9 September 2008—The Large Hadron Collider (LHC) at the European Organization for Nuclear Research (CERN), set to start up tomorrow, is the largest physics experiment in history, and it’s probably the most power hungry. Spanning the border between Switzerland and France, the 27-kilometer accelerator ring with its accompaniment of radiation-hardened integrated circuits, feeder accelerators, computers, and supercooled superconducting magnets will, according to varying estimates, draw between 220 and 300 megawatts of electricity—enough to power the city of Geneva twice over. Keeping the power flowing reliably takes a good bit of ingenuity, as a sudden loss of power could mean serious damage to the machine and months of lost work.
Once all of these accelerators are fully operational in 2009, CERN’s estimated annual electricity consumption could approach 1000 gigawatt-hours, IEEE Spectrum learned on a visit to the lab in July. The massive LHC will account for about 60 percent; less than 15 percent of the total will go to mundane functions like keeping the lights on; and the other accelerators in the complex will account for the rest. A big part of the consumption is the hundreds of enormous superconducting magnets, though they draw much less power than equivalent conventional magnets would. The superconductors must be cryogenically cooled to temperatures between 1.8 and 4.5 kelvins (colder than outer space). If the temperature creeps even a fraction of a kelvin above that, the magnets stop working and lose control of the beam. An uncontrolled beam can melt 500 kilograms of copper in an instant, causing serious damage and halting the experiment for months. So it is crucial to keep power flowing into CERN at all times.
But CERN does not generate any of its own power, so how does it ensure an unbroken supply of electricity?
The LHC’s location enables a unique power procurement system: power comes in from both France and Switzerland. CERN has an agreement with French supplier Électricité de France (EDF) that guarantees a source of reliable, affordable electricity, with one caveat: for 22 days a year during the winter, power costs become prohibitive. (During that time, all the experiments at CERN are shut down.) The contract stipulates that the accelerators will operate mainly from spring to fall, when the public strain on the electrical grid is low. The agreement also means that CERN must reduce its electricity consumption on demand or pay a whopping fine.
But what if EDF’s system fails? Because the results of a power outage would be so disastrous, CERN also has a number of backup plans. For one, the laboratory has a system that can seamlessly switch to the Swiss power grid. In the event of a catastrophic failure that knocks out both the Swiss and French grids due to, for example, a natural disaster, CERN has several massive diesel generators designed to power submarines, which are poised to roar to life at the first hint of an emergency.