Green ICT is concerned with all the resource consumption involved with creating and operation ICT gear. Significant amounts of water are used in everything from chip fabrication to PC manufacture to data center operation.

Data centers are thirsty creatures just by virtue of the energy they consume. "The national weighted average for thermoelectric and hydroelectric water use is 2.0 gal (7.6 L) of evaporated water per kWh of electricity consumed at the point of end use," said the National Renewable Energy Lab in 2003. This means that a 5000 square foot, 1000 kW data center could be responsible for an annual consumption of over 17 million gallons of water just for its electricity.

Cooling adds another level of water consumption. Our hypothetical data center could consume almost 9 million gallons of water a year in cooling, for a total footprint of ~26 million gallons.

Any reduction in power consumption is also a reduction in external water consumption. Reducing the need for evaporative cooling through hotter operating temperatures and use of outside air are two techniques to reduce internal water consumption.

Google noted other techniques last year: "two of our facilities [already] run on 100% recycled water... and we are planning for recycled water to provide 80% of our total data center water consumption by 2010... The idea behind this is simple: instead of wasting clean, potable water, use a dirty source of water and clean it just enough so it can be used for cooling. Cooling water still needs to be processed, but it's much easier to treat it enough for data center use compared to cleaning it for drinking use. For example, the data center we're building in Belgium will use water from an industrial canal and treat it in an on-site water purification facility before it is evaporated in the cooling towers. Other sites will use alternative sources of recycled water, such as city wastewater or rain water collected on site."

Yahoo's 2010 "Chicken Coop" data center consumes "at least 95 percent less water than conventional data centers."

The Green Grid has announced a new data center metric called Water Usage Effectiveness. "WUE will help managers determine the amount of water used by the facility, and the amount used to deliver work from IT operations...Materials related to WUE will be made available in the first quarter of 2011."

How will WUE handle the question of direct water use versus that embodied in a facility's energy consumption? The Green Grid told me, "This is a topic the Green grid is putting the finishing touches on, but the current preferred direction is as follows: WUE will come in two forms, a facility only form which will be used for day-to-day operations and site optimization around water usage and a source-based WUE to aid in design questions and site selection that will capture the embodied water in the energy as well."

The gear installed in a data center has an additional water footprint. See The Water Footprint of a Chip Fabrication Plant.

Water consumption is an issue with edge gear, too. Computer Aid cites a 2003 analysis reporting that the production of a PC consumes 1,500 kg. of water. After production, much edge gear ends up generating heat in offices conditioned by evaporative cooling.

The NREL and Computer Aid statistics are from 2003. Are current ones better or worse? Please comment below or Tweet us if you know where to source more up-to-date information.

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