The search for new sources of energy has stirred excitement and alarm in northwest England, where an ambitious tidal power project for Morecambe Bay has fired up activists and may become a test of the government’s commitment to combating climate change. Promoters of a 12-mile-long pair of tidal barrages across one of the UK’s biggest bays claim the £8.5bn scheme would generate energy for 2m homes and prove the seriousness of Theresa May’s newly announced campaign for Britain to have zero net carbon emissions by 2050. Opponents worry that bridging the bay with causeways containing turbines, sluice gates and navigation locks would damage the UK’s largest area of continuous mudflats and sandflats. The muddy sands of Morecambe Bay are a magnet for migrating birds, fish and molluscs. “We love renewable energy and want to see the decarbonation of our energy network,” said Susannah Bleakley, chief executive of the Morecambe Bay Partnership, a local conservationist group. “But this is the wrong development in the wrong site.” The Northern Tidal Power Gateways project is the brainchild of Bury-based Alan Torevell, a former economist who set up a wealth management business in Manchester. Torevell claimed last week that Morecambe Bay could be the starting point “for producing 10% or more of the UK’s power needs through a series of tidal power projects around the UK”. About 1bn cubic metres of water enters and leaves the bay with every tide.