A Strategy for the Development of Ireland’s Electricity Grid for a Sustainable and 25 Competitive Future

www.eirgrid.com EirGrid is a state-owned company and is the independent electricity Transmission System Operator (TSO) in Ireland and the Market Operator (MO) of the wholesale electricity trading system. EirGrid's role is to deliver quality connection, transmission and market services to electricity generators, suppliers and customers utilising the high voltage electricity system. We are responsible for the Grid infrastructure required to support the development of Ireland's economy, as well as connecting the Irish Grid to the European Grid. EirGrid plays a key role in the operation of the Single Electricity Market (SEM) which services the island of Ireland. EIRGRID’S MISSION IS TO DEVELOP, MAINTAIN AND OPERATE A SAFE, SECURE, RELIABLE, ECONOMICAL AND EFFICIENT TRANSMISSION SYSTEM FOR IRELAND. Contents

3 Foreword by the Minister for Communications, Energy and Natural Resources, Eamon Ryan, T.D. 5 Introduction by Dermot Byrne, Chief Executive, EirGrid 6 Executive Summary 11 Introduction to GRID25 13 Vision 19 Future Grid Requirements 21 The Grid Development Strategy 23 A Regional View

Appendices 44 Technical Options for Grid Development 47 Glossary

1 2 A Strategy for the Development of Ireland’s Electricity Grid FOREWORD BY THE MINISTER FOR COMMUNICATIONS, ENERGY AND NATURAL RESOURCES, EAMON RYAN, T.D.

The last few years have seen extraordinary changes in global electricity markets, EirGrid is taking as climate change and energy security have moved to the top of policy imperatives on the challenge at home, in Europe and across the world. These issues are likely to continue to put upward pressure on the price of fossil on behalf of fuels and are thus a call to action in energy policy. EirGrid’s Grid Development Strategy, GRID25, is a critical element in future-proofing Ireland’s electricity needs Irish business by facilitating more sustainable, competitive, diverse and secure power supplies in support of economic and social development and renewable energy deployment. and consumers, The Strategy, when implemented in full, will provide a platform so that in each of building a region of Ireland we can harness our abundant renewable energy resources and provide clean and competitively priced electricity for homes, businesses and new network fit for high-tech industries. GRID25 builds on the significant investment that has already been made in our the 21st century. transmission network and moves us towards a cutting-edge intelligent electricity system. We are also extending that network by connecting to the UK and in due course to the European Grid. This will enable us to participate in the European market and facilitate both the export and import of electricity. GRID25 has been informed by the findings of the ground-breaking All-Island Grid study which demonstrates the feasibility of at least 40% renewable electricity in our system by 2020 if we develop our Grid in a smart manner. This level of renewable supplies will help us meet our domestic targets and support the European Union’s 2020 climate change targets. However, in developing such long- lasting infrastructure we must be cognisant of the future when larger emissions reductions will be needed and the supply of fossil fuels may be much less secure. EirGrid is taking on the challenge on behalf of Irish business and consumers, of building a network fit for the 21st century. Doing so is the first crucial step to allow us to position Ireland as a world leader in clean energy production. Getting our Grid development right can give other developers the confidence to invest in the jobs and plant that will power our future. The Grid to be delivered by GRID25 will ensure our transition to a low-carbon economy. The delivery of GRID25 is a collective enterprise and requires all stakeholders including enterprise, local communities and the regions to work with each other. I have every confidence that together we can deliver.

Eamon Ryan, T.D. Minister for Communications, Energy and Natural Resources

for a Sustainable and Competitive Future 3 4 A Strategy for the Development of Ireland’s Electricity Grid INTRODUCTION BY DERMOT BYRNE CHIEF EXECUTIVE, EIRGRID

I am pleased to present EirGrid’s Grid Development Strategy, GRID25. This is a major It is vital that initiative to put in place safe, secure and affordable electricity supply throughout Ireland has the Ireland, supporting economic growth and providing a roadmap to a bright future for renewable and sustainable energy. electricity supply Electricity is a vital service for domestic, business, farming and industrial customers and this Strategy is designed to ensure that the transmission network has the capacity infrastructure to provide for growth in electricity demand between now and 2025. A strong transmission grid is essential for Ireland to attract and retain high-tech to ensure our industrial investment, for the country to have competitive energy supplies and balanced economic growth regional development and in order to reduce our dependence on fossil fuels in light of the major issue of climate change. and maximise our It results from a robust and stringent analysis of the long term needs of electricity users nationwide and includes very practical and progressive solutions to deliver high competitiveness. quality, secure and economic power supplies in line with best international practice. Putting in place infrastructure is never easy and does require sensitivity to differing needs and concerns and this document addresses those issues in a comprehensive way. It is vital that Ireland has the electricity supply infrastructure to ensure our economic growth and maximise our competitiveness. EirGrid is committed to the delivery of this Strategy for the national good and will consult widely on the Strategy and its implementation. The implementation of GRID25 is essential if Ireland is going to meet its targets for generating electricity from renewable sources. It also enables Ireland to link to Britain and further afield with potential to both export and import electricity. The Strategy reflects the output of the All-Island Grid Study and is consistent with the Gate 3 process for connection of wind generation. I am very grateful for the support of the Minister for Communications, Energy and Natural Resources, Eamon Ryan, T.D., in launching this Strategy. GRID25 also enables the different regions to develop their potential in attracting new high-tech industry and to accommodate population growth and represents a total investment of €4 billion, which has been carefully considered and will be delivered in a responsible and cost-effective way. The Commission for Energy Regulation (CER) will have an overall monitoring and approval role to ensure the investment is delivered effectively and efficiently. There are very significant opportunities and challenges over the coming years. The Irish power system has successfully provided the energy for major economic growth in the past 20 years and I am convinced that this Strategy will set the stage for further growth. Developing the National Electricity Grid requires support from all stakeholders and the importance of progress in delivery cannot be over-emphasised. Putting this Strategy in place will ensure that Ireland has the best possible platform in terms of a world-class, competitive and sustainable electricity system.

