chasing cheap kilowatts has its limits by doug mohney

Views and Opinions on Green IT (Aug 27 2009) Power and Cooling

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   Least-cost energy routing (LCER) could save big online businesses "millions" of dollars each year in power, says a study written by researchers at MIT, Carnegie Mellon University, and Akamai.  Digging deeper, there are interesting subtleties within the actual scheme – and one hard limit.

    Energy pricing, to no great surprise, fluctuates for a variety of reasons, including seasonal changes in supply, fuel prices and changes in consumer demand.  There is a lot of volatility baked in, even with geographically close locations, and researchers say there's no "nirvana" of cheap power at any given time.

    The MIT/CMU/Akamai team cooked up a routing scheme to take advantage of daily and hourly fluctuations in electricity costs around the country – note "country"; I'll come back to it in a moment. The algorithm weighs up physical distance needed to route information against likely cost savings from reduced energy usage. Under best case circumstances, a company with a sufficiently distributed infrastructure could slash energy consumption by 40 percent.

    One idea thrown out in the study is the ability for an energy company to negotiate for data center usage to be virtually moved elsewhere if demand was high.  This could be a boon during the summer when power demands are high and tied directly to daytime hours, with usage shifting rolling from East to West as air conditioners kick in and then "leaping back" to the East as the West Coast hit peak usage.

    But there's no such thing as a free lunch.  The concept games energy costs rather than actual total energy usage or pollution, so if the cheapest electricity is available from a coal-fired plant, that's not factored in (yet).  Further, nearly all current server hardware doesn't have a big power consumption difference between idle and peak; Google's custom servers only consume 65 percent of peak power when "idle." Net-net is if you are going to have to buy new server hardware, you might as well look at re-building the whole data center to be more energy efficient from the ground up – not exactly a low-cost prospect.

    Finally, shifting around computer usage based upon energy costs is likely going to be limited to multinational corporations with large geographic footprints and limited to continental, if not country boundaries.  Undersea cable capacity is not cheap to build and don't even get me started about the expense of satellite broadband. 

   
   

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