Carbon emission reductions by the implementation of a smart grid By Steven Keeping, Technology Writer, NOJA Power ABSTRACT A smart grid – a computerised electricity transmission and distribution network incorporating monitoring, reconfiguration and real time feedback – promises to revolutionise energy delivery by lowering costs, minimising outage frequency and duration, and simplifying the interfacing of renewable energy sources to the system. Constructing a smart grid demands a systematic approach and relies on investment in equipment, personnel and training to alter the decades-old operating practices of the electricity distribution sector. Because of an emphasis on safety and reliability, change in electricity distribution is typically slow and other sectors have been quicker to embrace computers and information technology (IT). Nonetheless, pressure from customers reacting to increasing prices and an environmental lobby opposed to adding more fossil fuel-based generating capacity has brought implementation of a smart grid to the fore. Initiatives in China, the U.S., EU and Australia are already having an impact on electricity distribution in these countries and planning in other developed and developing nations is advanced. Distribution automation (DA) – intelligent sensors, processors and communication technologies that enable an electric utility to remotely monitor and coordinate its distribution assets, and operate these assets in an optimal manner with or without manual intervention – is a fundamental enabler for the smart grid. Investment in DA, for example state-of-the-art automatic circuit reclosers, will allow utilities to realise the full potential of a smart grid. Smart grids also promise to help utilities in continents like Europe and Australia – where carbon-trading and pricing schemes are now enshrined in law – the opportunity to significantly decrease their carbon liabilities. This could be achieved by making better use of existing generating capacity and intermittent renewable sources of power to match highly variable demand - rather than building more power stations to cover anticipated peaks and wasting energy at times of lower demand. Further (indirect) carbon savings would be possible because a smart grid provides a catalyst for the uptake of electric- and plug in electric hybrid-vehicles.

PART 1: WHAT IS A SMART GRID? Origins The electricity transmission and distribution grid – the network that carries electricity from generating plant to consumers, including wires, substations, transformers, switches and more – typically comprises infrastructure that has been in place for decades. Such infrastructure can be traced back to Serbian-American inventor Nikola Tesla’s alternating current (AC) power grid design published in 1888. AC won out against direct current (DC), promoted by Thomas Edison, because it was much easier to step up the voltage – with relatively simple and inexpensive transformers – to mitigate line losses over long transmission distances, and then step the voltage back down again for local distribution, than with DC. (However, note that high voltage DC is used today to provide grid transmission connections over long distances and cross border transmission line connections between supplies of different frequency.) Early distribution grids were constructed as centralised, unidirectional systems, controlled according to demand. As local grids proliferated, it made sense to connect them together to improve the reliability of supply.

 

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  Further development of grids is characterised by large gigawatt-rated power stations typically sited away from population centres – in order to be close to large bodies of water to drive the turbines of hydro-electric power stations and cool the reactors of nuclear facilities, and to limit the proportion of the population exposed to pollution from coal-fired generation – attached to high-voltage, longdistance transmission lines. Electricity from the high-voltage transmission and subtransmission lines is stepped-down to a medium voltage at substations sited close to consumers for distribution and secondary distribution via local infrastructure (see figure 1).

Figure 1: Conventional electricity grids use remote, centralised power generation. Consumers are charged according to usage recorded on so-called smart meters sited at their own premises. Smart meters record energy usage every half hour, allowing the entities that comprise the electricity supply chain to initiate flexible charging plans that take into account whether electricity is consumed at times of peak demand or quieter periods. Increased demand is met using surplus capacity in the system or adding more, and often larger, power stations to the grid. Unfortunately, the huge turbines used to generate the majority of the power cannot be easily stopped and started to meet the highly variable demand due to relatively infrequent yet large peaks (for example, on hot days when consumers switch on air conditioning). The problem is made worse because as yet there are no means to effectively store large quantities of electricity during quiet periods to meet later high demand. The high costs associated with such inefficient generation are passed on to the consumer. Contemporary electricity grids in developed countries are massive. The century-old U.S. electricity grid, for example, is said to be the largest interconnected machine on Earth. This grid comprises more than 9,200 electric generating units with more than 1,000 gigawatts of generating capacity connected to more than 480,000 kilometres of transmission lines[1]. While other industries have been quick to embrace bidirectional communications and the power of modern computing to improve productivity, efficiency and lower costs, electricity distribution has been slower to do so because of the industry’s focus on safety and reliability. In addition, the sector is typically heavily regulated and much emphasis has been placed on keeping costs down – which is hardly a recipe for innovation and investment in technology (see figure 2).

