Tidal Power

Although it isn't considered one of the main renewable energy sources, tidal power still has huge potential in the fight to replace fossil fuels with green energy alternatives.

One of the key benefits of tidal power, as discussed by Denny (2009), is the predictability of wave energy. It is a far more reliable source than both wind or solar, however there still limitations, as energy production can only occur when the tide is flowing in or out. 

The largest tidal power stations in the world are the Sihwa Lake Tidal Power Station in South Korea, closely followed by the Barrage de la Rance in France. Both are tidal barrages, dam-like structures containing turbines which capture the waters energy as it moves in and out of the barrage during high and low tides. 

Barrage de la Rance, Brittany, France
Source: Britannica.com 

One highly controversial tidal barrage proposal is the Severn Estuary Barrage. There has been much concern surrounding its viability, both environmentally and economically, and as a result, there are still no formal plans for its construction. There have, however, been developments in its design, with a new tidal fence proposal which would have fewer environmental consequences as it can be placed in shallower, slow moving water, allowing migratory fish to move up and downstream and continuing to expose mud flats during low tide. A 14km stretch of this tidal fencing would result in circa 600MW of energy being produced at peak times. 

Many claim however, that barrages are not the way forward for tidal energy, and the potential of this resource can only truly be exploited using underwater turbines which capture tidal energy from the currents. O'Rourke et al. (2009), state that tidal turbines are not currently the most economic option and are still relatively underdeveloped, but despite this, it is one of the most popular methods, seeing huge investment in developing the technology. In time, it is likely to improve in efficiency, decrease in cost, and become more environmentally friendly as technology advances. An underwater tidal turbine project is currently underway off the north coast of Scotland, with an initial 86MW development currently under construction. This will potentially be followed by a second 212MW development in the coming years.

There seems to be a significant amount of development in tidal power technology, and although there are limitations on availability of suitable sites that can exploit this resource, it is an interesting concept. If significant amounts of energy can be produced by one of these developments, it is certainly an area worth investing in.