Pumped storage developments

I used to wonder why Ffestiniog and Dinorwig were apparently unique in Wales. Surely the concept of a power storage facility making use of the natural contours of Wales had proved itself, and could be scaled up or down as appropriate. Indeed, it would complement the increasing acreage of wind farms, regulating the inherent unpredictability of their production.

Thanks to CAT's Clean Slate magazine, I now know that others were ahead of me. The Quarry Battery Company's scheme at Glyn Rhonwy, due to be completed in 2017, could be the first of many second-tier pumped storage schemes in a size bracket below Dinorwig, and for that reason less obtrusive.