 

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Figure 2: Investment in R&D as a percentage of revenue for selected industries. (Source: U.S. Dept. of Energy.) Utilities continue to send workers out across the grid to gather data from meters, confirm the integrity of equipment and check localised performance by measuring voltage. Most of the devices utilities use to deliver electricity are not automated and computerized. If Tesla and Edison were alive today, they would not begin to recognise the elements of modern telecommunications (even though the first practical telephone was invented during their lifetimes) but would be very familiar with the electrical grid (although perhaps not with some of the underlying technology). However, more recently, consumer backlash to rising prices, increased raw energy costs, deregulation and pressure from the environmental lobby to limit the construction of new power stations has encouraged utilities to explore the benefits of “distribution automation” (DA) in order to enhance the performance of the grid. According to industry analyst Pike Research[2], “[DA] comprises a family of technologies, including controls, switches, capacitors, regulators, communications and associated management software, applied in the distribution portion of the power network, including distribution feeders. The term typically includes [automation technologies within substations]”. S. Massoud Amin and Bruce F. Wollenberg have been credited with popularising the term “smart grid” in an article entitled “Toward a Smart Grid” published in IEEE P&E Magazine in 2005[3]. But there is anecdotal evidence of the term being used – particularly by electricity meter manufacturers – as far back as 1998. The term has now been universally adopted and encompasses DA in addition to other computer and communication technologies. Definition The Office of Electricity Delivery and Energy Reliability (OE) in the U.S. defines a smart grid as a “computerised electric utility grid”. The OE says this computerisation means fitting each device (for example power meters, voltage sensors and fault detectors) on the network with sensors to gather data, plus adding bidirectional digital communication between the devices in the field and the utility’s network operations centre.

 

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  The OE also notes “a key feature of the smart grid is automation technology that lets the utility adjust and control each individual device or millions of devices from a central location”. A similar definition for a smart grid comes from the U.S. Energy Independence and Security Act of 2007. The Act describes the smart grid as “a modernisation of the electricity delivery system so that it monitors, protects, and automatically optimises the operation of its interconnected elements – from the central and distributed generator through the high-voltage transmission network and the distribution system, to industrial users and building automation systems, to energy storage installations, and to end-use consumers and their thermostats, electric vehicles (EV), appliances, and other household devices”. The U.S. National Institute of Standards and Technology (NIST) describes the smart grid as “a modernised grid that enables bidirectional flows of energy and uses two-way communication and control capabilities that will lead to an array of new functionalities and applications”. NIST adds that unlike today’s grid, which primarily delivers electricity in a one-way flow from generator to outlet, the Smart Grid will permit the two-way flow of both electricity and information. According the U.S.-based Electric Power Research Institute (EPRI)[4], a smart grid “[represents] the migration from the current grid with its one-way power flows from central generation to dispersed loads, toward a new grid with two-way power flows, two-way and peer-to-peer customer interactions, distributed generation, distributed intelligence, command and control”. In the U.K., the Department of Energy & Climate Change notes that “with a progressively smarter grid, operators get more detailed information about supply and demand, improving their ability to manage the system and shift demand to off-peak times. Consumers are offered far more information about, and control over, their electricity use, helping reduce overall demand and providing a tool for consumers to reduce cost and carbon emissions. Smart grids offer the prospect of delivering electricity in a low carbon future more efficiently and more reliably, intelligently integrating the actions of all participants in the system”[5]. And in Australia, “smartgrid smartcity”, a joint initiative between EnergyAustralia, Ausgrid and the Australian Government echoes EPRI’s definition, describing a smart grid as “a new, more intelligent way of supplying electricity. It combines innovations in digital communications, sensing and metering with the electricity network to create a two-way, more interactive grid. Smart sensors and devices installed in the electricity distribution network will help achieve fewer and shorter outages. In the household, new generation smart meters provide up to the minute information about electricity use to help [consumers] monitor and control [their] energy costs”. Construction To make these visions of smart grids a reality requires the introduction of computerised digital technology, automated control and autonomous systems to electricity distribution. Such investment would provide the foundation for a grid that is more reliable than conventional infrastructure, offering fewer and briefer outages, ‘cleaner’ power and ‘self-healing’ properties. Power generation for a smart grid will comprise a mix similar to that used by conventional grids; for example, coal-, hydro- and gas-powered plant, with a contribution from wind-, wave-, geothermaland solar-renewable energy installations. These facilities may be owned by a vertically-integrated utility or, increasingly, separate generation companies (or subsidiaries) in less regulated markets. Renewable energy sources may also be owned by large customers who will put any excess power back into the grid. But while the sources of electricity remain similar, the bidirectional information flow built-in to a smart grid will allow the generating plant to be utilised in a far more efficient manner. The smart grid will utilise the same high-voltage (i.e. above 100 kilovolts) transmission lines used for contemporary long distance- and high capacity-transmission. Substations will then convert high voltage to medium voltage (usually 34.5 kilovolts or below, often 11 to 16 kilovolts) for distribution and secondary distribution.

 

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  Distribution transformers and/or secondary substations – located on poles, small buildings or underground vaults – will convert the distribution feeder voltage to the service voltage (for example, 110/220 volts in North America, 220/480 volts in Europe and 230 volts in Australia). The distribution lines in a smart grid will also be equipped with DA devices. Such units will be essential for protecting the integrity of the grid, isolating faulty lines, re-routing power to communities affected by line failures (by reversing power flow if necessary) and switching in renewable resources (when they are able to provide power) to cover demand peaks. The smart grid will supply commercial and industrial consumers that may take power delivery at higher subtransmission (if they are large power users) or distribution feeder voltage levels. Residential consumers will be able to take advantage of smart metering which will offer greater choice and control over electricity use. Such meters will provide consumers with accurate real-time information on their electricity use, and make it possible for energy supply companies to offer their customers varying tariffs through the day that match system power demand. Consumers will also be able to buy ‘intelligent’ appliances that can autonomously determine when to operate based on the cost of power at a particular time. In addition, consumers will be able to operate as microgenerators, feeding power back to the grid through bidirectional distribution lines. Figure 3 shows how a smart home of the future could look.

