I think I smell something.

[Ian.M]

Evaporation from reservoirs can be reduced by up to 90% using modular floating covers.
Also Nevada has a deep pit lake remediation problem: https://www.newsreview.com/reno/pit-lake-challenge/content?oid=7176643 so there's a lot of water that isn't fit for drinking already in big holes in the ground.  Building banked reservoirs next to them for pumped storage hydro, to make them revenue generating could help pay for treating them to avoid ground water contamination.

NiFe cell batteries are very long lived and can be designed to be fully rebuildable.   After the first couple of decades, you'd be running a maintenance program of taking the lowest performance bank out of service, and testing the batteries to see which need their plates shipped off to be reconditioned, or you might even have reconditioning facilities on-site if the installation was large enough. 

[rx8pilot]

If we can achieve 80% efficiency (end-to-end) with pumped hydroelectric storage then I think the claimed 86% of the train storage is certainly not impossible.

The train rails have less friction than the long water pipes and a geartrain has also less losses than a pump. Not by much but they can certainly make that 6% difference.

So, they can take energy from the grid or whatever cyclic renewable source - transport that to the train - convert it to motor voltage or vector drive or whatever - go through the transmission system losses - and drive the unit uphill only losing 7% of the original energy? I am not an expert at all, but that is a pipe dream. What motor from input terminals to to output shaft can do that without considering any other losses - a few, but not many. I read about some 95% motors, so if you go with that the rest of the entire system can be no more than 2% loss?

No way. Not even close. Can the reverse (downhill leg) be any better? No, it is most likely worse than the uphill. Projects like this get funded by making rediculous claims. By the time the claims are proven crazy - the organizers already have a pile of cash in the name of green energy. It's a government funded Kick Starter with similar craziness.

[Brutte]

4600 tons raised/lowered ~ 1km. Rails typically have 20 ton limit on an axle load = 230 axles... Because of the gradient I suppose all/most driven.. Plus power rail, back and forth. Serious piece of gear.

Now, lets calculate the volume of water that weighs 4600 tons. Ok, 4600m3 = 16.5m^3
Olympic swimming pool is 2500m3.

I bet pouring two roofed concrete tanks (although cheaper are not cube but have chamfered sides) on that desert, piping and pumps would peak at 0.003% of the investment cost of that railerizer.

[johansen]

So, they can take energy from the grid or whatever cyclic renewable source - transport that to the train - convert it to motor voltage or vector drive or whatever - go through the transmission system losses - and drive the unit uphill only losing 7% of the original energy? I am not an expert at all, but that is a pipe dream. What motor from input terminals to to output shaft can do that without considering any other losses - a few, but not many. I read about some 95% motors, so if you go with that the rest of the entire system can be no more than 2% loss?

Baldor says their 200hp induction motors are 96.2% efficient at full load, 96.4% at 3/4th load.

just the motors make 92.5% possible.

train wheels slip as well, and you have gear box losses.

[CatalinaWOW]

Need to do apples to apples comparison.  Pumped storage normally doesn't have transmission losses since it is done in conjunction with generation.  If you are building a pumped storage facility somewhere other than a major point of generation then appropriate transmission losses will need to be included in pumped storage efficiency.  Scale also needs to be considered.  Piping losses and some other losses drop with scale for pumped storage, probably not for the rail system.

There are many issues with this rail storage concept, but as others have said, it at least doesn't require over unity power conversion, magic materials or technology that doesn't exist.  Whether the business case exists or not depends on the specific application.  Batteries and many of the other concepts laughed at in this thread have been deployed successfully where the unique circumstances justify them.  One interesting possibility is that there might be locations that have appropriate time varying loads to make the physical delivery of the power an interesting part of the analysis.  That is, cases where a heavy, short duration load exists at or near the top of the hill being used, while an excess of power is available nearer the bottom of the hill and appropriately time phased. Potential significant reduction in transmission losses.

[Brutte]

There are many issues with this rail storage concept, but as others have said, it at least doesn't require over unity power conversion, magic materials or technology that doesn't exist.

Ok, now there are seven zillion ways to store energy that could be characterized same way. What about a 100000 ton bamboo clockwork spring?

The railerizer imposes unprecedented constraints. How would you imagine finding/building a ~1.2km high "mountain" with a 5.5mile, 8 degree incline capable of ~straight track for the load of 230 driven axles?! Even if you found such place (of course close to both consumers and the producers, for that   93% efficiency), that 8.8km mountain track earth work (or should I write rock-blasting work) would require tunneling and bridging technology that does not exist to be economically and energetically viable (with relation to pumped-storage).

