Planning permission has been granted for two slate quarries in Wales to house the first electricity storage facility to be built in the UK for 30 years.
The two abandoned slate quarries at Glyn Rhonwy in Snowdonia will be turned into water reservoirs that will store electricity.
The reservoirs could supply 200,000 homes with electricity for seven hours a day over a projected operational lifetime of 125 years or more.
Developer Snowdonia Pumped Hydro (SPH) say the Glyn Rhonwy facility will bring a significant economic boost to North Wales, supporting hundreds of jobs during the construction phase and creating up to 30 high quality full time local positions to operate the site.
But there is controversy over the plan with local people concerned about contamination.
Construction of the facility could begin as early as 2018.