ARES system to put energy storage on the right track


July 22, 2013

The ARES system uses electric locomotives as a form of energy storage

The ARES system uses electric locomotives as a form of energy storage

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We’ve recently looked at ocean-based energy storage system concepts from MIT and Subhydro AS that are designed to overcome the intermittency problems of renewable energy sources like wind and solar by pumping water out of large tanks and using gravity to let it back in and generate electricity when needed. Santa Barbara, California-based company Advanced Rail Energy Storage (ARES) has come up with a land-based alternative that would provide grid scale energy storage using electric locomotives.

ARES’ technology uses heavy rail cars that are pushed to the top of a grade using excess power from renewable energy plants or when electricity demand is low. Then, when the wind drops, the sun stops shining, or electricity demand rises, the rail cars are released back down the hill, generating electricity through regenerative braking.

Because the system doesn’t rely on the use of water like the aforementioned ocean-based systems, the company says the technology is suitable for a wider variety of areas with minimal environmental impact. The company says the system can also respond to increases or decreases in demand in a matter of seconds, boasts a charge/discharge efficiency of 86 percent, and can deliver constant power for periods of up to eight hours.

ARES’ Director of Technology Development, William Peitzke told us to think of the system as basically a “grid-scale flywheel or battery, but one which is able to lock into direct synchronization with the grid providing heavy inertia for added grid stability.”

The company says its system is scalable and can be configured to provide grid-frequency regulation systems from 10 to 200 MW power and grid scale energy storage systems from 200 MW power with 1 GWh of energy storage, up to regional energy storage hubs of 2 GW power and 32 GWh of energy storage. ARES adds that its system also boasts a higher energy-to-power ratio than flywheels, a lower life-cycle cost than batteries and a faster ramp-up rate than pumped-storage.

With multiple vehicles position on the same track, the vehicles move independently and can be positioned mid-elevation in a queue. As one vehicle comes out of the queue at the end, another enters the queue to maintain a constant power into or out of the grid.

Power is transferred to and from the vehicles by way of a conductor rail, while vehicle speed and location information gathered from small leading wheels on the vehicles is transmitted to a control station that coordinates the vehicles based on current energy requirements and prevents the vehicles from crashing into each other. In the event of a power disruption, air brakes on the vehicles activate automatically.

ARES recently held an open day at its R & D facility located in Tehachapi, California. Built as a proof of concept for its patented Regulation Energy Management (REM) system, the pilot plant is designed to even out intermittent power supply from a neighboring wind farm. This facility features a pilot vehicle that weighs 12,500 lb (5,670 kg) and runs on a 15-inch (381 mm) gauge track that is 880 ft (268 m) in length, making it 3.75:1 scale when measured against a standard 4 ft 8.5 inch (1,435 mm) gauge track.

The company is currently in the middle of the permit process to construct a full-scale commercial 50 MW REM system in Pahrump, Nevada for the Valley Electric Association and the California Independent System Operator (CA-ISO). This system will extend the length of the track to 5 miles (8 km) and up the weight of the individual vehicles to 300 tons (272 tonnes). The single track will be on an eight percent grade and have 32 vehicles operating on it, each able to absorb or provide around 1.5 MW of power.

ARES CEO Jim Kelly adds that the system can "be deployed at around half the cost of other available storage technologies. Just as important, ARES produces no emissions, burns no fuel, requires no water, does not use environmentally troublesome materials and sits very lightly on the land.”

The following video illustrates how ARES’ REM system coordinates multiple vehicles on a single track to deal with intermittent power supply.

Source: ARES

About the Author
Darren Quick Darren's love of technology started in primary school with a Nintendo Game & Watch Donkey Kong (still functioning) and a Commodore VIC 20 computer (not still functioning). In high school he upgraded to a 286 PC, and he's been following Moore's law ever since. This love of technology continued through a number of university courses and crappy jobs until 2008, when his interests found a home at Gizmag. All articles by Darren Quick

This is outstanding, who needs batteries when you have trains? Ok maybe a little early to go that far but it's still impressive.

Sydnee Brooker

I think this is a really good idea.


I designed a similar system (albeit a simpler, less refined one) as part of my Engineering degree a couple of years ago, I'm so pleased to see that someone else has come up with this idea and that it is being realised. Hopefully full scale systems will be rolled out and address the intermittency problems of renewable energy sources.

Jonathan Lodge

Rail is great for lessening friction, but that can be a problem when accelerating or breaking. Wonder if they'll end up with another track for that purpose and regular track to roll the carriages on.

Craig Jennings

Seems like a good idea, however, once the last car rolls down to the bottom, that's it! I would like to see a 'looped' or similar system where some of the power is diverted to pushing a few cars back up again - simultaneously - while using the downward-moving cars to generate power. i.e. 20 cars available for generation, move 5 cars back to the top slowly or gently while the last 15 generate. Tagging on the top end makes at least 25 cars plus possibly another 5 added to the total movement overall for extra generating.. Not 'perpetual motion' but every little helps!

The Skud

You could put solar panels on the track vehicles as well or the tracked vehicles could use a hybrid battery/flywheel system as well to maximize the surface area exposed to the sun.


