The revenge of direct current

At the end of the XIXe century, the case seemed heard. Nikola Tesla, the inventor of alternating current, had won the technological battle in the transmission and distribution of electricity against Thomas Edison, who advocated the use of direct current. But it was only a postponement.

Because the development of renewable energies is reviving what specialists call the “War of the currents”. Electricity for wind and solar farms is produced by direct current. The arrival of these new production capacities, often very far from consumption areas, requires a rethinking of the network architecture.

“Over long distances and when it is necessary to pass electricity through submarine cables or underground, direct current is essential, because it causes less losses”, explains Hubert de La Grandière, managing director of SuperGrid institute, a research center on electrical networks. This is the case, for example, for wind farms at sea or for large interconnections, such as this cable which has just entered service between Norway and the United Kingdom, or the new ones which will be laid to connect the France to Italy and Spain.

In Germany, residents’ opposition to the construction of new high-voltage overhead lines is also forcing the authorities to bury them. “The ten-year development plan for the European electricity network provides for more than 50% of direct current projects”, emphasizes Gabriel Bareux, R & D director of RTE, the operator of the electricity transmission network, even though they are almost five times more expensive than for alternating current lines.

The fall in costs in photovoltaics is pushing the emergence of projects that were unimaginable a few years ago. Indonesia, for example, has just given the green light to the installation of a 4,200 km submarine cable along its coasts to link Singapore to the largest solar farm in the world, located in Australia.

In Europe, the idea of ​​recovering photovoltaic electricity produced in North Africa, already mentioned fifteen years ago with the Desertec project, could well resurface.


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