitive with conventional buses based on fuel savings over the vehicle's 12-year life, based on current oil and electricity prices. Sinautec estimates that one of its buses has one-tenth the energy cost of a diesel bus and can achieve lifetime fuel savings of $200,000.
"The ultracapacitor bus is also cheaper than lithium-ion battery buses," says Ye. "We used the Olympics (lithium-ion) bus as a model and found ours about 40 percent less expensive with a far superior reliability rating." Ye adds that the environmental benefits are compelling. "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."
Recent studies point to the potential of ultracapacitors to augment conventional batteries.
US is not a good market for this. In greater Tokyo there are lots bus routes where the speed limits on the roads is 40kph~50kph and the bus stops are close together.
Re: US not good market for this
Note: The original version of this story said that the bus is limited to 30 miles miles per hour. That's true of the ultracapacitor bus in Shanghai, because that's the speed limit there. But the buses can go much faster--up to 80 mph if necessary, according to the company.
batteries hold something like 1/100th to 1/200th the energy of chemical fuels
this holds 5% or 1/20 the energy of batteries.
so overall capacitors hold the energy equivalent of 1/100 * 20 = 1/2000 the energy of chemical fuels?
might as well have hamsters running in a fly wheel inside the bus. scale this up to capybaras (giant rodents from the Amazon) on a larger wheel. Feed them some renewable grains and voila! an eco-friendly bus energy source with at least as much power. have a 5cents - feed the capybara - recharging station at each bus stop.
I'm all for renewable power sources or sources that can have power fed from the grid, which can be converted to renewable over time. And it looks like capacitors have a place with their quick discharge, but this looks lame.
BTW, I've seen those declare lithium ion batteries 'safe'. or safer than gasoline or hydrogen. On an solar electric car race documentary (on discovery channel) they mentioned that lithium ion batteries, when they catch fire (and appears they can catch fire instead of exploding like Sony laptops or exploding Apples) they burn at 2500o, pretty much unstoppably melting a hole in the concrete below them similar to thermite.
We could place bike pedals at every passenger seat, and then the passengers would collectively run the bus. Americans are obese anyway, so it won't hurt to exercise.
batteries hold something like 1/100th to 1/200th the energy of chemical fuels
this holds 5% or 1/20 the energy of batteries.
what's your measure? volume? weight? I don't think your comparison is relevant. The whole point is that these buses don't need to store a whole lot of energy -- just enough to get them to the next stop. If the stops are less than a mile apart, it should be simple to store enough energy on board, even at a tiny fraction of the energy density.
Yes - a mouse powered bus makes sense until you realize the rat turds would cause Hantivirus outbreaks, make people sick and die and then the rider frequency drops off to the point the route is no longer economically feasible. The bus company goes belly up and we're back to walking, riding bikes or taking another form of transportation.
Technology has been in use for several years already
Urban trains in Mannheim and others have been using it for about 3 years already. Check:
http://electronicdesign.com/Articles/Index.cfm?AD=1&ArticleID=17465&pg=2
for more information.
Re: Technology has been in use for several years already
According to that link, the Mannheim system is used to capture energy from braking and hence improve efficiency - it's not the sole means of energy supply. On the other hand, haven't Gyrobuses used the same principle (with flywheels instead of ultracaps) since the 1950s?
Re: Technology has been in use for several years already
hopefully flywheels will begin to emerge in the USA as the preferred technology to L-Ion batteries and capacitors... capacitors are very unstable and there isn't enough lithium in the world to sustain fully electric vehicles.
Hopefully we will be able to secure funding and complete our work and make this world a much better place by drastically reducing our need for fossil fuel.
supposedly there is only a '10 year supply' of lithium at industrial sites ready to be mined.
The problem with that is there is only a '10 year supply' because when you have 10 years supply you don't go looking for more!
the history of oil and many other natural resources is exactly the same. For many years (around 100) there has been 'about 10 years left' of oil. It is just now that we are rounding the peak of oil and the reserves (easy to get to ones) are REALLY running out.
Bolivia for example has vast reserves of lithium, undeveloped, in salt lakes. Admittedly unstable country, perhaps the peasants would be 'less revolting' if they got a mine to employ them.
Other countries similarly have undeveloped reserves and are spending billions to develop them. Lithium power sources will NOT replace all other energy storage systems. However they will be a BIG PART likely of any future energy supply chains for transportation and other uses.
BTW, lithium batteries can be more dangerous than gasoline. Exploding in laptops, incidents from sony and apple show this, and burn at 2,500degrees, which is quite hot for a fire, and will burn a hole thru concrete. A solar car racer burned alive in a lithium battery car fire and this was mentioned on show documenting solar car race.
Well, if they want to improve the range they might start by making the front-end of the bus a more aerodynamic than a wall.