Figure 3: Future smart homes will take advantage of IT to manage electricity usage. Control Implementing a smart grid will require extensive use of substation and feeder DA to allow faster and more precise control than is typical for contemporary systems. Neil Higgins, a Senior Systems Development Engineer with Energex, a Queensland, Australia, government-owned electricity distribution company, explains that DA devices such as reclosers and sectionalisers will be a key element of a smart grid. These devices will act as switches and circuit breakers, enabling power re-routing – in the event of Fault Protection, Isolation and Restoration (FPIR) events or the interfacing of local sources of

 

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  renewable energy to supplement base load in times of peak demand – demanded by a smart grid to maintain high availability. Reclosers operate in cases of faults, for example, when a phase-to-phase or phase-to-ground fault increases the current in the feeder above normal levels (see figure 4). The recloser can also be triggered by a fault resulting in a current lower than normal levels, as, for example, in the case of a fallen conductor touching a high resistance surface such a concrete. A sectionaliser operates in conjunction with an upstream recloser (that isolates the supply before the sectionaliser opens) because it is unable to switch while the feeder is carrying the abnormal current associated with a fault.

Figure 4: Reclosers will be essential building blocks for smart grids. (Source: NOJA Power.) Neil Higgins says that utilities such as Energex have already invested in sectionalisers and reclosers to ensure that the company can meet its reliability targets and avoid regulator-imposed penalties for interruption in supply. The recloser opens to protect the feeder when it detects faults caused by lightning or objects such as branches shorting across lines. After a short period, the recloser automatically closes to check if the fault has been cleared (by, for example, the branch falling to the ground). This process can be repeated up to three times and if the fault is still present, the recloser remains open to isolate the fault. Sectionalisers complement reclosers and allow utilities finer subdivision of the grid, isolating faulty feeders by opening while the line is not under load as the recloser performs its last cycle. By re-routing the supply via remote switching of other sectionalisers and reclosers, the utility can quickly restore power to customers affected by the original fault. Thereafter efforts are concentrated on the rapid repair of the isolated faulty section of feeder (see figure 5).

 

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Figure 5: Reclosers open to isolate faulty sections of feeder and switch to restore power from alternative sources to sections not directly affected by the fault. Fault-protective devices such as reclosers are “graded”. This means that devices closest to the fault operate first, regardless of the location of the fault. On a radial feeder, for example, the furthest downstream recloser that is upstream of the fault operates faster than other upstream devices that sense the same fault current. Grading is achieved through a combination of current and time settings (noting that the fault current level decreases further along the feeder). Reclosers also offer engineers information about grid performance, power quality and even the location of faults. However, for conventional grids much of this information isn’t available in real time because communication infrastructure coverage between the devices and control rooms isn’t comprehensive. Energex’s Neil Higgins says that IEC 61850 - an international standard that defines an interoperable protocol for substation automation, designed to promote high interoperability between systems from different vendors - has capabilities that potentially make it suitable for improving communication deficiencies. But he cautions that the full benefit will only be realised if the standard is supported by high-speed communications of the right form. Providing this support is available, reclosers and other devices that are able to communicate via high speed Ethernet Local Area Networks (LANs) using an IEC 61850-defined protocol would be able to coordinate their operation with substations and other units. Such ‘smart’ units are called Intelligent Electronic Devices (IED). Communication between substations, sectionalisers and reclosers will allow finer grained control of feeders because IED operation could be coordinated rather than just relying on timings set when equipment is installed - which from a practical perspective in contemporary grids have to include relatively wide tolerances. Moreover, coordinated operation allied with supervisory software and custom algorithms would allow the smart grid to detect a fault, isolate a small a section of feeder, advise the exact location of the fault to maintenance staff, determine capacity requirements and re-route sufficient power to as many consumers as possible. All of this would be done without requiring intervention from human operators.

 

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  Benefits A smart grid promises improved efficiency that reduces total energy demand by limiting line losses and encouraging consumers to reduce consumption – especially at predictable periods of peak demand – by flexible pricing and other tariff incentives. Allied to this key benefit is the positive contribution that a smart grid makes to an improved environment. Reduced line losses, decreased consumption, and greater use of efficient fossil fuel- and renewable-power sources combine to reduce the generation of carbon emissions and other pollutants. Key to realising these efficiency and environmental benefits is enabling consumers to balance their energy consumption with the real-time supply of energy. Variable pricing will provide the incentive for consumers to upgrade their own metering to support a smart grid. Another benefit of a smart grid is the continuous monitoring that allows automated systems or operators to detect and act upon dangerous situations or security breaches that threaten reliable and safe operation of the network. In addition, cyber security and privacy protection for customers is significantly enhanced. Finally, the built-in intelligence of a smart grid allows rapid automatic intervention in the case of faults, limiting outage duration and lowering the utilities’ liabilities to penalties under “availability of service” agreements with the regulators. Figure 6 shows a schematic of a typical smart grid; note how the unidirectional power flow of the grid shown in figure 1 is replaced with bidirectional flow.

