Lithium ion Japanese tram recharges in <1 minute
Streetcars are classy. There's an entire romanticism that goes along with memories of these city people movers. In most of America, of course, GM helped put an end to streetcars. But, if you're a fan of trams, take a glimpse at the future of streetcars. Naturally, it's available in Japan.
A place called the Railway Technical Research Institute in Kokubunji, Tokyo, has announced the development of a lithium-ion powered tram with a battery that can be recharged in under a minute. The batteries will get a serious test when they start being used in Sapporo at the end of next month (let me tell you, it gets cold in Sapporo in the winter). The tram can do 40 kph for 15 clicks and about 70 percent of the energy used to decelerate is sent back to the battery. Even with all that, these trams still only use about 10 percent less energy than existing streetcars, says Far East Gizmos quoting the RTRI.
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[Source: Far East Gizmos via NewLaunches, h/t to Ray]
Reader Comments (Page 1 of 1)
Chris M 4:37PM (10/30/2007)
Adding batteries to trolleys increases cost, adds weight and reduces performance, so why do it? Even the energy from regenerative braking could be better handled through the overhead wiring and power grid, and modern trolleys are already equipped for that.
The only advantage would be the potential to eliminate overhead wires for parts of the route. Perhaps someone complained about the appearance of those wires, so they are planning an expensive solution to that "problem".
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Domenick 5:23PM (10/30/2007)
"Adding batteries to trolleys increases cost, adds weight and reduces performance, so why do it?"
In this case, the addition reduced their energy use by 10%. I suppose that's why. If they can also reduce some of the overhead wires as well, that's also good.
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rgseidl 7:05PM (10/30/2007)
Overhead wires are incredibly expensive assets to install. Plus, they're a bit of an eyesore and in Japan (= earthquake country), a potential fire hazard.
The weight of the batteries is irrelevant in a light rail application because it just replaces ballast, e.g. sand for emergency stops. The friction coefficient of bare metal against bare metal is low, so you actually need a lot of weight to get any decent traction.
Of course, if you don't have an overhead line to worry about, you could use rubber tires and regular roads instead. Technically, that would make it a bus and permit sharply lower weight. The Frauenhofer Institute's AutoTram is a half-way house in-between buses and trams.
Btw, regarding that 10% energy savings. The number underlines how bad many overhead line systems are at handling recuperative braking. Few are equipped with a network of stationary energy stores that can absorb the power that is suddenly fed back into any given segment of the dedicated overhead grid. Instead, snubber circuits are used to dissipate any power that cannot be used immediately to accelerate another tram somewhere else.
The number also underlines that even with an amazing 1-min recharge time (involving massive power flows), batteries just aren't ideal for recuperative braking events that last just a few seconds. That's what supercaps, hydraulic accumulators and superflywheels are good at. Perhaps a combo could increase range on a single charge and reduce the number of recharge points required for this concept of occasionally-connected trams.
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Tim 9:42AM (10/31/2007)
So much for that "battery swapping" lunacy.
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Nils 1:54PM (10/31/2007)
The sand in trams is not used as ballast weight but is blown between the weels and the tracks when needed. I think Alstom makes a tram with batteries already. It's meant to cover short distances where overheads are hard/expensive to install. In Bordeaux, they even did that because of aesthetics in the historic city centre!
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pmgpmg 3:44AM (11/01/2007)
"I think Alstom makes a tram with batteries already... In Bordeaux, they even did that because of aesthetics in the historic city centre!"
Little correction:
- In Bordeaux, Ground-level power supply, also known as surface current collection, Alimentation par Sol (APS), is used. It was invented for the Bordeaux tramway.
- Unlike the track-side third rail used by most metro trains and some main-line railways, APS does not pose a danger to people or animals, and so can be used in pedestrian areas and city streets.
-APS uses a third rail placed between the running rails, divided electrically into eight-metre segments with neutral sections between.
- Each tram has two power collection skates, next to which are antennae that send radio signals to energise the power rail segments as the tram passes over them.
- At any one time no more than two consecutive segments under the tram should actually be live.
http://en.wikipedia.org/wiki/Ground-level_power_supply
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