Rail Energy Storage Harnesses the Power of Gravity All the Livelong Day

A California startup is repurposing trains and rail cars to help renewable energy utilities compete with fossil fuels.

By Glenn McDonald


From Seeker

August 21, 2017

6:45 AM EDT

What goes up must come down. This principle applies to most things in our current gravitational setup — college tuition being a conspicuous exception — and it could provide a significant boost to green energy initiatives, too.

A California-based company called Advanced Rail Energy Storage (ARES) is using the power of gravity to help renewable energy utilities compete with coal and gas. The idea is to help solve the perennial problem of energy storage. Because wind and solar installations can’t always generate energy on demand — sometimes it’s cloudy and the air is still — green utilities need a reliable method of storing surplus energy.

There are several ways to do this using high-tech industrial batteries, flywheels, or hydroelectric facilities, but these approaches tend to be expensive and complicated.

ARES’s solution? Run some old trains up and down a hill.

The company harnesses the power of potential and kinetic energy to help utilities add and subtract to the energy grid as needed. When the wind or solar farm is producing excess energy, that power is shuttled over to the adjacent ARES facility. The surplus energy is used to power repurposed electric locomotives, which in turn haul enormously heavy railroad cars to the top of a hill.

When less energy is being produced but more is needed for the grid, the railroad cars roll back down, turning potential energy back into kinetic energy by powering onboard generators with the force of their descent. The technique is similar to the regenerative braking system that is used in electric and hybrid vehicles, which routes deceleration energy to the vehicle’s battery.

RELATED: Next-Gen Geothermal Could Unlock Vast Energy Supplies Just Below Earth’s Surface

The system is also similar to existing hydroelectric (“pumped hydro”) solutions that essentially do the same things with water — pumping water uphill and capturing downhill flow. A benefit of the rail energy storage solution is that it doesn’t need to be near a large source of water. That’s good for wind and solar installations, which are often located in remote areas.

It’s cheaper, too. Ares contends that its rail energy solution costs about half as much as competing energy storage solutions, and has less of an environmental impact.



“We use no water, burn no fossil fuel, produce no emissions, and use no hazardous or environmentally troubling materials like lithium,” ARES CEO James Kelly told Seeker. “We are excited to be a green storage solution that can enable higher penetration of intermittent renewable resources — like wind and solar — in the US and around the world.”

Pushing rocks up a hill might seem like a curiously low-tech approach to energy storage, but Kelly said that this very simplicity is what gives rail energy storage an edge. Building a railroad loop is a lot simpler than maintaining a giant battery farm, and the ARES system can easily use repurposed locomotives and freight cars. An ARES site can be quickly and cleanly decommissioned and restored in months rather than years or decades, Kelly said.

None of this matters unless the system is efficient. Rail energy storage has about an 80 percent efficiency rate, meaning that the descending railroad cars can output 80 percent of the energy that was initially used to get them up that hill.

That’s better than pumped-storage hydroelectricity, Kelly noted, which typically runs in the 60 percent range. Batteries can return a higher efficiency, but their capacity degrades over time.

“The real question is how much you get out when you need the energy,” Kelly said. “If you discharge your storage batteries tomorrow, you will probably get 90 units out. If you discharge in six months, you may get 40 or 50 units. ARES units have essentially infinite cycles with no degradation.”

“What we’ve done with ARES is harness the inexhaustible, entirely reliable power of gravity,” he added.

Read the full story at Seeker

HT/Rod Everson

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August 23, 2017 6:04 pm

Ok, thinking outside the “box”.

Reply to  Macusn
August 23, 2017 7:56 pm

80% efficiency seems to be a bit of a stretch. An over-reach. More likely it’s closer to 60% or less due to the multiple energy conversions and distribution system. It remains that the “wonderful” renewable energy systems are seeking to be propped up by multiple used energy systems. All of this means more infrastructure and more bandaids on systems that are inherently flawed, overly expensive, high maintenance, high infrastructure, huge ecological and geographical foot print, materials that are unrecyclable, use rare elements, and patently unreliable because the sun goes down and the wind ceases.
The ONLY reason wind and solar are present at all today as energy sources is because government has pushed them on us by funding them with our tax dollars. In a free market, wind and solar would only be useful to end users, such as a small wind turbine on a sailboat to keep the batteries charged. Only huge government funding and the insistence of government policy has led to the pathetic and expensive wind and solar we have today. As soon as they lose their subsidies and their rate protections, wind and solar will crash and burn, which, as we already know, they are prone to do anyhow physically.

Reply to  higley7
August 24, 2017 3:26 am

This idea is one step from a solar powered fan pointing at a wind powered light. Terrific if it wasn’t for the laws of physics.

Reply to  higley7
August 24, 2017 6:04 am

Actually 80% doesn’t seem far off, transformers are 98%, motors depending on loads can get into the 90%’s, so once to push it once to regenerate, about 80%.
But how much can you really store for a large city, or rather how many tracks would you need.
Now you could do the same by drilling holes, and running the trains up and down in a vacuum.

Reply to  higley7
August 24, 2017 8:01 am

And what are the hysteresis losses from the rolling stock into the ground. Rail beds are not rigid. They flex significantly. One may assume the aerodynamic drag losses are low if the velocities involved are also low, but surface winds will effect things. Furthermore regenerative breaking efficiency diminishes as the revolutions decrease, so will a transmission to regulate rpm vs. ground velocity be required?
First and foremost one must have a significant grade to achieve any potential. The shallower the grade the higher the rolling losses. The steepest operating grade is only 5.9%. Unless they propose cogged railways this might have some real limitations, or are they also proposing huge transmission lines between the wind mills in the prairie and the tracks in the foot hills?

Leonard Lane
Reply to  higley7
August 24, 2017 1:30 pm

Another appropriate use for “so -called renewables” is a solar panel or two to aerate a small fish pond. Or a solar panel to keep a 12 volt automobile batter charged when the vehicle is only used occasionally. Finally, dollar stores have some wonderful toys powered by light on small PV cells that will offer amusement over time.

Joe Crawford
Reply to  higley7
August 24, 2017 3:39 pm

One of the freight haulers, I have forgotten which company, use to advertise 500 ton-miles per gallon of diesel. That implies pretty low total losses per mile from track friction, air resistance, etc. I don’t think they defined where they measured that but I assume it wasn’t all down hill.
Also, the steepest standard-gauge mainline railway grade in the United States is the Saluda Grade running from Tryon, North Carolina up the front range of the Blue Ridges to Saluda, North Carolina. At least according to wikipedia it has a maximum grade of 4.9% for about 300 feet and averages 4.24% for 2.6 miles. As kids we were always told it was the steepest grade east of the Rockies. Back in the ’50s, when it was still in heavy use, the Tryon Boy Scouts, along with anyone else they could round up, use to get called out several times each summer to go fight the fires started by the engines grinding there way up the mountain. On the down hill side it had two run-out areas for when any east-bound train lost its breaks. But, we were told it was always the uphill trains that caused the fires when the engine’s drive wheels started to slip, throwing sparks out onto the dried out weeds and grass growing alongside the track.

Pop Piasa
Reply to  Macusn
August 23, 2017 10:17 pm

Yikes! I hope I can keep enough acreage to not have to see any of that foolishness happening.
Every hair-brained idea they present is fraught with costly maintenance, and efficiency sacrifices, plus there is unintended ecological collateral damage likely.

Reply to  Pop Piasa
August 24, 2017 2:14 am

80 percent of the energy that was initially used to get them up that hill.
That’s better than pumped-storage hydroelectricity, Kelly noted, which typically runs in the 60 percent range.

I’d heard much higher claims for hydro which always seemed improbable to me in view of turbulent losses and viscosity. This makes more sense.
In view of the limited incline which standard rail lines can pull freight, my gut feel is that this will need to pull a lot of rocks an awful long way but it seems like a good way to address the intermittent problem. Ironically hydro storage is used for nukes for exactly the opposite mismatch, supplying intermittent demand from a technology which has to run flat out 24/7.

Don K
Reply to  Pop Piasa
August 24, 2017 3:14 am

“I’d heard much higher claims for hydro which always seemed improbable to me in view of turbulent losses and viscosity. This makes more sense.”
You’re probably right about the efficiency of pumped storage. The Gilboa-Blenheim pumped storage facility in upstate New York says it operates with about 73% full-cycle efficiency. Since it’s been around for decades and the turbines were upgraded toward state-or-the-art about a decade ago, that’s probably a reasonably realistic number.
OTOH, I doubt these guys can really do 80% with a real rail based system. And maintenance costs are likely to be non-trivial.
One possibility though are the existing RR grades like the 40km or so grade from Cajon Pass (3700ft-1100m) down to San Bernardino. . Since loads — and there are a lot of them — have to come down that route anyway, it might be economically viable to generate electricity on the way down and use renewable power when available on the uphaul.
Only question is: If electricity generation would be economically viable, why isn’t SP doing it now?

Reply to  Pop Piasa
August 24, 2017 6:07 am

One possibility though are the existing RR grades like the 40km or so grade from Cajon Pass (3700ft-1100m) down to San Bernardino

Hmm, what could go wrong with a train at the max weight limit, running on as little maintenance as possible (nonhuman cargo), continuously being dropped down a long runway towards a city?

Reply to  Pop Piasa
August 24, 2017 8:04 am

It’s possible that they could use the same land that is being used for wind and solar generators. Run the “trains” under the windmills or below the solar panels.

Don K
Reply to  Pop Piasa
August 24, 2017 8:23 am

“Hmm, what could go wrong with a train at the max weight limit, running on as little maintenance as possible (nonhuman cargo), continuously being dropped down a long runway towards a city?”
Already happened — https://en.wikipedia.org/wiki/San_Bernardino_train_disaster
But the trackage over Cajon Pass is still in use and I’d guess that most of the cargo inbound and outbound from the container port at Wilmington passes along those tracks.