Figure 6: A smart grid enables rapid response to outages and diversification of energy generation. Implementations The transmission and distribution grid in developed and developing countries is still primarily based on infrastructure planned and installed over several decades. But utilities in countries such as Australia, China, the U.S. and other parts of the world are increasing investment in IEDs and other DA in order to make the grid smart. In Australia individual state governments have for several years actively pursued smart meter programs. Most notably, Victoria mandated in November 2008 that smart meters be installed in all homes and small businesses. The project, which aims to roll out 2.5 million smart meters by 2013, will provide utilities and consumers with meter data every 30 minutes and will eventually lead to

 

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  dynamic electricity pricing based on time of use. WA and NSW have also launched smaller pilot projects. In June 2010, the Australian Federal Government signed an AU$100 million contract to install 50,000 smart meters in five sites in NSW by 2013. Additionally, some 15,000 dwellings in the state will be provided with information about their energy and water usage and carbon dioxide emissions. The project will also extend its scope beyond just smart meters to include tests of renewable energy, smart charging stations and battery storage in Sydney’s central business district. A similar situation exists in the U.K. where energy suppliers are required to install 53 million smart gas and electricity meters to 30 million homes and small businesses between 2014 and 2019 at a cost of £11.5 billion (AU$17.9 billion). Neil Higgins of Energex explains that Australia traditionally uses a radial topology for its distribution and secondary distribution grid. The feeders fan out in a branching topology from substations fed by the high-voltage transmission grid to reach within about 400 metres from the customer before being stepped-down to the commercial or domestic mains voltage. This traditional topology is not suitable for smart grid implementation because, in the event of a line fault or undercapacity, it is difficult to re-route power from alternative sources. Higgins says that his company is implementing a new mesh (or “honeycomb”) topology to overcome the problems of the traditional distribution system. Branch endings from one substation are connected up to those of another so that an alternative source of supply can easily be switched in. However, Higgins notes that such connections can be a challenge because, in the original branching topology, conductors further away from the substation were made thinner – to save cost – because they weren’t required to carry the high current of the feeders closer to the substation. Switching to an alternative supply could expose these conductors to greater current than their design capacity. Moreover, while the medium voltage carried by the distribution lines is nominally the same across the grid, voltage is slightly reduced towards the end of branches. The transformers that step down the medium voltage to commercial or domestic voltage are manually adjusted to take into account the lower supply voltage. Again, switching to an alternative supply may expose the transformers to a higher voltage than that to which the units were set. The limitations of legacy infrastructure need to be recognised and replacement costs incorporated into cost estimates for smart grid implementations. For its part, China is embarking on a huge smart grid program. According to consultants McKinsey & Company, much of the investment in the smart grid is driven by the commitment of the country leaders to reduce the “carbon intensity” of its GDP by 40 to 45 percent by 2020 relative to 2005 and to increase the use of renewable power. In addition, the Chinese smart grid will support a rapid introduction of EVs in urban areas. The estimated five million EVs that will be on Chinese roads by 2020 will add significant load to the electricity grid and this will need to be managed carefully. McKinsey notes that combined spending by China’s two largest distribution utilities reached US$43 billion (AU$41.3 billion) in 2008 and is set to grow at an annual rate of 15 to 20 percent over the next decade[6]. In the U.S. ten states – including California, Florida, New York, Pennsylvania and Texas – are leading the national effort to deploy the country’s smart grid. Together, these states have been the recipients of US$1.9 billion (AU$1.82 billion), of the US$4.5 (AU$4.32 billion) (earmarked in the American Recovery and Reinvestment Act for investment in the smart grid. About 5 percent of Americans were equipped with some form of smart grid technology by the end of 2009. That number is forecast to increase ten-fold by 2014[7]. According to U.S. analyst Northeast Group, Brazil is expected to cumulatively spend US$27.7 billion (AU$26.4 billion) on total smart grid investments by 2022, (although this is down on an original forecast of US$36.6 billion (AU$34.9 billion). These smart grid investments cover the transmission,

 

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  distribution, metering and home energy management segments of the market. The largest reduction in the original forecast was found in the smart metering segment of the market. Distribution and transmission network investment forecasts remain largely unchanged[8].

