China's first super capacitor tram

[David Benton]

https://youtu.be/GX4o-2qFH40" onclick="window.open(this.href);return false;

tram can recharge at 30 - 50 second stops , no catenary needed between stations.

[george matthews]

That could be an important step towards introducing more trams and tramway systems. And the Chinese are beginning to be serious about cleaning up their horrible air pollution.

There used to be a man who posted frequently his belief that non-battery electrostatics could be an important technology but he never seemed to get beyond the idea. It may be that the Chinese have made it work. If so it should have many applications. Trams are obviously an ideal application if the capacitor can be recharged at every stop. Perhaps buses too. The main advance on present day technology would be that it eliminates most of the overhead and this reduces the capital cost of transport. I suspect it is less applicable to conventional heavy rail.

[philipmartin]

It sounds wonderful. It can carry 380 piple (in the four small units depicted. Must be small piple, no fatsos allowed.)

[David Benton]

That could be an important step towards introducing more trams and tramway systems. And the Chinese are beginning to be serious about cleaning up their horrible air pollution.

There used to be a man who posted frequently his belief that non-battery electrostatics could be an important technology but he never seemed to get beyond the idea. It may be that the Chinese have made it work. If so it should have many applications. Trams are obviously an ideal application if the capacitor can be recharged at every stop. Perhaps buses too. The main advance on present day technology would be that it eliminates most of the overhead and this reduces the capital cost of transport. I suspect it is less applicable to conventional heavy rail.

I think advances in Lithium batteries overshadowed the supercapacitor technology , which is at work in some transit system substations. My feeling is this will change , Lithium will not advance much more than it has, and supercapacitors, or some other technology will leap ahead. I am abit surprised by the claimed life span (25-30 years), as my experience with ordinary capacitors is they tend to wear out when they shouldn't.
By the way , I accidently shortened the title, its not China's first super capacity tram , but the first wholly built by a Chinese company.

[David Benton]

It sounds wonderful. It can carry 380 piple (in the four small units depicted. Must be small piple, no fatsos allowed.)

Standees included, I would say . Pretty normal for Asian or European systems.

[george matthews]

That could be an important step towards introducing more trams and tramway systems. And the Chinese are beginning to be serious about cleaning up their horrible air pollution.

There used to be a man who posted frequently his belief that non-battery electrostatics could be an important technology but he never seemed to get beyond the idea. It may be that the Chinese have made it work. If so it should have many applications. Trams are obviously an ideal application if the capacitor can be recharged at every stop. Perhaps buses too. The main advance on present day technology would be that it eliminates most of the overhead and this reduces the capital cost of transport. I suspect it is less applicable to conventional heavy rail.

I think advances in Lithium batteries overshadowed the supercapacitor technology , which is at work in some transit system substations. My feeling is this will change , Lithium will not advance much more than it has, and supercapacitors, or some other technology will leap ahead. I am abit surprised by the claimed life span (25-30 years), as my experience with ordinary capacitors is they tend to wear out when they shouldn't.
By the way , I accidently shortened the title, its not China's first super capacity tram , but the first wholly built by a Chinese company.

If this works as well as it is claimed it could be a very serious improvement in energy handling.

[David Benton]

It appears the super capacitors ability to charge alot more quickly than a battery, is what gives it the advantage in this application.
Rail use covered towards the bottom of this wiki page.
https://en.wikipedia.org/wiki/Supercapacitor" onclick="window.open(this.href);return false;

[george matthews]

It appears the super capacitors ability to charge alot more quickly than a battery, is what gives it the advantage in this application.
Rail use covered towards the bottom of this wiki page.
https://en.wikipedia.org/wiki/Supercapacitor" onclick="window.open(this.href);return false;

That article is very interesting. I haven't been keeping up with the work being done in this field.

I think it is clear there are a number of applications that can replace both batteries and overhead for a large number of uses. Probably it won't have any uses for long distance heavy rail. But if we can have electric vehicles in towns without overhead it would be an immense improvement. As China has some of the worst urban atmospheric pollution in the world it is understandable that they want to adopt this technology as soon as possible. However, it is probably too soon to evaluate whether this method of storing energy will be reliable enough for general adoption. How often will the electrostatic elements need to be replaced?

The most common objection to urban trams has been the presence of the overhead. If that can be eliminated they would prove more acceptable. In general this seems to be a useful development. Perhaps it can be applied to private cars for some purposes, and taxis.

[george matthews]

It appears the super capacitors ability to charge alot more quickly than a battery, is what gives it the advantage in this application.
Rail use covered towards the bottom of this wiki page.
https://en.wikipedia.org/wiki/Supercapacitor" onclick="window.open(this.href);return false;

Yes, I think it possible that this technology has very important applications and may well transform urban transport as well as several other fields. I don't see it as of much use to long distance heavy rail but in making possible more electric urban transport it seems likely to have a great future. It may well be more useful for buses than rail. But trams have less friction and therefore smaller energy needs than buses. The Chinese are taking their horrible urban pollution seriously and need transport that doesn't add to it. The same is true all over the world so I think this technology is likely to be adopted quickly.

