GREEN TELECOMMUNICATIONS IN SMART GRID
Anja RAJFALLOVSKA
ABSTRACT
The traditional electrical power grid is currently evolving into the smart grid.
Smart grid integrates the traditional electrical power grid with information and communication technologies [ICT] and is motivated by the need to modernize aging infrastructure, improve efficiency and empower customers. In addition to these benefits, smart grid deployment present significant opportunities to reduce greenhouse gas emissions and emerges as a critical tool to address global climate change.
But smart grid is only possible with high-speed, standardized and secure communication infrastructure.
Although the studies on smart grid, renewable energy, environmental and ecological challenges have been surveyed, research in the environmental impact of the ICT technologies as a part of the future smart grid networks has not been properly classified.
The on-growing demand of communication resources for the smart meters, substation automation, etc. would result in huge energy consumption. Therefore, the need to develop green communication systems turns out to be more and more urgent.
This paper discusses some of the communication research challenges and opportunities in the area of smart grid and smart meters. In particular, I focus on the green telecommunications that strives for improving energy efficiency as well reducing environmental impact and energy independence of telecommunications.
Advanced communication technologies will be investigated to be used for the communication layer of smart grid, like green transmission technologies (green wireless and wireline communications), energy-efficient green data centers powered by renewable energy, cognitive radio, hardware energy-efficient systems...
Keywords: Green communications, smart grid, communication technologies, energy-efficiency, renewable energy.
INTRODUCTION
Energy security is the adequate, reliable and competitive supply of sustainable, low-carbon energy and energy services at global, national and local scales; across short, medium and long-term timeframes. It is a broad concept which can mean many things depending on how it is defined. It can be used to mean a policy objective, to justify military action, to compensate owners for closing carbon intensive power plants, and to encourage investment in research and development. I focus on the last one, specifically on the environmental and ecological challenges. Climate change is a substantial energy security concern not only because direct flooding and
natural disasters can damage power plants and transmission lines, disrupt the delivery of imported energy fuels, and destroy crops for biofuels but also because it has severe impacts on food security, health and environmental refugees, [4], Though climate change is certainly a global phenomenon, in many ways it is becoming an Macedonian problem. Sustainable development and environmental security recognizes that the environment needs to be protected for its own sake as well as for utilitarian reasons.
Environmental security in relation to energy is to prevent the degradation of Local ecosystems and other global systems. Examples include preventing the depletion and degradation of aquifer and surface water sources, over - exploitation of agricultural land for biofuel production, air pollution from fossil fuel burning, and greenhouse gas production from fossil fuel burning.
On the other side, the traditional electrical power grid is currently evolving into the smart grid. Smart grid integrates the traditional electrical power grid with information and communication technologies (ICT). Such integration empowers the electrical utilities providers and consumers, improves the efficiency and the availability of the power system while constantly monitoring, controlling and managing the demands of customers. A smart grid is a huge complex network composed of millions of devices and entities connected with each other through communications. The grid is operated, controlled and monitored using information and communication technologies (ICT). These technologies enable energy companies to seamlessly control the power demand and allow for an efficient and reliable power delivery at reduced cost.
The smart grid offers significant reductions in environmental impact through two sources: conservation and greater renewable generation integration. Greenhouse gas emission reduction can be traced directly to Smart Grid capabilities - such as timevarying rates and customer energy management systems - offering a conservation effect.
The reason for focusing on communication networks and data centers is their large power intake that positions them as significant players in the power grid, [1], [5], So, they benefit from smart-grid driven techniques to enhance energy savings and emission reductions.
In this paper, I provide survey on the interaction between smart grid and information and communication infrastructures and the smart grid - driven approaches in energy-efficient communications and data centers. Energy-efficient communications targets communication networks with less OPEX, less power consumption and less emissions with minimal service degradation and are referred as green communications.
This paper is divided into five sections. The second section will give brief introduction to the smart grid and capture the benefits of smart grid towards environmental responsibility and energy-efficiency. The third section will size up the smart grid concepts from ICT perspective and the role of the telecommunications in smart grid. The fourth section will explore the green telecommunications and identify and quantify specific smart grid mechanism which enhance the energy efficiency of the information and communication infrastructures and through which telecommunications can help address climate change.
FINALLY, SECTION FIVE CONCLUDES THE PAPER.
SMART GRID ENVIRONMENTAL BENEFITS AND CHALLENGES
The smart grid offers significant reductions in environmental impact through two sources: conservation and greater renewable generation integration [4], [6].
Greenhouse gas2 emission reductions can be traced directly to Smart Grid capabilities - such as time-varying rates and customer energy management systems - offering a conservation effect.
The smart grid enhances end-use energy conservation by providing real - time feedback on energy usage and using home area networks to communicate time sensitive price information to customers. Smart grid infrastructures can improve grid efficiency to reduce line Losses by networking distribution automation devices (e.g.- capacitor banks), to minimize reactive power flows through adaptive voltage control (i.e. Volt-VAR optimization) and with other concepts.
And of course, there are the renewables: the greater the level of renewable generation the smart grid can reliably and efficiently accommodate, the larger the environmental benefits will be. However, few limiting factors could not be forgotten.