PART 2: CARBON EMISSION REDUCTION DURING ELECTRICITY GENERATION Carbon liabilities for electricity utilities Among the key drivers encouraging utilities to invest in a smart grid is the need to generate and distribute electricity as efficiently as possible with minimal impact on the environment. In some geographical regions the incentive to do this is more than just good corporate citizenship – it can affect the bottom line. Both Europe and Australia have implemented legislation to put a price on carbon emissions. By investing in smart grid infrastructure (that, for example, allows simple interfacing of renewable energy sources to the distribution network) utilities can lower carbon emission costs. Europe’s flagship carbon emission scheme, launched in 2005, is the European Union Emission Trading Scheme (EU ETS) that operates on a “cap and trade” principle. The cap is a limit on the total amount of certain so-called greenhouse gases that can be emitted by factories, electricity power plants and other installations. Companies and utilities receive emission allowances up to their cap level. If a company or utility reduces its emissions, it can keep the spare allowances to cover future needs or else sell them to another company that has exceeded its cap. If a company can’t buy the allowances to cover its excessive emissions it faces heavy fines. The flexibility that trading brings ensures that emissions are cut where it costs least to do so. The number of allowances is reduced over time so that total emissions fall. In 2020 emissions will be 21 percent lower than in 2005. The EU ETS operates in 30 countries: the 27 EU Member States plus Iceland, Liechtenstein and Norway[9]. Australia’s model is different. The country introduced a carbon-pricing scheme in July 2012 that applies to Australia’s largest 500 emitters, which are companies that emit more than 25,000 tonnes of carbon dioxide or supply or use natural gas. Emitters pay a fixed price for each tonne of carbon emitted of AU$23 per tonne in 2012-13 rising to AU$25.40 in 2014-15. After 2015, the scheme will become more like the EU ETS because the government will start to issue carbon “units” - the number of which will be capped by regulators. Most carbon units will be auctioned by the Clean Energy Regulator and the price will be set by the market, starting from a floor price of AU$15 per tonne. Europe and Australia are far from alone when it comes to carbon pricing schemes. It’s estimated that by 2013, 33 countries and 18 sub-national jurisdictions will have a carbon price in place covering around 850 million people, around 30 percent of the global economy and around 20 percent of global emissions[10]. Matching supply and demand Reducing carbon emissions and hence financial liabilities while still satisfying consumers’ demand for power can only be facilitated by a smart grid with bidirectional feeders, fast and widespread communications, and precise grid control using modern DA. But there is another major challenge that needs to be addressed: traditional electricity systems are planned around a strategy that ensures that power generation is sufficient to comfortably meet peaks in demand with an additional margin to guarantee security of supply. At other times, and especially at night when demand is low, much of the capacity of the grid lies unused yet large generators can’t easily be stopped and restarted. An idling generator is 100 percent inefficient - that’s hardly the best way to reduce carbon emissions.

 

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  Today, to meet anticipated demand, electricity supply companies schedule how much electricity will need to be generated, often up to a year in advance. Power is generated by base load-, load followingand peak power-plants. Base load units normally run at maximum output and only reduce output during maintenance or repair. These plants produce electricity at the lowest cost of any type. Base load power plants include coal, nuclear, hydroelectric, biomass and combined cycle natural gas plants. Load following power plants supplement base load facilities during the day and early evening, Output is greatly reduced or the station is shut down during the night and early morning, when the demand is at its lowest. Gas turbine, hydroelectric and some forms of nuclear plant are used for load following[11]. Extra demand for the peak demand times is mainly met by power stations that are both high-cost and big carbon emitters. Peak demand is usually during the afternoon, particularly in countries like the U.S. and Australia where consumers use a lot of air conditioning. Gas turbine plants burning diesel oil and jet fuel, or more economical units using natural gas, are used to meet peak demand. The conventional electricity supply system is inherently inefficient, because much of the generating capacity continues to consume fuel and produce carbon emissions when no electricity is being generated. This is because there are currently no proven technologies to store energy from intermittent sources such as wind-, wave- and solar-power to “smooth” output; consequently, utilities have to maintain a high level of fossil-fuel generation in reserve. While the intermittent nature of renewable resources can be mitigated to some degree by improved forecasting – particularly in the case of wind which can be forecast with good accuracy for several days ahead – these resources still can’t be relied on to the same degree as conventional plants and could lead to periods where demand exceeds supply (see figure 7) without the reserve fossil-fuel generating capacity. This discourages a change in investment away from conventional plants and towards renewable sources that could otherwise bring carbon emission savings.

Figure 7: Power cuts are inevitable when peaks in demand exceed generation capacity. At other times power plants continue to run – and produce carbon emissions – even when power isn’t being generated. A smart grid makes it possible to turn the traditional approach to electricity generation on its head by enabling more precise management of demand. Demand management cuts generation costs and

 

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  carbon emissions due to reduced reliance on expensive peaking plants, reduced need for new base load generation capacity, and a lower requirement for reinforcement of electricity networks. A large installed base of wind-, wave- and solar -power would provide utilities with some assurance that when one resource is offline due to, for example, lack of wind, another will be available to take its place. However, this would require investment in the distribution infrastructure to ensure customers are linked to several alternative energy sources so that their supply can be easily switched from one to another. Nonetheless, some governments are doing their bit to encourage this diversification. Figure 8 shows how the energy mix of Denmark, for example, has changed over the last two decades, from one reliant on centralised large power plants to one where those plants have been supplemented with hundreds of sources of renewable energy.

