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PDC Center for High Performance Computing

Sustainable computation and data storage with PDC

Want to minimise the use of electricity for your research computations and use "green" power? Need to meet your organisation's sustainability goals in terms of the computational resources used for doing research?
PDC can help: our computation and data storage resources for research are energy efficient and utilise renewable energy sources.

Running large computing systems is demanding, both in terms of electricity and cooling requirements. This can make it hard for research groups or companies to achieve their organisation's sustainability goals if they try to run their own system for performing massive simulations or other research calculations.

It can be a lot more efficient to use a supercomputer, such as PDC's Dardel system, that is based on highly energy-efficient hardware and that takes advantage of a much larger heating and cooling network to reduce the overall environmental impact. In fact, the new graphics processor unit (GPU) partition of Dardel came fifth in the world in the June   and November  2023 Green500 lists and eleventh in the June 2024  list. (The Green500 lists rank supercomputers in the Top500 list in order of energy efficiency.) These rankings are largely thanks to AMD's energy-efficient CPUs and GPUs. You can read about them in this case study by AMD  about Dardel's energy efficient hardware. In addition, PDC's systems all run on electricity from renewable sources.

What makes PDC's computing systems energy efficient?

  • Using energy-efficient hardware
    The GPU-partition of PDC's Dardel system uses GPUs which give higher performance for specific power consumption (see "More performance per watt from AMD" on page 2 of AMD's case study about Dardel )
  • Re-using heat produced by the PDC systems via the KTH Royal Institute of Technology​​​​​ heat re-use system  and heating/cooling network

What is heat re-use and why is it good for the environment?

Supercomputers use a lot of electricity and become very hot as they run, so some form of cooling is needed to stop them from overheating. For example, air-conditioners can cool air and fans can blow the cooled air over a supercomputer. However, this adds significantly to the amount of electricity that is needed to run the system. While it is possible to use electricity from renewable sources to provide the required cooling, the heat produced by the supercomputer is essentially being wasted if the hot air is just blown away. In environmental terms, it is much better to take advantage of the heat produced by the system and to (re-)use it in a beneficial way as that reduces the overall environmental footprint. Information about PDC's pioneering work on re-using the heat from its systems is provided in the last section on this page.

PDC uses electricity from renewable sources

PDC continues to be committed to operating its computer systems in as environmentally friendly a manner as possible. As well as reducing the amount of electricity that is needed via heat re-use, 100% of the electricity that PDC uses is from renewable sources. KTH has a commitment to sustainability, and the electricity supply agreement for KTH requires that all the electricity that is provided to KTH comes from renewable sources. This is noted in the yearly reports to the Swedish Environmental Protection Agency. (See, for example, section 2.3 of the KTH's report to the Swedish Environmental Protection Agency for 2023 , which is only available in Swedish.) KTH as a whole embraces the UN sustainable development goals (SDGs) - there are some details about this in English at www.kth.se/en/om/miljo-hallbar-utveckling/forskning-miljo-hallbar-utveckling/kth-s-forskning-och-fn-s-globala-hallbarhetsmal-1.863900 , with additional information on the Swedish page.

PDC uses cooling from renewable sources

The cooling needs of PDC's systems are met by the KTH heat re-use system, and KTH's report to the Swedish Environmental Protection Agency for 2021  notes that 100% of KTH's cooling is from renewable sources.

PDC pioneers re-using heat from supercomputers

Since long before sustainability became popular on a global scale, PDC has worked to provide energy-efficient and environmentally friendly high-performance computational resources, for example, decades ahead of some centres that are only now turning to more efficient water-cooling systems.

When a new supercomputer system was being procured in 2009 and 2010, PDC developed a method of capturing the excess heat (that would be produced by the system) and using it to help to heat another building at KTH. The inspiration for this came from the hydronic/district cooling and heating that is available in many cities and towns in Sweden, which is based on cold or hot water running through underground pipes and into buildings.

The method that PDC developed was based on cool air being blown up from underneath that new system, a CRAY XE6 known as Lindgren, and becoming much hotter as it passed over the sections of the supercomputer. That hot air went through ventilator hoods to heat exchanger coils which in turn heated water that was then used for heating a building. PDC worked with Akademiska Hus, the company that owns the buildings at KTH, and with CRAY on this project - further details about this ground-breaking heat re-use project (and a photo of the heat re-use equipment with Lindgren) can be found in this article . CRAY went on to incorporate water cooling into subsequent models of their supercomputers. PDC took advantage of that development with the next system (Beskow, a CRAY XC40 installed in 2014) to utilise a more direct form of heat re-use, where the air-to-water heat exchangers were included in the racks/cabinets of the computer. Inspired by the success of the earlier Lindgren project, Akademiska Hus installed a huge heat pump for the KTH main campus in Stockholm in 2015. It was linked to water heated by Beskow and reduced the amount of heating required for the KTH buildings in general. Some years later, the current system at PDC (Dardel, an HPE CRAY EX) was also connected to the KTH heat pump in a similar manner.

The following are some earlier articles about PDC's ongoing journey into greener computing.