Saturday, August 17, 2013

Energy footprint of the digital economy

Back in 2009 we looked at the carbon footprint of ripping color documents for digital presses and published the result in the EI 2010 paper "Font rendering on a GPU-based raster image processor." Assuming the raster image processor is run at maximum capacity, the state of the art system at the time consumed 38,723 KWh and generated 23,234 Kg of CO2. By using GPUs, we were able to rip the same data with 10,804 KWh respectively 6,483 Kg of CO2. At the time we thought saving 16,751 Kg of CO2 per year per RIP was a pretty cool result, but at the end the product never shipped, despite — or maybe because — it was much lower cost. (See the paper for the details of the calculations.)

This month the Digital Power Group published the white-paper "The cloud begins with coal: big data, big networks, big infrastructure, and big power." The work was sponsored by the National Mining Association and the American Coalition for Clean Coal Electricity, which explains why some of the numbers appear a little optimistic in terms of the coal needed to keep the smart phones running and serving contents, but even if we divide the numbers by 5 to make them a little more realistic, the numbers are quite staggering when we add everything up. It turns out, that a smart phone requires as much coal as a small refrigerator. Cloud computing will consume an ever increasing fraction of our total energy consumption. This is a good reason to work on more efficient and greener storage systems.