Figure 8: Over a period of two decades, Denmark’s generation capacity has changed from one based on large, centralised plants to a diversified system. (Source: U.S. Dept. of Energy.) Smart grid policy in Australia is part of larger efforts at increasing renewable energy sources to reduce CO2 emissions. In 2009, the Australian government announced a Mandatory Renewable Energy Target (MRET) of 45,000 megawatts or 20 percent of the country’s electricity supply to come from renewable energy sources by 2020[12]. A key difference between a traditional grid and a smart grid using diversified power sources is that the former delivers power from large remote plants via a high-voltage transmission grid and the later simplifies the connection of renewable sources of power directly to the medium voltage distribution network. Previously, the engineering resource and equipment for interfacing renewable resources to the distribution grid safely while ensuring the power quality was maintained was too expensive to justify for power sources of less than a few megawatts. However, fully-integrated DA devices such as reclosers now allow electricity distributors to make cost-effective enhancements to make their infrastructure ‘smart’ while avoiding the expense and risk of ‘over-engineering’ associated with custom solutions. Enhancements that improve the grid’s reliability and reduce the frequency and duration of outages are vital for ensuring transmission and distribution infrastructure is able to cope with future demand. Moreover, relatively inexpensive standard DA justifies connecting power sources of less than one megawatt to the distribution grid.

 

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  For example, a department store carrying photovoltaic (PV) panels on its roof (see figure 9), or a municipal swimming pool’s gas water heater using some of its spare capacity to generate power, are relatively small sources of electricity that will soon become practical options for connecting to the grid via reclosers.

Figure 9: PV panel arrays will soon cost effective to interface directly to the distribution grid. Diversified generation, rapid communication and DA will allow utilities to take a further step with a smart grid to set up “microgrids”. Microgrids will be self-contained “islands” with their own source of energy that could keep a community powered in the event of major failure of the main grid. The IEC 61850-defined protocol could allow utilities to control generation, DA and energy storage of the microgrid rapidly enough to keep the system stable. While microgrids are not feasible today, DA manufacturers are developing products that will make such a system practical in the near future. Diversified power sources will be a boon for utilities because not only will they reduce the risk of outages – and the financial penalties such failures bring – but they will also ensure enough power is available for the peaks of a few hours on summer days when consumers are, for instance, all running their air conditioners. That eliminates the requirement to build, run and maintain expensive peaking plant – just to cover for the occasional spikes in demand – along with their associated inefficiencies and carbon emissions. This advantage of diversified power is especially important because while the average load on the grid has decreased in recent years, utilities report that the transient peaks have been getting higher. A smart grid aids demand management in another important way by allowing the electricity supply chain to set dynamic tariffs, reflecting the costs (and carbon content) of generation, transmission and distribution at any particular time, or rewarding consumers for using electricity at times when renewable sources are producing a lot of power. Consumers could even opt for packages that allow appliances to be turned on and off automatically by the grid operator to help maintain the second-by-second balance between supply and demand. In Queensland, Australia, for example, airconditioners can be turned off for short periods during peak demand using special electronic controllers. The impact of EVs on future peak demand Many major vehicle manufacturers are planning to introduce EVs that could be plugged in to a standard household electrical outlet to recharge their batteries. Capable of travelling up to 65 km in electric-only mode, the majority of EVs operating on battery power would meet the daily needs of most drivers, according to the Edison Electric Institute (EEI) in the U.S.

 

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  EPRI estimates that EVs and Plug-in Hybrid Electric Vehicles (PHEV – cars that use a conventional petrol engine once their mains-charged batteries are exhausted) could reduce fossil fuel consumption by about 60 percent compared to conventional vehicles. In addition to petrol savings, a fleet of EVs and PHEVs would reduce U.S. greenhouse gas emissions by two-thirds compared with an equivalent fleet of fossil fuel-powered cars. The U.S. Dept. of Energy estimates that could add up to 9.3 billion tonnes from 2010 to 2050[13]. These emission savings are made directly from the cars’ exhausts and would be of little benefit if they were to be offset by additional emission from power plants generating the electricity to recharge the EVs’ batteries. A smart grid could avoid this happening by ensuring that the recharging power comes from spare capacity from continuously operating base-load plants or, better still, from renewable resources when they are generating electricity.

