A Broader View on Greening the Internet

Submitted to Science

In his Perspective “Toward a Green Internet," in Science Magazine (29 March 2013), D.R. Recupero rightly argues for reducing the Internet’s environmental impact, but gives an incomplete picture of the literature, the problem, and potential solutions. While the article suggests that interest in the topic is recent, widespread recognition of the issue has developed over the past two decades, leading to many new policies, initiatives, technologies, and implementations (1-8).

The analysis does not adequately distinguish between the communications network known as the Internet (now extending to a myriad of device types) and the upstream high-density data centers that deliver content. The importance of emissions from underlying electricity sources is overlooked (9)—efficiency alone is not enough for achieving improved environmental performance. While acknowledging the magnitude of energy use associated with cooling data centers, Recupero’s assessment of applicable efficiency opportunities does not do justice to this topic (10) or to that of downstream networks (11) and IP-connected devices (12), where massive amounts of energy can be saved. Integrated assessments must also account for net energy benefits achieved by information technology in comparison to alternatives (13) and the broader role ICT itself plays in reducing environmental impacts (14).

Avenues for improvement span the gamut from the link (15) to the processor (16) to the customer’s router, the latter of which is responsible for more than 75% of broadband energy use in the case of Telecom Italia noted by Recupero (17). The largest source of potential energy savings is putting devices to sleep—be they servers in data centers or end user devices such as PCs, printers, game consoles and set-top boxes that are functionally on but do not need to be and that can be proxied (12, 18). The great majority of savings are to be found in residential and commercial buildings, though the savings in data centers and telecom facilities are still well worth additional effort (14).

Evan Mills

Energy Technologies Area

Lawrence Berkeley National Laboratory

Berkeley, CA, USA


Jonathan Koomey

Steyer-Taylor Center for Energy Policy and Finance

Stanford University

Stanford, CA 94305, USA


Eric Masanet

McCormick School of Engineering

Northwestern University

Evanston, IL, 60208, USA


Bruce Nordman

Energy Technologies Area

Lawrence Berkeley National Laboratory

Berkeley, CA, USA


Ken Christensen

Department of Computer Science and Engineering

University of South Florida

Tampa, FL, USA



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8.”GreenTouch.” 2013. URL: http://www.greentouch.org.

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15. Christensen, K., P. Reviriego, B. Nordman, M. Bennett, M. Mostowfi, and J. A. Maestro. "IEEE 802.3az: The Road to Energy Efficient Ethernet," IEEE Communications 48, 11:50-56 (2010).

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18. Jimeno, M., K. Christensen, and B. Nordman, A Network Connection Proxy to Enable Hosts to Sleep and Save Energy, Proceedings of the IEEE International Performance Computing and Communications Conference, pp. 101-110, December (2008).