Reply to  Pop Piasa
August 24, 2017 10:34 am

“80 percent of the energy that was initially used to get them up that hill.”
Of which, what percentage was lost getting an ultra-heavy load up that hill? Heat loss, gear transmission loss, etc.

Reply to  Pop Piasa
August 24, 2017 11:07 pm

It is like reading one of those fifties Popular Mechanics rags I used to enjoy so much when I was about 14 years of age and knew naught of thermodynamics and other real stuff.
They would always resurrect a perpetual motion scheme ever two months or so, under many aliases and disguises.
There were the atomic powered cars and aircraft, as well as diet chocolate.
Great fun to see it all coming back to the mainstream again.

Reply to  Macusn
August 24, 2017 1:26 am

call Sizifcomment image

August 23, 2017 6:08 pm

Might be even better if they used a series of stationary motors on cable connected railway cars.
Run a whole batch of them at once, and the generator mechanism doesn’t have to move

Reply to  AndyG55
August 23, 2017 6:09 pm

Electricity doesn’t have to be transferred by overhead wires back to a central point.

John Smith
Reply to  AndyG55
August 23, 2017 6:15 pm

What’s wrong with moving the generators? It’s all just extra weight that increases the amount of energy stored.

Reply to  John Smith
August 23, 2017 6:58 pm

nothing, its just that a single big fixed generator will have more synchronous mass

Pop Piasa
Reply to  John Smith
August 23, 2017 10:25 pm

Yes, synchronization of many small generators does not make as much sense economically either. They must all be synchronous with the grid and that complicates the (grid) interface.

Reply to  AndyG55
August 24, 2017 8:04 am

All those cables are going to have a lot of friction.

John Smith
August 23, 2017 6:10 pm

But what happens when they use up all the gravity? Do they have to move the system somewhere else?

Reply to  John Smith
August 23, 2017 6:41 pm

If there was any possibility of using up all the gravity then you simply enforce a tax on all those people who are using gravity.
This is a very grave situation.

Reply to  toorightmate
August 23, 2017 9:22 pm

Overweight people use up more gravity, so they should pay more taxes.

Reply to  toorightmate
August 23, 2017 10:47 pm

(yeah, like gore)…

Reply to  toorightmate
August 24, 2017 2:31 pm

yeah, like gore)…
Al Gore is fat!

Reply to  seaice1
August 24, 2017 2:48 pm

Al Gore, is Sooooooo Fat, he rides on top of the 747!

R. Shearer
Reply to  John Smith
August 23, 2017 7:39 pm

Yes, peak gravity is a concern. Fortunately, it’s possible to re-frack it, although certain states like New York will outlaw it.

Gerry, England
Reply to  R. Shearer
August 24, 2017 4:03 am

Isn’t gravity affected by CO2, or is that methane, or ozone?

Reply to  John Smith
August 23, 2017 8:02 pm

Ah, when the gravity runs out, the government will just legislate a new constant and we’ll be back in business.

Pop Piasa
Reply to  higley7
August 23, 2017 10:30 pm

Do you mean they’ll float a loan to those who float alone?

Reply to  higley7
August 24, 2017 8:05 am


August 23, 2017 6:14 pm

Another real-estate hog and blight on the landscape.

D P Laurable
August 23, 2017 6:16 pm

Simple and clever, but no mention of capacity, whether practical or theoretical. Utility scale storage needs to be truly utility scale, not some interesting windup toy. I would like to know what is actually possible.

Tom Halla
Reply to  D P Laurable
August 23, 2017 6:24 pm

Yes, just how many megawatt-hours is this system good for? If they start measuring the system in gigawatt hours, then perhaps it might be useful.
I also noted they stated it was about half the cost of batteries. This is like discussing skinny sumo wrestlers .

Reply to  Tom Halla
August 23, 2017 6:28 pm

Yes, just how many megawatt-hours is this system good for?

Knew somebody would try to derail this idea!
runs —————————>

Reply to  Tom Halla
August 23, 2017 7:00 pm

The conversation is going off track !!

Brian R
Reply to  Tom Halla
August 23, 2017 8:42 pm

It’s all down hill from here.

Reply to  Tom Halla
August 23, 2017 10:50 pm

(i think i can, i think i can, i think i can)…

I Came I Saw I Left
Reply to  Tom Halla
August 24, 2017 2:55 am
Reply to  Tom Halla
August 24, 2017 10:55 am

“Yes, just how many megawatt-hours is this system good for?”
You might get an idea by looking att the ore railway over the Scandinavian mountains from Kiruna to Narvik. That has a maximum grade of 1 % going westwards (=full trains). The trains weigh 8500 tons and the coupled double locomotives output 10.8 MW. So at that grade, a bit more than 1 kW per ton weight. Steeper grades would equal more power per ton, but railways can’t have steep grades because even very heavy locomotives will start slipping and ruin both wheels and rails. Railways are very economical power-wise because of the very low frictional losses between a steel wheel and a steel rail but the price is near-zero hill-climbing capacity. And incidentally low capacity for this new power-storage concept-
And for how long could they produce? It of course would depend on how long the grade is, but realistically at the very most an hour or two per train. You would need to store lots and lots of trains at the top to get a significant amount of power storage.
Better pump hydro – simpler. cheaper and much lower maintenance costs.

D P Laurable
Reply to  D P Laurable
August 23, 2017 6:31 pm

I went to the company website and it is claiming 16-24GWh capacities are possible. Worth looking at the site. I am willing to see what happens here. A good idea worth pursuing. Certainly better than Tesla’s battery storage. Even good ideas fail sometimes.

Reply to  D P Laurable
August 23, 2017 6:46 pm

Easy, dplorable, they just need a few thousand acres of land to build a whole series of rail-lines next to each renewable power plant. And if there are no hills nearby, they can be built very easily using unemployed people with shovels shipped in from the city & housed in pop-up villages. Who cares if the result is a storage system which is visual pollution, kills native animals, & interferes with their migratory patterns? Anything good for the owners of renewable power companies is good for the planet, & we are obliged to sign off on it.

D P Laurable
Reply to  raybees444
August 23, 2017 6:51 pm

The siting criteria for a big facility seems to be 3000′ elevation gain over 4 miles. Seems like a lot.

Reply to  raybees444
August 23, 2017 7:38 pm

Suggest you use old electric street cars (lots of them around) and fill them with homeless folks (lots of them around) for ballast. Solves two problems at the same time!/sarc

Reply to  raybees444
August 23, 2017 7:59 pm

Don’t forget that you can also use the urine from homeless to make electricity. They can contribute to hauling the mass up the hill by peeing into the provided tubes. Keep the water flowing, LA needs more power!

Reply to  raybees444
August 24, 2017 2:22 am

” … build a whole series of rail-lines next to each renewable power plant. ”
There is no reason why the storage has to be next to the wind / solar generation. It should be somewhere between generation and point of consumer usage. It should be possible to find suitable hills rather than trying to build them.

Another Scott
Reply to  D P Laurable
August 23, 2017 7:23 pm

Also it depends on extra power being generated during the day, wonder how much of that there is….

Leo Smith
Reply to  D P Laurable
August 23, 2017 11:28 pm

easy to work out capacity.
weight times height essentially.
which has mire energy storage? a lake up a mountain or a rain up a mountain?
think about the weight of water behind a dam, against the weight of a train…
PS pumped storage achieves around 75% eff.

Reply to  Leo Smith
August 24, 2017 8:07 am

All you need is a slope for this system to work. Pumped storage needs a bowl that can be dammed.

Reply to  Leo Smith
August 24, 2017 2:35 pm

“Pumped storage needs a bowl that can be dammed.” And a lot of water.

John M. Ware
Reply to  D P Laurable
August 24, 2017 8:22 am

Also, maybe I didn’t read attentively enough, but I’m missing the actual method for producing and transmitting electricity. How does simply letting a train descend a slope produce energy? There has to be some physical way. Perhaps it is self-evident, and my non-scientific mind doesn’t recognize it.

Paul Penrose
Reply to  John M. Ware
August 24, 2017 8:42 am

The electric motors used to drive the cars up the hill are reversed and used as generators on the way back down.

Reply to  John M. Ware
August 24, 2017 2:36 pm

“but I’m missing the actual method for producing and transmitting electricity”
The purpose is to store energy rather than produce it.

Reply to  D P Laurable
August 24, 2017 11:09 pm

In this case, ZIP.
So not to worry.

August 23, 2017 6:17 pm

Interesting, but the key question seems unanswered… How many of these systems would be needed to store the required amounts of power?

Leo Smith
Reply to  TDBraun
August 23, 2017 11:29 pm

why do you think it isn’t answered?
inconvenient truth

Reply to  TDBraun
August 24, 2017 10:17 am

That’s what I’m wondering. How many trains rolling down the hill will it take to supply the required electricity shortfall for say 12 hours? I’m thinking they are going to need one heck of a large train yard. I used to be a railroad yardmaster at one time in my life so I find this very interesting.

August 23, 2017 6:17 pm

Don’t you also need a long, steep, nearby hill, I mean mountain?

Steve Ta
Reply to  co2isnotevil
August 24, 2017 2:21 am

Put the whole system on a see-saw – then it can run uphill forever.

John in Oz
Reply to  co2isnotevil
August 24, 2017 4:39 pm

Looks like another use for a hockey stick – large slope to run the carriages down and a flat section at the bottom. As CO2 is such a miraculous element, it can probably raise carriages up the hill as well as raise temperatures.

August 23, 2017 6:19 pm

Waste of time. A train is a class 100 load. 100 tons, Let’s say it goes up 500m (quite a lot actually). A bit of math and this is less than 20 kW-h. It could power a city block in the suburbs for an hour. On the scale of what is needed, this is butterfly sneeze. Even if the train was 10x heavier, or you went up higher, it isn’t even close to being enough. We need a million times this amount.

