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Is HPC green?

We all know that home computers often need a fan (or, if they’re high-spec ‘gaming’ PCs, sometimes liquid-cooling) to keep them from overheating. Running the fan or pumping liquid coolant around the system takes energy. Imagine how much more energy it takes to cool down many thousands of processing units all linked up in a supercomputer! The rooms that house supercomputers need special air conditioning, with high-powered fans and take an incredible amount of energy to run. The highest recorded total power draw taken to operate a supercomputer is for Japan’s K Computer, at 9.89 Megawatts. An average household might use 1.3kW, which means that the K computer is using as much as nearly 7500 homes.

Energy security and climate change, as well as cost, are important considerations for any large national and international projects, public or corporate, that need a lot of energy. This is equally true for supercomputers. Interestingly, some of the more inventive solutions for dealing with these issues have come from the corporate world, driven by cost efficiency and corporate responsibility considerations.

Both Google and Facebook have located data centres in the colder climate of Scandinavia – Google in Finland, where its machines are cooled by the Baltic Sea, and Facebook in Sweden, where its location close to the Arctic Circle and a large hydroelectric dam can simultaneously keep it cool while providing it with renewable energy. Apple is building a huge solar farm to make use of the plentiful sunshine where its data centre is located, in North Carolina, USA.

Just as a processor’s clock speed isn’t the only measure of its efficiency (and isn’t particularly accurate, anyway), some scientists have questioned whether the single-minded pursuit of ‘faster’ necessarily means ‘better’ or ‘more efficient’. Green500 is a website that lists the greenest supercomputers. It takes its name from the much more established Top500 list.