Ward Van Heddeghem

Trends in worldwide ICT electricity consumption from 2007 to 2012

Information and Communication Technology (ICT) devices and services are becoming more and more widespread in all aspects of human life. Following an increased worldwide focus on the environmental impacts of energy consumption in general, there is also a growing attention to the electricity consumption associated with ICT equipment. In this paper we assess how ICT electricity consumption in the use phase has evolved from 2007 to 2012 based on three main ICT categories: communication networks, personal computers, and data centers. We provide a detailed description of how we calculate the electricity use and evolution in these three categories. Our estimates show that the yearly growth of all three individual ICT categories (10%, 5%, and 4%, respectively) is higher than the growth of worldwide electricity consumption in the same time frame (3%). The relative share of this subset of ICT products and services in the total worldwide electricity consumption has increased from about 3.9% in 2007 to 4.6% in 2012. We find that the absolute electricity consumption of each of the three categories is still roughly equal. This highlights the need for energy-efficiency research across all these domains, rather than focusing on a single one.

Power consumption in telecommunication networks: overview and reduction strategies

One of the main challenges for the future of information and communication technologies is reduction of the power consumption in telecommunication networks. The key consumers are the home gateways at the customer premises for fixed line access technologies and the base stations for wireless access technologies. However, with increasing bit rates, the share of the core networks could become significant as well. In this article we characterize the power consumption in the different types of networks and discuss strategies to reduce the power consumption.

Power consumption modeling in optical multilayer networks

The evaluation of and reduction in energy consumption of backbone telecommunication networks has been a popular subject of academic research for the last decade. A critical parameter in these studies is the power consumption of the individual network devices. It appears that across different studies, a wide range of power values for similar equipment is used. This is a result of the scattered and limited availability of power values for optical multilayer network equipment. We propose reference power consumption values for Internet protocol/multiprotocol label switching, Ethernet, optical transport networking and wavelength division multiplexing equipment. In addition we present a simplified analytical power consumption model that can be used for large networks where simulation is computationally expensive or unfeasible. For illustration and evaluation purpose, we apply both calculation approaches to a case study, which includes an optical bypass scenario. Our results show that the analytical model approximates the simulation result to over 90% or higher and that optical bypass potentially can save up to 50% of power over a non-bypass scenario.

Worldwide electricity consumption of communication networks

There is a growing research interest in improving the energy efficiency of communication networks. In order to assess the impact of introducing new energy efficient technologies, an up-to-date estimate for the global electricity consumption in communication networks is needed. In this paper we consider the use phase electricity consumption of telecom operator networks, office networks and customer premises equipment. Our results show that the network electricity consumption is growing fast, at a rate of 10 % per year, and its relative contribution to the total worldwide electricity consumption has increased from 1.3% in 2007 to 1.8% in 2012. We estimate the worldwide electricity consumption of communication networks will exceed 350 TWh in 2012.

Overall ICT footprint and green communication technologies

Green communication technologies currently receive a lot of attention. In this paper we give an overview of the environmental issues related to communication technologies en present an estimation of the overall ICT footprint. Additionally we present some approaches on how to reduce this footprint and how ICT can assist in other sectors reducing their footprint.

Energy-efficiency in telecommunications networks: Link-by-link versus end-to-end grooming

The large share of energy consumption in telecommunication networks is expected to shift from access networks to core networks. Estimating the power consumption of core networks is not easy, as they vary a lot in size and topology. Using an exemplary but realistic core network, we estimate its power consumption for both a link-by-link grooming and an optical end-to-end grooming scenario. We show that optical end-to-end grooming consumes about half the power of the alternative scenario.

Distributed computing for carbon footprint reduction by exploiting low-footprint energy availability

Low carbon footprint energy sources such as solar and wind power typically suffer from unpredictable or limited availability. By globally distributing a number of these renewable sources, these effects can largely be compensated for. We look at the feasibility of this approach for powering already distributed data centers in order to operate at a reduced total carbon footprint. From our study we show that carbon footprint reductions are possible, but that these are highly dependent on the approach and parameters involved. Especially the manufacturing footprint and the geographical region are critical parameters to consider. Deploying additional data centers can help in reducing the total carbon footprint, but substantial reductions can be achieved when data centers with nominal capacity well below maximum capacity redistribute processing to sites based on renewable energy availability.

TREND in energy-aware adaptive routing solutions

Energy saving in telecommunications networks has become a well established topic in the research community. We look at the electrical and optical layers of IP-over-WDM networks, and present a list of evaluation criteria for energy- aware adaptive routing solutions (EA-ARSs) from the perspective of a network operator. Furthermore, we briefly explain the adaptive routing solutions originating from the European Unions TREND and the FP7 Network of Excellence, show saving of energy consumed by line cards in a reference scenario, and use the evaluation criteria to identify the next steps toward introduction of the EA-ARSs into real operation.

Evaluation of power rating of core network equipment in practical deployments

Reasonably accurate reference power consumption values are required for any work that evaluates power consumption in telecommunication networks. Many existing works provide or use optimal power rating (W/Gbps) values, i.e. the power rating achieved for the maximum capacity of the system, with the shared relative overhead thus being the smallest. In this paper, we evaluate how power rating values are influenced by practical equipment filling levels for core IP-over-WDM equipment. We show that, over the equipments lifetime, for IP/MPLS routers it is reasonable to almost double the optimal power rating value under real-life equipment filling conditions. For Optical Line Amplifiers a correction factor of 1.5 is appropriate, and for WDM terminals the required correction is almost negligible, i.e. 1.1. Furthermore, power measurements on IP routers and Optical Line Amplifiers show that their power consumption marginally depends on traffic load.

Energy in ICT - Trends and research directions

Power consumption of IC T equipment has a growing impact, both on economic and environmental level. To reduce its energy footprint, drastic actions will be required on four fronts: energy-efficient components, power management techniques, new network paradigms and policy supporting actions. This paper outlines the cur rent trends and research for each category.