Reply to  bill
August 23, 2017 6:40 pm

That was my reaction.
Suppose we wanted the same energy from pumped hydro. Suppose also that we had only a 100 m head. We’d need to pump 500 tons of water. That would be about 500 cubic meters. That’s a cube about twenty feet on a side. That’s not much. The average lake is way bigger than that. 🙂
The capacity of the average pumped hydro installation is measured in thousands of megawatt hours. link
Viable pumped hydro locations are not common but neither are twenty five km 2% grade rail lines.

Gary Pearse
Reply to  commieBob
August 23, 2017 7:49 pm

They’ve used mined out mines for pumped storage.

Reply to  bill
August 23, 2017 8:11 pm

It seems that you have gravely under-estimated the weight of trains. The Fortescue from Australia can store 8Mw-h by your estimate (40 KTons load).

Anders Valland
Reply to  Pulsar
August 24, 2017 12:19 am

I was thinking that as well. With that really heavy train, the city block would stay online for 16 days. Or 16 blocks for a day. Question is, as always – are you storing energy for peak load or for base load?

Reply to  Pulsar
August 24, 2017 2:29 am

” A train is a class 100 load. 100 tons”
100 tons per wagon maybe, not per train .

Reply to  Pulsar
August 24, 2017 10:26 am

“100 tons per wagon maybe, not per train .”
That’s correct. A loaded coal or grain car is 100+ tons.

John Hardy
Reply to  bill
August 24, 2017 12:59 am

IIRC correctly, the formula is Theoretical maximum Energy (in joules) = mass of train in kg x acceleration due to gravity in m/sec2 x height loss in metres. World record train weight is roughly 10,000 tons (https://www.railserve.com/stats_records/worlds_fastest_trains.html). Assume height drop is 1000 metres. Plugging in those numbers gives just under 100,000 megajoules or 28 megawatt-hours. I have no idea where their gigawatts come from unless they are talking thousands of trains. US wind generation looks like about 20 Gw/month (https://en.wikipedia.org/wiki/Wind_power_in_the_United_States#Statistics) or maybe 700 megawatt hours per day. Roughly then a world-record weight train dropping 1000 metres vertical height has a potential energy yield = 1 hour of US wind energy production. Actual yield is less (round trip regeneration efficiency in EVs is ~ 70% (http://papers.sae.org/2013-01-2872/)
It isn’t going to time-shift renewable energy production but could in theory help with short term peak smoothing (the surge when a million people watching a soccer or baseball game make a coffee at half time.

Reply to  John Hardy
August 24, 2017 2:37 am

” 20 Gw/month ” unit mix up. GWh/mo
” = 1 hour of US wind energy production.” Storage is needed for hours of production when there is not demand to avoid dumping or disconnection. 8 such hypothetical trains could store the totality of US overnight wind production. Even using more reasonable height drop , it seems ballpark workable.

John Hardy
Reply to  John Hardy
August 24, 2017 3:02 am

greg – quite right: typo.
wuld you explain your second statement (8 such trains…)

David A
Reply to  John Hardy
August 24, 2017 3:15 am

…assuming ( big word) it is workable sometimes, what has been accomplished?
Now your conventional steady state producers can ramp up or down less often? This also means they sell less. ( become more expensive) So, are you simply part time replacing your steady state lowest cost ( before regulations added cost) producers with more expensive producers and at the same time further increasing the cost of your steady state producers?

Reply to  bill
August 24, 2017 10:24 am

It will only produce while in motion so if it takes 10 minutes to run downhill that is all you get. I bet it will take 3 times as long to get the train up the hill as it takes to get down.

Reply to  gbm
August 24, 2017 10:33 am

Yeah, if you want hours of electricity from train generation, you are going to have to run a heck of a lot of trains because their time going downhill is short. One train right behind the other, for hours and hours. Meanwhile, if your wind and solar are not producing, how do you get your trains back to the top of the hill?

Reply to  bill
August 26, 2017 12:41 am

Try 100 tons per car.

August 23, 2017 6:24 pm

I say “Rube”
You say, ..

August 23, 2017 6:25 pm

Dear Lord…can’t we just burn something and be done with it………

Moderately Cross of East Anglia
Reply to  Latitude
August 24, 2017 2:17 am

Ha ha, excellent comment.
Anyway is this energy source going to work to provide power on the NASA Mars mission – could be tricky launching half a dozen old train and tram cars as well .

Reply to  Moderately Cross of East Anglia
August 24, 2017 2:39 am

plenty of rocks available, they just need 3D printer to make the trains 😉

August 23, 2017 6:28 pm

If they use depleted uranium as the freight, they might ( big might) make it competitive with the pumped hydro.
Low friction on rails and high energy density ( sepecific mass of the freight) might (might) do it .
The capital cost could be lover than pumped hydro significantly as well.
I just cannot see how it can be scaled up to any size of significance.
A GWhr(e) of storage? Yeah, show me the wares!

August 23, 2017 6:30 pm

Marvelous idea actually — using excess, unsold, green intermittent power to run heavy trains uphill, and then running them back down to recover the power.
VERY much like “pumped hydro” — the question is what are the power losses involved.
Lots of old unused rail lines running up mountains.

Dodgy Geezer
Reply to  Kip Hansen
August 24, 2017 1:57 am

The HUGE problem for energy storage is energy density and scaling. Power losses are less important, given that the power will only be going to waste anyway. And this proposal is likely to fail on both of these. Scale it up to any useful size and the costs become prohibitive, amongst other things…

Reply to  Kip Hansen
August 24, 2017 6:14 am

Dodgy ==> Pumped hydro is used here in NY State — and has been for a long time. There are losses.
As far as physics is concerned, it doesn’t matter what you move uphill, you get the energy back when it is allowed to come back down. If one had a tall enough tower, you could crank a huge weight up with a rope and then let it come down again spinning a generator. The train idea is similar — run an electric train up and then run it down as a generator.
I would be concerned about all those overhead wires though…..

Reply to  Kip Hansen
August 24, 2017 8:11 am

You could do it as third rail, larger conductor would have less resistance losses. Of course the overhead line is safer.

Reply to  Kip Hansen
August 24, 2017 3:46 pm

Mark ==> Yeah, and maybe some problems with snow cover etc — none insurmountable. Might have more acceptance than new pumped hydro — and re-purposing abandoned rail lines is a plus.

J Mac
August 23, 2017 6:33 pm

Additional information from the “All About ARES” tab on their website:

August 23, 2017 6:37 pm

Maybe they can recommission those thousands of cabooses which are in storage and fill them with whatever, as they are already rail worthy… I saw a storage place in Lock Haven. PA with hundreds of them in storage there…:
I had a photo – probably a color slide of hundreds of them… I guess restaurants bought them up???

August 23, 2017 6:40 pm

If this was practical idea methinks it would already be in use.
It’ll never replace Niagara Falls.

Reply to  clipe
August 24, 2017 5:50 am

My biggest gripe. Niagara Falls has a pumped storage facility – water fills the reservoir at night and supplies peak power during the day. At least that was the theory. Now they don’t even max out the Falls direct power. They let the turbines idle (practically free) on windy days so they can pay wind operators the wholesale cost plus feed in tariff. So Niagara Falls doesn’t generate anything, we pay wind operators a subsidy, and then sell to the US at a discount because we have excess capacity. We have excess capacity partly because of lost employment due to high energy costs. (This is all on the Ontario Canada side)

Reply to  Greg61
August 24, 2017 6:45 am

Well, gee! It looked good on paper.

August 23, 2017 6:43 pm

Don’t ya just think mining companies have been looking at these concepts for 50 years. But what would they know?

David A
Reply to  toorightmate
August 24, 2017 3:19 am

…and they have the advantage of bringing up empty cars.

Andy Krause
August 23, 2017 6:47 pm

Where is the this “excess” energy from solar, or wind being sent right now?

Reply to  Andy Krause
August 23, 2017 8:08 pm

Here in Ontario we pay other jurisdictions to take it.
Ontario Power Generation is routinely told to spill water at Niagara Falls, to reduce the amount of hydroelectric power generated.

David A
Reply to  clipe
August 24, 2017 3:20 am

Indeed, handicap your best player to make others appear adequate.

Roger Sowell
August 23, 2017 6:49 pm
Dodgy Geezer
Reply to  Roger Sowell
August 23, 2017 10:52 pm

Yes, indeed, you did.
And you said that “This appears to be a viable solution to grid-scale energy storage.”. But without any of the scaling calculations required. I wonder why you did this?

Reply to  Roger Sowell
August 24, 2017 8:13 am

So What? Like anyone reads your site.

August 23, 2017 6:52 pm

ARES units have essentially infinite cycles with no degradation.

Trains quit working if you don’t maintain them. It ain’t cheap. link

Reply to  commieBob
August 24, 2017 3:52 am

The rail line they run on, too. In fact, if that goes anywhere along the line, you are completely down. If it also involves the derailment of your cars, you are talking about several weeks, a bunch of heavy equipment, and a seven-figure check before you get back into service.
If you insist on doing gravity storage, and don’t have an economic place handy for hydro – build a set of vertical towers. More efficient, and one going down doesn’t put you out of business while it’s repaired.

Reply to  Writing Observer
August 24, 2017 10:45 am

“The rail line they run on, too. In fact, if that goes anywhere along the line, you are completely down. If it also involves the derailment of your cars, you are talking about several weeks, a bunch of heavy equipment, and a seven-figure check before you get back into service.”
Railroads are pretty efficient at cleaning up derailments. Their incentive is very high because they cannot afford to be shut down for long.

Reply to  Writing Observer
August 24, 2017 10:49 am

“If you insist on doing gravity storage, and don’t have an economic place handy for hydro – build a set of vertical towers.”
That might actually work, without decimating the countryside.

