To reduce his gas consumption, Frédéric Vaucelle, a veal calf breeder, has just invested in a solar thermal power plant. The equipment selected captures all types of radiation and stores the heat produced.
Using energy that generates no or very little charge of operation: the idea had been trotting for three years in the mind of Frédéric Vaucelle, a farmer who installed in EARL in Saint-Georges-du-Rosay (Sarthe). It became a reality last June, with the start of operation of a new generation solar thermal power plant.
Here, to capture the sun's energy, no panels, but two parallel rows of tubes. Frédéric Vaucelle, whose operation was selected as a pilot site within the framework of the European Icare4Farms project, opted for Fengtech technology (Mayenne). In total, for this breeding of 400 calves under an integration contract with the company Van Drie, sixteen blocks of 30 tubes each were installed. These are "Sydney" type vacuum tubes, the inner wall of which is made of an iron / copper / aluminum alloy. A detail that is important, these tubes are placed on metal plates painted white. “We are using a system that captures light over 360 ° and all types of radiation: direct, diffuse and reflected,” confirms Liqun Feng, from Fengtech (Sarthe).
Store heat
In renewable energies, the question of storage is central. "At the end of breeding, the calves consume 8 liters of hot water per day, or 3,200 liters in total, recalls Frédéric Vaucelle. For the water / milk powder mixture to be very homogeneous, this water must have been heated to 80 °. At the EARL du Boulay, three systems are cumulative. First, 16 balloons positioned above the tubes. “Each balloon is connected to a block of tubes. The set can store 4,800 liters of hot water. The second storage solution is not visible to the naked eye. In fact, 160 meters of coils are buried under the installation, one meter deep, between two layers of sand. They make it possible in particular to manage overheating situations when all the balloons are filled with water at 80 °. “By passing this water through the coil, we lose a little heat because the ground collects it. "
Finally, a final storage is planned in a tank (2,400 liters) in the building. A closed circuit The plant operates on the basis of a closed circuit. The cold water coming from the barn first passes through the coil and then enters - from below, at a rate of three liters per minute - into the first tank. It is heated there and then naturally pushed, without eddying, from one balloon to another. As it advances, its temperature increases. In the end, the water from the last, hottest tank is returned to the building. "It then goes into the gas boiler, but it is triggered only if the water is not at 80 °. We are on a system where the gas is complementary, ”recalls Liqun Feng.
Lower charges
Frédéric Vaucelle has invested € 68,000, subsidized up to 60%, in this solar thermal power plant. With a return on investment that is already visible. “When the plant started up, I had a batch of 400 calves in place for a month. By the end of October, on the eve of their departure, I had consumed 1300 kg of propane; that's 66% less than normal, ”explains the breeder. "Ultimately, I think we can go down to - 70% and get to 3 kg / calf raised. By comparison, out of the five lots bred since 2018, I was at 9.5 kg. "As a result, based on an average price of € 730 / tonne of propane since 2018, the cost savings will be substantial. “The big advantage of this system is the operating expense, which is almost zero. We just need a little electricity to run the pump that brings the water, ”summarizes Frédéric Vaucelle who, thanks to this investment, also reduces his CO2 emissions by about 15 tonnes per year.