The limits of renewable generation saturation that can be reliably and efficiently accommodated by Smart Grid capabilities and the speed with which renewable generation levels will grow varies widely by geography and the level of investment utilities (and ultimately customers) wish to make in order to reliably and efficiently integrate renewable generation.
Carbon emissions can be significantly reduced through vehicle electrification and utilizing off - peak power generation and energy delivery capacity to charge plug-in electric vehicles.
Information and communication technologies have central role in smart grids, because they manage reliable grid operation, enable smart metering and bidirectional electricity flows and so on.
So, on one side smart grid-driven approaches impact the way energy-efficient communication technologies are implemented, on the otherside smart grid involves dense communications and it is impacted from energy-efficiency techniques implemented in this communication.
Despite the smart grid cause, cost savings and environmental responsibility are the driving reasons for looking to high-efficient communications. These are defined as green telecommunications and green networking.
AN OVERVIEW OF ICT IN SMART GRID
What makes a grid smart, or at least different from the grid of today, is the fact that it must deliver both energy and information. The delivery of both energy and information must also be end-to-end and bidirectional. Smart grid integrates advanced sensing, remote control, smart metering, demand management techniques, interaction of distributed renewable energy generation.
Almost most people are naturally excited by the prospect of smart grid devices and applications, but at the core of the smart grid must reside communications and computing technology that enables utilities to enjoy insight into what is happening
at every node of their network at any given moment. In smart grid, all of the entities are connected through communications. So, communication and data centers have gained another dimension with these smart grid concepts, [REF] Smart grid incorporates three types of communication: Home Area Network (HAN), Neighborhood Area Network (NAN) and Wide Area Network (WAN).
A HAN connects the in-house smart devices across the home with the smart meter.
NAN corresponds to a group of houses possibly fed by the same transformer.
WAN, on the other hand, is a bigger network that connects the smart meters, service providers and electricity utility.
Fig. 1. Smart grid and telecommunications
Generation
Transmission
j Informaton
Distributed generation
4
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These networks can be implemented using a variety of communication technologies, wireless, but also wireline and optical.
The WAN can communicate using third generation (3G), fourth generation (4G) and LTE cellular networks, as well as WiMAX.
Similar to WAN, 3G, 4G and WiMAX can be utilized in the smart grid NAN. IEEE 802.11 family of standard, such as WLAN and Bluetooth, offers also promising deployments for urban smart grid NANs.
Zigbee is IEEE 802.15.4 short-range, low-data rate technology that is widely adopted smart home and smart energy standard in smart grid HANs. WiFi is another strong candidate.
HAN and NAN may be implemented using wireline communication technologies, also.
PLC (Power Line Communication) and Energy Efficient Ethernet are among promising wireline communications. Power Line Communication (PLC) is a technique that uses the existing power lines to transmit high speed (2-3 Mbps) data signals from one device to other. PLC has been the first choice for communication with the electricity meter due to the direct connection with the meter. In a typical PLC network scenario, smart meters are connected to the data concentrator through power lines and data is transferred to the data center via cellular network technologies.
Optical communication may be used in WAN, implemented by core technologies and used in NAN as metro or access technologies.
In that direction, it would be contradictory to use non-efficient communication technologies in concept that is fully eco-oriented.
GREEN TELECOMMUNICATIONS IN SMART GRID
From a strict environmental point of view, the objective of green telecommunications and networking is to aim minimization of the GHG (Green House Gasses) emissions. First step in this direction is to enforce as much as possible the use of renewable energy in ICT. Another natural step is to design Low power components, able to offer the same level of performance.
GREEN WIRELESS COMMUNICATIONS
In wireless communications, energy-efficiency is generally quantified by the
"bitsper-joule" metric which corresponds to throughput versus unit energy consumption. [11].
New applications need much higher bit-rates. In order to fulfill this requirement bigger, transmit powers are used in cellular networks.
Also, MIMO (Multiple Input Multiple Output) which is a common technique in 3G, 4G and WiMAX and offers diversity and increases throughput, because of the multiple antennas incur high energy consumption. New concepts and transmission techniques open new issues.
So, the focus is on optimizing transmit power. In this networks power saving often require a degradation in network performance (i.e. higher latency and lower throughput). Designing efficient power management is therefore challenging in compromising between power saving and network performance. Some of the new techniques in cellular networks for this purpose are: relaying - specifically useful to extend the typical cell diameter, cooperative communications, such as interference alignment, which provide energy efficiency because they benefit from channel diversity [11], cognitive radio technology (sensing the unused spectrum), real time pricing, where base stations adjust their power consumption based on electricity prices and so on.
Supplementing the conventional power in powering base stations (BSs) in cellular networks with renewable energy sources, such as solar panels and wind turbines, is the simplest example of implementation of smart-grid driven concept in telecommunications.
In some places where the conventional power grid is still under-developed, the deployment of renewable energy sources is even more attractive.