Reply to  Bartemis
August 24, 2017 11:02 am

“If you insist on doing gravity storage, and don’t have an economic place handy for hydro – build a set of vertical towers.”

That might actually work, without decimating the countryside.

Like to Geosynchronous orbit, and elevator cars.
I’ve long thought linear induction motors, where you drop one full in orbit, while you have one on earth with cargo to go up.
But heck, you could use it for storage too!

Reply to  Bartemis
August 25, 2017 3:18 am

Note that I was not the first by any means to propose this here (I hadn’t read down far enough in the comments). Something about great minds…

Reply to  commieBob
August 24, 2017 9:14 am

Well, yes and no.
From that link, it’s about $15 per train-mile to maintain the hardware (trains and track). That’s for a fully-crewed passenger and freight system, though, running at several times the speed of a “storage” train.
With a much-simpler system, mostly automated, you should be able to get the hardware maintenance costs down to about $5 per train-mile, which means (using a one-megawatt, thousand-ton system) about $20 to $50 per megawatt-hour for storage. Which puts it down near 2 cents to five cents per kilowatt-hour.
Note that the system itself is fairly cheap – rail cars can go a LONG way between major maintenance cycles when running at lower speeds, and if you buy used train cars and abandoned right-of-ways, the whole system price is pretty cheap to begin with.
Considering how cheap energy is in the first place, though, it’s not really attractive, economically.

August 23, 2017 6:59 pm

The along came the skunk to the garden party, nuclear. Compact, dispatchable, no storage needed – and liquid fluoride thorium reactors (LFTR) dispose of stored nuclear waste from legacy nuclear systems. But don’t spoil a fine garden party.

Reply to  majormike1
August 23, 2017 7:24 pm

Name one (just one) LFTR in operation today.

Reply to  Mark S Johnson
August 23, 2017 7:56 pm

We had one at Oak Ridge for decades, and China has a crash program (with our help) to build one in ten years.
“In 1973, the Nixon administration made a momentous decision that altered the course of civilian nuclear power: It fired the director of the renowned Oak Ridge National Laboratory, scuppering development of a reactor widely regarded as safer and superior to the complicated, inferior behemoths that define the global industry to this day.
Nixon banished a reactor that was virtually meltdown-proof, left comparatively little long-lived waste, made it more difficult to fashion a bomb from the waste, ran at friendlier atmospheric pressure instead of the potentially explosive pressurized environments of conventional reactors, and ran at much higher temperatures, making it more cost-effective as an electricity generator.”
Mark, can you name one solar or wind back up storage system which right now is capable of providing the power necessary to carry normal demands for a week in winter in the Northern Hemisphere when it’s heavily overcast and wind is dormant. This happens for periods in Germany every winter, which is why they are turning to burning a lot of coal.

Reply to  Mark S Johnson
August 23, 2017 8:01 pm

“had” is past tense, so you acknowledge that there isn’t one operationg TODAY?

Reply to  Mark S Johnson
August 23, 2017 8:02 pm


Reply to  Mark S Johnson
August 23, 2017 8:23 pm

And do you acknowledge that there are not and have not been any industrial-level back up power storage systems that would meet the power needs of say, Germany for a week in winter, without need for coal, natural gas, and hydroelectric support? The lack of a viable LFTR generation capacity was political, not practical, just as the various Rube Goldberg solar and wind back up systems are political, and are not practical until the crazy day when money is no longer an object.

Reply to  Mark S Johnson
August 23, 2017 8:27 pm

I don’t have to acknowledge anything, because there is not a single LFTR in operation today. They tried them a long time ago, and they didn’t pan out.

Reply to  Mark S Johnson
August 23, 2017 8:54 pm

As Ken Finney notes, there is one in operation today, and the Chinese will have industrial sized ones within 15 years. Is there a rail energy storage system you would like to show us in operation?

Reply to  Mark S Johnson
August 23, 2017 9:28 pm

The main reason that there are no LFTR reactors in operation today is that they did not produce enriched weapons grade materials to build bombs with. They were actually found to degrade weapons grade materials to the point that they could not be used. Hence the claim that nuclear wastes could be disposed of using a LFTR. There were a number of LFTR test reactors built and operated but to upscale it to a commercial reactor needed the support of the Atomic Energy commission. At the time the Atomic Energy commission was looking for ways to make more weapons grade materials quickly. So they shutdown all of the LFTR’s and instead supported the development of the fast breeder liquid sodium cooled Plutonium reactors. The Fermi 1 outside of Detroit Michigan was an example of this misdirected focus. You should look for a copy of the book “WE Almost Lost Detroit” by John G. Fuller. it makes for interesting reading about what was going on at the Atomic Energy commission and why they went down the wrong road of development they did. While we are on the topic of Fast breeder sodium reactors maybe look up the SImi Valley California nuclear accident at the Rocket-dyne facility in 1959. The Atomic Energy commission kept this accident secret from the public until it was discovered in 1979 when some grad students who stumbled across some old files of the accident reports from the reactor meltdown in storage at a university. The Atomic Energy commissions mind set and priorities back in the 1960’s killed the development of the LFTR and today there are a number of scientists who are trying to revive this technology because it maybe a way to give us cheap reliable energy again.

Reply to  Mark S Johnson
August 24, 2017 12:17 pm

majormike, your conspiratorial mind is delightful. But please note, there was never any thorium in the reactor at Oak Ridge. Not a bit. You have no clue what you are talking about.

August 23, 2017 7:02 pm

A sisyphean idea.

Roger Knights
Reply to  otsar
August 23, 2017 11:51 pm

That’s what the company should name the system.

Reply to  otsar
August 24, 2017 1:05 am

Yes, like most things the ancient greeks had it covered.
And even more pertinent when you discover that Sisyphus’ father was Aeolus, the keeper of the winds.
A match made in heaven perhaps?

August 23, 2017 7:07 pm

This looks to this old cynic like yet another distractor by the pro-CAGW crowd to try to fool a few more gullibles into thinking that there are practical ways to make useless, subsidised, non-dispatchable ‘renewable’ power appear not to be. Good luck with that.

Loren Wilson
August 23, 2017 7:10 pm

Scenario: 50 cars, 263000 lbs gross weight each car (standard max weight for commercial rail lines) 1000 meter rise (possible in Spanish Fork Canyon in Utah hauling coal down to the power plant in Delta, UT) = storage of 59 GJ which sounds like a lot of energy until you convert it to MW-hrs. Delivery on a 2% slope at 50 MPH = a drop of 0.44 m/s = 26 MW delivery. I guess you could run several trains at a time up and down the tracks, but this is still in the ballpark of one or two gas turbines (the big boys from GE are 280 MW). They cost less and have a footprint measured in feet instead of miles.

August 23, 2017 7:23 pm

In 1968, the main author of the proposed reform of the Czechoslovak socialist economy with a human face, Dr Ota Šik of Pilsen, found a mine and a coal power plant in the city of Ostrava such that the plant burned all the coal from the mine, and the mine consumed all the electricity produced by the power plant. A useful pair, indeed. 😉

Dr Deanster
August 23, 2017 7:30 pm

How bout this idea. Instead of using rail lines that take up lots of land, how bout just digging vertical wells, with a giant weight attached to cable that drops 3000 feet. Use the renewable energy to run a motor that lifts the weight to the top …. then when you ne d the energy, drop the weights, and turn the generator. May be a tad more costly to build, but would take up a heck of lot less space. Just imagine how many of these units you could make on a single acre of land.
You can get my contact info from Anthony to send me my royalty check …. err government subsidy check! 🙂

Dr Deanster
Reply to  Dr Deanster
August 23, 2017 7:32 pm

And we could make the weights out of recycled junk, …. addressing another environmental issue.

Reply to  Dr Deanster
August 23, 2017 7:48 pm


Gunga Din
Reply to  Dr Deanster
August 23, 2017 8:34 pm

No, no, no!
Don’t drill. Build towers to suspend weights in sight off, oh, say, Hollywood or DC or Martha’s Vineyard or New York City and/or everywhere else the natives seem to be divorced from reality.
(I forgot Berkeley.)

Reply to  Dr Deanster
August 23, 2017 9:33 pm

We could actually use all of those dead windmills out there for the the weights. Kill two birds with one stone. Oh sorry there are not many birds left because of the windmills killing them off.

Clay Sanborn
Reply to  Dr Deanster
August 23, 2017 9:50 pm

Come on, this is the 21 century; think space! Capture an asteroid (as huge a mass as you desire), bring it to say, within 10,000 miles of Earth in orbit, lassoed and held by a single nanotube carbon fiber filament. Store energy by reeling the asteroid in, get energy back by playing it out. But stay the heck away from the filament! Bonus: you get a secondary use for the filament – as a launch elevator cable for satellites. We could send Algore up to see if it snows in space.

Alan Watt, Climate Denialist Level 7
Reply to  Clay Sanborn
August 24, 2017 5:22 am

I’ll bet the environmental impact statement on that would be interesting — changing the period of earth’s daily rotation. Suggest it and wait for all the studies which show (based on modeling) how changing the length of the day will cause mass extinctions, more severe weather, smaller fish, etc., etc.

Greg Woods
Reply to  Dr Deanster
August 24, 2017 3:48 am

Maybe you could combine the bird choppers with the weight droppers and get a two-fer one….

Gunga Din
August 23, 2017 7:31 pm
August 23, 2017 7:34 pm


In 1968, the main author of the proposed reform of the Czechoslovak socialist economy with a human face, Dr Ota Šik of Pilsen, found a mine and a coal power plant in the city of Ostrava such that the plant burned all the coal from the mine, and the mine consumed all the electricity produced by the power plant. A useful pair, indeed. 😉

Eric Elsam
August 23, 2017 7:41 pm

Come on, folks. It’s a California company, making it certain the Brown Government will give it a some seed money. Say, a few mil.

