Monaco has set itself the goal of reducing its CO emissions by 50%2 in 2030 and achieve carbon neutrality in 2050. To meet its commitments, the Principality is relying in particular on thalassothermal energy – which it calls blue gold – to heat and cool its buildings. A technology that she masters well since in 1960, it was the first city to develop this type of renewable energy on its coast.
Thalassothermy consists of using sea water as a source of energy to heat or cool buildings. The principle is similar to that of geothermal energy, but instead of drawing heat from an underground water table, the sea is used.
Sea water is pumped to a depth of ten meters where its temperature varies between 12 and 25 ° C depending on the season. Sent to a series of heat exchangers, it gives up part of its energy to a fresh water loop which supplies reversible heat pumps (PAC). These increase the temperature of the secondary circuit for heating and domestic hot water, or on the contrary reduce it to provide coolness during the hot season.
Compared to heat pumps which draw their energy from the outside air, the seawater cycle offers a much better performance: it produces up to 5 kWh of heating or air conditioning for 1 kWh of electricity consumed, i.e. 30% better.
Monegasque know-how in thalassothermal energy dates back to the 1960s. The Principality was in fact the first State to develop this type of renewable energy on its coast, with the installation in 1963 of a first heat pump on its coast. seawater at the Rainier III nautical stadium to heat the swimming pool water.
Today there are more than 80 thalassothermal installations in Monaco. They cover 17% of the energy needs of its inhabitants and they supply nearly two thirds of the buildings of the Rock, which represents an annual saving of 15,000 tonnes of oil equivalent.
Among the most emblematic examples of Monegasque buildings powered by thalassotherapy are the Grimaldi Forum, the Oceanographic Museum, the Auditorium Rainier III or the establishments of the Société des Bains de Mer (SBM), the Principality’s largest employer. , which manages numerous assets in the luxury hotel and leisure industries.
In addition, the new Fontvieille district has already benefited for several years from a thalassothermal network which serves its businesses as well as around 2,000 housing units.
Two new thalassothermic loops at Monaco
Anxious to accelerate its energy transition, the Principality has decided to ban the use of fuel oil for heat production as of January 1, 2022. The objective is obviously to largely replace this fossil fuel with “gold blue ”. To prepare for the conversion, Pierre Dartou, the new head of government and Thomas Battaglione, director general of SMEG (Société Monégasque de l ‘lectricite et du gaz), a subsidiary of Engie, recently signed a concession agreement for two new thalassothermal loops that will supply the Larvotto and La Condamine districts.
These structures, currently under construction, will be operated over a period of 30 years by a consortium of companies formed around SMEG. The project will produce 35 GWh per year of carbon-free energy, which represents a saving of 6,925 tonnes of CO2. The network will be connected to 3,500 homes over an area of 200,000 m2, or 7% of the total area of buildings in the city.
Along the Mediterranean, but not only …
For several years, Monaco is no longer the only city to bet on thalassothermy. In France, there are now seawater heat pumps in Marseille, Sète, La Seyne-sur-Mer, la Grande-Motte, but also in Biarritz, Cherbourg, Brest and Boulogne-sur-Mer. In Marseille, the Thassalia plant operated by Engie was inaugurated at the end of 2016 to heat and cool 500,000 square meters of buildings in the Euroméditerranée business district.
Installed on the port, the Massileo power station – the second thalassothermal network in Marseille operated by Dalkia – is intended to serve more than 500,000 m via a 9 km network.2 of buildings in the Euroméditerranée 2 zone. The “Smartseille” eco-district was the first to be connected to it in 2016.
Thalassothermia is developing well on the coasts of the Mediterranean, favored by the proximity of urban areas to the coast, the absence of tides and favorable bathymetry. But not only: it is also very popular in certain Nordic countries such as Norway, with capacities of several tens of MW per installation and technologies suitable for cold seas. In fact, the greater the difference between the temperature of the sea water and that which is necessary for heating, the more energy will be required to transfer this heat.
Negligible impact on biodiversity
Finally, we should also point out that a study led by Dalkia over a period of four years has shown that seawater heat pumps have a negligible impact on flora and fauna. The temperature variations induced by water discharges do not exceed 1 ° C, within a perimeter of five meters around the discharge point. The study establishes thalassothermal energy as a technology with great potential along densely urbanized coastlines and as a competitive solution to the energy transition, provided that the installations are well designed and built.
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