Dermot Byrne Chief Executive, EirGrid

for a Sustainable and Competitive Future 5 EXECUTIVESUMMARY

The Transmission Grid provides a vital conventional generation, to the rest of link between all generators and the the country, enabling all market users users of electricity. It provides physical to benefit from reliable electrical access to all generators to a central energy at the most economical price. market and it enables all users to avail For the Grid to play its part fully, of electricity from the central market it must be developed. The bulk at the most economic rates. transmission system, comprising Over the next 15 to 20 years, major circuits at 220 kV or higher, changes will take place in Ireland’s represents the motorways and dual electricity needs, in its sources of fuel carriageways of the electricity and in its fleet of power stations. transport system. Capacity has Change will increasingly be driven remained largely unchanged in the by issues of energy security, last 20 years, a period that has seen competitiveness, climate change a growth of 150% in the electricity and by the need to move away demand being carried by the system. from imported fuels. EirGrid calculates that to facilitate GRID25 will bring new levels the necessary increase in renewable of wind generation, both on and generation and to adequately meet off-shore and an introduction of the demands of the electricity commercial ocean technology-based customer, the capacity of the bulk generation to Ireland. It will also transmission system will need to require flexible conventional be doubled by 2025. generation, as well as market This will be achieved through structures and networks that major reinforcements to the existing encourage competition, and which network using the best technological enable consumers to benefit from solutions available. The Grid will be economic electricity. developed taking account of the What will remain constant through continuing need to balance the this period will be the requirement reliability and security objective with of all consumers – householders, the costs and environmental impact of farmers, small and medium sized developments in a sustainable way. businesses and large industries – for The Strategy described here will high quality, reliable power supplies. involve upgrading the high voltage The National Electricity Grid will system and an investment of remain a vital channel for essential approximately €4 billion over supplies delivered reliably, for the period to 2025. This new infra- sustainable and renewable energy and structure is every bit as essential for open competition within the sector. to the future growth of the country A strong grid will bring the energy as any investment in road, rail supplies which will enable Ireland to and broadband. prosper economically and to provide GRID25 strikes a balance between good quality of life to its people. costs, reliability and environmental The Grid will be a key pillar impact. It examines the totality of supporting balanced regional developments and considers a development, linking parts of the variety of options to minimise the net country rich in renewable energy or length of new line build in a region

6 A Strategy for the Development of Ireland’s Electricity Grid through a number of initiatives GRID25 is essential to: The consequences of non-action are: designed to maximise the use ■ Supporting growth in the regions ■ Within the next five to ten years key of the existing network. and ensuring continued parts of the Grid will have reached This level of new and upgraded reliability and security of supply; capacity and will be in danger of infrastructure represents a major ■ Providing high-quality, high- overloading, resulting in loss of shift in the scale of grid development voltage bulk power supply for supply to customers; from today’s levels and will present Ireland that will enable the ■ High-tech industry that requires significant challenges to all involved different regions to attract in secure, high quality energy in its delivery. We will have to future industry and boost supplies will be limited to locations develop innovative methods for existing industry; with strong grid infrastructure; upgrading existing network so that the disturbance and the costs to ■ Exploiting Ireland’s natural ■ The needs of new and current customers can be minimised. And renewable sources of energy residential clients will not be met; we will need to find quicker ways of (wind and wave); ■ The power system will not be able progressing through all the various ■ Reducing Ireland’s carbon to guarantee security of supply; phases of planning and construction emissions by transmitting ■ Access to the market will not to deliver a system capable of renewable energy in line be possible for all low-cost accepting large amounts of new with Government policy; generators limiting competitive- renewable and conventional ■ Increasing Ireland’s connectivity ness in the electricity market; generation. EirGrid is committed to to the European Grid, allowing ■ The drive to reduce Ireland’s CO ensuring that these developments 2 for both bulk exports of emissions and meet its targets are completed on time and in a electricity and imports of for the use of renewables in cost-effective way. electricity when appropriate. compliance with legislation will be seriously undermined; ■ Ireland will not be strongly connected to the European Grid and will be unable to participate fully in a pan-European electricity market. DEMAND GROWTH 1985-2025

9000

8000

7000

6000

5000

MW 4000

3000

2000

1000

0

1985 1988 1991 1994 1997 2000 2003 2006 2009 2012 2015 2018 2021 2024

for a Sustainable and Competitive Future 7 GRID25 IS AN ESSENTIAL INFRASTRUCTURE INITIATIVE TO FACILITATE RELIABLE, SECURE AND AFFORDABLE ELECTRICITY SUPPLIES THROUGHOUT IRELAND. Without it, within the next five to ten years key parts of the Grid will have reached capacity and will be in danger of overloading, resulting in ‘blackouts’.

8 A Strategy for the Development of Ireland’s Electricity Grid for a Sustainable and Competitive Future 9 10 A Strategy for the Development of Ireland’s Electricity Grid 01INTRODUCTION TO GRID25