Figure 10: Charging EVs using renewable resources will maximise carbon emission savings. (Source: Tesla.) EVs could also be used as a ready-made source of energy storage, being charged when renewable resources are online, and giving up the electricity to the grid when extra capacity is needed at peak times. While EVs represent a small fraction of today’s vehicle fleet – in the U.K., for example, figures from 2009 (the latest available) show that of the country’s 26 million cars, just 55 EVs were sold as buyers waited for government grants to become available – that number is sure to grow rapidly over the next two decades. In Britain, the government estimates that a total of 1.7 million electric cars will be needed by 2020 to help meet the country’s tough carbon reduction targets. Dr. Alan Finkel, Chief Technology Officer with Australian EV infrastructure provider Better Place, said that he expected in excess of twenty percent of new vehicle purchases will be EVs by 2020, during an interview with trade publication Electronics News[14]. And in the U.S., respected news journal Time noted that from 2013 the market will see increased competition leading to price drops. The article continued by concluding that “there will be more electric cars on the market, and they’ll be more affordable and practical”[15]. The Time article does note that while EVs are not the first choice for many consumers there will be a wide range of models to appeal to most tastes leading to many more on the road. EV pioneer Tesla, for example, has just released a premium car, the Model S, aimed squarely at the prestige market. The Model S boasts a 480 km range and the company claims the car “is the world’s

 

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  first premium sedan built from the ground up as an electric vehicle and has been engineered to elevate the public’s expectations of what a premium sedan can be”. While the benefits of the changeover to EVs would include large new revenue stream for the utilities, a large take up of the vehicles would inevitably put additional load on the traditional grid. Some organisations argue that a smart grid might be able to deal with the extra load without adding significant generating capacity by smoothing the demand. Innovations such as only charging EVs when spare capacity or renewable resources are available and using smart meters to determine when an EV is taking charge and then rewarding the consumer with a cheaper tariff if the charging is done at times of low demand could limit the magnitude of peaks. The International Transport Forum – an intergovernmental body which is part of the Organisation for Economic Co-operation and Development (OECD) – for example, suggests that smart grid technologies can make it possible for electric vehicles (EV) to proliferate without overloading the electric supply industry[16]. And according to the U.S. Dept. of Energy, the idle production capacity of the country’s contemporary grid could supply 73 percent of the energy needs of the vehicle fleet without building any new power plants. A smart grid would ensure that this excess capacity is tapped at the optimum time. But not everyone agrees with this optimistic viewpoint. In Europe, for example, as the number of EVs rises rapidly, there are serious misgivings about the existing electricity infrastructure’s capacity to accommodate the associated dramatic growth in electricity demand. So concerned are the Europeans that an EU-funded project entitled “Novel E-Mobility Grid Model” (NEMO) has been set up. NEMO intends to assess the impact of EVs on the power grid and evaluate possible solutions such as grid extension or load management[17]. In Victoria, Australia, the Australian Commonwealth Scientific and Industrial Research Organisation (CSIRO) has produced a report[18] that – assuming EV’s comprise 46 percent of the vehicle fleet by 2033 - concludes: “Under base-case penetration rates and demand charging, the increase in peak household load [due to EVs] is mostly less than 10 percent for the high-demand days, but can be up to 15 percent at the extreme for a handful of days and geographic locations. Peak load impacts under off-peak charging are mostly less than 5 percent”. And a study commissioned by the European Commission[19] came to a similar conclusion, stating “a complete electrification of the European fleet would result in an additional demand of about 10 to 15 percent”. While further research is required, utilities should be aware that the extra load on the grid due to a high penetration of EVs could prove difficult to satisfy without additional conventional generating capacity, even taking into account the benefit of a fully deployed smart grid. Quantifying smart grid carbon savings The precise control over capacity promised by a smart grid will allow utilities to meet occasional peaks in demand without continuously running huge installed bases of oil-, coal- or gas-fired power plants. Smart grid IEDs such as reclosers can be used to switch in supplies of renewable energy directly to the distribution network to meet peak demand. Smart grid infrastructure makes the adoption of EVs and PHEVs a more compelling proposition for the public. These three key advantages will lead to significant carbon emission savings; but exactly how much? According to an EPRI report published in 2008[20], in that year, total U.S. greenhouse gas emissions were equivalent to 7,053 megatonnes of carbon dioxide. Of this total, 2,359 megatonnes were attributable to CO2 emissions from the electric power sector, as illustrated in figure 11 from the U.S. Energy Information Administration (EIA).

 

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Figure 11: Emission of greenhouse gases in the U.S., 2008. 2,359 megatonnes was generated by electricity production. (Source: U.S. Energy Information Administration (Dec 2009).) The EPRI report concludes with an estimate of the emission reduction impact of a U.S. smart grid based on five applications enabled by the infrastructure: continuous commissioning for commercial buildings; distribution voltage control; enhanced demand response and load control; direct feedback on energy usage, and enhanced energy efficiency program measurement and verification capabilities. In addition, first-order estimates of CO2 emissions reductions impacts were quantified for two mechanisms not tied directly to energy savings: facilitation of expanded integration of intermittent renewable resources and facilitation of PHEV market penetration. The emissions reduction impact of a U.S. smart grid, based on these seven mechanisms, is estimated as 60 to 211 megatonnes tons of CO2 per year in 2030. (The saving in carbon emissions specifically attributed to PHEVs is 10 to 60 megatonnes.) In financial terms, the EPRI also estimated the environmental benefit net present worth of a U.S. smart grid would range between US$102 billion and 390 billion (AU$98 billion and 376 billion). In China, the estimated saving in carbon emissions per year by 2020 is a staggering 1,649 megatonnes of which 68.7 megatonnes is attributed to PHEVs[21]. According to the Australian Government’s Dept. of Climate Change and Energy Efficiency, the country’s carbon emissions were 580 megatonnes in 2012[22]. Of this, electrical power generation is estimated to be responsible for 35 percent of the country’s carbon emissions[23]. A fully implemented smart grid would reduce the electricity system’s carbon emissions by around 25 percent and overall emissions by 9 percent or 52 megatonnes per annum[24]. (This is a higher proportion than the U.S. savings that perhaps reflects Australia’s current greater reliance on high carbon emitting coal-fired power stations.) A saving of 52 megatonnes in carbon emissions equates to a saving of almost AU$1.2 billion in payments when carbon is priced at AU$23 per tonne. Summary

