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Electronics & Test

Energy Storage Could Make Electric Trains More Efficient

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Beth Stackpole
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High visibility, high utility
Beth Stackpole   7/5/2012 7:45:21 AM
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Wow. Very cool idea and great application of energy storage technology. Also a great test case for other cities and rail systems. My big question is who is paying for this pilot? It's got to be very expensive and with funding so tight for infrastructure-type projects across the country, I'm assuming this owned by the private sector. What's the likelihood that something like this has legs for being applied to other rail systems?

Rob Spiegel
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Re: High visibility, high utility
Rob Spiegel   7/6/2012 1:23:54 PM
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Good point, Beth. It would be good to know where the funding is coming from and whether there is a reasonable return on investment with this technology.

ttemple
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Why not manage schedules?
ttemple   7/5/2012 8:43:35 AM
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It looks like the energy could be managed by controlling who is starting and who is stopping, who is going up hills and who is going down hills, etc.  I didn't realize that they ever dumped energy.  I just figured things balanced out as some trains were stopping or going down hill while others were starting or going up hill, etc.  You would think that an intelligent scheduler could manage things such that energy storage was not needed.

I would think it would only take slight timing changes to keep the loads balanced to where you wouldn't have to dump energy, or store it.

tekochip
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Metrics
tekochip   7/5/2012 2:12:06 PM
It would be nice to see some numbers on how much energy could be saved and what they believe the ROI time would be.

Jerry dycus
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Re: Metrics
Jerry dycus   7/5/2012 4:39:36 PM
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  The ROI  and EROI isn't going to be good with this system, battery though using lead or molten salt might be cost effective near stations.

GE is currently doing a molten salt hybrid train Loco  that would be a better way.

The only reason the voltage might go too high is high resistance in the 3rd rail not able to pass the power along and train operators slowing the train too fast.  Training the engineers would be more cost effective eliminating the problem.

In the Rockies trains were scheduled so when one was going down it's energy was used to run another up the mountain.  They stopped that back when oil got so cheap.

 

herbissimus
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Re: Metrics
herbissimus   7/6/2012 1:50:37 PM
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beautiful, jerry ! i love the ge loco part with the molten salt battery. per a previous comment i've heard of stationary batteries deployed in japan, presidio, tx and now philly.

we're on our way !

Charles Murray
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Re: Metrics
Charles Murray   7/5/2012 8:43:19 PM
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To some degree, they are in unexplored territory here, tekochip. Although regenerative braking and power assist have been done, the concept of piggybacking frequency regulation on top of regenerative braking in an application like this is new. Over time, the pilot will tell them more about the ROI.

naperlou
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Intelligent storage
naperlou   7/5/2012 2:20:16 PM
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This is a great use of technology to enhance efficiency.  It seems like a trend.  Large diesel locomotives have begun using hybrid technology as well.  Similar to this idea, they capture energy generated during breaking to provide low latency energy for acceleration.  Thus, the diesel engines can be used more efficiently. 

As Beth asks, I wonder how much this costs.  Of course, the real metric is the cost to benefit ratio.  Even a costly battery is worth it if it saves money on electricity from the utility.

warren@fourward.com
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Energy Storage Could Make Electric Trains More Efficient
warren@fourward.com   7/5/2012 6:53:56 PM
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Now we're talking!  What a great practical use of wasted energy.  Especially when going down hill with megatons of load!  I hope there is a future for this energy and it doesn't continue to go to waste. 

Now, how can we do the same with other big systems on a large scale?  The problem is, I can't think of anything to compare with trains.  They are unique in this way.  Good luck to Saft.

Mydesign
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Re: Energy Storage Could Make Electric Trains More Efficient
Mydesign   7/6/2012 2:07:54 AM
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Warren, am totally agreeing to your concept. It's the time to think about energy conservation, regeneration and exploring natural energy sources. Even am thinking further about generating energy, while train runs through the track.

warren@fourward.com
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Re: Energy Storage Could Make Electric Trains More Efficient
warren@fourward.com   7/6/2012 7:57:53 AM
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How about piezoelectric generators under the tracks for when these hugh masses move over them?  It probably doesn't meet the ROI, but like capturing energy from the sun, waves, water, and oil, it starts somewhere!

Mydesign
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Re: Energy Storage Could Make Electric Trains More Efficient
Mydesign   7/11/2012 12:54:19 AM
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Warren, this is also a good idea, but moving this huge load over piezoelectric substance is feasible? What I meant is a different idea. Any way wheels are rotating, so some electro-mechanical mechanism to generate energy, which can used for the internal usages like lighting, working of a/c etc.

TJ McDermott
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Portable
TJ McDermott   7/6/2012 12:26:50 AM
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The image shows what looks like a somewhat standard shipping container.  Portable, 1.5 MW containers of power.  What could you do with that?