The need for change providing the necessary capacity for Grid25 provides Electricity is a fundamental component transporting power from source to a common under- of life in the modern world. Ireland, like point of use. many countries, faces the challenge of GRID25 provides an outline design standing of how providing the platform on which we for how the transmission network will will continue to support reliable and be developed in the long-term to meet the development affordable electricity services in the the challenges ahead. coming decades. The overall goal of GRID25 is to of the Grid should The world’s energy industry is develop the network economically to be undertaken to changing significantly to counter the reliably meet anticipated transport declining stocks of fossil fuels and needs of users of the Grid. In support a long- to limit the production of harmful achieving this goal GRID25 supports greenhouse gasses. The Government the Government’s priority actions term sustainable in its White Paper on “Delivering of increasing the penetration of a Sustainable Energy Future for renewable energy technologies and reliable Ireland”, published in 2007, has set and of improving energy efficiency electricity supply. targets for the electricity industry in and energy savings. Ireland to meet these challenges. A significant contribution to our The reasons for GRID25 sustainable energy future will come GRID25 provides a common under- from renewable energy sources. standing of how the development of Energy efficiency will be increasingly the Grid should be undertaken to important in moderating growth support a long-term sustainable and driven by population numbers and reliable electricity supply. economic development. EirGrid will The long-term view of transmission continue with active campaigns infrastructure requirements provides a to encourage savings in power use guide to the scale of grid development where possible and will also support required to correctly match the smart metering which will enable anticipated long-term needs. In the consumers to more directly absence of a long-term view, the participate in managing their developments may otherwise be own consumption. planned piecemeal to only meet The transmission network plays an the short-term needs as they arise, important role in transporting the resulting in inefficient investment and power from the variety of generation in many cases an ineffective grid. sources, both conventional and High voltage networks provide renewable, to the towns and cities, for much greater capacity than lower onward distribution to every home, voltages. For instance a 400 kV line farm and business across the country. provides about three times the EirGrid is responsible for developing capacity of a 220 kV line. Another the transmission network in Ireland. way of expressing this is that it would It does this to ensure that there is take three 220 kV lines to provide the adequate network capacity to carry same capacity as a 400 kV line. So, power from new generation stations where the long-term need may be and to ensure a reliable supply to for a 400 kV line, without foresight, meet growing demand for electricity. three 220 kV lines may be installed. A balanced forward-thinking Developments based on a long-term approach will be adopted to minimise view are therefore more economic and the impact on the environment while have less impact on the environment

for a Sustainable and Competitive Future 11 01INTRODUCTION

and the communities through which specify reinforcement project the circuits pass. requirements. The studies will assess environmental impact, technical Next steps issues and route identification for GRID25 provides an approach to grid the many necessary schemes. development over the next decade Once the information already and beyond. It also provides a scale to contained in this Strategy, such as the necessary infrastructure required the needs of a region, is collated with on a national and regional level. As the information from the studies, plans a matter of priority, EirGrid will for specific projects will be drawn up progress network development to and implemented in consultation with meet anticipated needs in line with the public and all key stakeholders, the GRID25 Strategy. and subject to regulatory oversight EirGrid has begun to undertake by the Commission for Energy detailed studies to more clearly Regulation (CER).

THE GRID25 PROCESS

briefing + feedback consultation

proposed project solutions development

12 A Strategy for the Development of Ireland’s Electricity Grid 02VISION

The demands for transmission services of energy favoured by industrial, By 2025, the Grid will be far different in 2025 to what commercial and domestic customers. will carry 60% they are today. We must plan now to A well established relationship exists meet these changing needs. between economic growth and more power to Our vision is of a grid developed to electricity consumption. The forecast match future needs, so it can safely for demand levels in 2025 are based cities and towns and reliably carry power all over the on the Economic and Social Research country to the major towns and cities Institute’s long-term forecast of across Ireland. and onwards to every home, farm moderate growth in economic activity. and business where the electricity One of the Government’s main is consumed and so it can meet the priorities towards creating a sustain- needs of consumers and generators able energy future is the area of in a sustainable way. energy efficiency and savings. A The drivers of grid investment are successful energy efficiency campaign complex in nature and require will improve performance across careful analysis. all energy sectors including the In many cases growth in demand for electricity sector. One plausible electricity results in higher power flows outcome of the energy efficiency on the transmission network. Where campaign is an increase in the share the power flows exceed the capability of electricity in the transport market. of the Grid, reinforcement is necessary. While GRID25 is designed to meet Demand forecasts are therefore a increasing demand for electricity, good indicator of the need for albeit at a slower growth than grid investment. experienced over the previous In general, the addition of decade, EirGrid will continue to generation creates a much greater monitor the success of the and immediate impact on the Grid Government’s National Energy than demand increases because of Efficiency Action Plan and adapt the size of a generator relative to its transmission development the more gradual increases in local programme as appropriate. demand. The Grid often has to be This Strategy envisages the use of reinforced to facilitate the flow of new ‘Smart Grid’ technology in the power from the generator to the rest form of smart metering, which will of the system. This is true whether play a key role in giving customers the generator is connected to the control over their consumption and transmission system or to the in efficient use of grid infrastructure. distribution system. The trend in geographical Customer demand close to a distribution of loads is regularly generator can reduce the amount of monitored by EirGrid. Analysis of power that must be transported away the current distribution indicates from the area. In certain parts of the that about 58% of the demand is in network, therefore, higher demand the gateway cities and towns. The levels may result in a reduced National Spatial Strategy (NSS) infrastructure build. defines gateways as having a strategic location, nationally and relative to Demand for electricity their surrounding areas and providing Demand for electricity has grown national-scale social and economic steadily since the early days of a infrastructure and support services. national electricity supply. Electricity GRID25 supports the NSS goal of is a safe, versatile and economic form developing gateways and achieving

for a Sustainable and Competitive Future 13 02VISION

balanced regional development ■ Meeting 33% of electricity or imports from abroad. Given that through planning for an increased consumption from renewable wind is expected to make up most of 65% share of the total system demand energy; the renewable portfolio, the amount of figure for the gateways and through ■ Meeting 40% of consumption conventional generation capacity must growing other demands at an equal from renewables. be adequate to ensure a reliable power rate across the country. supply for those hours when wind The following diagram illustrates the generation output is low. expected regional distribution of the Renewable generation GRID25 provides for a range of renewable generation capacity. Generation from renewable energy conventional generation scenarios sources is a key plank in the Strategy locating close to: Conventional generation to reduce carbon emissions and to If 40% of electrical consumption is met • principal sea ports; maintain a sustainable energy supply. by renewable generation, it follows • existing station sites; The Government has set a target of that 60% must be supplied from non- meeting at least 33% of electricity • strong transmission nodes. renewable “conventional” generation demand from renewable generation by 2020. It also intends setting further targets jointly with the relevant Northern Ireland authorities. REGIONAL DISTRIBUTION OF RENEWABLE CAPACITY It is recognised in the Government’s White Paper on “Delivering a Sustain- south east able Energy Future for Ireland” that 16% wind energy will play a pivotal contribution to meeting that goal. Ocean technologies and biomass are also expected to contribute. Many of the locations suitable for renewable energy generation north west schemes are in areas where there 35% have been little or no generation developments heretofore. The aggregate of renewable generation capacity in some areas is equivalent to large conventional generation stations south west and in many cases the network is not capable of carrying the power from 30% these generation sources. Significant reinforcement of the Grid will therefore north east be required to cater for the new power flows from renewable generation. It 4% will not be possible to utilise Ireland’s west natural resources of renewable energy east 8% without the essential upgrades 4% outlined in GRID25. The power flow analysis midlands underpinning this Strategy considered the impact on grid development 3% requirements of two distinct levels of renewable generation:

14 A Strategy for the Development of Ireland’s Electricity Grid FUTURE coleraine CONVENTIONAL coolkeeragh GENERATION ballylumford

LOCATIONS * kilroot

sligo

newry shankill moy bellacorick flagford louth

lanesboro castlebar drogheda (drybridge) mullingar

kinnegad athlone

cashla shannonbridge dublin cushaling dunstown tynagh

ennis carlow moneypoint kellis

limerick (killonan) kilkenny aughinish tarbert cahir great island

barrymore waterford

aghada

whitegate Large

Medium

Small

Natural Gas Network

for a Sustainable and Competitive Future 15 GRID25 ENABLES THE DIFFERENT REGIONS TO DEVELOP THEIR POTENTIAL IN ATTRACTING NEW HIGH-TECH INDUSTRY AND TO ACCOMMODATE POPULATION GROWTH. Without it, high-tech industry that requires secure, high quality energy supplies will be unlikely to locate in regions which have inadequate supplies.

16 A Strategy for the Development of Ireland’s Electricity Grid for a Sustainable and Competitive Future 17 02VISION

Interconnection The East-West interconnection project currently being progressed by EirGrid will provide a 500 MW link with the UK Grid. It is likely that by 2025 at least one further interconnector from this system to another off-shore system, either Britain or France, will be in place. Greater penetration of renewable sources may provide a case for still further interconnection projects. GRID25 will provide for the connection of further interconnectors along the south-east or southern coast as these are the most likely regions for interconnectors to connect to the system. These interconnectors could play a significant role in internationalising the Irish energy market and in facilitating the anticipated high levels of renewable generation on the island by providing a means to export excess generation when output from renewable generation is high and to import power when it is low.

18 A Strategy for the Development of Ireland’s Electricity Grid 03FUTURE GRID REQUIREMENTS

Additional grid capacity required Estimated grid development Through forward The Transmission Grid in Ireland is requirements planning we will made up of circuits and equipment at The following indicates the amount of three voltage levels 400 kV, 220 kV infrastructure development required achieve increased and 110 kV. The 400 kV network and to strengthen the Grid1. the more extensive 220 kV network ■ Approximately 1,150 km of new capacity with only are the main means of transporting circuits will be required. This a 20% increase in bulk power around the country. represents an increase of about The 220 kV network was first 20% on the total length of the the total length of introduced in the early 1960s and the existing network. Of this, 800 400 kV network was built in the early km will need to be at 220 kV or the network. 1980s. Since the mid-1980s this bulk higher; the other 350 km will power network has changed little while be at 110 kV. In addition to demand in the same period has grown these circuits, others will be by over 150%, leaving little capacity needed to connect many of the for further growth. The anticipated new generators to the Grid; increasing power flows on the system ■ 2,300 km of the existing means that between now and 2025 transmission network will need the capacity of the bulk transmission to be upgraded to provide system will need to be doubled. greater capacity. This includes The key factors that will cause 1,100 km or 70% of the existing power to flow and that therefore drive 220 kV network and 1,200 km future investment in the Grid are: of the 110 kV network. ■ Higher demand levels, up to There are a number of technical and including maximum options to achieve this increase in forecast demand of 60% network capacity. These are further distributed throughout discussed in Appendix A, “Technical every region; Options for Grid Development”. ■ Significantly higher renewable This level of new build and generation capacity levels; upgrading represents a major shift in ■ Location of new conventional the scale of infrastructure development generators and output levels; from today’s levels and will present ■ Connection point of further significant challenges to all involved interconnectors and in its delivery. transfer levels. Upgrading existing lines generally requires taking the lines out of service The 110 kV network, which brings for lengthy periods of time to make power from the bulk networks to changes to conductors and /or the individual towns and large loads, also structures supporting them. The needs to be substantially upgraded. reason the lines are being upgraded is that the power trying to flow on them exceeds their existing capabilities. Taking them out of service for

1 These figures do not include the current development programme as detailed in the “Transmission Development Plan 2007-2011”, or any new interconnectors, or the circuits that will be required to connect new generation stations, both renewable and conventional, to the Grid.

for a Sustainable and Competitive Future 19 03FUTURE GRID REQUIREMENTS

upgrading will put a severe strain on the operability, reliability and efficiency of the power system. EirGrid will have to develop innovative upgrading methods to limit the impact on customers both in terms of costs and supply security. Building 800 km of 220 kV or 400 kV lines will present its own challenges. In many cases, the new capacity provided by these lines will need to be in place before some of the existing lines can be upgraded. We will have to find quicker ways of progressing through all the various phases of planning and construction to deliver a system capable of accepting large amounts of new renewable and conventional generation.

