Glad Tidings for Sea Power Potential
The daily ebb and flow of the tides promise a renewable energy bonanza for countries such as Canada and the UK that have shallow seas and a steep tidal range.
By Paul Brown, The Climate News Network
Two countries with the highest tides in the world, Canada and the UK, both claim to be the world leaders in creating electricity from the tides. They are among a group of coastal states − including China, South Korea, the US and Australia − that are hoping to harness the enormous power of their local twice-daily tides to tap a new and reliable supply of electricity.
Unlike wind and solar energy, tidal power is entirely predictable. If it can be tapped on a large scale as a power source, it will provide reliable base load power for any grid system. There are all sorts of schemes in many countries, the most familiar being the tidal barrages that direct the ebb and flow of the tide through turbines to generate electricity.
Best known of these is the Rance tidal power station, which was opened in 1966 at St Malo, northern France. At 240 megawatts, it was the largest in the world for 45 years, until South Korea’s Sihwa Lake power station came into service in 2011, producing 254 MW.
But there is a new generation of tidal power schemes. They use undersea turbines, able to make use of the powerful tidal currents in estuaries and in relatively shallow water on continental shelves. Because water is far denser than air, the same area of turbine blade can produce four times more electricity than a wind turbine.
So far, 20 sites in the world have been identified where hundreds of underwater turbines could be deployed. These are in shallow water, where the tidal current moves swiftly and where cables can be connected to the onshore grid. The best sites are between islands or in other narrow stretches of sea where the tide flows strongly. Eight of these sites have been identified in the UK, and they could on their own generate around 20% of the country’s electricity needs – more than its 15 nuclear reactors are currently producing.
the Pentland Firth to the island of Hoy
