Particle accelerators and detectors as well as infrastructure equipment need to be supplied with electricity. Electricity consumption is, therefore, one of the important CERN environmental aspects.
The nominal annual electricity consumption reaches some 1000 GWh when all accelerators are in operation. Only about 8% of this figure corresponds to the basic consumption necessary for the laboratory infrastructure. The remaining 92% is attributed to accelerator facilities.
The Large Hadron Collider (LHC), which will start its operation in 2007, will gradually reach its nominal consumption of 390 GWh per year.
A large fraction of the LHC electrical consumption will be to keep the superconducting magnet system to the operating temperatures (1.8 and 4.2 K) depending on the magnets. Thanks to the superconducting technology employed for its magnets, the nominal consumption of the LHC is not much higher than that of the Super Proton Synchrotron (SPS), even though the LHC is much larger and stronger in energy.
The nominal annual electricity consumption of CERN
Electric power equipment
CERN is supplied by the Swiss companies SIG and EOS and by the French company EDF.
Saving electricity when it is most needed
CERN accelerators are typically operated from spring to autumn when the public demand of electrical energy is low.
The contract with the French supplier EDF contains a special reduced power consumption clause. This clause stipulates that, on notice given by EDF, CERN considerably reduces its electricity consumption to avoid paying a hefty surcharge.
The words "EJP PERIOD" in the sign stand for Effacement Jours de Pointe, the reduced power consumption clause mentioned opposite
Avoiding pulsed network load
CERN accelerators are pulsed machines, that is, they repeatedly consume power for only a fraction of a second. The resulting fluctuations are reduced by compensators.
Environmental improvements on electrical devices
Many electrical transformers have been in use at CERN. Some older transformers and other chemical electrical devices contained Polychlorinated biphenyls (PCBs), which negative impact on the environment is known. In the nineties CERN implemented the total replacement of these devices with PCBs-free ones, and carried out a campaign to eliminate any traces of PCBs from the soil of the areas where these old equipments were. Today CERN is a PCBs-free laboratory.