20 A Strategy for the Development of Ireland’s Electricity Grid 04THE GRID DEVELOPMENT STRATEGY

GRID25 will deliver an efficient 400 kV rather than 220 kV is more New bulk transmission network for Ireland’s efficient and provides greater power transmission lines social and economic development. carrying capability. Building one 400 It will have the necessary capacity kV circuit avoids the need for building will be built at to reliably transport the future a multiplicity of 220 kV lines and so anticipated power levels from has less long-term impact on the 400 kV. Building renewable and conventional environment and on local communities. generators and interconnectors to the In the longer term it may be one 400 kV circuit cities and towns and the villages and appropriate to upgrade the 220 kV avoids the need homes where the power is required. network to 400 kV for similar reasons We will follow international best of efficiency and capacity. We will for building a practice and innovative methods to examine each case as the need to provide the necessary transmission upgrade arises and consider the option multiplicity of capacity. The technology options of using a higher capacity conductor available to implement GRID25 will at 220 kV or rebuilding at 400 kV. 220 kV lines and increase as research and development so has less long- is carried out. We will be proactive Striking a balance in investigating and adopting new EirGrid has a statutory obligation term impact on technologies taking due consideration to balance the provision of reliable of the cost and effectiveness of transmission services with the costs the environment the technology. to the final customer and with the and on local New transmission lines will be built impact of transmission infrastructure communities. at 400 kV and at 110 kV. Building at on the environment.

security and reliability

costs and efficiency environment

for a Sustainable and Competitive Future 21 04THE GRID DEVELOPMENT STRATEGY

GRID25 strikes a balance between capacity. This is a more costly ■ We will examine the potential costs, reliability and environmental option and is somewhat less for using HVDC technology for impact. It examines the totality of reliable than having two appropriate applications such developments and considers social separate lines but it avoids as transporting high volumes acceptance at an affordable price in building a new line on a of power over long distances; the context of the overall long-term separate route; ■ We will consider the network development. In particular ■ In certain limited circumstances appropriateness of new tower we will endeavour to minimise the net we will put selected 110 kV designs and other mitigating length of new line build in a region circuits underground to measures outlined in the through a number of initiatives: minimise the impact of new Government-sponsored report ■ We will utilise the existing build in a region. This will be recently issued on “The network where possible to avoid considered in areas where Comparative Merits of Overhead building new overhead circuits. there is congestion of urban Electricity Transmission Lines In many cases re-utilising the development, a multiplicity of Versus Underground Cables” in existing network is more costly overhead lines, a relatively wide order to minimise the landscape than building new circuits but expanse of water or an area of and visual impact of necessary the Strategy results in less unique natural beauty. A 110 kV infrastructure. We will also impact on the environment; underground solution would not take account of the National ■ We will seek to up-rate existing be advanced where the ground Landscape Strategy when it lines by using a higher capacity conditions were unsuitable is published. conductor, where appropriate. either because of the risk to the Using traditional conductor environment or because of types would generally involve construction difficulties; modifying or taking down and changing the towers or poles that support the conductor. PROPOSED EXPENDITURE BY REGION A change that involves a long circuit outage of one or north west more years will have serious south east ramifications for the security of €830m €750m supply during the outage. We will therefore use new light- weight high capacity conductors as they become commercially available and where possible north east to avoid the need for major €300m structural changes and so to minimise security issues; ■ Where the required increase in capacity cannot be provided south west west by a new conductor operating €730m €315m at the same voltage, we will consider upgrading the circuit to a higher voltage; ■ Where appropriate, we will consider replacing an existing east line with a double circuit line to midlands provide the required additional €310m €800m

22 A Strategy for the Development of Ireland’s Electricity Grid 05A REGIONAL VIEW

donegal northern ireland

leitrim

sligo monaghan

north west cavan louth mayo roscommon north east longford

meath

westmeath dublin galway

offaly kildareeast midlands laois wicklow clarewest tipperary n.r. carlow

kilkenny limerick tipperary s.r. south eastwexford

waterford kerrysouth west cork

EirGrid has divided up the network into seven regions. It is emphasised that the maps here are illustrative only. All areas and regions of Ireland will be covered by GRID25.

for a Sustainable and Competitive Future 23 NORTHWESTREGION

A trillick sorne hill

bunbeg

kiltoy

letterkenny

meentycat donegal drumkeen tievebrack

to strabane

binbane golagh northern ireland

cathleen’s fall cliff

turleen

B leitrim to enniskillen lisdrum sligo C tawnaghmore corderry

srananagh monagha corraclassy bellacorick cunghillsligo gortawee moy arigna

shankill cavanratrussan carrick-on- shannon me hi tonroe gilra arva kingscourt castlebarmayo roscommonflagford longford dalton richmond lanesboro

knock

westmeathmullingar

cloon kinnegad athlone galway derryiron dunfirth

cashla thornsberry cushaling blake shannonbridge galway offaly somerset kil newbridge tynagh

derrybrien oldstreet dallow laois agannygal portlaoise athy

clare ikerrin

24 A Strategy for the Development of Ireland’s Electricity Grid This area is particularly rich in wind and ■ An additional investment € ocean renewable energy resources. of approximately 750m to Consequences of non-action The planned gas pipeline, connecting upgrade almost 700 km of the ■ By the second half of the the Corrib gas field off Mayo to Galway, existing transmission network next decade, there will be will provide the opportunity for gas and to build new circuits; no capacity in the network fired generation along the route of ■ Extension of the 220 kV network to cater for new customers the pipeline. into Sligo, already in progress; and the reliability of supply The transmission network in the ■ 110 kV reinforcements between to existing customers North West is predominately at 110 kV, Killybegs (Binbane station) and will fall below normal with very little 220 kV and no 400 kV Letterkenny and Ballaghadreen international standards; network in the region. There are two (Tonroe station) and Castlebar; 110 kV circuits linking the Northern ■ There will be not be enough Ireland and Republic of Ireland ■ Major infrastructural capacity in the network to transmission systems, Letterkenny to development from Mayo to the connect further renewable Strabane and Corraclassy-Enniskillen. main bulk transmission system generation; as the north These provide standby support in the eastern part of the region; west is a renewable-rich between relatively weak parts of ■ Further integration of the region this will have severe the two systems. Donegal and Northern Ireland consequences on the ability networks. of Ireland to meet its Key developments renewable targets and its It is expected that demand in the long-term sustainable region will grow by up to 60% by energy supplies. 2025. Area A (Donegal) is expected to have up to 691 MW of wind generation, Benefits with Areas B (Mayo/Galway) and C ■ (Leitrim/Roscommon) having 880 MW The North West can and 269 MW respectively. Area B is become a net exporter of also expected to have up to 240 MW power to the rest of the of wave generation and 31 MW of off- island, reducing its shore wind. If ocean technologies, reliance on generation for whatever reason, do not develop from outside the region; sufficiently for such large scale ■ Plans will facilitate the deployment by 2025, the network growth of renewable capacity that might have been generation connections attributed to it could be utilised by in the region; other more established renewable ■ The increased power technologies such as wind generation. supply will accommodate Grid development in the region and help attract future will include: industry.

