Battery Powered Tram Charges in 60 Seconds 176
SK writes to tell us that a new streetcar, powered by lithium battery, has been invented by the Railway Technical Research Institute in Kokubunji, Tokyo. The new transport is capable of speeds of 40 kph for 15 kilometers and can convert 70 percent of its deceleration energy into electricity which is then sent back to the battery which can recharge in under one minute.
Re:Correct me if I'm wrong... (Score:3, Informative)
Of course it is quite clear he meant $1 billion per year in terms of the cost of electricity had it been produced by a power plant (which includes fuel, construction costs, transmission losses and so on).
Always was this way. Batteries not included. (Score:5, Informative)
And it already works that way. And it has been working this way since brush-powered electric trains and buses were first built.
If you've got a speed-controllable electric motor hooked to an electric grid, you can do regenerative braking by setting the motor's desired speed to something lower than its current speed. The motor then DEcelerates the vehicle, acting as a generator and putting the vehicle's energy (less resistive, eddy-current, hysteresis, and excitation losses) back into the power supply.
If there are rotary converters (or suitably designed electronic converters) in the system (for instance: To turn line AC into DC or lower-frequency AC for the trains/buses), they do the same thing - pushing the energy back toward the main grid. If not, the energy is still usable by other vehicles on the system that happen to be consuming power, dropping the amount that needs to be pulled from the primary supply.
This is very convenient: In addition to the energy savings, the vehicle's mechanical brakes get much less use, and much less wear. They can be reserved for the last moments of a full stop, holding the vehicle motionless when stopped, and for emergencies. This drastically reduces the necessary maintenance.
What the super-fast-charge battery does is let you do the same thing - MAJOR regenerative braking - for a vehicle that's NOT continuously attached to a power grid. The current hybrids do some of this using more ordinary battery technology. But there are limits due to the batteries' slow charging, large losses, and weight. The fast charge means even a panic stop can be salvaged and a much lower weight of batteries is necessary for a given RATE of energy transfer.
Also: The fast charge implies that the batteries lose very little energy when storing it (otherwise they'd melt down or catch fire). This implies low internal resistance, which also means fast and efficient DIScharge when you want the energy back. So we finally have batteries that can perform as well as (or better than) a (still mostly impractical) flywheel/motor-generator system for "peaking" storage. (TFA's stated losses of about 30% per stop/start cycle look about right for a system where the losses are virtually all in the motor and controller. That would be about 84% efficiency on both start and stop cycles, which is right in the ballpark for a good motor.)
Size the batteries large enough to store the power of a vehicle coming down off about 8,500 feet of mountain freeway and making a full stop near sea level and you achieve the full potential of regenerative breaking: The engine then needs only to be big enough to fight friction - like under 20 horse - and can run at maximum efficiency when it runs at all. Size them maybe a tad larger to also run a couple long and hilly commute-and-shopping cycles on a line-powered charge without starting the engine - reserving the engine for long trips - and you also achieve a fully-functional "plug-in hybrid", a single vehicle adequate to completely replace a normal, non-hybrid, car in ALL service cycles and run off utility electricity (currently the equivalent of about $0.75/gallon gas) in all but cross-country trips.
The usual statement about such breakthroughs - that deployment is always 10 years away - seems to have been hurdled. This technology was at that stage a year or two back. But THIS announcement, of deployment in a vehicle (even though experimental) implies it's not just sitting in the lab, but getting some real-world production and testing. Once that's a production vehicle (if not sooner) the batteries will also be available to automobile designers...
Re:Awesome (Score:2, Informative)
A lot of questions about the why (Score:4, Informative)
Almost all trains are electrical nowadays, where they get their power from is the big question. Diesels get it from carrying a diesel generator with them. Handy because you can be totally disconnected from the net, disadvantage, extra weight (not that much of a problem in cargo trains where the locomotive needs all the weight it can get) and you are limited by the amount of fuel you can carry. Plus you smell bad.
The brits get their power from a third rail. Very hard wearing BUT you got a live wire exposed where everyone can touch it. Bad for level crossings, meaning the train needs facilities to be able to cross a spot without third rail.
Most other trains including light rail system like in the article and trolly busses, use an overhead wire (busses need two since they can't use the rails as the second wire). The problem with this is that it is fairly expensive, can easily break and gets in the way at level crossings where it puts a height restriction on traffic using the crossing.
There are ways around this, for instance at a bridge in holland by zaandam the overhead wire just has a missing part. Since trains typically only got one pentograph the train better be at speed or it will find itself without power (it is only a few meters and trains are notknown for their short stopping distances so this happening is highly unlikely).
This tram would allow itself to run off the overhead wires where they can be installed, but continue normal operation where they can't. This would make planning a lot easier because you can then keep roads open for special transports and still have tram system. This is extremely handy as lifting the wires everytime something big needs to pass is a hassle.
Finally why trams and not busses.
Several reasons, the simplest is driving license. Buss requires a bigger more expensive license then a tram/metro. This is important because while their not all that many jobs for a tram/metro driver, trucking has plenty of competition.
Trains offer a lot more space, because they can be build differently. A buss of the same weight as a tram simply can carry fewer people. While I have seen segmented busses with three segments now, that can carry a lot of people, they are still of lesser capacity then trams and have lost a lot of the freedom of movement of small busses.
Basically trams can move more people then busses can, on less real estate. The prime example might be in holland, between Leidseplein and Koningsplein, where trams run in both directions but the tracks "merge" in the street and split again on the bridges. If you know the area, imagine implementing the same amount of transportation with busses. YIKES!
Busses have their use, on infrequent routes, or routes that are too complex for a tramline. But when you have to move lots of people at street level, trams make a lot of sense.
Re:Trams are the wrong solution (Score:5, Informative)
Currently being implemented by BAA at Heathrow Airport... The busiest international airport in the world.
http://www.telegraph.co.uk/news/main.jhtml?xml=/news/2005/10/20/npods20.xml [telegraph.co.uk]
HTH.