ICT ENERGY CONSUMPTION – TRENDS AND CHALLENGES

Information and communications technology (ICT) systems are the core of today’s knowledge based society. Innovations in this area are adapted at tremendous speed and worldwide use of ICT has soared in recent years. However, this unprecedented growth comes at a price: ICT systems are meanwhile responsible for the same amount of CO2 emissions as global air travel. If the growth of ICT systems energy consumption continues at the present pace, it will endanger ambitious plans to reduce CO2 emissions and tackle climate change. Increasing the energy efficiency of ICT systems is thus clearly the major R&D challenge in the decades to come. I. ICT MARKET TRENDS Rarely have technical innovations changed everyday life as fast and profoundly as the massive use of the Internet and introduction of personal mobile communications. In the past two decades both grew from niche market applications to globally available components of daily life: The first GSM phone call took place 1991 in Finland – only 15 years later there were over 2 billion GSM users [1]. In November 2007, every second inhabitant of this planet possessed a mobile telephone [2]. In the same time span, the number of internet servers rose by roughly a factor of 1000: from 376’000 to 395 million [3]. The driving force behind these two developments was, and continues to be, "Moore's Law" (or rather the ITRS roadmap), according to which both the processing power of CPUs and the capacity of mass storage devices doubles approximately every 18 months. This in turn renders the use of ever more powerful ICT systems attractive for the mass market. In order to be able to transport this exponentially rising amount of available data to the user in an acceptable time, the data transmission rates both in the (wired) internet and wireless networks (including cellular, WLAN and WPAN) have been rising at the same speed – by about a factor 10 every 5 years, as illustrated in Figure 1. Many achievements of information society are based on the global success of information technology which has been made possible by innovations in microelectronics. In the last years, ICT systems have been responsible for the enormous economic boom not only of former developing countries like Taiwan, South Korea and Singapore, they have also been the source of at least a fourth of the BIP growth of developed nations like the United States [4] and the European Union [5]. Instead of opening up a "digital divide" between the first and the third world, the use of ICT has so far lead to the opposite. II. ICT ENERGY CONSUMPTION TRENDS The price paid for this enormous growth in data rates and market penetration is a rising power requirement of ICT systems – although at a substantially lower speed than "Moore's Law". Both in server farms as core units of the internet [6], as well as in mobile communications systems [7], a rise of the power consumption of 16-20% per year can be observed in the last years, corresponding to a doubling every 4-5 years, as illustrated by Figures 2 and 3. As result of this development, server farms meanwhile consume approximately 180 billion kWh of electricity per year – over 1% of the world-wide electricity consumption. This corresponds to the typical yearly electricity consumption of 60 million households – over a third of the number of households in the EU. 1 Based on the data from [6] and a 20% increase for 2006 and 2007. World wide electricity consumption and production data taken from [8]. 1995 200