The company, which filed an application for development consent to build the project at Glyn Rhonwy near Llanberis.

Snowdonia said that its scheme, which would re-purpose two abandoned slate quarries, already has planning permission from local authority Gwynedd Council at an output of 49.9MW.

The project represents the first in a series of schemes that QBC, the parent company of SPH, plans to develop throughout the country.

By increasing the capacity of underground turbines and associated equipment, SPH plans to double the power generation capacity of the Glyn Rhonwy facility.

During low electricity demand, the facility will pump water to a reservoir on the upper slope of Cefn-Du and at times of high electricity demand, the stored water will be released back through turbines to a lower reservoir in order to re-generate the electricity.

The scheme has been designed in consultation with AECOM, Gwynedd Council, Cadw, Countryside Council for Wales and Environment Agency Wales (now Natural Resources Wales).

Planned to be commissioned by 2019, the 600MWh facility is expected to play an important role in balancing supply and demand on the UK’s electricity grid.

In April, SPH signed an agreement with the Crown Estate for leasing of 13ha of land for the development of grid-scale electricity storage facility.

With an operational age of 125 years, the project will support hundreds of jobs during the construction phase and 30 full-time jobs upon completion.

According to QBC, a new 10GW fleet of pumped hydro schemes would reduce £3.5bn annually from the cost of decarburizing the grid, reduce carbon emissions by 5 million tonnes per year, and make the electricity supply more secure in the UK.

Following completion of UK-wide geographical survey, QBC identified sites with low planning risk for some 15GW of new pumped hydro storage.