Panama Channel is a piece of cake when compared to that thingy.

[hayatepilot]

So, they can take energy from the grid or whatever cyclic renewable source - transport that to the train - convert it to motor voltage or vector drive or whatever - go through the transmission system losses - and drive the unit uphill only losing 7% of the original energy? I am not an expert at all, but that is a pipe dream. What motor from input terminals to to output shaft can do that without considering any other losses - a few, but not many. I read about some 95% motors, so if you go with that the rest of the entire system can be no more than 2% loss?

No way. Not even close. Can the reverse (downhill leg) be any better? No, it is most likely worse than the uphill. Projects like this get funded by making rediculous claims. By the time the claims are proven crazy - the organizers already have a pile of cash in the name of green energy. It's a government funded Kick Starter with similar craziness.

ABB has induction motors (not the most efficient method) with 97.9% efficiency and with a synchronous motor-generator you can achieve 99%.
So with a 98% motor-generator the drivetrain (gears and rails) needs to be 95% to give you a total effieciency of 86%, which is actually pretty easy to achieve. Or you could choose a motor with high pole count so you wouldn't need a gearbox at all...

The efficiencies of those big machines are incredibly high. As I've said if it's possible to build a hydroelectric storage plant with 80% total efficiency (with the lossy pump and long pipes and flow losses), then it's certainly possible to achieve 86% with a big scale rail storage system.

Transmission losses are never included in the calculations since the power rarely comes and goes to the same place. Calculations start at the fence of the power plant. 

I don't say that this system should be built everywhere but where the topography is ideal and no water is available this could be a interesting alternative.

[RIS]

what would be overall efficiency of the system if the train carries batteries as cargo
and whether energy can be stored in the magnetic field big as the entire train.

[TinkerFan]

To be fair, this project is at least founded in real physics that can be measured. The key part that I appreciate is that it can be scaled up to sizes that are practical at costs that are, well, high, but not insane. Batteries, no matter what kind you use, just aren't practical that way, and at some point will need to be wholly replaced. Rail cars, electric drive motors, and generators can all last for many decades with decent maintenance—and unlike batteries, their lifespan can be extended nearly indefinitely with good maintenance.

I see your point, but especially when sotring energy, there is much more to it than just the physics behind it. If you pass water or trains up and down doesn't really matter and you need a special location for both. And how do you transport the electricity generated away from the train? Batteries? If you've got some kind of wiper, they will errode quite a lot, when you have trains going up and down all the time . And how do you hold the train up? You will always loose Energy there, the longer it has to stay there, the more (Or you need a lot of Energy to start it going downwards, which means the less energy stored, the less efficient it gets).
How about the running costs (maintenance etc.)?

[Ian.M]

Holding the train in place on the incline is quite simple: Its this amazing technology that's been around since the Roman empire called friction brakes!   Yes it takes power to either apply or release (or both) the brakes, but it takes very little if any power to keep the brakes released and none to keep them applied. Any sane design will have the brakes fail safe (ON) if power is lost.

[ajb]

If you've got some kind of wiper, they will errode quite a lot, when you have trains going up and down all the time .

  Every electrified rail system in the world deals with this one way or another, it's not exactly a new problem.  This application is potentially less challenging in this respect than a typical rail transit system, since the rail units will spend most of their time on a single straight segment, and you won't get the massive make/break arcing that a typical transit system experiences as trains move from one electrical block to another, or have to switch pickup sides.  I used to live right next to a metro rail station, the arcing you'd see at the beginning and end of third rail segments was impressive. 

And how do you hold the train up? You will always loose Energy there, the longer it has to stay there, the more (Or you need a lot of Energy to start it going downwards, which means the less energy stored, the less efficient it gets).

There's an interesting glimpse of their control strategy in one of the videos--they talk about queuing a number of active units in the middle of the slope, and at any point they can add or remove units to the top or the bottom of the queue and add or remove energy in the process.  That gives them a number of possible energy-positive, energy-negative, or energy-neutral maneuvers in adjusting the queue size, spacing, and position over one or more units.  With a simple mechanical brake, you could hold a couple dozen units idle in the middle of the queue with basically no power consumption while adding or removing units from the top or bottom to make small adjustments.  Then when you need a larger adjustment you can immediately start the entire queue moving up or down at once.

[calexanian]

One Cubic km battery storage center every here and there. What could go wrong with that?  O0

[ez24]

I think I smell something.

