The solar heat supply system of dairy processor Bonilait Protéines, which has its factory near the French town of Poitiers, is a unique showcase in many ways. First of all, it is currently the largest solar process heat installation in France. Second, it is equipped with drainback technology delivered by Belgium company Sunoptimo. And third, it is the first solar process heat installation which is operated by EDF Optimal Solutions as an Energy Service Company (ESCO). EDF Optimal Solutions is a provider of energy efficient solutions for all kinds of commercial users in a variety of sectors. The photo shows the around 1,500 m² collector field with flat plate collectors of type Vitosol 200 delivered by German heating boiler manufacturer Viessmann and installed on a support structure above the parking lot next to the factory.
“The solar process heat installation combined with a heat recovery system was a challenging project, and we have learned a lot,” confirms Fabien Ruiz, Head of the Innovation Department of EDF Optimal Solutions. “Industrial clients have a very different attitude towards and demand for energy consumption, so creating a heat delivery contract was a difficult task.”
Biomass and solar cover around 90 % of the client´s heat demand
The factory has two main heat-consuming processes: one of them is drying milk to make milk powder; the other consists of several cleaning processes, e.g., for petrol tankers and pipes. Only the cleaning process which uses water at a temperature of 80 °C has solar energy integrated, whereas drying is powered entirely by the wood boiler. Biomass and solar covers around 90 % of the manufacturing unit’s heat demand, according to the Bonilait website.
The collector circuit is operated as a closed-circuit drainback system without glycol, delivering heat via heat exchangers preferably straight to the process feedwater or to the storage tank. According to Jean-Baptiste Malaud, R&D Manager at Sunoptimo, the collector field produces twice as much energy as is needed when cleaning at noon during a sunny day. Then, the collectors supply half of their yield directly to the process via heat exchanger, and the remaining output is stored in the 30,000-litre storage tank. If there is no solar energy available, the heated-up water in the storage tank can supply the manufacturing process for up to 8 hours.
Because compressors and other machines need cooling in the factory, fresh water already reaches the solar system´s heat exchanger at 30 to 35 °C. The required process temperature is 80 °C. If newly generated and stored solar energy combined are not enough, the wood boiler will be used to raise the temperature to 80 °C.
EDF wants to open up the business field for solar process heat
The biomass boiler with a power of 5.2 MW from German biomass boiler manufacturer Weiss was installed back in May 2011, whereas the solar thermal system has been in operation since the last quarter of 2014. EDF Optimal Solutions was the turnkey supplier for both parts of the renewable heating system – but only operates the solar thermal system as an ESCO.
EDF Optimal Solutions was founded in 2009 as a 100 % subsidiary of the French EDF Group. With around 200 employees, the company generated a turnover of EUR 100 million in 2014. In February 2015, EDF Optimal Solutions merged with Dalkia, a new subsidiary of the EDF Group created in 2014 and with extensive experience in heating network operations. The expertise of both EDF Group subsidiaries is bound lead to an increase in the number of commercial clients supplied with energy-efficient solutions. “Once we have more experiences with the operation of the solar process heat plant near Poitiers, we want to open up the business field of solar process heat,” confirms Ruiz.