Advanced Rail Energy Storage

[najaB]

The Moroccan desert has lots of sun and no consumption, so is primarily a generator.

Erm... no. Morocco has a population of 33 million or so - they are very thirsty for energy. It is still a net importer of energy so their problems are supply side, not demand side.

They have a massive solar energy potential, which would allow them to be a net exporter, but the problem with solar is what do you do when it's dark? Hence storage.

Morocco and the southwest US are very similar - dense population centres that need energy and solar/wind potential in the desert. There are more similarities than differences.

 

[AndrewE]

I've never argued about pumped storage.

Even if you're not, I am! And what about "send it somewhere wet that can do pumped storage or other water related things?"

I was saying that a) finding appropriate places for more pumped storage and b) paying for the power lines between the two might well make this (ARES) the best option.

Think about it: SW USA. Hot and dry. Established seismic risk. Lots of local potential PV and wind generation. Sparsely-populated mountain ranges behind the coast. Big cities with lots of demand...
Why not give rail a chance? It seems that they might.

 

[najaB]

Think about it: SW USA. Hot and dry. Established seismic risk. Lots of local potential PV and wind generation. Sparsely-populated mountain ranges behind the coast. Big cities with lots of demand...

Methinks your definition of 'south west USA' doesn't match everyone else's...

 

[AndrewE]

Methinks your definition of 'south west USA' doesn't match everyone else's...

Look at post #24 (and add in California).

 

[najaB]

Look at post #24 (and add in California).

California is not a south western state. Well, the very easternmost corner of it is, I suppose.

 

[AndrewE]

California is not a south western state. Well, the very easternmost corner of it is, I suppose.

Well pardon me!
I actually said "See post 24 and add in California"
You might try looking at this:
http://www.americansouthwest.net/map.html

California's southern border is with Mexico, and it's on the west coast so I would have said it's in SW USA. But apparently it's not (not that I really care). It's a poor day when you don't learn something.

 

[DaveNewcastle]

I'm findng it hard to see where some of this conversation is going, and I have nothing to say about which parts of the USA fall within which regions, or how dense concrete is, or how a gravitational energy storage asssebly on rails would negotiate points.
But I will make these two points:

1. Water pumping.
The operational and effective energy storage systems in the UK operate over a height differential of only about 200 metres. That is not difficult to achieve on the west coast of the USA (however it is defined) or in thousands of other locations. The requirement for a water suppy is only in respect of replenishing losses (leakage, evaporation, etc); essentially it recycles the same volume of fluid up and down the same 'pipe'. The 'reservoirs' need not all be exposed to sunlight. Many alternative are available: where geological strata provides underground capacity - former oil wells provide potential for reserves underground; even a simple web of dark pvc membranes over the 2 or 3 square kilometers for a deep reserve will make a big difference to evaporation

2. Rail mounted rigid gravitational storage.
There is no reason to presume that this use of a rail-wheel interface (efficient as it is) need have any compatibility with existing passenger and freight transport systems. The electrical connections to the moving masses could be quite specific to the task in hand. e.g. full delta three-phase connections could be made via a novel triple-contact conductor, mounted on the ground between the rails, or alongside the powered vehicle. (I assume the entire site is fenced off against intruding people and wildlife, as are most power facilities).
But what strikes me as most eccentric about this proposal is the use of the smooth wheel-rail interface (which works so well for general purpose railways with all the clever geometry for turning corners). Surely this dedicated purpose track would achive far greater efficiencies with toothed rail and cog-wheels. No slippage and a near-perfect transfer between movement and energy.

All of these schemes do require a high level of maintenance and ultimately, it is the running costs of energy systems that are as crucial as the cost of consumable fuels in determining viability.

 

[najaB]

But what strikes me as most eccentric about this proposal is the use of the smooth wheel-rail interface (which works so well for general purpose railways with all the clever geometry for turning corners). Surely this dedicated purpose track would achive far greater efficiencies with toothed rail and cog-wheels. No slippage and a near-perfect transfer between movement and energy.

Or cable/chain over a drum.

In which case you could make it even more efficient by moving the mass straight up and down.

Which would reduce the land take, and allow you to keep the generation equipment stationary, removing the need for any conductor rail (and the losses which that entails).