Hmmm... Then perhaps a few solar cells on top of the bus itself?
And I imagine a few old fashion lead-acid batteries could provide some helpful reserve power.
But hell, while were at it, add some haptic floor tread to pick-up a little extra juice from all those people getting on and off the bus.
With a little bit of creative thinking I'm sure they could get those buses twice as far up the street per charge.
If you look at the ultimate energy density of the sun (or foot traffic) you will discover that no matter how good solar or haptic energy harvesting gets, the surfaces available on a bus could never provide more than 1/100th of the power required to drive it.
Wonderful idea. Unfortunately, here in USA, Cap and Tax will likely obliterate any fuel cost savings for electric vehicles.
Flywheels are far superior to L-Ion on any capacitor. With turnaround efficiencies in the 90% and having 100% usable energy storage it will be the way of the future. Any battery regardless of type can never be completely depleted of its energy nor can the be 100% recharged....batteries always must operate at the very top of the energy storage bell curve. What is most frustrating is all of the $$$ being thrown at battery technology and we cannot find any funding to complete our research!!! @#$*&!!
I don't understand the cap & tax comment. The Cap & trade system certainly is a poor substitute for a better carbon tax solution but they both will place polution costs where they belong, on dirty fuels.
This worked with controlling acid rain and is a good start controlling CO2. Of course if you listen to talk radio, you don't believe in climate change.
If dirty fuels cost more, then clean energy can be competitive. Ultra caps may be good for short trips like city buses but flywheels may serve the same purpose if they meet or exceed the energy storage for the same cost.
It's a great idea. The buses could be supplemented with some batteries to help out just in case the capacitors run low.
This is the kind of positive thing that the world expects from China (not shutting down Tor, and censoring people).
Are these ultracaps any better than batteries?
With only a few statistics given, it's hard to tell if ultracaps are better than other batteries, not just high-capacity lithium-ion laptop batteries. For a low capacity but high power (charge & discharge), what matters is kg/W, l/kWh, $/W, and $/kWh.
From the bus web site, it looks like the batteries are 120-144kW, 5.6kWh, 6 minutes of charge time (56kW charge power). At 6Wh/kg that makes them around 1000kG.
Compare that to a NiMH Prius battery-- these ultracaps are about equivalent in capacity and power to 6 batteries (20kW/1.3kWh each), but weigh 270kg for 6. There are no statistics on the bus regarding ultracap cost or volume.
Some of the new high-power lithium technologies have ~10K cycles and charge times around 5-15 minutes, but with more kWh/kg.
The quoted mileage is amazing-- at 1.5kWh/mi it almost seems too good to be true. Compare that to the 3.1kWh/mi Tesla or 2.5kWh/mi Volt.
since you cannot (quickly) fully charge a battery, and you can't discharge it at high drain very far (as noted above) I've seen estimates that you really only use 15-25% of a batteries theoretical capacity.
If this is correct, then the ultra-capacitors at 5% or so the capacity of the batteries is really at 20-30% of the usable capacity, and with the 10% that they have already achieved, that would be 40-60%
and since the capacitors can charge as fast as you can put power into them (without being damaged, and without wearing out with repeated charge/discharge cycles) it becomes much more feasible to really charge them when you are away from home.
Plus the trolley can pull a wheelie!
This is a great idea. It will definitely get put into place somewhere in the US quickly. Very rarely do you see a win win like this! Well done China.
interesting site. I have an interest in these supercapacitors. Looking for forward to more articles on them.
Passengers as an extra source of energy in buses?
Commentators above have not invented anything new. Read the historical text below:
On Tuesday 3rd November 1902 the President of the Bank of America, Albert Mann, was on his way to discuss a business deal with Thomas Edison. The appointment had been difficult to arrange in amongst the almost constant stream of guests to Edison’s New Jersey house.
As he approached the house, he saw the previous guest having real difficult opening the gate to leave. After passing pleasantries with the guest, Mann himself struggled to push open the gate before going inside to meet Edison.
As they sat down to talk, Mann said to Edison, “Before we start I have to ask why a man of your engineering genius can’t even fix his own gate?”.
“Oh but I have fixed the gate” Edison replied, “I’ve fixed it to the water pump, so that my very generous guests draw the water for the house.”
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ecodelta
1 Comment
use small generator
One solution for lower range with Air conditioning would be to use a small power generator to power it, maybe even battety or capacitor assisted.
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cenesdelavega
1 Comment
Re: use small generator
Or better yet, use existing diesel hybrids, (for example the Daimler/BAE serial hybrid) install in-pavement inductive charging stations along the route, thereby converting them into "plug-in" hybrids. This way, the buses become almost all-electric, but with the security of the diesel backup. Contact me at www.opbrid.com for details.
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