The Large Hadron Collider at CERN is one of the greatest engineering feats of all time. It's also one of the most expensive to run, clocking up around $23.5 million in electricity costs annually as it accelerates protons close to the speed of light.
The CERN facility as a whole uses 1.3 terrawat hours of electricity (1.3 trillion watt hours) every year, enough to power 300,000 homes. This has required some innovative steps to meet the energy demand, which continues to rise as more powerful accelerators and detectors are developed.
How much power does CERN use?
CERN's power consumption varies throughout the year, depending on the seasons as well as the experiments being conducted. It increased considerably when the Large Hadron Collider (LHC) went online in September 2008.
Power consumption is highest between May and mid-December when the LHC is in operation. During this time, the facility uses around 200 megawatts per month to power the 27-kilometre-long particle accelerator. This falls to 80 megawatts the rest of the year.
Where does this power come from?
Back in the 1950s, CERN was powered by its own dedicated substation fed by a local power plant. However, as the site grew and became more ambitious, the electricity supply struggled to keep up with the demand.
Since the 1970s, CERN has received its power from the European electricity grid, via a substation on the French side of the site. The original substation on the Swiss side is maintained as a backup.
Preventing energy loss
Electricity is transported around CERN using a high-yield copper line, which loses some energy to electrical resistance along the way.
The LHC itself uses superconducting wires made from niobium-titanium that conduct up to 100 times more current than standard copper wires. These are cooled to temperatures approaching absolute zero (minus 271.3°C) to eliminate electrical resistance.
To ease the transition from room temperature to the cryogenic environment around the LHC, the main copper line passes through water cooled to a range of temperatures.
The cost of cooling
Cooling the area around the accelerator to temperatures colder than outer space takes its toll on CERN's energy costs. In fact, the energy needed to cool the superconducting wires currently negates the energy savings of the superconductors themselves.
To make the process more energy-efficient, CERN researchers are looking into replacing the entire length of copper wire with cooled superconducting cable. Although this will require significantly more cooling, it would avoid the need to rapidly cool down the wires as they approach the accelerator.