 

[cjmillsnun]

but the video shows that this is flexible. Smaller units shifting a few concrete slabs can just stop and go back down when energy surplus changes to shortage. Try that with a huge train of iron ore. Mind you, high-density concrete (Iron-ore aggregate) is a good enhancement, I've read about it being used to stop skycrapers with big basements floating, but this is a far better use.
--- old post above --- --- new post below ---


The densest mass? Concrete is a lot denser than water, especially with iron-ore aggregate (even if you could find enough water in the southern USA), and I can assure you that there are a lot of frictional losses in moving water around. There are also the seismic risks which would concentrate your mind if you lived anywhere nearby.
As I said, there aren't many "reservoirs located directly above and below each other" in California or Oregon (or in the UK for that matter.)

There may not be many but they do exist. Have you ever been to Dinorwig?
--- old post above --- --- new post below ---

I'm findng it hard to see where some of this conversation is going, and I have nothing to say about which parts of the USA fall within which regions, or how dense concrete is, or how a gravitational energy storage asssebly on rails would negotiate points.
But I will make these two points:

1. Water pumping.
The operational and effective energy storage systems in the UK operate over a height differential of only about 200 metres. That is not difficult to achieve on the west coast of the USA (however it is defined) or in thousands of other locations. The requirement for a water suppy is only in respect of replenishing losses (leakage, evaporation, etc); essentially it recycles the same volume of fluid up and down the same 'pipe'. The 'reservoirs' need not all be exposed to sunlight. Many alternative are available: where geological strata provides underground capacity - former oil wells provide potential for reserves underground; even a simple web of dark pvc membranes over the 2 or 3 square kilometers for a deep reserve will make a big difference to evaporation

2. Rail mounted rigid gravitational storage.
There is no reason to presume that this use of a rail-wheel interface (efficient as it is) need have any compatibility with existing passenger and freight transport systems. The electrical connections to the moving masses could be quite specific to the task in hand. e.g. full delta three-phase connections could be made via a novel triple-contact conductor, mounted on the ground between the rails, or alongside the powered vehicle. (I assume the entire site is fenced off against intruding people and wildlife, as are most power facilities).
But what strikes me as most eccentric about this proposal is the use of the smooth wheel-rail interface (which works so well for general purpose railways with all the clever geometry for turning corners). Surely this dedicated purpose track would achive far greater efficiencies with toothed rail and cog-wheels. No slippage and a near-perfect transfer between movement and energy.

All of these schemes do require a high level of maintenance and ultimately, it is the running costs of energy systems that are as crucial as the cost of consumable fuels in determining viability.

Would a rack and pinion system (effectively what you are saying with toothed rail and cog wheels) not introduce more friction?
--- old post above --- --- new post below ---

The Moroccan Desert also has one big advantage. Lots of land and no NIMBYs. I cannot see this changing anytime soon.

For the UK pumped storage may have uses in Scotland and Wales and maybe the spine of England but I cannot see it happening elsewhere.

I reckon its going to be Fracking, Wave power, wind turbines (mostly out at sea given the political climate) and small scale solar on household roofs.

I would be interested to see if Hydrogen could be made to work but aren't there issues about its stability as a fuel source?

Don't discount Nuclear. It may not be based here, but could be shipped over from France. National Grid want to build another HVDC interconnector.

 

[DaveNewcastle]

Or cable/chain over a drum.

In which case you could make it even more efficient by moving the mass straight up and down.

Which would reduce the land take, and allow you to keep the generation equipment stationary, removing the need for any conductor rail (and the losses which that entails).

Yes. But I was trying to illustrate that the 'conductor rail' need not be so troublesome (look at the huge Megawatt powerhouses in open cast mine engines which 'walk' about with flexible three-phase power supplies traiing behind them!).
And the downside of vertical movements is the support structure - the need to find an adequately capacious cliff / mine / tower. The 'rail' option presumes that geology has already done the civil engineering works.

 

[GRALISTAIR]

Or cable/chain over a drum.
Which would reduce the land take.....

Again ---all due respect -- hardly a problem in the USA.

 

[HSTEd]

Advances in UHVDC (up to 1100kV bipoles are now considered feasible) and advances in undersea cables (making 1100kV cables plausible in the relatively near future if there was demand) means that in theory the UK could connect to the NF&L Hydro facility at Churchill Falls.

Which is rather insane and yet awesome at the same time.

 

[najaB]

Again ---all due respect -- hardly a problem in the USA.

Oh, I know that (and made the point myself if you look back in the thread), just pointing out that the vertical method has some advantages.

Even if you want to stick with the rail based method, cable on a drum keeps the generation equipment stationary.

 

[AndrewE]

Even if you want to stick with the rail based method, cable on a drum keeps the generation equipment stationary.