Although renewable energy sources are attractive for the above reasons, they also suffer from significantly higher variability as compared to conventional energy sources. As a result, even in BSs that deploy renewable energy sources, conventional energy sources, such as diesel generators or the power grid, is still required to compensate for the variability of the renewable energy sources. One practical method of mitigating the variability of renewable energy sources is through
energy storage such as fuel cells and batteries. Energy storage, however, is very costly to deploy and therefore, the amount of storage available at BSs will usually be quite limited. A key consideration in deploying BSs with renewable energy sources are hybrid power supplies (including both the conventional grid and renewable energy sources).
GREEN WIRELINE COMMUNICATIONS
Among the used wireline techniques are PLC, Ethernet and optical communication. PLC is a natural communication medium for smart grid, [8]. But smart-grid driven techniques have not found its way into energy-efficiency approaches in PLC.
Spectrum sensing scheme has been introduced for energy efficiency of the PLC.
Energy efficient Ethernet (EEE) is also considered. This technique uses low-power cycles to save energy. [10]
Optical networks offer high speed, large bandwidth and high degree of reliability that has enabled them to be widely deployed as the basic physical network infrastructure. Since utilization of renewable energy and ToU are part of the big smart grid picture, the stand out as example of the interaction of smart grid and energy-efficient core optical network. Research (Findings) show that non-renewable energy consumption is further reduced when renewable energy is employed in the nodes at the center of the network rather than the nodes at the edge of the network.
Also routing schemes are changed according to the access to renewable energy:
nodes with better access to renewable energy are put on preferred routes. ToU awareness, on the other hand, implies using off-peak electricity generators and reduces electricity bills, [2].
Metro and access optical networks emerge as a strong alternative for NAN communications. Putting an access unit to sleep completely or partially have formed the fundamental focus of energy-efficiency in access networks in optical domain.
GREEN DATACENTERS
Information infrastructure along with communication infrastructure is a significant consumer of electricity globally. Data center is the actual facility that houses the servers, UPS, cooling equipment, operations room and so on.
In proportion to growing user demands, emerging video and data-intensive applications, as well as increasing popularity of cloud computing, power consumption of data centers is increasing at remarkable rates.
Energy-efficient or "green" data centers become essential for reducing the energy expenses of the data centers service providers as well as reducing the environmental impact of the data centers. The term green data centers is used to refer to data centers that adopt energy-efficiency techniques or those that make use of renewable energy.
The goals are maximization of the Power Usage Efficiency (PUE), or to minimize the facility overhead energy which is related to cooling, lighting, UPS and so on, maximization the IT equipment utilization (ITEU), which corresponds to more efficient use of IT equipment, maximization of IT equipment energy efficiency (ITEE)
- use of IT equipment with higher energy-efficiency and maximization of the green energy coefficient (GEC) - utilization of renewable energy resources generated on
site by the data center operators.
The first one - energy savings can be provides by raising floors, running cooling equipment at higher temperatures, placing UPS in a separate containment, eco- modes of UPS and other techniques.
Because servers are the dominant users of electricity, most of the efforts focus on energy-efficiency on servers. Some techniques are dynamic adjustment of the frequency of the CPU of a server to save power, placing more virtual servers on a single machine, dynamic power management, when some servers may be left idle and put to sleep.
CONCLUSION
ICT are among the major power consumers and GHG emitters. For this reason, significant amount of academic and industry efforts should be put into to enhancing the energy efficiency of ICT.
Whether motivated by energy cost saving, incentive programs or ''green"
consciousness (or all), network service providers are beginning to recognize that energy efficiency must be implemented in order for them to continue to afford to upgrade and power their networks. In addition to traditional approaches, smart-grid driven techniques find their way to provide energy-efficiency. In this paper, I have focused on the challenges and opportunities arising from the interaction of the smartgrid with green ICTs.
From smart grid point of view, I focused on the works that enhance the energy efficiency of the ICT infrastructures by making use of concepts that have come under the spotlight with the emergence of the smart grid. I have elaborated on the use of energy-efficient wireless, wireline and optical communications in different domains of the smart grid such as HAN, NAN and WAN and surveyed the studies that take smart grid factors into consideration while managing data center's power consumption, emissions and electricity bills.
In order to regulate C02 emissions governments should institute incentive programs to encourage the use of alternative energy sources.
Academic and industry effort should be put into reducing the energy consumption of core and access network equipment.
In the end, we must accept that current patterns of energy consumption in telecommunication industry production and use have widespread and widely known negative impacts on the environment. We must remark, that we must face the prospect of changing our basic ways of living. We'll make this change either on our own initiative in a planned way orforced by the chaos and suffering by the inexorable laws of nature. It would be far better to incorporate the cost of negative environmental consequences into energy prices and to harness the power of energy efficiency now in proactive way rather than a few decades from now when forced by crises.
I believe that utilizing smart grid concepts for enhancing the energy-efficiency of communications and data centers is a research topic with significant potential. One
of the most important energy policy issue that drive energy security policy are innovation, forecasts, sustainability, the link between economic growth and energy use, energy supply chains, and energy sector reform and regulation.
Policy and technological innovation together should be driving forces in transforming the energy sector. Together, they have the potential to radically transform energy supply and end use. However, these developments have to occur in a collaborative process that considers economic, technical and social issues.
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