estimated total GRID25 € investment in the 750m North West Region

for a Sustainable and Competitive Future 25 IT IS VITAL THAT IRELAND HAS THE ELECTRICITY SUPPLY INFRASTRUCTURE TO ENSURE OUR ECONOMIC GROWTH, AND MAXIMISE OUR COMPETITIVENESS. Without GRID25, the power system will not be able to guarantee security of supply or competitiveness in the marketplace.

26 A Strategy for the Development of Ireland’s Electricity Grid for a Sustainable and Competitive Future 27 kiltoy

letterkenny NORTHEASTREGION

eentycat gal drumkeen

to strabane *

gh northern ireland

turleenan

tandragee

to enniskillen lisdrum monaghan rraclassy 275kV gortawee A dundalk

shankill ratrussan cavan louth mullagharlin meath hill louth arva B kingscourt

longford drybridge richmond navan gorman platin knockumbermeath stevenstown

baltrasna east west hvdc interc

westmeathmullingar woodland corduff glasmore huntstown kinnegad kilmore grange dublin

finglas macetown north wall college park poolbeg derryiron dunfirth maynooth rinawade shellybanks inchicore irishtown thornsberry cushaling blake cookstown ridge offaly monread carrickmines kildare kilteel fassaroe baroda newbridge charlesland dunstown pollaphuca allow turlough wicklowhill laois ballybeg portlaoise athy stratford

28 A Strategy for the Development of Ireland’s Electricity Grid This region has some potential for ■ Strengthening of power circuits on-shore wind generation and high between the North West region Consequences of non-action potential for off-shore wind. and the North East region ■ Within a matter of years The area shares a border with facilitating power flows; there will be no capacity Northern Ireland, which makes the ■ Reinforcement of 110 kV in the network to cater region and the interconnector that will networks supplying Cavan for new customers and run through it significantly important and Monaghan; the reliability of supply to the All-Island Single Electricity ■ Upgrading about 240 km of the to existing customers Market. The 220 kV and planned 400 existing transmission network. will fall below normal kV transmission network in the region international standards; provides a strong power corridor between Dublin and Belfast. ■ The network will not be A high capacity gas pipeline Benefits adequate to allow efficient operation of the All-Island runs between north Dublin and ■ The North-South market, meaning that the Northern Ireland gas system, interconnector and the customers will not benefit providing potential for gas-fired Woodland-Kingscourt line from the cheapest generation in the north east. will provide long-term electricity available; capacity between the Key developments Northern Ireland and the ■ There will be no capacity in Between 1995 and 2005 the demand Republic of Ireland the network to allow further in the region has grown by about 55%. systems and ensure renewable generation to be It is expected that by 2025 the demand security of supply to the connected; this will deny will have grown by a further 60%. North East region; Ireland the opportunity to Renewable generation connections exploit its off-shore wind ■ Provides for substantial are expected to include up to 145 MW resources and will have increase in electricity wind generation in Area A and 125 MW severe consequences demand in the region; off-shore wind generation in Area B. on the ability of Ireland ■ Grid development in the region There will be increased to meet its renewable will include: opportunities to provide targets and its long-term renewable energy in ■ An additional investment of sustainable energy the region; approximately €300m in supplies. ■ the region; Increased opportunities for gas-fired generation ■ The North-South Interconnector technologies. (400 kV) connecting Kingscourt in Cavan to Turleenan in Tyrone; ■ A new 400 kV circuit from Woodland in Meath to Kingscourt in Cavan;

estimated total GRID25 € investment in the 300m North East Region

for a Sustainable and Competitive Future 29 WESTREGION

cloon athlone galway

cashla shan galway somerset

tynagh

derrybrien oldstreet

agannygal clare

ennis westmidland

booltiagh tipperanenagh

tullabrack drumline ardnacrusha

ahane prospect mungret sealrock moneypoint moneteen killonan castlefarm tarbert aughinish ballycummin limerick rathkeale limerick tipp tippe

trien athea

c

clahane charleville

tralee

glenlara

mallow oughtragh kerry

barrymore knockearagh

coomacheo cork

clonkeen knockraha

30 A Strategy for the Development of Ireland’s Electricity Grid This region features an availability of ■ Strengthening the transmission natural resources for wind and ocean capacity across the Shannon technologies. Hydro-generated Estuary. electricity is already produced on the Shannon Estuary. The area already has large-scale Benefits power stations in Tarbert, Moneypoint ■ and Tynagh and a gas transmission Provides for substantial pipeline from Galway to Limerick increase in demand into which passes close to a number of the future; potential locations suitable for gas- ■ Allows for renewable fired generation projects. resources from both wind There are 400 kV, 220 kV and a and wave to feed into the number of 110 kV circuits in the region. National Electricity Grid.