What you smell is my money leaving my pocket.   Just another reason for California politicians to take it. 
This is to furnish "clean" power to CA, so we can say we saved the world (while lining their pockets)

[Brumby]

I think the rail system has great potential!

Just think .... MacGyver could increase output by loading big rocks on the top of the rail cars to save ... * something *

[Delta]

I think the rail system has great potential!

Just think .... MacGyver could increase output by loading big rocks on the top of the rail cars to save ... * something *

Why not drive the trains to the top of the hill empty, thus only using a small amount of electricity, then load the rocks on at the top before sending it down again to generate lots of electricity!  The rocks could be transported up the hill by truck, resulting in free electricity!

[Brumby]

** Looking for a facepalm LOL ....... **

MacGuyver only needs to do this once (as he always does), so a reusable/sustainable solution isn't required.

[jolshefsky]

I find it rather disconcerting that whenever a proposal like this comes around, engineers are eager to prove it impossible. But spend money building a new substation and there's not a peep about the transformer losses up and down, or the true efficiency of the grid (the US Government claims 6% losses which seems impossible given ~96% efficiency at each transformer), or how the chemical fuel source is finite, or how efficient the process is in terms of input-energy (e.g. chemical potential in fossil fuel) to output-energy (billable KWh near point-of-use). Weird. 

[Delta]

I find it rather disconcerting that whenever a proposal like this comes around, engineers are eager to prove it impossible. But spend money building a new substation and there's not a peep about the transformer losses up and down, or the true efficiency of the grid (the US Government claims 6% losses which seems impossible given ~96% efficiency at each transformer), or how the chemical fuel source is finite, or how efficient the process is in terms of input-energy (e.g. chemical potential in fossil fuel) to output-energy (billable KWh near point-of-use). Weird. 

Not quite.  A new idea has to be better than or at least have the potential to be better than established technology.

This is neither.  It's bollocks.  This kind of shit diverts money away from projects that could make a difference, and when it fails causes more people to be cynical of all environmental projects.

[CatalinaWOW]

One of the most valuable books I have read is "Profiles of the Future" by Arthur Clarke.  Originally written in 1960, his predictions of technology in the year 2016 have been proven both wrong and right.  But the really important part of the book comes in the first two chapters where he identifies the difficulties in prediction.  He identifies two sources of failure, failure of the nerve and failure of the imagination.  In illustrating these issues he concludes that if an expert in a field concludes that something is possible you can take that prediction to the bank.  If the expert predicts it is impossible - then not so much.  Two of the illustrations of this that he provides are a deep engineering analyses provided by Cornell University and by the British Planetary Society.  The analysis by Cornell was done in the 1930s, a time when Cornell was a leading institution in aeronautics.  They concluded that because of drag, engine efficiency etc. transatlantic passenger aircraft transport was a silly fantasy, that such an aircraft could only carry a handful of passengers and would never be economically viable.  The British Planetary Society did a learned study on the energy content of propellants, strength of materials etc. and concluded that it was physically impossible to place an object on the moon.  Neither of these analyses was technically wrong.  The physics and math were correct.  They just analyzed the problem slightly incorrectly.  The problem in the Cornell analysis was ignoring the reduced drag possible by flying at higher altitude.  The British Planetary society missed the improvement in system mass fraction that is achieved in a staged rocket.

I highly recommend reading the book.  Those introductory chapters are worth the entire price and more.  The later chapters involving actual predictions are amusing reading, and also illustrate the other side of the problem.  The things the experts who are sure something can be done and have proved to be wrong for various reasons.

Those who are sure that a system is not possible should be very sure that they understand all of the conditions on its operation.

[Delta]

But no one is saying that you can't store energy by moving a train up a hill, we're just saying it's a shit way to do it, and the economics and logistics of other methods are far better.

I will buy a copy of that book though... 

[johansen]

I find it rather disconcerting that whenever a proposal like this comes around, engineers are eager to prove it impossible. But spend money building a new substation and there's not a peep about the transformer losses up and down, or the true efficiency of the grid (the US Government claims 6% losses which seems impossible given ~96% efficiency at each transformer)

It really is that good. hard to believe, but even a 50MW transformer only weighs 50 tons. that's 1 kilowatt per kilogram power density, and the losses are about 1-2 watts per kilogram for the iron, and about the same for the copper.. assuming 50:50 cu:fe mass/weight. usually there is less copper than iron so there are more copper losses. the most efficient point is sometimes as low as 25% full load rating. so even if you figure 10 watts per kilogram losses.. that's still 99% efficient.

