Barrage and gas: energy and generation

There's debate brewing over the proposed Severn barrage; start here for the arguments: Colin Luckhurst: The Severn barrage would be good for renewable energy, but opposition from conservationists is powerful | Comment is free | guardian.co.uk: "A barrage stretching across the wide mouth of the estuary from south Wales to the northern coast of Somerset could hold the turbines that – judging by the example of the only European example now in place, at the mouth of the river Rance in Brittany – could generate electricity both from the incoming tide and the normal river outflow."

A creative bit of thinking notices that natural gas is very high pressure when released and gets really cold as it is slowed down; perfect candidate for electric generation by turbine and also uses for refrigeration ... check it out.