Key developments By 2025, peak demand for electricity is expected to increase by 60% (estimated in 2007). The region is Consequences of non-action expected to have up to 440 MW of ■ Within the next five to ten wind generation and 75 MW of years there will be no wave generation. capacity in the network to Grid development in the region cater for new customers will include: and the reliability of supply ■ An additional investment of to existing customers approximately €315m in will fall below normal regional transmission network; international standards; ■ Upgraded networks supplying ■ There will be no capacity in the large urban centres of Ennis the network to allow further and Limerick; renewable generation to be connected; this will have ■ Up-rating over 250 km of severe consequences on the existing networks to facilitate ability of Ireland to meet its higher capacity power flows, renewable targets and its using existing corridors long-term sustainable where possible; energy supplies.

estimated total GRID25 € investment in the 315m West Region

for a Sustainable and Competitive Future 31 EASTREGION louth arva kingscourt

rd drybridge navan gorman platin knockumbermeath stevenstown

baltrasna east west hvdc interc

stmeathmullingar woodland corduff glasmore huntstown kinnegad kilmore grange dublin

finglas macetown north wall college park poolbeg derryiron dunfirth maynooth rinawade shellybanks inchicore irishtown cushaling blake cookstown

monread carrickmines kildare kilteel fassaroe baroda newbridge charlesland dunstown pollaphuca turlough wicklowhill laois ballybeg portlaoise athy stratford

shelton arklow ballyragget abbey carlow kellis carlow

ballycadden banoge

kilkenny kilkenny londgewood

crane ballywater wexford

32 A Strategy for the Development of Ireland’s Electricity Grid This region has the potential for high ■ Strengthening of network into levels of conventional generation as and out of the region to allow Consequences of non-action a result of the existing gas grid and the demand to be met by ■ In the medium term, there the proximity of Dublin Port. Wind renewable generators located will be no capacity in resources are confined mainly to mainly in the west of the country; the network to cater for off-shore locations. There are large- ■ Strengthening of network new customers and the scale thermal generating stations at serving Dublin City load; reliability of supply to Poolbeg, North Wall, Huntstown and ■ Development to allow north- existing customers will fall Irishtown and a pumped storage south flows to by-pass the below normal international facility at Turlough Hill in Wicklow. network serving the Dublin load; standards; The 220 kV network within Dublin and the 220 kV and 400 kV network ■ Construction and connection of ■ There will not be adequate linking the East region with the rest new 220 kV stations in north capacity in the network to of the island will require significant and West Dublin to cater for the allow for excess renewable development to increase the flow of rapidly growing developments generation to be exported power to and from the region and to in these areas; over the planned East- accommodate future imports and ■ Reinforcement of the network West interconnector; this exports of power through the to cater for strong growth in will curtail renewable interconnector between Ireland Kildare and North Wicklow. generation at times, (Woodland, Co. Meath) and Great reducing the commerciality Britain (Deeside, Wales), due to be of renewable developments operational during 2012. and consequently the Benefits likelihood of necessary Key developments ■ Improvements will ensure progression. The demand for electricity in the East security of supply to region is expected to increase by over the region; 80% by 2025 and will then be 30% of ■ Infrastructure to attract the demand of the island. Up to 240 future industry; MW of wind generation is expected to ■ Provision for the use of be connected to the Grid in this region. renewable energy in Grid development in the region the region. will include: ■ An additional investment of approximately €800m through upgrading approximately 450 km of the existing network and building new circuits;

estimated total GRID25 € investment in the 800m East Region

for a Sustainable and Competitive Future 33 GRID25 WILL ENSURE THAT IRELAND HAS THE BEST POSSIBLE PLATFORM IN TERMS OF A WORLD-CLASS, COMPETITIVE AND SUSTAINABLE ELECTRICITY SYSTEM. Without it, the needs of new and current residential clients will not be met.

34 A Strategy for the Development of Ireland’s Electricity Grid for a Sustainable and Competitive Future 35 MIDLANDSREGION roscommon longford richmond navan lanesboro knockumberme

westmeathmullingar woo cloon kinnegad athlone galway derryiron dunfirth maynooth

cashla thornsberry cushaling blake shannonbridge offaly somerset kildarmonread barod newbridge tynagh dunstown derrybrien oldstreet dallow laois agannygal portlaoise athy stratfor

ikerrin

westmidland ballyragget carlow tipperarynenagh n.r. kellis lisheen carlow e ardnacrusha

thurles ahane mungret killonan oneteen kilkennykilkenny limerick merickballycummin tipperary s.r. tipperary w

doon cahir ballydine anner charleville

great island waterford killmurry cullenagh killoteran

36 A Strategy for the Development of Ireland’s Electricity Grid The main Dublin-Galway gas ■ Reinforcement to cater for transmission pipeline passes continued demand growth in Consequences of non-action through the Midlands region close to the gateway towns of Athlone, ■ Over the next five to ten transmission stations at Athlone, Mullingar and Tullamore; years, there will be no Edenderry, Kinnegad and Mullingar. ■ Upgrading will facilitate power capacity in the network to There are modest wind resources flows from both renewable cater for new customers available in the Midlands region. and conventional sources and and the reliability of supply There are three peat-burning stations maximise the use of existing to existing customers at Lanesboro, Shannonbridge and power corridors. will fall below normal Cushaling stations. Supply in the international standards; region is served mainly through the 110 kV meshed network, although a ■ There will be no capacity in number of higher capacity 220 kV Benefits the network to allow further and 400 kV lines pass through ■ Future growth in demand renewable generation to providing potential for substantial will be accommodated; be connected. increased supplies. ■ There will be increased security of supply to Key developments the region; By 2025, the demand in the Midlands ■ Increased transmission region is expected to grow by over capacity will allow for 40%. It is expected to have up growth of renewable to 160 MW of wind energy. generation connections Grid development in the region in the region; will include: ■ Network capacity to allow ■ An additional investment for small-scale thermal of approximately €310m generation in the region. through upgrading 225 km of transmission network and new circuit build; ■ Tapping in to the existing 400 kV line to strengthen the 110 kV network around Portlaoise providing capacity to supply the continuing strong growth in Kildare and Laois;

estimated total GRID25 € investment in the 310m Midlands Region

for a Sustainable and Competitive Future 37 SOUTHEASTREGION

huntstown kinnegad kilmore grange dublin athlone finglas macetown north wall college park poolbeg derryiron dunfirth maynooth rinawade shellybanks inchicore irishtown thornsberry cushaling blake cookstown shannonbridge offaly monread carrickmines kildare kilteel fassaroe baroda newbridge charlesland dunstown pollaphuca dallow turlough wicklowhill laois ballybeg portlaoise athy stratford

