EPFL has brought an innovative heating plant online and will connect it to a large data centre. The plant will help its Ecublen campus optimise how it generates and consumes energy, with the goal of achieving carbon neutrality.
Opened this year, the company’s new heat-pump-powered plant stands out for its aesthetic appeal, innovative approach and energy-saving performance. Adjacent to the building is two chimneys connected to gas boilers. These have provided heat to the campus for the two years while the plant was under construction but they will be used only in the case of a system failure in the future.
The new pumping station will draw water deeper from the lake at a constant temperature of 7°C. It is connected to next-generation heat pumps that raise the water temperature to 67°C thanks to a thermodynamic process that involves compression, condensation, expansion and evaporation, thus delivering significantly better energy performance.
The plant will also make use of thermal waste generated by a data centre built on top of it, with server racks whose doors are designed to accommodate filtered industrial water cooled by lake water. Cooling the servers to heat the rest of EPFL generates considerable electricity savings, particularly in comparison with the conventional approach of cooling the servers with refrigeration units. In a standard system, 3.3 units of electricity are needed to deliver one unit of electricity to the servers. Here, after factoring in savings in heating, this figure is 1.3 units, a 60 reduction. There are also solar panels covering the sides and roof of the building. Switching from the oil-fired turbines to heat pumps will cut EPFL’s CO2 emissions by 1,800 metric tons a year. The energy savings from the solar panels will only be marginal, however, since they will generate a total of just 160 kW, whereas a single heat pump requires 2,000 kW.
The construction work on the facility itself was delayed several times due to COVID. The delays affected EPFL’s new data centre, which is still under construction. The project managers are now waiting for the server racks to be delivered. The new heating plant will be linked to a data centre that will eventually house 12 rows of servers, including one for the University of Lausanne. The server racks used at the data centre will be slightly higher than conventional models and have water-cooled doors. It’s a design that’s already been used in other buildings, but until now only for cooling purposes. The plan is to have the heat generated by the servers recycled into the heating plant, which should start this winter. That will increase the campus’ data storage and processing capacity, initially to half capacity at 2 MW, and then to 4 MW.