Not surprisingly, gravity railroads – which were among our nation’s first railroads – are making a comeback – or are poised to. The gravity railroads that I’m speaking of are not in the business of hauling freight per se. Instead, the gravity, as employed in the application I’m talking about, is tied to energy production and energy storage.
Sound far-fetched? One company doesn’t think so, apparently.
Enter ARES: the Advanced Rail Energy Storage system.
Here is my understanding of the way the system works.
A railroad, constructed between two train storage yards – one at the top of a grade and one at the bottom – in this case serves as a platform for energy consumption and production. Shuttle trains in this case carry blocks (the blocks themselves having a given mass or weight) between the two yards – with transfer of rail vehicles or shuttle trains from the lower to upper rail yards occurring during off-peak hours when electricity demand is low, taking electricity supplied from the grid to power trains going uphill. Contrastingly, trains going downgrade produce power through a process known as regenerative braking. It is this power produced through the regenerative braking process that fuels the grid; ideally at times when energy demands are high. (A brief overview of the regenerative braking process is covered in: “CATS: Breaking friction-braking barriers with regenerative braking”).
Furthermore, and also as I understand it, the draw of grid-supplied electricity to run the rail vehicles during low-demand periods is small compared to that which is railcar generated and fed back into the same electric grid during periods of high energy demand. In fact, ARES cites an almost “80 percent charge / discharge efficiency” ratio.
Using a system that relies on electric motors, in the downgrade application, such have the capability to become electricity generators. It is through these generators that electricity can be produced; all made possible by train-axle rolling action which, in essence, turns mechanical into electrical energy. The reverse is true when electrical energy or electricity is converted into mechanical- or rail-traction power. In the latter application electric motors do the work, whereas in the former, the work of gravity is relied upon. (See also: “CATS: ‘Contactless’ energy-storage features give transit an edge” and “Capacitor energy storage feature to make U.S. October debut on light rail transit system”).
From a June 26, 2012 press release, it is noted: “ARES is designed to: guarantee grid security and reliability; support the increased use of renewable technologies; and to provide a grid-scale energy storage solution that does not rely on water. ARES is the first viable alternative to pumped hydro energy storage. ARES is less expensive, more efficient, and more widely deployable than pumped hydro storage technology and all other comparable storage technologies.”1
Also, from what I understand, Tehachapi, California is the locale of a scaled-down or reduced-scale track platform on which ARES system testing has taken place. Full-scale implementation roll-out may be right around the corner.
For more, see: “Grid Scale Energy Storage.”
- “James A. Kelly Joins ARES as CEO,” Advanced Rail Energy Storage (ARES) Press Release, Jun. 26, 2012.
– Alan Kandel