Tidal power works by using underwater turbines similar in appearance to windmills that are placed in areas with strong tidal currents. These turbines can range in size from 2 square meters to 100 square meters. Larger turbines are able to capture more energy from the tides. Currently, tidal power plants exist in certain areas of Spain and not in the Netherlands, as the Netherlands lacks suitable deep bodies of water with strong tidal currents needed to effectively harness tidal power. While tidal power has potential as a renewable energy source, there are also environmental concerns about its effects on fish migration and noise pollution.