Gary Pearse
August 23, 2017 7:42 pm

Interesting idea, but wheels on track, wheels turning axles, turning a rotor, “copper losses”, “iron losses” (field magnet losses) electrical connections, pushing air,… 80% energy recovery is a pipe dream, maybe 65%. Sounds like a physicist’s calculation.

Reply to  Gary Pearse
August 24, 2017 10:54 am

Agreed. I noticed also that they talked about downhill efficiency, but not uphill, which is when you would get major heat loss.

John Smith
August 23, 2017 7:44 pm

Why not just build the dang thing vertically and reduce the land used? You could put one inside each windmill tower – a 50 tonne weight that gets wound up to the top when its blowy and released when it isn’t. For a 50m tower that would store enough energy to power a typical house for a couple of hours… OK, it’s a bad idea.

Steve Fraser
August 23, 2017 8:10 pm

Apparently, a photoshopped solution, integrated on the ‘brouchure level’.

August 23, 2017 8:18 pm

I swear I read a science fiction story where orbital launches were made from an equatorial mountain based electromagnetic rail launcher power by hundreds of trains that were sent up hill one by one [to store up energy] and then all rolled down at once to power the launcher. It was written in the 50’s.

Reply to  Randy Bork
August 24, 2017 6:24 am

Fountains of Paradise
Diamond cable i think

Reply to  rockyspears
August 24, 2017 6:25 am

Ah, no, that is the “Elevator” thing,

Gunga Din
August 23, 2017 8:23 pm

Our current grid supplies energy at a constant rate, variable as needed. No need to store it.
Wind and solar can’t do that.
To store energy, cost energy.
Storing energy to supply a grid when the wind don’t blow or the sun shine?
Less subsidies (for all) or regulations selectively applied against what works, how can wind/solar/bio-fuel compete with fossil/hydro/nuclear?
Except for the CAGW hype, such would would be reduced to “infomercials”.
“Why pay the electric bill to recharge your smart phone, notebook or laptop? For just $19.99 you can have you’re very own FREE energy source! And if you buy now….”
Wind and solar have a place in supplying power for everyday, non-critical situations (recharging combat devices would be an example of critical situations), but a hospital? An airport? A water plant?
(Remind me never to have a heart attack on an airplane when I’m thirsty.

August 23, 2017 8:33 pm

“has less of an environmental impact.” So building a rail system doesn’t tear up a bunch of ground and permanently alter the environment? Besides it isn’t very attractive. Just how many MW capacity can be developed by this method. Interesting idea. Not sure it is all that viable.

Steve R
August 23, 2017 8:38 pm

All things considered, This seems to be a pretty elaborate scheme to store a relatively modest amount of energy. Is this really the best use of resources and real estate?

Patrick MJD
August 23, 2017 8:51 pm

Ok, this seems reasonable until one considers maintenance. They may be on steel rails with steel wheels and tyres (Yes, trains have tyres. Unless the wheel/tyre is of a solid type), but they do wear. How much energy is needed to replace a steel tyre on a steel wheel? Are the tyres heated and then cooled to fit the wheel, or is the wheel cooled to fit the tyre, or both. Each wheel/tyre combination weighs tonnes, that’s tonnes of steel. Where does that steel come from, how much energy used. It seems pie-in-the-sky stuff when one looks at how rail systems are built.

Timo Soren
August 23, 2017 8:55 pm

Every windmill should have ‘Cuckoo Clock Weights’, say rings around the tower. Wind blow – they wind up.
Drop when needed and turn the same generator. Just hope they don’t fall over.
Do I need a /sarc tag?

Patrick MJD
August 23, 2017 9:07 pm

Ah, it’s a startup. So CA taxpayers, via Gov.Brown, will fund this boondoggle to the tune of millions. The CEO and all senior staff will buy Tesla cars and then fold after a few years and fade away to live a comfortable life, maybe in another state or country.

Reply to  Patrick MJD
August 24, 2017 6:41 am

In another state with lower taxes and energy costs due to the lack of boondoggle funding, so their boondoggle money will stretch further.

Walter Sobchak
Reply to  Patrick MJD
August 24, 2017 8:38 am

“maybe in another state or country.”
Preferably one without an extradition treaty.

August 23, 2017 9:09 pm

You don’t need to wait for excess solar or wind generation to provide this storage. Just get a couple of diesel engines and tow the cars to the top, then release them. Then tow them back up and release them again. Keep up the process and you won’t have to worry about cloudy or wind-less days. Or even about installing wind turbines or solar installations at all. It will work even better if you fill them with oil at the top and deliver the oil to a refinery at the bottom. Less weight going up, more weight coming down. This makes more sense than the rail energy system described in the article, so I’m undecided about a /sarc tag.

Reply to  majormike1
August 24, 2017 3:25 am

Why use diesel? There are plenty of old steam engines that can burn coal that is very cheap these days. Or if you want sustainable, use wood! They can work all night, and when it’s not windy. And steam engines are quite heavy.

John MacDonald
August 23, 2017 9:17 pm

The linked article at Seeker says 50 MW. Not too shabby…same as a GE Frame 6 gas turbine.
This might be one of the better and simpler storage ideas to come along lately.
We’ll know soon when the Nevada system is finished.

August 23, 2017 9:41 pm

I’m not seeing the numbers. Please check my math. From the company website (linked below):

The facilities are highly scalable in power and energy ranging from a small installation of 100MW with 200MWh of storage capacity up to large 2-3GW regional energy storage system with 16-24GWh energy storage capacity.

one Watt-hr = 2655 ft pounds
claimed storage = 20 GWh = 20E+9 Wh
claimed storage foot lbs = 20E+9 Whr * 2655 ft-pounds/Wh = 5.3E+13 ft-lbs
typical railroad car weight =2.63E+5 pounds
claimed storage in “foot-cars” (one loaded car descending one foot) = 5.3E+13 ft-lbs / 2.63E+5 lbs/car = 2e+8 foot cars.
Now, a loaded train will climb a maximum grade of around 2% in all-weather conditions. Suppose we have a mile of track. It will drop about a hundred feet.
On this track (or multiple parallel tracks as envisioned by the company), we’d need a total of 2E+8 foot-cars / 100 feet = 2 million railcars …
What am I missing here?

Reply to  Willis Eschenbach
August 23, 2017 9:59 pm

They claim a track grade of 7.5% in their press kit:
And they claim their patented technology can run at up to 25%. Even then that’s a lot of cars. Their press kit says:
140 4-car shuttle units
• 11,400 concrete weights weighing 234 tons each

Patrick MJD
Reply to  davidmhoffer
August 23, 2017 10:43 pm

“davidmhoffer August 23, 2017 at 9:59 pm
• 11,400 concrete weights weighing 234 tons each”
They also claim no emissions (Of CO2 I presume). 11,400 slabs of concrete 234 tons each. How much CO2?It seems these “green” planet saving boondoggles can’t work without CO2 emissions.

Nigel S
Reply to  davidmhoffer
August 24, 2017 4:02 am

This one has been managing 3.5% for over 135 years but it needs someone sitting on the front of the engine with a box of sand to sprinkle on the rails. Quite challenging weather conditions too sometines.

Nigel S
Reply to  davidmhoffer
August 24, 2017 4:07 am

Some emissions too although probably less than an EV powered by Drax burning US forests.comment image

Curious George
Reply to  Willis Eschenbach
August 24, 2017 8:06 am
August 23, 2017 9:49 pm

I’m trying to understand how much electricity they can store versus capex. Their site says:
Estimated capital costs $1,350kW / $168/kw-hr
I’ve no idea what that means. Anyone?

Reed Coray
August 23, 2017 9:58 pm

Let’s do a back-of-the-envelope calculation (BOTEC). According to D P Laurable’s comment (August 23, 2017 at 6:31 pm), the company’s, Advanced Rail Energy Storage (ARES), web site claims a storage capacity of 16-24 GWh (gigawatt-hours). For the BOTEC, I’ll use 20 GWh. A Wh (Watt-hour) is equivalent to 3,600 joules, so 20 GWh is equivalent to 7.2×10^13 joules. At sea level, the potential energy PE (in joules) associated with elevating a mass M (in kilograms) a height h (in meters) is
PE = M x g x h
Where g is the acceleration due to gravity at sea level or g = 9.8 meters per second^2. For the BOTEC I’ll use g = 10 meters per second^2. For the BOTEC I’ll assume h = 1,000 meters or approximately 3,300 feet. Using these values [g = 10 meters per second^2 and h = 1,000 meters], the mass, M, required for a potential energy storage of 20 GWh, is M = 7.2 x 10^9 kilograms.
According to https://www.google.com/search?q=weight+of+a+fully+loaded+railroad+car&rlz=1C1EODB_enUS545US701&oq=weight+of+a+fully+loaded+railroad+car&aqs=chrome..69i57.14027j0j7&sourceid=chrome&ie=UTF-8, most railroad cars hold slightly under 200,000 pounds or slightly under 91,000 kilograms. For the BOTEC I’ll use 100,000 kilograms as the mass of a railroad car. Then 72,000 railroad cars are required to reach a mass of 7.2 x 10^9 kilograms. That’s a lot of railroad cars.
Now let’s discuss the rate energy can be recovered using such a system. According to http://cs.trains.com/trn/f/111/t/171899.aspx, a representative maximum grade for a 19th century freight train is 2.2%. Thus, the length of track required to increase elevation by 1,000 meters is approximately 45.5 kilometers.
Unless the train track is dead straight, the speed of railroad cars is limited. For my BOTEC I’m going to limit the speed of the train to 80 miles per hour or approximately 35.8 meters per second. A train traveling at 35.8 meters per second will cover the 45.5 kilometers of track in approximately 1,271 seconds or approximately 21 minutes. At a 2.2% grade, the rate of vertical drop is approximately 0.8 meters per second. At this rate in one second a mass of 7.2 x 10^9 kilograms will drop by approximately 0.8 meters. This corresponds to a potential energy loss of approximately 57.6 gigajoules every second or an energy generation rate of 57.6 GW. In summary, if you have 45.5 kilometers of track at a 2.2% grade and on which trains can travel at 80 miles per hour, assuming 100% efficiency of energy recovery as the train rolls down the track, you can generate 57.6 GW of power for a 21 minute period. If you use dynamic breaking (i.e., recover all of the potential energy loss in batteries inside the train) to slow the train down to say 8 miles per hour (3.58 meters per second), then you can generate approximately 5.76 GW for a 210 minute (3.5 hour). And if you want to recover the potential energy uniformly over a 12 hour period (43,200 seconds) by using “dynamic breaking” to slow the speed of the descending train, the speed of the train will be approximately 1.04 meters per second (vertical drop rate of 0.0229 meters per second), and power will be generated by such a configuration at a rate of approximately 1.65 GW.
Let’s summarize. With (a) 72,000 railroad cars each with a loaded weight of 100,000 kilograms, (b) 45 kilometers of track over a vertical rise of 1,000 meters, and (c) 100% energy recovery efficiency, we can generate power at 57.6 GW for 21 minutes, or 5.76 GW for 3.5 hours, or 1.65 GW for 12 hours. This BOTEC does not take into account the energy required to “lift” the train 1,000 vertical meters. At a 100% lift efficiency, (a) a 20 GW generator can supply the necessary energy in one hour, and (b) a 1.7 GW generator can supply the necessary energy in 12 hours.
I think I’ll pass on voluntarily investing my money in such a plan. However, given how our government works, I’ll probably be forced to subsidize the company.