The lowest efficiency transformer is the pole transformer at the end of the line. i don't know what the usuall efficiencies are for them, but most of their losses are no load losses just due to the fact that the average residential load is only 2KW, and they put a 25KW transformer most everywhere feeding 1 or two or three houses.

the highest efficiency transformer is at the other end of the line, stepping up 25KVAC to something like 10-20 times that for the long distance lines. those ones are in the realm of 99.5% or better.

because the efficiency of the grid is so high.. when 5 volts dc per mile shows up on the power lines due to a magnetic disturbance from the sun, etc.. this is enough to cause 100's of amps dc to flow. which then saturates the transformers and thousands of amps of harmonic current start flowing and blow up the transformers.. takes about a minute for that to happen worst case senario.  one of the problem with current transformers is the dc may saturate the current transformer so the grid won't even know there is a problem..

What is insane that we haven't spent the 50 million estimated cost.. to install a large capacitor, resistor, and spark gap in series/parallel with the neutral of the top 1000 large distribution transformers, lifting the ground return and breaking the loop for the dc voltages appearing on the line.

[johansen]

But no one is saying that you can't store energy by moving a train up a hill, we're just saying it's a shit way to do it, and the economics and logistics of other methods are far better.

I will buy a copy of that book though... 

i'm not convinced its a shit way to do it, as i described earlier the cable drum method proposed by the "gravity battery" folks is really a cable fatigue experiment.

I described elsewhere that 600 dollars in stainless steel aircraft cable (at 1/3rd the breaking load) stores about as much energy as does 10 laptop batteries.
a 1200 foot length of polypropylene rope stretched to 1/3rd its breaking strength stores about as much energy as 1 laptop battery, and costs about 44$.
But you have to have a 1200 foot deep mine shaft, and you have to keep water out of it..

Motors can run 24/7 for 25 years, so can the gear boxes provided the oil is changed. its really a cable fatigue experiment in my opinion.

but with rail cars.. motor gear box.. same problem. no cable fatigue, but now you have 100 times as much weight on the bearings. so you've traded cable fatigue for wheel bearing fatigue, and wheel bearing losses. it may turn out to be a wash.

also you have wheel creep which may cost you as much as 1% each way.

wheel creep on a train is no different than the same creep problem that differential roller screws have (used for positioning milling machines and etc), which does not provide absolute motion and must be used with glass scales.

[TheWelly888]

The point of energy storage is to be instantaneously available to fill in the gaps when demand spikes above capacity which is what we have the well proven pumped hydroelectric storage for.

I noticed that these rocks have to be pivoted to fit on the railcars before the potential energy is converted to kinetic - how long is that going to take and how much energy be expended to turn the rock 90 degrees each way?

[station240]

Not sure why they are using concrete as the mass, have you seen the price of scrap steel lately.
Yup load it up with scrap steel as it's cheaper! (thanks China)

I can think of easier methods involving hydro power.
Build a big underground reservoir (or find an existing one), and put a smaller one on the surface.
When power is in excess, pump water to the top, when it's night/high demand let whatever water is in storage back down via turbine.

[Delta]

But no one is saying that you can't store energy by moving a train up a hill, we're just saying it's a shit way to do it, and the economics and logistics of other methods are far better.

I will buy a copy of that book though... 

i'm not convinced its a shit way to do it, as i described earlier the cable drum method proposed by the "gravity battery" folks is really a cable fatigue experiment.

I described elsewhere that 600 dollars in stainless steel aircraft cable (at 1/3rd the breaking load) stores about as much energy as does 10 laptop batteries.
a 1200 foot length of polypropylene rope stretched to 1/3rd its breaking strength stores about as much energy as 1 laptop battery, and costs about 44$.
But you have to have a 1200 foot deep mine shaft, and you have to keep water out of it..

Motors can run 24/7 for 25 years, so can the gear boxes provided the oil is changed. its really a cable fatigue experiment in my opinion.

but with rail cars.. motor gear box.. same problem. no cable fatigue, but now you have 100 times as much weight on the bearings. so you've traded cable fatigue for wheel bearing fatigue, and wheel bearing losses. it may turn out to be a wash.

also you have wheel creep which may cost you as much as 1% each way.

wheel creep on a train is no different than the same creep problem that differential roller screws have (used for positioning milling machines and etc), which does not provide absolute motion and must be used with glass scales.

You seem to be under the misapprehension that someone is arguing in favour of building storage systems using drums of cable...