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>>e think these ki of mention is all lia. they are n true green. they are fake ones. >> reporter: take the case o sihwa. environmentasts say while using tidal power is a good idea rinciple the plant could end up floodin neighring mud flats, destroying the habitat of migratory birds. the government admits ere are shortcomings b says the overalbenefits of providing cleaner air caonly be better for everne, including the wildlife. steve chao, al jeera, sihwa, south korea. >>> so, a you just heard in that report, some don't thin th tidal power i as green as it's being made out to b we want to tk more about that tonight with our rular science analyst, michael novac. he's the provo of science at the amican museum of natural history rit here in w york. michael, good to see you ain. >> nice be here. >> looking at that report fom south korea, iteems positive but it is alsoeen by some as bein environmental controversial. lk about that some re detail. >> absotely. this is a big project. it involves e constructn of a massive sructure made of concrete and steell