Comments on: Advanced Rail Energy Storage

By: Space Nookie

Space Nookie — Thu, 16 Apr 2015 21:51:44 +0000

Yeah, that’s how I read it. They may have been worried that the utilities would build just a few small facilities with excessive storage to game the requirement, e.g. pumped hydro with a small generator and a very large reservoir.

By: Isegoria

Isegoria — Tue, 14 Apr 2015 23:07:59 +0000

So, they used the wrong unit, but it was on purpose?

By: Space Nookie

Space Nookie — Tue, 14 Apr 2015 19:22:50 +0000

According to this article and this followup article the California Public Energy Commission (CPUC) has required utilities in that state to purchase an amount of energy storage denominated in megawatts and that storage could be as little as 15 minutes capacity (or less) if that is "enough to bring value in this context".

By: Bob Sykes

Bob Sykes — Tue, 14 Apr 2015 11:44:08 +0000

Environmentalists successfully killed off pumped storage. It remains to be seen whether this is acceptable to them.

Aside from their low capacity factors (which require 1 kW of fossil fuel backup for each kW of installed solar or wind), solar and wind often produce excess power when it is not needed. This raises havoc in distribution systems, and the solar or wind systems have to be shut down. People are desperately looking for energy storage systems to capture this lost power. Chemical batteries can’t do it for reasons of cost, energy density and recharge time. This scheme might work if the costs are reasonable.

Of course, the environmentally correct solution is to shut down all solar or wind systems.

By: David Foster

David Foster — Mon, 13 Apr 2015 22:07:47 +0000

Yeah, it seems impossible for most journalists to grasp the difference. But if it’s really 50 megawatts, that seems unimpressive…it could store the output of a 500MW plant for all of 6 minutes.

Here’s a pumped storage hydro project that says it will be able to store 17,000 MWH.

By: Isegoria

Isegoria — Mon, 13 Apr 2015 20:05:09 +0000

I'm so used to pop-science writing that I (correctly?) assumed they meant megawatt-hours.

By: David Foster

David Foster — Mon, 13 Apr 2015 19:44:47 +0000

I don't think "Megawatts" is a very good metric for an energy storage system: it just indicates the rate at which energy can be delivered, saying nothing about how long it can be delivered for. Megawatt-hours would be a much more meaningful number.