Reed Coray
Reply to  Reed Coray
August 23, 2017 10:35 pm

It just occurred to me that if each railroad car was 20 meters long, the 72,000 railroad cars would stretch over a distance of 144,000 meters (144 kilometers) which is three times the length of the 45 kilometer track in my BOTEC. Not to worry. If we construct 1,000 parallel tracks, then we can run 72 railroad cars per track (1.44 kilometers of railroad cars per track). Yeah, that’ll work.
My BOTEC says the idea is so ridiculous it’s laughable, which means my BOTEC is probably wrong. Would somebody please check my calculations?

Reply to  Reed Coray
August 23, 2017 11:24 pm

Freight trains usually run about 60MPH. Passenger rail will run up to 90MPH on good track. The faster you want to go, the better-maintained (higher cost) track you need.

Reply to  Reed Coray
August 24, 2017 6:15 am

Minor flaw – because you are trying to capture energy from the cars they will probably not be barreling full speed at 80mph – if you were, you probably aren’t extracting energy from the system.
It is a variation on the kucku clock principle, where you lift up wieghts by any means and let them drop while extracting energy from them.

Reply to  Reed Coray
August 24, 2017 3:06 pm

It looks like the BOTEC is OK. The unit they describe has 11,400 weights of 234 tonnes each, or a total weight of 2.7 x 10^6 tonnes or 2.7 x 10^9 kg. This is in the same ball park as your calculation.
The difference is that these weights are stored at the top “sideways on”, as it were. They are dropped off and picked up by the drive units and stored in large sidings at the top and bottom. The drive units shuttle them up and down.
They claim patented technolgy for “a traction drive system that uses electric locomotives to carry weights up grades that are less than 10% (6 degrees) and its Ridgeline© funicular cable drive technology that can operate on slopes up to 50% (25 degrees).
They say “Following are the specifications of a 670 MW ARES energy storage system:
• Estimated capital costs $1,350kW / $168/kw-hr
• 8 hours discharge at full output
• 5,344 Mw-hr discharge capacity
• 2 rail storage yards @ 3000’ elevation differential
• 5 interconnecting tracks between yards
• Track grade of 7.5%; 8 miles in length
• 140 4-car shuttle units
• 11,400 concrete weights weighing 234 tons each.”
I think this is broadly in line with your BOTEC.

Reed Coray
Reply to  seaice1
August 25, 2017 10:01 pm

Thank you seaice1. I’ll now continue my BOTEC using the values you provided above. The change in potential energy, deltaPE, an object of mass M incurs when displaced a distance deltah in the direction of a gravitational field of acceleration g is given by
deltaPE = – M * g * deltah
The time rate of change of the potential energy is thus
deltaPE-dot = – M * G * deltah-dot = – M * g * v
Where v is the speed of the object of mass M in the direction of the gravitational field. Conservation of energy requires that a negative change (loss) of potential energy must appear in another form. In free-fall the form that energy takes is a gain in kinetic energy, which for a fixed mass corresponds to an increase in speed. However, instead of converting the loss of potential energy into speed, it is possible to convert the loss of potential energy into useful work. Assuming the conversion of the loss of potential energy into useful work is 100% efficient, an object of mass M traveling at a constant speed v in the direction of a gravitational field of acceleration g can do useful work at a rate work-dot given by
Work-dot = M * g * v
An ARES “unit” has a mass of 234,000 kilograms. The ARES energy recovery system places units on railroad cars and rolls the railroad cars down one of five 8-mile (12,875 meters) railroad tracks each having a vertical crop of 3,000 feet (914.4 meters).
The ARES energy recovery system converts the loss of potential energy as the railroad cars roll down the track into useful work. For this discussion, assume (a) the slope (7.12%) of each railroad track is everywhere the same over its 8-mile track length and (b) the railroad car(s) travel at a constant vertical speed v, which corresponds to a constant track-speed, vt, of
Vt = 14.08 * v
The ARES system claims a power output capacity of 670 MW for an 8-hour time period. For the moment, let’s assume a single unit is rolling down each of the five railroad tracks. Then each of the five tracks must be generating energy at a rate of 134 MW. This means the unit’s mass of 234,000 kilograms must be travelling at a vertical speed of 58.434 meters per second (track speed of 822.75 meters per second). The time required for the unit to drop 914.4 meters is 15.65 seconds. Thus a different car must start its path down the track every 15.65 seconds. To generate 134 MW of power for 8 hours (28,800 seconds), 1,840 units are required. The ARES system employs 11,400 units, which corresponds to 2,280 units per track. Obviously, a track speed of 822.75 meters per second (1840.4 miles per hour) is not practical; but assuming 100% energy recovery efficiency, the system has a sufficient number of units.
Instead of employing one unit on each track at a time, employ 100 units. The required vertical and track speeds will then be reduced by a factor of 100 to the more reasonable values of, respectively, 0.58434 meters per second and 8.2275 meters per second (18.404 miles per hour). Furthermore, a new train of 100 units need only be started every 1,565 seconds (26.08 minutes). These numbers are not inconsistent with the ARES design numbers. Thus, at an energy recovery efficiency of 100%, the proposed ARES system is viable.
However, if the energy recovery efficiency drops to 50%, then the number of units per train required to generate the stated output power increases from 100 to 200, which in turn implies 3,680 units per track or a total of 18,400 units.
Let’s examine another specific case. Assume (a) we assemble trains of 142 units per train, (b) over an 8-hour period, start a train down each of the five 8-mile tracks once every half hour, and (c) let the trains travel at a track speed of 16 MPH—all reasonable numbers. Per track, such a configuration, (a) will require 16 trains of 142 units (80 total trains and 11,360 total units), and (b) will provide constant power for an 8 hour period. For this configuration on a per track basis, over an 8 hour period a mass of 33,228,000 kilograms will be dropping at a vertical rate of 0.508 meters per second. In one second, the loss in potential energy will be 165,425,955 joules. At 100% efficiency, the power generated by each track will be 165.426 MW and the total power generated by five tracks will be 827 MW. Thus to achieve the stated output power of 670 MW for an 8-hour period, the system must operate at a potential-energy-to-electrical-energy conversion efficiency of 81%. That seems awful high to me, but then I have no experience with the generation of electricity using rolling railroad cars.

August 23, 2017 10:12 pm

Hmmm, my caboose storage post never got posted, with links and where the cabooses are stored. You can fill them with whatever, and they are rail ready…there are thousands of retired cabooses stored…

Reply to  J. Philip Peterson
August 23, 2017 11:22 pm

Nope. Nearly all excess cabooses have been sold off or scrapped.

Greg Woods
Reply to  Russ Nelson (@russnelson)
August 24, 2017 3:56 am

I think Al Gore is still available…

Bob boder
Reply to  Russ Nelson (@russnelson)
August 25, 2017 7:35 am

but where are you going to find a big enough engine to move his caboose, see the problems are always in the detail.

Shanghai Dan
August 23, 2017 11:22 pm

Just use a big, magnetically suspended flywheel. Don’t go for speed of rotation, go for mass of rotation. Huge, slow rotating concrete flywheels store massive amounts of energy, and with magnetic suspension (and stability if you rotate it within a fairly broad range of rotational velocities. And the stress inside the flywheel is greatly reduced by cutting down the velocity – and increasing the rotational mass. A flywheel the size of the base of a windmill could conceivably store 20 MHh of energy; two could easily store the 2 day output of a typical wind turbine.

Leo Smith
Reply to  Shanghai Dan
August 23, 2017 11:39 pm

energy in moving mass proportional to mass and velocity squared.
so high rotation speed is better than lots of mass

Shanghai Dan
Reply to  Leo Smith
August 24, 2017 7:39 am

Except that construction costs grow with internal stresses, and internal stresses scale as the square of velocity but only linearly with diameter. So you can make a small flywheel that turns fast but it is extremely expensive to build. Additionally the gyroscopic effect goes with velocity, so rotational forces on any magnetic bearings is greatly reduced by lowering the RPM of the gyroscope.
Then we get into air friction from high speed flywheels, which typically need vaccum chambers as opposed to something turning at 60-100 RPM which has no such needs.
At the base of a windmill, you have LOTS of space available. Some rebar, concrete, permanent magnets, and a little electrical and you can have a LOT of energy stored with little technical effort. Just a ~140 foot diameter spot for the flywheel.