But their videos show they can store enormous amounts of power by moving hundreds of concrete slabs up what might be a couple of miles of curving railway. Probably easier to use conventional railway pick-up gear (OLE or third rail of some kind) than to find a straight enough slope up a mountain and work out how to make the haulage cable system work.

 

[najaB]

But their videos show they can store enormous amounts of power by moving hundreds of concrete slabs up what might be a couple of miles of curving railway.

Which means a couple of miles of losses before the power has even left the generating facility, and a couple of miles of OHLE/third-rail that needs to be maintained.

It can work - clearly as they have a working prototype - but everything in me screams that this is unnecessarily complex. To me, moving parts = breakage points. This has all the moving parts that a static generation plant would have, plus it's on wheels.

 

[edwin_m]

Which would be cheaper to build, an inclined railway or a vertical shaft with the same height difference?

Also the railway can easily run several trains in succession along the same track, using multiple rakes of wagons stabled in sidings at the top or bottom as required. You could even run the locomotives back light to collect another train, reducing the number of expensive locos.

To have this sort of repeat usage of a vertical shaft would need at the very least a large chamber at the bottom containing some kind of handling system to stow the weight clear of the shaft. It's also difficult to see how a set of weights could start their vertical journey before a previous set had finished theirs, although that journey might need less time vertically than on a train.

As to friction losses, a railway is a very efficient system - an unbraked train can roll away on a gradient of well under 1%. The greater loss would be the efficiency of the locomotives for motoring and regenerating. But if what is being stored is renewable energy that would otherwise be wasted, then what counts is the cost per unit of energy recovered, not the amount of energy that is lost in the storage and recovery process.

Incidentally I think there are three overhead lines on the picture - the third pantograph is partly hidden. Overhead line would allow for higher voltages than third (fourth, fifth) rails without risk of arcing between live rails and ground. Even though losses are largely irrelevant, a high voltage would be necessary to transmit the amount of power these trains would be consuming and generating.

I do agree that a rack and pinion system at a steeper gradient should be considered.

 

[AndrewE]

Which means a couple of miles of losses before the power has even left the generating facility, and a couple of miles of OHLE/third-rail that needs to be maintained.

Why a couple of miles? You would have as many concrete blocks as you needed for the system's capacity and optimise the number of sidings and their length. One of the videos shows groups of 4 loco underframes picking up slabs that are stacked sideways to minimise the siding length and running back empty to collect another load. That way the load would provide its own adhesion. Maybe they have gone off that particular idea if they found couldn't fit a transformer under the solebar.
I think that rack systems are relatively expensive to maintain, they are trying to use off-the-shelf technology and equipment, and electric locos are pretty well established now (mature, as they put it.)

- and every system has running costs of some kind.

 

[najaB]

Why a couple of miles?

Because there's a couple of miles between the start and end of the track.

 

[AndrewE]

Because there's a couple of miles between the start and end of the track.

I don't understand the problem
You pick up a slab and proceed to the end of the level siding, certainly not miles (but using a little power, agreed) then
start climbing the main line, converting electricity into potential gravitational energy all the way
then park the slab at the top - and return to the bottom for another if there is still a power surplus.

when there is a need for power in the grid you pick up a slab, move gently back to the main line and use regenerative braking all the way down to re-create the electricity you mopped up earlier. I think the whole main line/gradient might only be a few miles long

 

[TheKnightWho]

I think it'd be wise to remember that the size of the "trains" involved is likely to be much, much bigger than standard locomotives, and that generators (rather than OLE) are likely to be used. An ordinary train will not generate anywhere near enough power for peak demand.

 

[najaB]

I don't understand the problem.

You've got to get the power from the generation train to the distribution transformers. So that means a couple of miles of OHLE or conductor rail. Compared to some kind of winch/pulley system where the generator stays stationary and it's only cable that's moving. Plus you can have one generator set with several cables tied to several trains which run down separate tracks.

One set of expensive stuff (generator, transformer, etc.) and several sets of cheap stuff (rails, concrete, cable).

 

[GRALISTAIR]

Advances in UHVDC (up to 1100kV bipoles are now considered feasible) and advances in undersea cables (making 1100kV cables plausible in the relatively near future if there was demand) means that in theory the UK could connect to the NF&L Hydro facility at Churchill Falls.

Which is rather insane and yet awesome at the same time.

Wow - is that 1.1 million volts - technology has progressed? I though the British grid at 400kV was pretty impressive. What is the insulator that must have an impressive breakdown voltage?

