The internet is often viewed as a green technology, one that reduced the need for paper consumption, and increased the productivity of major corporations without increasing their carbon footprint. However, we must also recall that the internet does present an energy cost, which will continue to grow as internet consumption skyrockets.
Cisco publishes a paper every year called the Visual Networking Index, which uses a combination of internet traffic numbers sent through Cisco devices as well as estimates to pin down the growth rate of IP traffic around the world. The 2010 version found that, among other things, North America's IP traffic reached 5,155 PB/month, a growth of 30% from the previous year.  Due to the increase in utilization, companies like Google (which controls a large percentage of all internet traffic) must build massive datacenters to process all the traffic requests. These datacenters contain some of the most efficient machines ever created, but they still consume tremendous amounts of power. Currently, the IT sector makes up about 1.5% of total US electricity consumption .This may not seem like much for now, but with the continued growth of internet bandwidth, the amount of energy consumed by the IT industry will increase exponentially.
Clearly, the only way to prevent exponential growth in greenhouse gas emissions is to continually decrease the energy cost/data unit. This means that datacenters must increase efficiency at the same rate as IT growth. Almost no industry can maintain an efficiency increase of 30%/year, so this seems like a far-fetched goal. So let's look at the numbers and understand what this industry looks like.
In 2006, the EPA published a report on data center efficiency which estimated the total energy consumption of US servers and data centers (the backbone of the modern internet age). In this report, the EPA estimated that this sector (servers and data centers) "consumed about 61 billion kWH." However, this report also estimated that according to current growth and efficiency trends, this number will nearly "double in another five years (2011) to more than 100 billion kWH." 
On the other hand, according to Cisco's numbers, the total IP traffic in North America was 1,471 PB/month in 2006, and increased to 5,155 PB/month in 2009.  Thus, in only three years, IP traffic has more than tripled. Cisco estimates that IP traffic will surpass 10,000 PB/month in 2011, which gives us an interesting question: how can IP usage increase 8 fold while energy usage only doubles?
What this small sample indicates is that the technology powering today's internet usage is incredibly powerful, yet ruthlessly efficient. However, the power consumption of the internet is still eclipsing all efficiency gains from these technological advances. This phenomenon brings up an important question: will the growth of internet consumption wane before technological advances in internet infrastructure start to decline? If this is not the case, then what does this mean for the future of the internet as a global communication mechanism, and are current growth trends sustainable?
While we can always push off worrying about internet power usage due to the efficiency of the IT industry, we cannot ignore the threat of a rapidly growing appetite for bandwidth. This implies that a forward-looking government can and should place constraints on personal and corporate bandwidth consumption in order to slow this bandwidth demand curve. These constraints can come in the form of a tax on data consumption, or even a mechanism where Internet Service Providers (ISPs) charge per unit of bandwidth, rather than allowing unlimited access in monthly service plans. Interestingly enough, mobile broadband is moving towards the latter, and it seems inevitable that the entire internet industry will be forced to limit bandwidth in order to cope with the reality of internet power consumption.
© Salahodeen Abdul-Kafi. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
 "Report to Congress on Server and Data Center Energy Efficiency: Public Law 109-431," U.S. Environmental Protection Agency, 2 Aug 07.
 Cisco Visual Networking Index: Forecast and Methodology, 2009 - 2014," Cisco Systems, 2 Jun 10.
 Cisco Visual Networking Index: Forecast and Methodology, 2007 - 2012," Cisco Systems, 16 Jun 08.