August 24, 2017 12:31 am

Regenerative braking is also in use on UK electrified rail networks (including the ‘Tube’)

Patrick MJD
Reply to  Griff
August 24, 2017 1:19 am

“Griff August 24, 2017 at 12:31 am
Regenerative braking is also in use on UK electrified rail networks…”
And has been for about 100 years.

richard verney
Reply to  Griff
August 24, 2017 1:26 am

Did you read Reed Coray August 23, 2017 at 9:58 pm and at August 23, 2017 at 10:35 pm comments upon the practicalities of the system before posting?
Maybe the scaling up is not as easy as suggested in the promotional material. Who would have thought that, then again the promotional material is designed to be read by lobbyists and politicians and they are not the sharpest tool in the box..

Michael S. Kelly
August 24, 2017 12:40 am

I’ve been thinking about exactly this approach for many years. It’s truly the best energy storage method available on a mass scale, and it’s cool to see someone doing it.
The biggest elevation change in Southern California is about 6,000 feet. A “unit train” (one holding a day’s worth of coal for a 1,000 MWe power plant) has a mass of about 10,000 tons. So the total energy storage capacity for this system is about 120 billion ft-lb, or 45 MW-hr. 80% of that (which, yes, is realistic) is then 36 MW-hr.
Nothing else would be as cheap, or easily built. But it is a sneeze compared to the supply and demand for energy on a grid scale. It’s the equivalent of charging 424 Tesla Model S roadsters. That alone should tell you how difficult the problem of storage is.

August 24, 2017 12:51 am

Sounds like a souped up version of the good old clock mechanism using weights that needs to be “rewound” once a week.
The question is what happens when the train hits the bottom of the track and there is no surplus to wind it back. Also a train run can only be for a short period of time as long tracks will both be impractical in terms of acreage and rewind time. Meaning the system can only be used for peak loads topping up the general supply for short periods.

August 24, 2017 12:53 am

The Iron Ore Line (Malmbanan)
In Scandinavia, the Kiruna to Narvik railway carries iron ore from the mines in Kiruna, in the north of Sweden, down to the port of Narvik in Norway to this day. The rail cars are full of thousands of tons of iron ore on the way down to Narvik, and these trains generate large amounts of electricity by their regenerative braking.

From Riksgransen on the national border to the port of Narvik the trains use only a fifth of the power they generate. The regenerated energy is sufficient to power the empty trains back up to the national border.

Any excess energy from the railway is pumped into the power grid to supply homes and businesses in the region, and the railway is a net generator of electricity.
Iron ore on the way down to Narvik
In the immortal words of Douglas Adams “the trick is to bang those rocks together, guys!”

Sandy In Limousin
Reply to  Philip Mulholland
August 24, 2017 1:33 am

That is a perfectly sensible scheme. Unlike building a Solar PV at Errol in Perthshire 56′ N, 1348 hours sunshine annually, or Moray 57’N also about 1300 hours annually. Despite being built on the “sunnier” side of the country. The sunniest time of year is May-June with a monthly mean of about 180 hours. Dec-Jan the monthly mean is 40 hours (less than 2 hours a day) Naturally the BBC thinks these are a wonderful investment.

Reply to  Sandy In Limousin
August 24, 2017 2:08 am

Dec-Jan is very cold up there at times and I have often been wildfowling in temps of -5C and below at that time of year.
It also snows frequently in the winter months!

Dodgy Geezer
Reply to  Philip Mulholland
August 24, 2017 2:01 am

This works because ALL the infrastructure is already in place. The lines, the generating capacity, the distribution system, even the weight from which you are extracting the potential energy is all provided ‘for free’. The generated power is icing on the cake.
Now suggest building the same system JUST to store power and see how viable it is.

Reply to  Dodgy Geezer
August 24, 2017 4:23 am

Too bad there is so much negativity on this site. We should applaud efforts by people who are trying to find solutions to difficult problems. That’s how progress is made.

Dodgy Geezer
Reply to  Dodgy Geezer
August 24, 2017 4:52 am

@Trebla August 24, 2017 at 4:23 am
Too bad there is so much negativity on this site. We should applaud efforts by people who are trying to find solutions to difficult problems. That’s how progress is made.
These are NOT solutions. They are not even new ideas. They are attempts to obtain access to taxpayer or venture money by joining in the ‘renewable energy’ scam.

Reply to  Dodgy Geezer
August 24, 2017 4:43 pm

“Too bad there is so much negativity on this site.”
That’s because most posters are capable of simple arithmetic.

Michael Keal
Reply to  Dodgy Geezer
August 24, 2017 5:23 pm

Too bad there is so much sanity on this site which can be very boring. Instead we should applaud, indeed enjoy the amusement to be had, by watching people claiming to have solved a problem that was solved by Newcomen’s steam engine (patented in 1698) and later improved on by James Watt in 1781. That’s apart from those who still believe Big All and the global warming gang of course although this can in itself can be quite amusing.
Although there’s nothing at all amusing about what these ‘solutions’ to a non-existent problem has cost us or the damage it has inflicted on Western economies while somehow by some strange quirk of fate enormously benefited the communists in China who are presumably excused because they are emitting special magical Green ‘Carbon’!

Reply to  Philip Mulholland
August 24, 2017 1:22 pm

Mulholland the railway is a net generator of electricity. these people have cracked the problem!
If this railway can be a *NET* generator of electricity, then just copy this railway system across the world and shut down all power generators!
Job done!

Peta of Newark
August 24, 2017 2:13 am

All anyone needs to know is that they put the word ‘advanced’ into the name of the thing.
Its like when they use ‘sophistikerated satistsks’ or ‘suepr cmoptuer’ or even when something ‘uprencedneded’ has been discovered.
At some point in people’s lives, they get to realise this stuff is all just fake. Huffery pufferey in a succesion of poor attempts to inflate something that is beyond inflation – increasingly lame attempts to get laid.
The ‘get laid’ attempts patently don’t work any better than than the ‘advanced’ systems.
It gets worse because the hapless 50% of the population these things are aimed at are all on anti-depressants – whether that be Prozac from their doctor or simply troughing-out on sugar and getting morbidly obese (yes Ben & Jerry, I’m looking at you).
You’ve just got to laugh

August 24, 2017 2:42 am

I had this idea years ago, sort of. And I thought when I saw them build those bird roasting water heating towers in the desert, that they would surly implement the idea.
But my idea was to build a tower with a elevator type setup, which during the good Sun hours, say 6 hours, the extra 18 hrs worth of generated power would go toward raising whatever sized/calculated weight to gear ratio was needed to generate a couple three days worth of no Sun power for a system. The solar panel Kwh would be sized to at least be able to generate 24 hours worth of power in that 6 hours of good Sun time. While the weight would be raised (sized and geared) to a height which would fill the other 18 hours of non generation time. Plus a few extra hours to ideally build up a couple three days worth of backup over time.

son of mulder
August 24, 2017 3:00 am

What about giant undersea balloons being inflated by Solar and wave energy over the Marianas trench, floating massive bags of rocks to the surface, then getting energy from the rapidly deflating bags at the surface and GPE from the rocks sinking back down the 7 miles to the bottom? Or something similar?

David A
Reply to  son of mulder
August 24, 2017 3:47 am

Hum, perhaps a bit problematic to inflate balloons under an ocean of pressure, bit that I want to burst bubbles.
However if we can get middle income folk to pay for it, and give some of that income to rich Tesla owners, we can probably get funding in Kalifornia.

Dodgy Geezer
Reply to  David A
August 24, 2017 5:00 am

The boys from the East Side have had an idea which could make us more money than vice or gambling.
It comprises an office with cheap researchers looking for Green government grants being offered. These are passed to a group of accountants/lawyers for evaluation. Those deemed profitable are passed to a small team of failed engineers whose job it is to put forward vaguely believable proposals for machinery that can attract funding. The lawyers then put a grant application in.
We can get start-up costs funded by Soros, and we will need sign-off from Greenpeace – for which I propose to offer them 10% of the take….

Michael S. Kelly
Reply to  David A
August 24, 2017 8:35 am

Dodgy Geezer, that is brilliant. I’m in!

Mariano Marini
August 24, 2017 3:17 am

I’ve a better idea for windmills backup system: A pendulum clock system.
When rid or wind is high the extra power will lift a weight and when the rid require and wind is low the weight will supply the power.

Mariano Marini
August 24, 2017 3:23 am

I’ve a better idea for windmills: A pendulum clock system!
I think, I can… I think, I can …

August 24, 2017 3:28 am

A bit slow here at WUWT.
Euan Mearns over at his blog site Energy Matters ran through and analysed the claims and the figures on this ARES rail line energy storage project in April 2016.
He also has a graphic comparing this and other energy storage systems in the same blog article.
It might even work if the good citizens of the USA wish to spend a good high percentage of their GDP setting such an energy storage system up.

It doesn't add up...
Reply to  ROM
August 25, 2017 6:00 am

Just one of an excellent series of posts at that site on various forms of energy storage, and also on the requirements for storage to support various energy sources. Few seem to realise the timescales over which storage is required to make intermittent energy sources viable without other backup, and just how large those energy stores need to be.

August 24, 2017 3:31 am

Pushing s**t uphill.

