France a trailblazer in the innovative generation of power.

With the year almost at an end one might look back and reflect on any milestones that have been crossed.

One milestone that we all surely would have preferred to miss, was the detection of carbon dioxide levels in the atmosphere which topped 400 parts per million at a key observing station in Hawaii for the first time since measurement began there in 1958. Earth's atmosphere hasn't had this much carbon dioxide in it for at least 800,000 years.

Paradoxically this year marks the fiftieth anniversary of a technological breakthrough by France when it pioneered the generation of large volumes of electrical power from a source, which had until then been neglected. In so doing, France anticipated by several decades the contemporary drive to alternate, renewable sources of energy that do not consume fossil fuels and which do not pollute the environment.

If this technology had been more widely adopted in the intervening years, we might not have attained so soon the above unfortunate record levels of CO2 in the atmosphere.

Fifty years ago 'Électricité de France' (The country's counterpart to South Africa's Escom) sealed off Normandy's 'La Rance' estuary from the sea to create the world's first large-scale tidal power plant. The main justification for choosing this estuary, which lies on the north Breton coast between Dinard and St Malo, as a site for construction of the tidal plant was its unique advantage of a great difference between the ebb and flow of the tide, ranging from an average of eight meters to a maximum of nearly fourteen meters.

Building of the Rance tidal power plant began in 1960. The project involved the construction of a barrage 330 metres long which was to also house the turbines, a lock for enabling the passage of small craft, a rock fill dam of 165 metres length and a mobile weir with six gates for quickly balancing water levels by emptying and filling the reservoir.

View of La Rance barrage

Special reversible turbines were devised for use in the Rance barrage. They can produce energy during both the rising and falling tides, thereby increasing their efficiency. Two dozen turbines were installed each with a capacity of 10MW to produce a total peak power of 240MW, enough to supply energy for 250,000 households.

On its completion the barrage was inaugurated by President Charles de Gaulle when it officially began operations. Since that time, La Rance has annually delivered 500 to 600 gigawatt-hours, reliably generating power for more than 15 hours per day, which it continues doing to the present.

The investment in the undertaking of some € 94.5 million (about  € 580 M in today's money) was a relatively high one, but this has been recovered after twenty years and electricity is delivered from that project at a cost lower than that of power generated from nuclear reactors.

France's achievement of such high yields of energy from this non-traditional source was not matched by anyone else until two years ago, when South Korea installed turbines in an eleven kilometer long seawall, which impounded its Lake Sihwa.

Generally, a disadvantage of tidal barrages is their adverse effect on the environment and in that regard the 'La Rance' barrage was for the first three years of its operation a big embarrassment to its sponsors. The progressive silting up of the estuary devastated the Rance's ecosystem and nearly killed off all its marine flora and fauna. However, the estuary gradually recovered and reached a new equilibrium after a decade, when it saw the return of sea bass and cuttlefish to its waters.

These disadvantages seem to be outweighed by the attractions of this source of energy, judging by the renewed interest as evidenced by President François Hollande's launch this past September of a tender for four pilot projects off the Normandy and Brittany coasts. This is interpreted  by some as a push by his government to re-invigorate France's tidal energy sector.

The French engineering firm Alstom and GDF Suez responded to President Hollande's call by teaming up to bid jointly on the project for the Raz Blanchard Tidal power plant.

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Comment by Christophe Viarnaud on November 8, 2013 at 3:12pm

George, what an excellent post. Well done and thanks for your incredible contribution to the community. It is very appreciated.


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