Mike M
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Re: Portable
Mike M   7/6/2012 2:21:32 PM
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You'd be surprised TJ. The container pictured is a high cube 20' unit. These containers can be  up to 53' in length and can be utliized in a number of ways. My company does this type of integration in ISO containers:)  I'v seen that unit up close, it's a good looking unit and some innovative technology

Mydesign
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Re-generation of Energy
Mydesign   7/6/2012 2:03:16 AM
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"An energy storage project in Philadelphia promises to capture braking energy and provide a voltage boost for electric trains"

Charles, what would be the amplitude of this barking energy. Since most of the components in braking systems are electro-hydraulic components, I feel that only a little amount of energy can be regenerate in normal course (Am not sure). But anyway regeneration or reusing the energy is the best part.

warren@fourward.com
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Energy Storage Could Make Electric Trains More Efficient
warren@fourward.com   7/6/2012 8:11:33 AM
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I have a friend who works with heater strips that place them on rails to keep ice from causing wheels to spin in train stations.  I could see this little bit of accumlated energy created by braking being used to power this system at the stations.  Or maybe use this energy to keep the lights on and heat/AC going in the cars while sitting in train stations rather than using the engine power.  The list goes on and on and the needs are everywhere!

DB_Wilson
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Regenerative Braking
DB_Wilson   7/6/2012 10:19:47 AM
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Railroads have used regenerative braking with energy recovery for years.  The Northern Pacific used it going over the Rockies: the downhill train was pushing energy into the overhead wire which was used by a train coming uphill.  The high cost of maintaining the overhead wire was the eventual demise of this operation.  Other locations tried this but found the ROI did not justify the expense.  Currently, I don't recall any major railroads or shortline freight railroads that use electric power as their principle energy source.

In the Northeast, the electric trains are for passenger operations.  These are either 600 Vdc for subways and other third rail operations or about 11,000 Vac, 25 Hz, for the overhead wires.  In the subways, the grades as slight and the trains relatively light.  Trains are frequent.  This may help with using regerative braking with energy recovery.  The problem is that many of the old subway cars are not designed and built to provide regenerative operation.  With the units operating on 25 Hz. power, the trains are more widely distributed.  For these trains, regenerative braking with energy recovery must have either energy storage for the recovered energy or needs the converter stations to be able to change the 25 Hz. energy to 60 Hz.  Most of the electric locomotives use dc motors and do not have inverters for regenerative operation.   The point this leads to is that the locomotives and/or infrastructure will need some substantial modifications to use energy recovery systems.

One last point, many freight railroads do use regenerative braking without energy recovery.  It is dynamic braking where the recovered energy is converted to heat and dissipated into the air.

William K.
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Energy storage and energy recovery
William K.   7/6/2012 10:27:03 AM
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The amount of energy turned into heat in a standard braking system is very large. Most regenerative systems that store it in batteries are unable to recover very much of it because the battery can only accept so much charge. How much energy? consider that a freight train may spend ten minutes getting up to speed, and yet do a fast stop in thirty seconds or less. Think about a passenger car, possibly ten seconds for zero to sixty MPH, but in a panic stop, sixty to zero in much less time. The limitation is always in the energy conversion process, it appears. Asking an inverter that delivers up to 10KW for an acceleration to convert 50KW back into electrical power is asking for component failure unless the system is built for much more than the driving loads would ever be. 

Forcing power back into the grid is a similar situation, in that each element is only sized for driving power peaks which are usually much smaller.

herbissimus
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Re: Energy storage and energy recovery
herbissimus   7/6/2012 1:59:15 PM
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i worked in an open pit copper mine and the trucks we used had a gross wt 0f 300 tons loaded uphill and 150 tons empty yet their diesel-electric system included 100% retarding i.e. electric to resistance braking which was effective up to 40mph downhill to a 2-5mph stop. then you'd use the hydraulic brake. pretty cool eh ?

tekochip
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Re: Energy storage and energy recovery
tekochip   7/6/2012 2:05:42 PM
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The real beauty to this system would be pushing the energy back into the grid rather than having to carry the heavy storage media on the train.

Jerry dycus
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Re: Energy storage and energy recovery
Jerry dycus   7/6/2012 11:08:29 PM
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   The accereration and regeneration amount is set by the motor specs and are the same in most cases, just reversed.

   A123 batteries in a 150lb pack can put out, take back 450hp, 350kw. Most battery can charge at the same max rate of discharge.

 Piezo isn't viable as it sucks power from the train as extra drag to make the rails move and not eff either so you get back probably 10% vs 50% in braking style regeneration after losses.