It looks good if not great. It needs a large number of motor/generators but it is certainly something that could be built with off the shelf components today.

It might be worthwhile to put sails on the cars.


How could anyone imagine this as cheaper than pumped hydropower storage? One way to do it does involve a railway, but the cars get used over and over, not left at the top of the hill.

Bob Stuart

I have thought about the use of trains for energy generation, but more in the line of capturing the energy that is wasted during the braking process. If there was a way to use a passing train that was decelerating to help lift these other cars or to generate energy (mechanical or electrical). This energy may also be used to help with getting the train rolling again after stopping. After all locomotives are run with electric motors that huge diesel generators power.


a simple gravity storage system. Would work well.

Max Kennedy

Maybe this works fOr emergency power purposes, but I fail to see the everyday utility, since we ARE STILL DEALING WITH REAL PHYSICAL LAW effects LIKE FRICTION, POWER CURVES, AND REDUCED CAPACITY AT EVERY TURN.

Barry Dennis

As someone doing RE, EV's, etc this looks real good except train rails won't work on such slopes needed, not enough traction. But a rack on the ground solves that as with other mountain trains with the same problem.

You could store weight cars at the top to reduce loco needs. With say 3 roads, it doesn't have to be tracks, such a unit could be very useful leveling demand, supply loads.

If you happen to have a at least small mountain handy that is. You'll need over 1,000' rise likely to be good but many places are like that on both coasts. Sadly not here in Fla.


re; ElTerencio

The problem with the train based generation is the intermittent nature of the power supply. I have been trying to figure out a cheap way to store the power ever since it occurred to me how much energy was generated buy the trains carrying coal from Wyoming to Texas.


In California "Regulation" providers need to have 25% of a systems rated Power as Energy -- hence for a provider like ARES to bid 50MW they need 12.5MW as energy -- this is 15 minutes at full power which is why the ARES system for Regulation does not load or unload masses or concern with "running low" -- it is only intended to operate as a grid scale flywheel. In California this is called a LESR or Limited Energy Storage Resource -- this is the market ARES is going for with their single track system. Their energy storage system is altogether different and has a large field of masses that store energy. Their website has animations for their two system designs and the only thing one has in common with the other is the vehicle.


re; Bob Stuart

The track is not that much more expensive than the pipe for the hydroelectric system and you do not have to build the reservoirs

I think that the hydroelectric type system would work better long term especially in adverse weather.


If they could figure some kind of useful work for this to do besides slowly shuttling cars back and forth it would be a real winner. Also another related idea would be to make windmill towers much beefier and have giant doughnut shaped weights around the towers that hauled up to store the excess power. The weights are lowered when the wind dies to keep the generators spinning.

Michael Crumpton

Why use a rail, which requires lots of space? The energy comes from the vertical distance traveled. So why not just have those massive generators move UP and DOWN within a vertical structure? That way this approach could be used anywhere, even within cities.

Roger Garrett

re; Roger Garrett

Adding cars to this system is a lot cheaper so adding capacity ton this system is a lot cheaper. However if you happen to have a large vertical drop available such as a ventilation shaft for a deep abandoned mine there is very little reason not too but then plugging the surface accesses and using the mine to store compressed air works as well.


Rather than using railcars, which would involve the building of track, and the use of any available hill or mountain (this is hardly going to be environmentally viable if you have to build a giant incline!), why not use existing spaces in vertical buildings- eg using independent weights rising and falling in the voids in elevator shafts not filled by the elevator cars themselves (or possibly retro-fit smaller cars in existing shafts, with larger shafts in new builds?

The independent weights could be raised by surplus energy from rooftop solar, wind, or even regenerative technology from the lift itself. Seems common sense to me.


The video on has a pretty good overview of their vision. Regarding water their point is not many places have enough water to be shuttled up and downhill and the impact on land due to the reservoir/dam. I agree on the 'slipperiness' of the tracks but that could be solved by cogs or perhaps not 'polishing' the rails and wheels as we normally see - seemingly both would introduce some loss but surely minor in the overall system. The idea of a weight moving vertical is awesome. Using a tower to do it could be limited by cost of building a something capable of support the weight needed but a small support structure over an existing hole sounds promising. Jason


Why not loading the cars with big flywheels instead of heavy blocks? That way the system could be smaller or larger capacity, as the same mass would be storing energy in two different ways.


It might be nice to use a few cars for bring all the components for wind farm construction up the hills as well thus saving the fossil fuel needed to transport all that mass to the useable elevations.

Leif Knutsen

For those of you that think this could be done vertically how are you going to lift 9600 tons of weight straight up? There are only a handful of cranes large enough to take that kind of weight and they are very, very much more expensive than a few miles of rail line. Plus they can only lift a few hundred feet at most and their cables wouldn't last nearly as long as the track and have to be replaced much more often at great expense. The cost of such a tower would run billions of dollars while the rail line would only cost a few million. Of course schemes like this just add to the expense of already expensive power supplies and would never be used if government didn't force power companies to use them or pay for them with tax dollars.

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