 

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  Electricity utilities adopt a risk-averse operational strategy that restricts investment in new technology, results in a slow pace of innovation and sees companies focussing on large, centralised power generation facilities to ensure that sufficient power is available to cover occasional large peaks – even if that results in inefficiencies. The consequence is a grid that is expensive to run and maintain and is a huge contributor to carbon emissions. Worse still, interfacing renewable sources of energy is difficult and expensive, discouraging investment in this technology. However, deregulation, increased competition and financial incentives to limit carbon emissions are providing a much-needed stimulus for utilities to adopt proven technology to endow the grid with intelligence. A so-called smart grid is more efficient, allows utilities to closely match supply and demand, encourages energy supply from diversified resources and emits less carbon. But moving from the decades-old network to a smart grid requires large investment in computerisation, communication networks and essential automation ‘building blocks’ such as reclosers in addition to a complete overhaul of management and maintenance working practices and a program of consumer education. Nonetheless, the momentum towards implementing smart grids is increasing, spearheaded by China and followed closely by the U.S. and other developed and developing nations. With finite supplies of fossil fuels and evidence of planet-wide warming that many scientists attribute to anthropometric carbon emissions, this progress can’t come a minute too soon.

Figure 12: A smart grid helps utilities decrease reliance on carbon-emitting power plants. References

 

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  1.

“The Smart Grid: An Introduction”, U.S. Department of Energy

2.

“Smart Grid SCADA Systems”, Daryl Cowie and Bob Gohn, Pike Research, 3Q 2012.

3.

“Toward a Smart Grid”, S. Massoud Amin and Bruce F. Wollenberg, IEEE P&E Magazine, vol. 3, iss. 5, pp34–41, 2005

4.

“Estimating the Costs and Benefits of the Smart Grid: A Preliminary Estimate of the Investment Requirements and the Resultant Benefits of a Fully Functioning Smart Grid”, Electric Power Research Institute

5.

“Smarter Grids: The Opportunity”, U.K. Department of Energy & Climate Change, December 2009.

6.

“Evolution of the smart grid in China”, McKinsey & Company, 2010.

7.

http://www.smartplanet.com/blog/smart-takes/top-10-states-leading-us-smart-grid-deployment/9399

8.

http://www.prnewswire.com/news-releases/brazils-smart-meter-regulations-not-a-binding-mandate-but-stillindicate-significant-smart-grid-market-potential-168583546.html

9.

http://ec.europa.eu/clima/policies/ets/index_en.htm

10. http://www.sbs.com.au/news/article/1492651/Factbox-Carbon-taxes-around-the-world 11. http://en.wikipedia.org/wiki/Load_following_power_plant 12. http://smartgrid.ieee.org/resources/public-policy/Australia 13. “How the Smart Grid Promotes a Greener Future”, U.S. Department of Energy 14. http://www.electronicsnews.com.au/features/where-are-the-electric-cars15. “Electric Cars: More Models, Cheaper Prices Coming in 2013”, http://business.time.com/2012/12/13/electric-carsmore-models-cheaper-prices-coming-in-2013 16. “Smart Grids and Electric Vehicles: Made for each other?”, International Transport Forum, July 2012 17. “Collaboration to protect European electricity networks for influx of electric vehicles”, http://www.dnv.com/press_area/press_releases/2013/collaboration_to_prepare_european_electricity_networks_for_ influx_of_electric_vehicles.asp 18. “Spatial Modelling of Electric Vehicle Charging Demand and Impacts on Peak Household Electrical Load in Victoria, Australia”, Australian Commonwealth Scientific and Industrial Research Organisation (CSIRO), June 2012 19. “Impacts of Electric Vehicles - Deliverable 3: Assessment of the future electricity sector”, CE Delft, April 2011 20.

“The Green Grid: Energy Savings and Carbon Emissions Reductions Enabled by a Smart Grid”, EPRI, June 2008

21. “A Primer on the (Strong) Smart Grid and its Potential for Reducing GHG Emissions in China and the United States”, A. Lu, October 2010 22. http://www.climatechange.gov.au/en/government/reduce/national-targets/factsheet.aspx 23. “The Garnaut Climate Change Review: Final Report”, R. Garnaut, 2008. 24. “An Australian Smart Electric Grid – Critical infrastructure for addressing global warming”, Telecommunications Journal of Australia. Brendan Herron, CURRENT Group, LLC, 2009.

© NOJA Power 2013 www.nojapower.com.au

 

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