Panic stops are rare and frowned on as they rapidly wear the rails and make flat spots on the wheels so not a regen issue.  Trains run the same thing day after day by the same people on the same track usually so surprises are rare. 

Much of New England is electric and all going through NYC by law are.

If the US was smart they would nationalize the rails, upgrade them to electric and charge by the mile, weight givng credits to pay for buying the rails from former owners. A kind of interstate or the rails.  The fiasco we have now of many hundreds of company  lines and too few double, 2 way tracks  has seriously effected our economy, shipping costs and time to get from one place to another. 

Ann R. Thryft
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Re: Energy storage and energy recovery
Ann R. Thryft   7/9/2012 12:32:54 PM
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Energy dissipated as heat is wasted all the time in mechanical and electronic systems. I'm curious about efforts to recapture that heat, which were being discussed a few years ago, for example, in server farms and various IT environments. Chuck, do you know if those efforts are still ongoing in any industry?

Charles Murray
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Re: Energy storage and energy recovery
Charles Murray   7/9/2012 8:10:47 PM
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Although I'm not personally aware of whether those efforts are ongoing in any particular application, Ann, I'm sure our readers are. It makes sense that it would be ongoing in a number of different industries.

Ann R. Thryft
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Re: Energy storage and energy recovery
Ann R. Thryft   7/12/2012 3:14:08 PM
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Thanks, Chuck. It would be interesting to know the results of some of those efforts and if they were abandoned, continued, or replaced with other attempts/technologies.

ttemple
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Re: Energy storage and energy recovery
ttemple   7/10/2012 8:21:38 AM
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I have seen cases where manufacturing plants effectively move "process heat" around to reclaim it.  I have never seen it on a very meaningful scale, however.  Even in the case where there is excess heat, and a demand for heat under the same roof there are difficulties moving the heat around.  In the cases I am thinking of, heat pumps are involved in concentrating the energy enough to effectively move it from areas that are too hot to areas that are cool.

An example is an automotive plant that has heat treating ovens at one end, and space that needs heated in the winter at the other end of the building.  They use heat pumps in the heat treat area to concentrate the energy, and pipe it to other areas of the building that reclaim the heat.  I believe they also use some of the heat in other processes within the plant that need heat.

The issue with energy in the form of heat is the difficulty in transporting it to where it is needed. (A few hundred feet is one thing - miles is another)  If it were easy, we wouldn't need fossil fuel to heat houses. There are always places on earth that are too hot, and other places that are too cold, so we would just move the heat where we want it.  Unfortunately, the means does not currently exist to effectively do this. Attempts to drag icebergs around is about as close as we have come.

A mechanism to efficiently transport energy in the form of low grade heat would be a game changer for mankind.

Ann R. Thryft
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Re: Energy storage and energy recovery
Ann R. Thryft   7/10/2012 11:59:41 AM
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Thanks ttemple for the comments about the difficulties of heat harvesting. In the IT environment, there was a lot of talk about harvesting waste heat from data center equipment a few years back after the info came out about their high amounts of energy use, and about the proposed extension of Energy Star-type ratings to commercial equipment. So I was wondering about the in-plant solutions; larger-scale "solutions" like dragging icebergs around just sound ridiculously complex, not to say unwise from a climate standpoint.

k4man
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This idea has merit
k4man   7/6/2012 10:51:40 AM
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Certainly transit systems, Metro's in particular, are huge power users. The shorter the vehicle headways, the greater the potential benefit & ROI, methinks.  Couple this with more electrically efficient aluminum/stainless steel 3rd rail (compared to the steel rail still in use on many systems) and you could reap some significant benefits.

There may also be an opportunity for this technology with ship-to-shore cranes or intermodal facility cranes where high duty cycle,  repetitive lift & drop motions of heavy containers would make good use of energy storage & retrieval.  Slab handling or ladle cranes in a steel mill may also be good candidates for this technology.

tluxon
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Conservation of Energy ROI
tluxon   7/6/2012 12:38:17 PM
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Wouldn't time be better spent on flywheel energy balancing, which should have far less of an environmental impact?

Charles Murray
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Re: Conservation of Energy ROI
Charles Murray   7/6/2012 5:51:32 PM
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Good question, tluxon. We'll try to get a definitive answer for you.

William K.
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Energy storage and trains
William K.   7/7/2012 6:34:12 PM
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The trains that I have watched come into the local train station all brake MUCH faster than they accellerate as they leave. Most traffic brakes much harder than it accellerates, except for drag racers. Even circle track cars seem to brake much harder than they accellerate. Not because they must, but because they can. And the biggest limitation on regenerative braking is putting the energy someplace. I can draw about 700 amps from a standard car bettery for cranking, but putting 700 amps into it would cause a lot of damage after a short time, I am sure.

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