text: There was a protest in the public gallery after the decision on the Glyn Rhonwy pump storage project was made.
  The Snowdonia Society is concerned about its possible effects on wildlife, culture and heritage.
  But developer Quarry Battery Company (QBC) said it was the "missing piece of the jigsaw for renewables".
  The proposed pump storage scheme is based on the same principle as Dinorwig's First Hydro plant in Llanberis.
  By Iolo ap DafyddBBC Wales environment correspondent
  The value of pump storage is that it offers almost immediate access to electricity by allowing water to rush down the mountainside from one abandoned quarry - Cefn Du in this instance - through a pipe into hydroelectric generators and a lower reservoir in the second quarry Glyn Rhonwy.
  The water is then pumped back up the mountain at night when the price of electricity is cheaper.
  The biggest value is energy or electricity when needed. Demand in the UK is not constant.
  The focus is now on smaller sites, including using old quarries, because large holes in the mountains have already been excavated to mine slates over the past 100 to 150 years.
  So provided the company can find investors, contractors for this scheme could build and engineer smaller scale pump storage commercially.
  Water there is pumped uphill to a reservoir and then released back down through a turbine to generate electricity to sell on to suppliers.
  Under the proposals, a dam will be built at the upper reservoir.
  QBC managing director Dave Holmes said the project can help Britain "keep the lights on" and was environmentally more acceptable than another Dinorwig-sized facility.
  He said: "Our scheme for the Glyn Rhonwy quarries is just the start.
  "By putting small-scale storage near to centres of energy generation such as wind farms, and others near centres of heavy consumption such as major cities, we will cut down on distribution losses and network transmission costs, making whole regions of the UK increasingly self-sufficient in renewable electricity.
  "Not only will pumped storage smooth out the supply of electricity, but it will enable conventional power stations to be stood down, rather than kept on standby to fill gaps in generation.
  "This will save further costs and carbon emissions."
  The Snowdonia Society has said it was concerned about the effects of construction.
  The society is also concerned about how the scheme will be connected to the national grid, fearing that extra pylons would have to be built.
  The Open Spaces Society had added its objection, claiming the scheme would encroach on common land and be an eyesore.
  It previously said the applicant needed to be aware that it could not develop common land unless it offered land in exchange.
  The site has previously been the subject of planning applications for schemes ranging from a large ski dome to a mountain biking centre.
target: Controversial plans for a £100m mini hydroelectric power scheme on the edge of Snowdonia National Park have been backed by Gwynedd councillors.