Sustainable colliders: the Green-ILC project

Energy for innovation, innovation in energy

Sustainable Energies on the top powering ILC underground.

The Green-ILC project addresses the energy consumption of ILC, the International Linear Collider expected to be hosted by Japan. As a first step toward "sustainable colliders", its is aiming at increasing the power efficiency and at introducing renewable energies in the operation of this large scale research infrastructure. An innovative organization structure is proposed housing in the same "ILC Energy Center" a high energy branch dedicated to the construction and running of the collider and a sustainable energy research branch covering all energy R&D issues and using the ILC as a reference. Both branches would have their own budgets.

Energy consumption is coming to the front due to the rise in energy price and to higher power requirements needed to reach the precision, intensity or energy frontiers.

ILC is certainly the less power hungry of the current collider projects/proposals, but still with its estimated 164 MW power figure, it slightly overpasses the current LHC consumption. CERN with the LHC running in 2011 before a 2 years shutdown for a 'rehab' of the superconducting magnets amounted to 1.3 TWh including LHC pre-injectors and additional beam facilities. This is the equivalent of 50% of the electricity consumption of the Geneva canton housing half a million residents.

No doubt, Japan has the capacity to power ILC, but still the electricity cost may very well end up as the double of the LHC electricity bill, specially in 10-20 years from now.

Higher energy projects like CLIC at CERN or preliminary estimates for the FCC (Future Circular Colliders: ee or pp) or the Chinese CEPC-SppS projects multiply the ILC estimates by factor 2 or maybe even 4 which may become a serious roadblock.

Therefore the future of high-energy physics strongly relates to how HEP will address this energy challenge and how it will proceed toward sustainable colliders.

Sustainability is actually based on two pillars: efficiency and energy renewability. The required R&D should then focus on energy efficiency for all basic accelerator sub-modules like RF (klystrons,..), cryocoolers, magnets, ... but also on how to recover and recycle equipment heat wastes (more than 80% of the consumed electricity) as well as those produced in the beam dumps.

The intake of renewable energy in a mix with the grid basic supply is the next step. It will be progressively implemented in a way adapted to ILC requirements (24/7, short and long shutdowns, ...). In the long term this should reduce the overall running cost and give, through the access to multiple energy sources, a better operational flexibility.

All renewable sources will be considered: wind, sun, sea, geothermal or biomass but a lot of efforts will be dedicated to the energy storage issues.  For example liquid nitrogen (LN2) often used as a primary coolant for cryogenics system can also be used for energy storage. Produced on site by wind mills equipped with air compressors/liquifiers, it could be stored to supply cryocoolers 24/7. Surplus would produce electricity, on demand, when vaporized, by the heat wastes in a high pressure turbine.

HEP would therefore focus on its core business: "Energy" and more particularly on how to transform low-energy particles (eV) high entropy energies to high-energy particles (TeV) low entropy beams. Accelerators are actually power converters.

ESS, energy managment project (see also the report)

The Green-ILC project as well as other initiatives at the ESS, CLIC and others are meant to be merged in a more global endeavor beyond projects and frontiers, as the energy consumption challenge is quite universal.
The first joint meeting actually started, at the last LCWS2014 (International workshop on future Linear Colliders) in Belgrade (Oct. 2014) and at  HF2014 (55th ICFA Advanced Beam Dynamics Workshop on High Luminosity Circular e+e- Colliders – Higgs Factory). A common session was organized and 5 talks were presented. (see here and here (Thursday Oct 9 at 18:) as well as the summary talks (here and here).

Meeting this energy challenge can have substantial impacts on the society. Often when basic research meets technological difficulties, innovation is at the corner. The daunting management of documentation at CERN sparkled the World-Wide-Web; filtering micro black hole fussy signals gave birth to algorithms which are at core of WIFI transmission; the annoying synchrotron radiations hampering the reach to higher electron energies ended up being a major tool to analyze materials and biological samples,  and the list is long. With more than 30,000 accelerators in industry and hospitals, no doubt that energy efficiency will reduce the price tag for products and medical treatments.

But what is even more important is that the gathering of multidisciplinary expertise from high-energy physics, energy R&D and industry in an international and open research framework may provide the best way to boost innovation in energy and may give light to new disruptive energy technologies.

This is what the "ILC Energy Center", at the heart of a "global science city" as discussed in Japan, could modestly initiate and contribute to.