Development of the first pumped-storage scheme with an underground lower reservoir

The integration of renewable energy generation systems such as wind and solar power has resulted in a growing interest in pumped storage, which can provide a flexible means of managing peak demands and high variation in energy production by renewable sources. An independent power producer, in association with AECOM Engineering Consultants, has proposed the construction of several underground pumped-storage projects across North America. Creating the lower reservoir underground has several advantages, the most important being the possibility to locate the plant near load centres, as this concept is not limited by the constraint of having two nearby surface reservoirs at different elevations. This paper gives an overview of the concept, with emphasis on the Wiscasset site.