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More travelogue to follow.

*Lunatic*, n.
One whose delusions are out of fashion.
by DoDo on Sat Sep 8th, 2007 at 02:32:53 PM EST
Thanks for this diary. I have friends in Le Mans now I know when I'll visit them :).

Do you know what is the passenger capacity of a tramway used in Le Mans and expected energy use per km of a fully loaded tramway?

by Laurent GUERBY on Sat Sep 8th, 2007 at 04:28:02 PM EST
[ Parent ]
With capacity, do you mean one line, or the full network? The former is 209 for the Citadis 302 vehicles, the latter is 50,000/day.

I don't know enough about operating conditions to say something definite about energy use, especially per km. You can get a rough value from

  • the vehicle's power: 4x120kW = 480 kW
  • the first opened line will be c. 12 km with a 38 minute travel time, so travel speed is c. 20 km/h

E.g., what you look for must be below 24 kWh/km. Regarding operating conditions: due to accelerations (when motors run at full power) and short distances, not to mention elevation in Le Mans, I am pretty certain that energy use is high, say 50% of the above calculated maximum. What I don't know is to what extent regenerative electric braking is used in modern trams, if at all.

*Lunatic*, n.
One whose delusions are out of fashion.
by DoDo on Sat Sep 8th, 2007 at 05:41:50 PM EST
[ Parent ]
Thanks, I meant for one train. The passenger/day figure depends on number of train bought plus minimum safety/practical delay between train (plus first and last train hours :).

For electric cars the energy use is about 100-160 Wh/km, your approximate figure is 115 Wh/km/passenger for a fully loaded Citadis 302.

Electric cars do have regenerative breaking which I assume Citadis doesn't have (no battery / no injection).

As I've said on ET I don't know why train don't appear that efficient in energy use (they have many other advantages of course but that's not my point here).

As usual if you know where to get real world electricity usage for electric train and tramways in front of passenger*km, I'm interested.

kcurie link says for Citadis 302 in Spain:

19 vehicles work on the TramBaix network, with 18 similar Citadis 302 LRVs on Trambesos. The 32.3m-long trams are 100% low-floor, air-conditioned, and can carry up to 218 passengers (72 seated). The trams were built at Alstom's plant in the city, and are maintained at depots at Sant Joan Despì (Trambaix) and Sant Adria de Besos (Trambesos).

by Laurent GUERBY on Sun Sep 9th, 2007 at 07:53:47 AM EST
[ Parent ]
Thanks, I meant for one train.

Me too (that about "one line" was a braintzypo :-))

Electric cars do have regenerative breaking which I assume Citadis doesn't have (no battery / no injection).

No, electric trains don't feed back into a battery, but into the catenary. With the spread of AC motors and modern power electronics, using the motors as generators is no problem. However, the system is most efficient and convenient if the catenary is on a rail-only AC grid, and least if it is fed DC (limited uptake, adverse effects of change in voltage) -- and trams are fed DC.

However, with some search, I found the new trams do use regenerative braking, even if to a limited extent. I now found that one light rail project on Tenerife, which calculated with Citadis trains (and wind turbines as power source), expects 20% energy savings from regenerative braking.

I don't know why train don't appear that efficient in energy use

Because the bus (and plane) advocates' numbers are spun?

I should dig up numbers about this, I long promised the same on high-speed trains to Luis de Sousa too, but certainly not on the workdays this week, I'm too busy.

kcurie link says for Citadis 302 in Spain:

Note: even trains/trams of the same model can differ strongly (not only in front styling and seating, but carbody width). Modular construction makes it possible.

*Lunatic*, n.
One whose delusions are out of fashion.

by DoDo on Mon Sep 10th, 2007 at 03:11:18 AM EST
[ Parent ]
So there is a Citadis model that does power injection, interesting! The 20% is in range with the numbers for electric cars (up to 35% depending on the cycle).

For comparison I mostly refer to electric car numbers which do exist for a wide variety of cars (including cars in use by customers) and are all more or less the same so I think we can trust them.

A few diaries ago I said I would ask http://www.effet-de-serre.gouv.fr/ and they just answered me today citing page 33 of this PDF:

http://www.effet-de-serre.gouv.fr/images/documents/memento.pdf

Which gives the following relative energy use for passenger-km:

Walk/bike 0
Paris Tramways 0.10
Paris subway 0.13
Paris RER 0.14
Paris "banlieue" trains 0.21
Paris area buses 0.44
France buses 0.56
Motorcycle 0.62
Individual car 1.0

(I don't know if the car data is for one passenger only ... these "green" paper could be more informative).

by Laurent GUERBY on Mon Sep 10th, 2007 at 02:37:28 PM EST
[ Parent ]
Thanks, interesting set of data! I think I have something similar for Germany somewhere, will look up in the uncertain future.

So there is a Citadis model that does power injection

The way I understand it, it an inherent feature (it should be with IGBT inverters), and use depends on whether the tram line power supply was made suited. With some more search, I found other examples of active use (Rotterdam, Sydney, Basel, etc.), so it may not be uncommon. Recovery rates are usually low, but in Basel, a phenomenal 41.6% was achieved with Siemens Combinos in a test. The latter link also gives you kWh/km figures (page 8).

*Lunatic*, n.
One whose delusions are out of fashion.

by DoDo on Mon Sep 10th, 2007 at 03:14:26 PM EST
[ Parent ]
Great finding!

If I do the math on the Basel data:

  • 18908 - 7870 = 11038 kWh consumed
  • 7215.70 km with average 65 passenger
  • gives 23.5 Wh per passenger-km.

So better than car with 2 passenger which is around 50-80 Wh/km-passenger.
by Laurent GUERBY on Mon Sep 10th, 2007 at 03:33:00 PM EST
[ Parent ]

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