 

[HSTEd]

The trains would move sufficiently slowly that two conductor trolley wire would be sufficient, and at 50kV resistive losses will be negligible.
--- old post above --- --- new post below ---

Wow - is that 1.1 million volts - technology has progressed? I though the British grid at 400kV was pretty impressive. What is the insulator that must have an impressive breakdown voltage?

One conductor in the bipole is at +1100kV (yes 1.1 million volts) and the other conductor is held at -1100kV.
So each amp flowing carries 2.2MW

And as for the size of the insulators, this is a wall bushing (it carries a cable through a wall and stops its arcing to the building wall).

It is rather huge as you can see. Spark distance is over 30 feet.

 

[broadgage]

Electricity storage is inherently expensive and should so far as possible be avoided.
A reliable and efficient grid system does benefit from some storage, mainly to cover for short term unexpected peaks in demand or shortfalls in supply.

However apart from a limited emergency reserve it usually makes more sense to produce electricity as needed.
There are many ways to achieve this before costly storage is needed.

Natural gas is readily available, but should be conserved and used wisely. Many nations could produce almost all their daytime power from solar, only resorting to natural gas at night.

Other nations including parts of the USA have considerable hydroelectric generation. In most cases this could be supplemented with wind or solar sources. Every MWH generated from renewables is a corresponding amount of water not used and therefore still stored behind the dam for use when wind or sun is lacking.
The output of many hydroelectric plants is limited, rationed or otherwise restricted due to want of water, sometimes resulting in power cuts. By meeting the daytime demand from solar and saving water for night time use, such shortages could be eliminated.

International interconnectors can help a lot also, We could export UK wind generated power to Norway when wind is plentiful and import hydroelectric power from Norway in calm weather.

 

[HSTEd]

International sharing implies that the electricity rates in numerous countries would tend towards the average due to exchange of power.

However places like Quebec have such low rates they are not likely to want to share if it means they will pay far more.

And there are limits to how much can be backed up by Norwegian hydro, it is already propping up the German and Danish grids.

 

[GRALISTAIR]

Nuclear of course can not just be switched on and off and needs to baseload. So at night when demand is lower running electric powered freight trains on an almost 100% electrified rail network is my dream. Cheap storage will help this vision.

 

[najaB]

Nuclear of course can not just be switched on and off and needs to baseload.

It can. While the reactor can't be completely shut down on a whim, there's nothing saying that the heat has to be used for electricity generation. The ocean is a wonderful heat sink.

You're right though that it costs pretty much the same to generate as it does to warm the ocean, so you might as well generate and store.

 

[HSTEd]

Nuclear of course can not just be switched on and off and needs to baseload. So at night when demand is lower running electric powered freight trains on an almost 100% electrified rail network is my dream. Cheap storage will help this vision.

Nuclear can reduce production but it increases maintenance costs. And considering the only cost you would actually save is 0.5 US cents per kilowatt hour for the fuel [they wil never let you send the staff home] then you might as well just run flat out and get rid of the electricity any way you can.

Interruptible power options for supplementary photosynthetic lighting in greenhouses for example.

 

[notlob.divad]

It can. While the reactor can't be completely shut down on a whim, there's nothing saying that the heat has to be used for electricity generation. The ocean is a wonderful heat sink.

You're right though that it costs pretty much the same to generate as it does to warm the ocean, so you might as well generate and store.

Sorry I have to question this? Are you seriously suggesting pumping excess heat into the ocean or have I miss understood the context.

I thought the world wide problem we where trying to stop is the oceans getting warmer and thus Ice caps melting, sea levels rising, and weather events getting more extreme. Not sure how using the ocean as a heat sink helps this.

 

[najaB]

Sorry I have to question this? Are you seriously suggesting pumping excess heat into the ocean or have I miss understood the context.

I thought the world wide problem we where trying to stop is the oceans getting warmer and thus Ice caps melting, sea levels rising, and weather events getting more extreme. Not sure how using the ocean as a heat sink helps this.

No, you haven't misunderstood the context. But the thermal output of a large nuclear power station is say 1500MWt, the volume of the Earth's oceans is 1.3x10^9 cubic kilometers. A little rough calculation says that if 100% of the reactor's capacity was dedicated to warming the oceans, in a year it would raise the temperature of the oceans by about 1x10^-20 degrees - that's one ten millionth of one billionth of a degree.

In short, it's not worth worrying about. (I'm probably off by a few powers of ten, at this scale it doesn't really matter).