With roughly 2% of total worldwide electric energy consumption the share of energy consumed today by ICT systems seems not that substantial. In fact, more than half of it is caused by peripherals and printers. The potential for future energy savings enabled by the progress of semiconductor technologies according to Moore’s Law is however completely absorbed by the even stronger increase of societal demand for communication and information processing. The growth rate of ICT energy consumption caused by increasing network penetration and explosion of data traffic is significant (about 7% per year), resulting in the situation that in spite of increasing energy efficiency of the network, the ICT-related share of worldwide energy consumption may increase dramatically in the longer term if no measures are taken.

According to a rough calculation, the average energy efficiency of overall wireless access networks is approximately 70 bps/W (bits per second per Watt). This value is comparable to the situation in the fixed access network, whereas the efficiencies of routers (79 Mbps/W), optical core (166 Mbps/W) and switches (454 Mbps/W) are considerably higher. Beside environmental protection, energy costs become a substantial share of operators’ operational expenditure, becoming a major driving force for developing more efficient solutions. We know from Shannon’s information theory (late 1940s) that the minimum amount of energy required for transmission of a bit is by a factor of 25,000 smaller than the amount consumed by current systems. Thus, there is much room for improvement. Figure 1 shows the functional breakdown of the energy flow inside a radio base station.

Figure 1: Energy consumption of a base tranceiver station

The figure highlights the dominating role of the RF power amplifier and antenna feed. Consequently especially the improvement of power amplifier efficiency has been in the focus of a number of research activities throughout the past 10 years leading to a remarkable efficiency increase (see figure 2).

Figure 2: Improvement of power amplifier efficiency

Research activities for increasing network efficiency are focusing on the reduction of the components’ power consumption, but also on lowering overall energy consumption in the network by reducing cell size to save transmission power, by introducing Multiple Input-Multiple Output (MIMO) systems, interference coordination and dynamic load adaptation, avoidance of idle system capacities, and by performing self-organising network management for reconfiguration.

lightRadio

A first impressive contribution for increasing wireless access network energy efficiency is demonstrated by the lightRadio concept, recently presented by Alcatel-Lucent Bell Labs (see figure 3).
The advantage of the small cube shaped antenna modules (5 cm edge length) is that they can be installed at any location having power and network connection, thus reducing significantly operators’ site rental cost. Additionally they offer a high degree of flexibility by addressing a broad range of communication standards. lightRadio represents a new architecture where the base station, typically located at the base of each cell site tower, is broken into its components and then distributed into both the antenna and throughout a cloud-like network. Breaking down and distributing the components adds an additional degree of flexibility in deployment, avoiding bulky installations and reducing the site rent, and complex thermal management at the antenna site.

Figure 3: lightRadio cube

Additionally, today’s clutter of antennas serving 2G, 3G, and LTE systems are combined and shrunk into a single powerful, multi-frequency, multi-standard Wideband Active Array Antenna, pioneered by Bell Labs, that can be mounted on poles, sites of buildings or anywhere else where there is power and a broadband connection. Utilising active antenna array technologies and efficient power amplifier technology, the lightRadio concept features an increase of energy efficiency by a factor of two.

GreenTouch

In 2010 Bell Labs launched the GreenTouch initiative in collaboration with service providers and other leading research organizations around the world (http://www.greentouch.org). The consortium has launched more than 25 internal projects with a focus on increasing the overall energy efficiency of today’s communication network technologies and concepts by a factor of 1,000 within the next 5 years. The identified potential and targets for efficiency increase depend on the network (i.e. access, metro or core) and are highest for the wireless access network (x2000), followed by wireline access network (x1600), as to be expected from the above cited efficiency figures.

The work started with a thorough analysis of the existing network technologies, identifying and quantifying the effect on energy efficiency of each function, architectural module, and system element. Within the following months for all the major network parts a number of various architectural and technological concepts promising substantial efficiency increase have been developed.

For example, by focusing the radiated radio frequency energy onto the receiving terminal device, thus avoiding energy loss by misdirection, active antenna arrays consisting of a high number of elements allow for reduction of emitted energy in wireless access networks by a factor of 100. Another factor of 10 may be achieved by introducing superior power amplifier technologies, low power electronics and passive cooling concepts.

ICT leveraging energy savings

The amount of energy consumed by ICT, however, is negligible when compared to its huge leveraging potential, e.g. avoiding person transport, heating and air conditioning of office space by enabling telework and remote conferencing. According to an analysis by ITU replacing a weekly business trip between Yokohama and Tokyo with a video conference can reduce energy consumption by 53%. The replacement of postal mail with e-mail saves up to 98% of greenhouse gases. The SMART 2020 report cites fivefold saving potential, i.e. every ton of greenhouse gases spent for such ICT tasks may save up to five tons.

Smart power grid scenarios

Design and architecture of today’s medium and low voltage level electric distribution grids meet the requirements of a world from 50 years ago and are not capable of meeting the future challenges of a green industrial society. The transformation to a modern smart grid infrastructure, enabling a flexible, safe and reliable energy supply being largely based on volatile renewable resources, is based on ICT. In the smart grid scenario, ICT will enable the integration of a large share of fluctuating distributed energy sources like photovoltaic, wind turbines or gas turbine power stations together with charging or re-feeding electric vehicles, e.g. by automated load control (load shaping) and demand supply management strategies, involving flexible tariffs.

Within private homes and industrial estates ICT can enable substantial energy savings via smart control of lighting, machinery, air conditioning and appliances. Several distributed energy sources may be clustered to virtual power stations replacing disposable power resources. In addition, a number of homes or estates might form an autonomous microgrid which acts as an entity in the grid environment. Stability and operational safety of the power supply always has preference and implies high challenges to ICT. Especially the broad introduction of electro mobility requires the existence of a smart grid infrastructure in order to enable the management of charging a high number of vehicles or the utilization of vehicle batteries for buffering renewable energy sources.

Figure 4: Smart Metering service concept

The application and business potential of smart grid technologies is huge. Today’s situation is occasionally compared to the situation of the Internet in the early 1990s. According to market researcher Zpryme the global smart grid market is predicted to grow forcefully from $69.3 billion in 2009 to $171.4 billion in four years (the sum includes installation and meter equipment etc.)

Although a high number of initiatives have been launched already, standardisation needs to be driven strongly in order to not to impede the progress.

The broad introduction of suitable smart metering systems supporting flexible and dynamic energy tariffs is only a first step. Today’s smart meter solutions already support remote polling, flexible tariffing and analysis of energy consumption via a web interface. To this end, the smart meter is communicating (e.g. via xDSL, GPRS or PLC) with a meter data management system which may store the information in an external data base.

As data security is of utmost importance, privacy issues need to be observed thoroughly because the communicated data may allow for drawing conclusions on people’s habits. Additionally, tariff data and other technical control information may interact via a home gateway and a smart meter device with an internal home energy management system.

Conclusion

ICT is today consuming about 2% of worldwide energy with a strongly increasing tendency. There is however a very high potential for efficiency increase which can be addressed by a combination of new component technologies, system architectures and concepts. First promising steps have been performed. By introducing intelligence into the electrical power grid, ICT will pave the way for even higher energy savings, overcompensating the ICT related energy consumption by a factor of five. Smart grid technologies offer huge business opportunities and will be the foundation for a future green industrial society.