“Governments may have to contribute a greater share of the development costs, but this could be a small price to pay for harnessing this immense source of clean, predictable energy”.
Fossil fuels emit damaging CO2, wind and solar are variable, nuclear generates radioactive waste, while biomass, depending on the source, can encourage deforestation. On paper, tidal and wave power would appear to be the best solution, using the ferocious force of the oceans to deliver clean, abundant and consistent energy. Yet despite the fact the first large-scale tidal project opened in La Rance in France in the 1960s, sea power provides just a fraction of the energy delivered by its renewable counterparts - currently just 0.5GW compared with almost 400GW of wind power. But renewed determination to develop new technologies to harness the ocean's power means the tidal industry could be set for something of a renaissance. A tidal project similar to that in La Rance has been built in South Korea, with smaller plants in China, Canada and Australia. Together, these make up nearly all the tidal power generated across the world. All take advantage of what is called the tidal range - the change in the height of water between low and high tides. An artificial barrier is built, generally across an estuary, to hold water when the tide goes out. This water is then let back into the sea, driving turbines in the process. When the tide is high, the water is let back in, again driving the turbines. The problem, as Cedric Philibert at the International Energy Agency (IEA) explains, is that: "You can only make a tidal barrage where there is a huge difference in sea levels, and there are only a limited number of places where this happens, mainly Canada, Northern Europe and Korea." There are also some environmental concerns, particularly with building barriers across estuaries, which are biologically very diverse and home to fish nurseries. Mr. Philibert says it took 20 years for the natural environment to recover fully from the La Rance barrage. He says artificial lagoons, such as that proposed in Swansea, are far less disruptive. High costs and the very challenging ocean environment will continue to hamper development, but the industry is confident these barriers can be overcome, with tidal and wave power eventually making a meaningful contribution to global energy supply.