Slashdot Mirror
Battery Powered Tram Charges in 60 Seconds
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.
But a tram runs on rails which mean it always follows a known route rather precisely and can therefore be supplied with electricity directly... No batteries required.
Isn't this just solving a problem which doesn't really exist?
Deleted
... Sony will be lead supplier for the lithium ion batteries to power the vehicles, thus affording the industrial conglomerate an excellent opportunity to diversify into the burgeoning mass-traffic-explosion industry.
Oh, say does that Star-Spangled Banner entwine / The myrtle of Venus with Bacchus's vine?
Trams in particular have very short distances between stations, often only 500m or so. Great for getting on and off, it makes them very accessible unlike traditional rail which doesn't get used much because the stations are so far apart, but, because the distance is so short, they literally spend all of their time accelerating, decelerating and stopped.
Now, the most efficient way to run a vehicle is at a constant speed, acceleration is expensive in terms of energy, and the more mass you have, the more energy you expend. Trams almost never reach a constant speed and because they're basically rail, they're extremely heavy as well.
Essentially trams are a square peg beaten into a round hole. Hence the battery kludge to try to make them more efficient.
Deleted
Actually, for light-rail systems, this would be great.
- 40kph is enough. That's approximately 25mph, which is just right for light-rail.
- 15km is not quite enough. Many light-rail systems have stops that are farther apart than that. Double that number and it's golden. (15km = approx. 9 mi. 18 mi. should be enough for 90% of light-rail systems.)
Recharging at each stop is not unfeasible if the wait is only 60 seconds.
Now for the real problems:
- What does it cost?
- What does it cost to maintain?
If either of those numbers is large, it won't work in the US until mass transit catches on with the masses it's named after. Gasoline will have to be $10/gallon before that will happen.
Power delivery is not a problem at all. Look at the cable cars in San Fransisco, any modern subway... really most modern rail systems. However, if they can turn 70% of their breaking power in to electrical energy, accelerating the train back up to speed or, apparently, 15Km of crusing can be done absolutely for free.
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...
Bantam Dominique roosters crow a four-note song. Once you've heard it as "Happy BIRTHday" you can't NOT hear it that way
Wow, what a strawman. This isn't about your freedom.
However, I agree with some the arguments you make, if you view things from a purely American point of view. You describe an implementation and a system where public transportation has failed. However, one flawed implementation does not mean that the entire idea is bad.
Public transportation works in Europe. Granted, there are geographical differences as well as cultural differences. If you spent enough time in the right European cities, you would probably see systems where public transportation is working.
Here is one case study... I spent a year in Poznan, Poland (pop 567,882). In that city, there are 20 trams (streetcar) lines and 57 bus lines. The trams run center-city and through the more dense areas, with buses making up the difference. While some own vehicles, the public transportation system has high ridership, to the point that during rush-hour one must be careful not to be crushed... People are not living by loud trains, but they are more comfortable with walking and riding bikes, and there are sidewalks (something quite rare in the USA). It may be 1-2 kilometers to the nearest tram stop, and that is perfectly fine by the city inhabitants. In fact, I would drive to the mall a few kilometers away, I would get heckled by my wife's friends -- who would drive if it was only a 30 minute walk? That said, I lived right next to the tram on the 6th floor of a high-rise, and hardly noticed the tram. It wasn't much, if at all, worse than the traffic of an average suburban street in the USA.
The area in discussion is fairly low income, relative to the prices for gasoline and for automobiles themselves. While the salaries were magnitudes lower than those in the USA, gas prices were around $6/gallon. So, if gasoline was lower, or if salaries were higher, would public transportation falter? Perhaps slightly, but one must also remember that the streets in this particular city couldn't handle that much traffic. In fact, this is already a situation occurring in Poznan, as more become capable of affording the cost of an automobile. The streets are becoming crowded at rush hour, and many drivers are choosing to return to public transportation as it is simply a much faster method of travel. Why wait in a traffic jam, watching the tram go past?
In other cities I've visited where the cost of travel was not as much a concern, such as Germany, I found cities where public transportation was not popular, but on the other hand, good city planning had eliminated the need. Walking from one side of the city to the other was no more than an hour, and much less by bicycle. They simply built a number of smaller cities with great urban planning, and in the 20th century linked them with high speed light rail. Thus, if you would rather take a train for 40 minutes, rather than walking for 40 minutes, you could do that as well.
Either way, I'm not sure I've ever met anyone in Europe that spent more than 40 minutes getting to work. I only knew a small handful of people that used a car for work travel, and they were in sales, freelance photography, and real estate. All cases were they were constantly 'on the go' where a car made more sense. (and even then, they would often use public transportation)
In the US, the combination of suburban sprawl and law have created an environment where companies have pulled themselves out of the downtown environments. This amongst other practices has have undoubtedly lead to much success, raising profits, and has helped make us a rich nation. However, these are also the things that, if you want to bring freedom into this, have stripped us of freedom, such as the freedom to walk down the street without the fear of being run over -- something that Ray Bradbury certainly predicted with 451/451' vision.
Finally, my point isn't that you're wrong that there are challenges, I admit that there are. In the USA, city planning is simply not pedestrian and public-transportation friendly. To ch
What utter piece of crap that can come out of someone's mouth who has never seen a good public transportation in action. Move on dude, modern public transport can do much more than transport from Central Business District (what you call downtown in the US) to outer suburbs (which is the point your whole argument is based on). In Melbourne, Australia, you can get from virtually any outer suburb to any other outer suburb without going anywhere near the CBD. The combination of trams and trains works wonders, you have tram stations every 200-300 meters so you are bound to be within easy walking distance of one wherever you are, and you have trains to get you to far-away suburbs fast (and Melbouren is one of the world's most geographically distributed cities) Apartments do not exists here outside of the CBD, everyone likes and lives the "Australian Dream" of having quarter of an acre for their backyard garden, and yet everyone still uses the public transport. I am too familiar with the confused looks of shock, awe and hidden admiration whenever an American collegue or friend comes down here for a visit and realise how well a public trnasport system can work.
And this is the best part for you Libertarian slashdotters: we don't pay any taxes for it as it has been privatised for 8-9 years now. We used to subsedise it heavily but it has been self sustaining for the past couple of years and is actually turning a modest profit recently. Beat that!
And guess who is defending the public transport system here...a self proclaimed petrolhead. I have 3 cars and I absolutely love'em. A track-biased M3 beemer for my track days (soon to be replaced by an R8), a Megane R26 F1 hot hatch for my general use, and a super-hungry comfy V8 Holden (with the Corvette engine) for when I just want to enjoy the sound of that huge engine. But for me, cars are for Sunday mornings and track days and especial occassions, public transport is much more easier, cheaper and more comfortable for daily commute. If a public transportation system is built correctly, it can be so comfortable (short wait time, Air Condition in all trams, quiet and peaceful where I can read the newspaper or listen to my podcasts, never overcrowded) that you would loath having to take out your car and deal with the morning and afternoon traffic, just to get to work.
Get over your stereotypical notions of what a public transport system is and how it works. The world has moved on.
--