New, Completely Unworkable Concept in Energy Storage

Six or eight years ago, a client paid me a small fee to provide my opinion of a concept called “advanced rail energy storage,” or “ARES.”

It’s essentially pumped hydro without the hydro.  In other words, it replaces water with extremely heavy train cars that are pushed up a hill powered by a motor driven with off-peak electrical power, the energy from which is later released as needed by allowing the train to come down the hill, slowed by the motion of an electrical generator.

IMO, as I told my client at the time, this is probably not going to make it to the market, because:

• As is the case with pumped hydro, it can only be sited in places that have significant natural elevation changes.

• It’s a combination of the discoveries of Newton (ca. 1660) and Faraday (ca. 1830), and cannot be improved upon significantly in terms of efficiency, nor can the costs come down too much, as the costs of the components (rails, cars, motor/generators, etc.) is fixed.

• Contrast this with batteries, whose energy and power densities are constantly improving, while their costs come down.

Here’s another variation on the ARES theme called “Energy Cache” (think ski chair lift carrying pebbles).  It shares all the adversities above, and adds some new ones in terms of complexity, reliability and efficiency losses.   From bad to worse.