Amsterdam Schiphol Airport, early December. Night has already enveloped the Dutch sky. Jérôme Stubler, the president of Equans, invites us to “a journey into the future”. For this, planes are superfluous. Head to the underground parking lot of an office building not far from the terminals, where a series of pipes, pumps and exchangers have replaced the cars. The French company, sold by Engie to Bouygues in 2022, is finalizing the installation of a shallow geothermal system called Ates (Interseasonal Heat Storage, in French), which will be ready in February 2025. The ideal tool, believes the boss, to “cross a new frontier: that of the decarbonization of heat”.
Ates uses underground water as a natural reservoir to store thermal energy in the long term. In the Netherlands, its temperature in groundwater is on average 12°C. In winter, the water taken from a first well, approximately 80 meters deep, passes through a heat pump, allowing the buildings to be heated, before being cooled and then reinjected into a second underground cavity. In summer, reverse course to cool the premises and do without air conditioning. The water from the two pockets, nearly 300 meters apart, does not mix, guaranteeing the possibility of drawing hot or cold depending on the season. A renewable, local and almost invisible resource. “It should allow us to be ‘zero emissions’ in 2030, twenty years ahead of the national objective,” smiles Jörgen Pikker, real estate manager for Schiphol. The airport area – including terminal 3 – already has more than twenty Ates systems, including one of the oldest in the country, almost all from Equans. And it’s not over: the operator will invest another 6 billion euros over the next six years, in particular to equip terminals 1 and 2.
“No building in the country is built without this type of installation,” assures Richard Dujardin, executive vice-president of Equans, in charge of the Netherlands and Switzerland. A few kilometers from the airport, the Keulenhof park reception building, famous for its millions of colorful tulips, is equipped with them. The Zuyderland hospital, in the south of the territory, which dates from the mid-2000s, benefits from five pairs of wells – cold water and warm water – allowing it to be one of the best in the country in terms of energy efficiency . More recent, the Brainport Industrie Campus (BIC), a sort of Station-F with Dutch sauce and industrial style, also has its own Ates system. Enough to guarantee the fifty or so companies focused on high technology and robotics, such as Philips or ASML, the semiconductor giant, heating completely exempt from natural gas.
Favorable terrain in France
For decades, the Netherlands has been enriched by generous fossil deposits, notably that of Groningen. To the point of becoming one of the most prosperous nations on the continent. But numerous earthquakes caused by gas exploitation, and underlying security issues, have pushed the country towards radical change. The problems of electricity availability, with a very congested network, have only complicated the Dutch puzzle. The authorities therefore sought all possible solutions to quickly reduce their gas consumption. Geothermal energy has benefited from this… Equans too, since the energy and services specialist has already built nearly 700 installations.
Those of Schiphol allow the airport to avoid the consumption, each year, of 625,000 m3 of gas. If “the other cheese country” is a good student in this area, it is not the only one: Belgium, Switzerland and Germany have also invested heavily in geothermal energy. France is not there: all the projects, all technologies combined, represent only 1% of the heat produced, according to government figures.
The geothermal potential nevertheless exists. This renewable energy would be available on almost all of French soil. In detail, “between 50 and 60% of the population could have access to interseasonal storage,” says the president of Equans, previously head of Vinci Construction. This system requires certain soil conditions: aquifers (rocks housing water) and a porous underground where the water moves slowly. The Netherlands is well endowed, especially Amsterdam airport, built on a former polder. In France, the large sedimentary basins meet approximately the same criteria: the north, the east, and a Paris-Bordeaux corridor passing through the Centre-Val-de-Loire, as well as the alluvial valleys. “The notion of climate is also important for the success of an Ates,” continues Jérôme Stubler. “It’s perfect for the north, but not interesting for the south, where it is too hot.”
Costs and procedures
Fewer than five projects are currently operational. A few others, with similar functioning, are emerging from the ground, such as that of the Nanterre Cœur Université eco-district (Hauts-de-Seine), where several dozen geothermal probes provide inter-seasonal storage. “The technique is in place, certifies David Coutelle, president of the geothermal commission of the Renewable Energy Union (SER), also director of trades at the Ginger Burgeap design office. Except that two obstacles persist. The first is regulatory: the procedures , which are based on the mining code, are long for large projects The second, surely the most important, is the cost: it is very economical once in operation, but very expensive in investments. It is profitable if you think about it. in the long term, which is not always the case…”
The boss of Equans, who would like to multiply his system in France, regrets that certain past failures have cooled minds on the development of these solutions. “There were poor performances in the 1980s and 1990s, with installations breaking down due to a lack of monitoring, hampering their growth somewhat,” agrees David Coutelle. However, the situation has changed with the urgent need to reduce CO2 emissions. In a report published in December 2023the Academy of Technologies judges that “inter-seasonal heat storage is an asset for the climate and for sovereignty. This would make it possible to decarbonize at a lower cost over time, to do so using less electricity, particularly during peak periods. consumption, to valorize surplus renewable electricity more efficiently than other processes.
The government seems to have realized this. He presented in February 2023 an action plan to accelerate the deployment of geothermal energy. Two months later, the Minister of Ecological Transition, Agnès Pannier-Runacher, visited an Equans site in the Netherlands equipped with an Ates system. But since then, little progress has been made. “If the plan is not carried out, it is not enough. And if we do not make clear choices on fossil fuels – in this case gas, the main competitor of geothermal energy – we will not progress,” laments the head of the SER. Political and budgetary uncertainties, particularly regarding the budget of Ademe and the heat fund, have not helped the situation.
Could it change with François Bayrou as Prime Minister? The Béarnais region supports the sector. The government action plan also comes straight from a report published a few months earlier by the High Commission for Planning, a body he headed. At the end of 2022, the mayor of Pau even pushed for the creation of new training in surface geothermal energy at the French Drilling School, located in Lescar, in the suburbs of his city. It now remains to be seen whether he will have enough latitude to carry out this commitment from Matignon.
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