Submerged in about 40 meters of water off Scotland’s coast, a turbine has been spinning for more than six years to harness the power of ocean tides and generate electricity. The trade association Ocean Energy Europe says keeping such a large turbine operating in the harsh sea environment that long is a record that demonstrates the technology’s commercial viability. Tidal energy technologies are still in the early days of their commercial development, but their potential for generating clean energy is big. The MeyGen tidal energy project has four turbines that power up to 7,000 homes annually.