Is an almost inexhaustible resource of energy right at our feet, in the seas and oceans that surround us? Sunday January 16, during a meeting in Nantes, in an immersive setting where 3,000 people had gathered to listen to him, Jean-Luc Mélenchon delivered a vibrant plea in favor of marine energies. “The one that occupies 70% of the planet: the sea. Look at its power, its strength!” exclaimed the candidate of La France insoumise in the presidential election.
For Jean-Luc Mélenchon, the sea is “the nuclear exit door” : “EIt is there forever, night, day, with the movement of the tides, the movement of the currents in the depths, the circulation of the Moon around our planet.” In support of his demonstration, the leader of the rebellious, who sets the objective of 100% renewable by 2050, affirmed that the sea “contains 66 times the energy we need”. So, is he saying true or fake?
The sea contains 66 times the energy needed on land. It is our way out of nuclear power. We need to get out of it because the danger is immense.
There will be offshore wind turbines, there will be water-powered machines. We know how to do them. #MelenchonNantes pic.twitter.com/h1ZSCUpgnS
— Jean-Luc Melenchon (@JLMelenchon) January 16, 2022*
Contacted by franceinfo, Jean-Luc Mélenchon’s team cites as a source an article by researcher Jacques Guillaume, published in 2014 on the site Géoconfluences.ens-lyon.fr. “In total, the renewable energy potential of the global ocean is enormous, some estimating it at the equivalent of 100,000 billion kWh”, wrote at the time this pProfessor Emeritus of the University of Nantes and member of the Institute of Geography and Planning, without further details on this estimate.
A report published in 2017 by the Institute for International and Strategic Relations (Iris) figures the currently exploitable potential at “108,000 TWh/year”, that is 108,000 billion kWh/year, an estimate close to that mentioned by Jacques Guillaume. However, this exploitable potential could increase depending on the development of new technologies.
Jean-Luc Mélenchon’s team then did the calculation, dividing the “100,000 billion kWh” (i.e. 100,000 TWh) mentioned by Jacques Guillaume by “1,562 TWh”, the energy consumption in France in 2020, which can be found on the website of the Ministry of Ecological Transition. According to this calculation, the seas and oceans of the planet therefore have the potential to satisfy a little more than 64 times the energy needs of France.
But what about the planetary level? According to the OurWorldinData website, global energy consumption amounted to 173,340 TWh in 2019. On an Earth scale, the sea therefore does not contain 66 times the energy consumed worldwide, but 0.58 times, or just over half of energy consumption. By not taking taking into account only electricity (23,398 TWh in 2018), then the sea would contain 4.27 times the world consumption. But be careful: estimates of marine potential are complex and constantly changing. VScalculating the energy contained in the sea depends on multiple variables which can lead to very different results, warn several experts contacted by franceinfo.
If they cannot immediately cover all the needs of the planet, can renewable marine energies appear as the “nuclear exit door” evoked by Jean-Luc Mélenchon? The scenario is possible according to a report (PDF) of the Electricity transmission network (RTE). Among the six hypotheses studied by the French network operator, one scenario envisages “a 100% renewable system and a nuclear exit between 2050 and 2060”. According to Anne Georgelin, marine energy manager at the Renewable Energies Syndicate, “this scenario has the same robustness as the others, which include nuclear power. It just as much ensures the security, stability of the network and the carbon neutrality of the country by 2050”.
Director General of France Marine Energies, an institute responsible for developing the sector, Yann-Hervé De Roeck recalls, however, that if this scenario is possible, the diversity of renewable energy sources is a necessity: “It will take an energy mix. It is a security vis-à-vis several factors such as intermittency, cost or energy independence.” Christophe Le Visage, expert in maritime policies and marine energies at the Sea and Coastal Strategies firm, insists on the advantages of marine energies: “There is no need to wait for a technological breakthrough. It’s not like nuclear fusion, for example.”
Especially since France, the world’s second largest maritime domain, also has industrial know-how in renewable marine energies. “Four of the twelve European factories that produce offshore wind turbines are located in France”, recalls Anne Georgelin. According to Christophe Le Visage, France could even become an exporter of marine energy: “France could very well be in the lead in this sector of the future.”
“We are lucky in France to have a lot of resources and technical know-how that would allow us to develop and even sell marine energy to other countries.”
Christophe Le Visage, marine energy expertat franceinfo
Paradox: today France does not have a commercial offshore wind farm, unlike other countries such as the United Kingdom, Germany or Denmark. The first offshore park should enter into service in May 2022 off Saint-Nazaire (Loire-Atlantique) and three other parks will follow in 2023 and 2024. Delays in particular linked to strong opposition, in particular from fishermen, but also certain associations defending marine biodiversity.
For Anne Georgelin, we must reassure people worried about seeing beaches denatured by wind turbines. “For a power of 50 gigawatts which would represent 25% of French electricity production, only 3% of the metropolitan maritime space would be necessary.”
“And it must be said that these parks are installed more than 10 km from the coast, even up to 100 km from the coast.”
Anne Georgelin, Head of Marine Energy at the Syndicat des Energies Renouvelablesat franceinfo
There remains a major problem: that of intermittency. Energy sources such as wind are inherently fluctuating. Above all, the electricity produced poses transport and storage problems. “But there are solutions”, assures Christophe Le Visage. “Hydrogen or its derivatives, such as ammonia, are gases that can be stored for a long time, and transported in pipes, tankers or trucks, like oil and natural gas. The marine energy revolution will therefore probably go through a switch from renewable electricity to gas or liquid.”