Nigel S
August 24, 2017 3:38 am

Off the truck he darted against the rocks he crushed
Upside down the engine turned and Georgie’s breast did smash
His head laid against the firebox door the flames were rolling high
I’m proud I was born for an engineer on C&O road to die
The doctor said to Georgie my darling boy be still
Your life may yet be saved if it is God’s blessed will
Oh no cried George that will not do I’d rather die so free
I want to die for the engine I love one hundred and forty three

Bob boder
August 24, 2017 4:01 am

You don’t even have to stretch it you could just spin the rubber band up like we used to do on those old balsa wood toy plains we had.

Bob boder
Reply to  Bob boder
August 24, 2017 4:03 am

For the solar just charge a big battery and then use it to shine a light on the panels at night. Or how about putting a giant mirror on the moon and shine it at the panels at night.

Bob boder
August 24, 2017 4:04 am

The storage idea is not totally ridiculous, its the generating idea that is messed up.

August 24, 2017 4:07 am

The challenge of transmitting the power generated from the roll back comes to mind.
But I guess tgat can be dealt with at the same time a mountain tall enough for the gravity train to roll down for days at a time is constructed.

John B
August 24, 2017 4:08 am

Pumped storage works because the electricity generator used to do the pumping off-peak is dispatchable, so the storage can be recharged as required and planned.
Wind power (and solar) is not dispatchable so once the train has run down the hill, there is no guarantee that the wind/sun generation will be available or sufficient to move it back up the hill when needed.
The train therefore is exposed to exactly the same problem it is suposed to resolve.

August 24, 2017 4:41 am

How great is this? The windmills can kill everything that flies and the rail system will kill anything that walks. What’s really needed is a renewable idea that will kill everything underground and in the ocean. That will achieve the dream of the enviromental folks.

August 24, 2017 5:25 am

This is an old.old idea that never got off the ground. I first heard of it over 5 years ago. This article is totally misleading in presenting this as anything new. The only viable large storage facilities has always been pumped storage. But pumped storage is only viable when it is an alternative to dumping unneeded power off the grid. It is not particularly efficient – I believe that you lose 25 to 30% of the power being stored via transmission losses, evaporation and the inefficiencies of pumps and generators. The reduction in cost of natural gas more or less eliminates any advantages of pumped storage. California, our own renewable crash test dummy has been constructing pumped storage facilities in the mountains, at tremendous cost (roughly the same as a nuclear plant, as I recall – about $4 to $5 billion).
All of this is the same old silly idea that one can make wind/solar generated power controllable.
Someone needs to inform these people that a stored power unit canot generate power – it can only store it, and it must be replenished after it is depeleted, which isn’t long. As I recall, at full capacity, those very expensive pumped storage facilities can only produce power for about 10 hours. The wind can die down for long periods of time, as can solar energy (except usually in a desert).
When are the technologically ignorant/inept Californians ever going to understand that we are on the threshold of a new form of nuclear energy (molten salt Uranium/Thorium reactors) which will transform the world. California is instead interested in this 19th century technology, a silly rail scheme using choo-choo trains and a big hill.
China and India’s govt are not energy-ignorant like the braindead California govt and are rushing to develop these reactors as we speak. I can pretty much guarantee that any Chinese or Indian energy scientists who read this article will be much amused and become overly confident that they have nothing to fear from American technology. They are probably laughing out loud about now.
Only in a country populated with large numbers of desperate global warming fear mongers could this article be published and taken seriously.

Reply to  arthur4563
August 24, 2017 1:04 pm

And yet, those who question this guff are the science deniers. Wow.
I mean look at all the money earned by those who built it! It’d be wasted and those poor folks would be unemployed!
All those bribes lost like tears in rain.

August 24, 2017 6:13 am

For crying out loud… How ridiculous. Just build a super critical coal fired power station and generate base load power at low cost.

August 24, 2017 6:19 am

Strikes me that you will use a lot of land for these trains – in much the same way as you need a lot of land for solar and wind generation. The critical energy factor is height and weight, but the generation factor here is friction – the train wheels on the track. This there is limit to how steep the rail line can be before slippage becomes a significant loss. Someone mentioned gradients of 2% up-thread so for a 1000 m height, you need a 200 km track. That is a lot of land.
One of the factors which makes pumped storage so popular is the speed of despatch – i.e. how quickly can you start generating power when you need it. Do these trains need to get to a certain speed before they can generate power? When they have to be brought up to phase to feed into the power supply, then the speed of the turbine is critical. For a 1000 ton train there is a lot of mass to get moving before any power is being generated.

Reply to  Rob
August 24, 2017 6:27 am

I see Reed Corey has already done these calculations (August 23 10.23pm). And I made an arithmetic error! Need more coffee!

Peter Morris
August 24, 2017 6:39 am

Huh. Sisyphus lives.

August 24, 2017 7:21 am

Daddy, We’re cold.
Sorry kids.
The train has come to the bottom.

Rod Everson
August 24, 2017 8:21 am

Anthony, thanks for the H/T. It’s nice to know that Tips and Notes serves a useful function.
While the comments were more heavily weighted toward snark than usual, many were interesting, as was reading more on the system at their website.
The comment that I suspect will turn out to be most on target was Bob Boder’s: “The storage idea is not totally ridiculous, it’s the generating idea that is messed up.”

August 24, 2017 8:50 am

You have to bear the cost of operating and maintaining a railway just to store a portion of the energy normally used for fuel. There is a reason why railways close underused lines. They are very expensive to maintain.
All of this depends on the train being at the top of the track when you need energy and at the bottom when you need to store. Intermittent energy sources and demand don’t align their timing with the needs of your storage system. Batteries have the same problem.

August 24, 2017 8:57 am

Yeah, but if it spun backwards, wouldn’t it just suck the power out of the lines? (▰˘◡˘▰)

August 24, 2017 11:16 am

I know the perfect place for this. The Medicine Bow mountains in Wyoming. There is a flat plateau about 10 miles across at about 10,500 feet a s l and a drop of about 2,000 feet over five to fiften miles almost all around.
We turn the plateau into the worlds’ largest marshalling yard and build a couple of thousand railways down the sides. It would probably not cost much more than a dozen transcontinental railways.

August 24, 2017 12:25 pm
August 24, 2017 3:17 pm

The cost of constructing or repurposing steeply inclined rail beds and tracks is extremely non-trivial. In order to have enough rolling mass to store any significant amount of energy, I’ll wager the construction costs would be in the billions of $ for anything over 100 MW or so of capacity. This is not counting all of the peripheral equipment like transformers for step-down and step-up, transmission lines, etc. Then you get into land use rights acquisition and environmental mitigation and permitting ….

The Reverend Badger.
Reply to  Hoo
August 24, 2017 3:43 pm

You have got the conductors for the transmission lines already, just need to work out how to stop the bogies shorting them out.

August 24, 2017 3:24 pm

For anyone considering vertical towers, bear in mind you need a 3000ft tower that stores 3 million tons at the top to have a similar capacity to the unit described in the promotional material. Or you could have 10 x 300ft towers, with 3 million tonnes at the top of each.
Actually, it makes more sense to increase the mass and reduce the height. How about a 30ft drop and a mass of 300 million tons? Getting the energy back could be a problem.

Reply to  seaice1
August 24, 2017 6:21 pm

A “3000ft tower that stores 3 million tons at the top” would have a capacity of 6.7 GW-hr.
It would have better efficiency, less maintenance, and there is no reason you couldn’t have a whole city of them with more realistic height and mass.

Reply to  Bartemis
August 26, 2017 2:30 pm

I am not sure that building a tower nearly 200m taller than the current tallest building in the world, then sliding 3 million tons up and down it, would have less maintenance than a railway up a hill.
The more realistic height and mass was my final point. A small height and a huge mass could store the energy quite well, but I do not know how to get the energy back. The movement would be very small and massive amplification or gearing would be needed. I don’t see how we could do this without huge losses.

The Reverend Badger.
August 24, 2017 3:39 pm

It’s a step in the right direction (thinking wise). One more step and we could cut out the middle man and apply gravity directly to the molecules in the atmosphere. There is a hell of a lot of P.E. up at 100km, and quite a lot of mass in the atmosphere to play with. I think an experiment might be in order when Doug have finished playing with my model railway.

John in Oz
August 24, 2017 5:37 pm

Useful concept for some applications – https://gravitylight.org/
We seem to be moving from consistent single source power plants (coal/gas/nuclear fueled) to wind (intermittent) supplemented with solar (intermittent) supplemented with batteries (limited) + pumped hydro (geographically limited) and now pumping train carriages uphill (see arguments above).
Damn that CO2.

Jeff corbin
August 25, 2017 10:07 am

All that static rail infustructure would seem to beg the question of cheaper and more flexible superconductive magnetic enery storage systems (scmes) at 95 percent efficieny a much better deal. Furthermore,I can’t put a train in my backyard to store my home generated electricity and distribute it on demand like I could with a SCMES.

August 25, 2017 12:41 pm

Then there’s that “mighty rough road from Lynchburg to Danveille,
A line with a three mile grade.” From “The Wreck of old ’97”

August 25, 2017 2:47 pm

The problem with this and similar systems is their finite size. For unreliable renewables it is virtually impossible to calculate the size of the storage backup system which is needed to avoid large scale blackouts !!!
And the other inherent problem is that when they are depleted you no longer have any back up. Also while you are recharging your back up you are robbing energy from the grid.
In the long term the system remains a high risk and unreliable installation.
The nameplate rating of the renewables must effectively be reduced by around 90% to account for this and the losses incurred in charging and recharging! That means a 100 mw system is practically only good for 10 mw….this in turn hugely adds to the real cost of the renewables. Then you have to add the cost of the storage system, and the transmission losses due to poor siting relative to the load centres.
It is hard to grasp that main stream has not locked onto these issues!!
Alan c

August 27, 2017 11:02 am

Couldn’t the same principle be used to hoist large concrete blocks up the sides of the wind towers, then lowered when needed to put the power back on the same lines the towers are using?
More granular, more compact, cheaper? nah…. they’ll never go for it…

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