[philipmartin]

Standees included, I would say . Pretty normal for Asian or European systems.

New York City too, during rush hour. Standees turn into sardines.

[kato]

However, it is probably too soon to evaluate whether this method of storing energy will be reliable enough for general adoption.

The local tram network over here have been using supercap systems - MITRAC Energy Saver - on regular trams for over five years now. The original intended application was to service a planned section without catenary which wasn't built; instead the supercap technology is now being introduced fleet-wide due to its other benefits. 200+ trams ultimately.

The "other benefits" to supercaps are primarily in using the supercaps as onboard batteries; the trams generate electricity to shed energy when braking, which previously was fed into the catenary to possibly be used by other trams in the same section. With the supercap system onboard this energy is not wasted when there are no other vehicles feeding from the same section - but can be reused by the same tram, thus lowering their overall energy bill . Stated savings are up to 30%, which isn't too shabby and apparently worth the initial investment.
Second nominal benefit is that when electric supply through the catenary fails for some reason then trams can use the stored energy to make it to the next regular stop. Short brown-outs can be completely compensated, which also affects planning for electrical supply systems for the catenary.

Expected lifetime of the supercaps used here is around ten years, the prototype in the local network has been running for 12 years now. It's in my opinion likely that a replacement cycle will ultimately be structured around the regular full inspection which takes place every 8 years, won't make much sense otherwise.

The same operating company is also testing a bus line with electric busses with supercaps with recharge at stops similar to the Chinese concept. The busses hit a real-life problem pretty fast though, namely that they were stuck in traffic and could not compensate for it by shortening stops since they recharged at these stops; they were supposed to run on the same timetable as the diesel busses previously serving the route. Meaning that either the timetable went really messy with delays as the day went on or the busses had to be pulled back into the depot around noon since by that time they had exhausted their reserves (usually the latter).

[David Benton]

Good info, thanks Kato.
I had not thought of that, every bus has to make every stop, you cant have an express service. A bus caught in traffic would not use extra power for traction, but still must power lights, aircon etc. 300 people in a tram are going to generate a lot of heat on a hot day, it must use a fair % of the total power requirement.

[David Benton]

For the buses , they could install intermediary catenary at traffic lights or oothr intersections.

[kato]

I had not thought of that, every bus has to make every stop, you cant have an express service.

That too. The primary problem is that they basically took the original timetable for the busses to run on - which had some extended wait times built in at some stops (including end stop) so that if the busses are delayed by traffic they could catch up by shortening these stops. Offhand I think for a 30-minute full route there were up to 8 minutes "disposable wait time" planned into the original timetable mostly at the end stop when the bus would turn around. The minimum recharge time required (to get the energy to drive the full round) ties them to waiting at stops for around 7 of those 8 minutes now, meaning if they're stuck in traffic they'll automatically start running late with no chance to catch up.

Since the bus recharge stations aren't at every stop for financial reasons (they use magnetic induction coils in a concrete plate sunk into the street at the stops, hence also requiring road construction works) there's no chance to use "extra recharges" at other stops either. In theory if you had the coils at every stop - or just more of them - you can lower the delays by recharging in more places where you'd otherwise only stop. This showed in the initial phase when only three of the five recharge coils on the route were operational; taking the fourth and fifth into operation reduced delays from "we could just as well stop service after noon" to "we need an extra 4 minutes on average per run".

The problem was then temporarily fixed by mixing in a diesel bus that'd give the other busses time to recharge every few hours by skipping a round and fully recharging, and then later was fixed by modifying the timetable slightly.

300 people in a tram are going to generate a lot of heat on a hot day, it must use a fair % of the total power requirement.

We simply don't fit the trams with aircon here - except for the driver's compartment

During winter - like now - there's significant amounts going into lights (early and long nights) and into heating, especially as you're opening doors to the cold every minute.

Most energy use is when starting from a standstill (while they're just trams they still weigh around 5 tons per axle) - and due to the many stops of trams this occurs about every minute though. Those trams that have them draw about 40% of the energy required for getting underway from the supercaps from energy stored when braking twenty seconds earlier for the stop.

The only problem in introducing supercaps with the trams was encountered when mixing vehicles with and without them in multiple-unit trains.

[george matthews]

Most energy use is when starting from a standstill (while they're just trams they still weigh around 5 tons per axle) - and due to the many stops of trams this occurs about every minute though. Those trams that have them draw about 40% of the energy required for getting underway from the supercaps from energy stored when braking twenty seconds earlier for the stop.

One way of arranging that would be to start the tram while connected to a short overhead - that is, use the external supply to power the start up and rely on the internal power once the tram is moving.