Image Credits: Orbital Marine Orbital O2, a floating tidal turbine off Scotland’s Orkney Islands, is the world’s most powerful operational tidal turbine. Developed by Orbital Marine Power, the 2 MW system started to export electricity to the grid in 2021 and serves as an apt example of how tidal power could be used to make clean-energy systems. The system is fitted at the European Marine Energy Center (EMEC) in Orkney, one of the world’s leading marine energy testing sites with tidal speeds of over 3 meters per second. The turbine can produce electricity to power 2000 houses and prevent 2200 tons of carbon dioxide emissions every year. Unlike traditional offshore wind turbines, which rise above the ocean surface, Orbital O2 extracts energy from tidal currents under water. The system includes a 74 m-long floating steel structure anchored to the seabed using a 4-point mooring system. Retractable legs are attached to either side of the platform to carry the two turbine nacelles, each housing a 1 MW generator connected to a rotor. Together, the twin turbines provide a total output of 2 MW. When tides flow through the narrow channels near Orkney, water passes through the rotors, causing them to spin and produce electricity. Unlike wind or solar power, which are not predictable, tidal currents are determined by the gravitational pull between the earth, moon and sun and can be predicted in advance. The flexible floating design allows the rotors and nacelles to be raised above water for servicing, which decreases operational and maintenance costs.