ikerrin A shelton arklow ballyragget abbey carlow erary n.r. kellis lisheen carlow

thurles ballycadden banoge

kilkenny kilkenny londgewood

crane ballywater ipperary s.r.B tipperary wexford

doon cahir ballydine wexford anner

great island waterford killmurry cullenagh killoteran waterford cullenagh

dungarvan

38 A Strategy for the Development of Ireland’s Electricity Grid This region has good wind resources. ■ Strengthening of the 220 kV There is at present a 220 kV network links to both Dublin and Cork to Consequences of non-action passing through the region providing facilitate increased power flows; ■ Over the next five to ten high-capacity supply to the region and ■ Strengthening the networks years, there will be no an underlying 110 kV network supplying the major cities and capacity in the network to throughout. towns in the region; cater for new customers There are existing large-scale ■ Reinforcement of current and the reliability of supply generation facilities with fuel- infrastructure, including up- to existing customers handling capabilities at Great Island rating 110 kV and 220 kV will fall below normal station. The main Cork to Dublin gas circuits, while maximising international standards; transmission network passes through the use of existing corridors the region. There is a possibility of ■ There will be no capacity in where possible. connecting the Great Island facility the network to allow further and other potential generation sites renewable generation to be to the gas transmission network connected; this will have in the future. Benefits severe consequences on the ■ Proposals will ensure ability of Ireland to meet its Key developments security of supply to major renewable targets and its Demand in this region is expected to urban areas and to the long-term sustainable increase by over 45% by 2025. Area region as a whole; energy supplies; ■ A on the map is expected to have ■ Will allow for substantial Further interconnection 335 MW of on-shore and 445 MW off- growth in renewable will not be possible in shore wind generation, while Area B generation connections in this region. should have 210 MW on-shore wind the region; generation. A new interconnector from ■ Future growth in demand this region to either Great Britain or from both industry and mainland Europe will enable the export domestic users can be and import of power when appropriate. accommodated. Grid developments in the region will include: ■ An additional investment of approximately €830m will be required to upgrade approximately 490 km of the existing network and to build new infrastructure;

estimated total GRID25 € investment in the 830m South East Region

for a Sustainable and Competitive Future 39 SOUTHWESTREGION

agannygal

clare ikerrin

ennis westmidland

booltiagh tipperarynenagh

tullabrack drumline ardnacrusha

ahane prospect mungret sealrock moneypoint moneteen killonan castlefarm tarbert aughinish ballycummin limerick rathkeale limerick tippera tipperary

trien athea

cahir clahane A charleville tralee

glenlara B mallow oughtragh kerry

barrymore knockearagh

coomacheo cork

clonkeen knockraha clashavoon coomagearlahy kilbarry inniscarra glanlee marina macroom coolroe trabeg hartnett’s carrigadrohid aghada cross raffeen whitegate brinny

bandon ballylickey dunmanway

40 A Strategy for the Development of Ireland’s Electricity Grid Cork and Kerry in particular feature an ■ Strengthening of the Cork abundance of natural renewable network to allow power to be Consequences of non-action resources for wind and ocean exported from the two large gas- ■ In the short to medium technologies. Hydro-generation on the fired generators in East Cork; term, there will be no River Lee also contributes renewable ■ Planned grid reinforcements to capacity in the network to energy to the National Electricity Grid. connect significant amounts of cater for new customers There are thermal generation wind generation; and the reliability of supply facilities at Marina in Cork City and ■ Significant strengthening of to existing customers Aghada in East Cork with plans for capacity between the South will fall below normal new generators at Aghada and West and the South East to international standards; nearby Whitegate well in advance. allow excess power to flow The gas network passes close to the ■ There will be no capacity from both renewable and transmission system at numerous in the network to allow conventional sources to other points providing further potential further renewable supply demand in other for gas-fired generation in the region. generation to be parts of the country. The transmission network in the connected; as the South region consists of both 220 kV and West is a renewable-rich 110 kV circuits. region this will have severe Benefits consequences on the Key developments ■ Increased security of ability of Ireland to meet its Demand in the region is expected supply to the region; renewable targets and its to rise by 60% by 2025. Area A is long-term sustainable ■ Greater number of expected to have up to 730 MW of energy supplies. renewable generators wind power and 145 MW of wave connected; generated power, with Area B having ■ up to 880 MW and 40 MW of both Improved network will technologies respectively. Large parts allow for exports of of the network will be upgraded to renewable generation accommodate this growth in demand from the region; and renewable generation. ■ Significant future growth in Grid development in the region demand from both industry will include: and domestic users can be ■ €730m will be invested in the accommodated. infrastructure of the region, to include the upgrading of approximately 130 km of transmission network and new transmission developments;

estimated total GRID25 € investment in the 730m South West Region

for a Sustainable and Competitive Future 41 THE IMPLEMENTATION OF GRID25 IS ESSENTIAL IF IRELAND IS GOING TO MEET ITS TARGETS FOR GENERATING ELECTRICITY FROM RENEWABLE SOURCES.

Without it, the drive to reduce Ireland’s C02 emissions and meet it’s targets for the use of renewables in compliance with legislation will be seriously undermined.

42 A Strategy for the Development of Ireland’s Electricity Grid for a Sustainable and Competitive Future 43 APPENDIX A TECHNICAL OPTIONS FOR GRID DEVELOPMENT

As outlined above the future grid Only where it is not possible to find be made for installing underground capacity requirements will be a route for overhead lines are high cable, even at 110 kV, unless determined by the customers’ long- voltage (HV) underground cables used confronted with a built up area, a vast term demands for electricity, by the worldwide. Such situations arise, for expanse of water or an area where output from generators built to supply example, when the area that has to there is a multiplicity of overhead that demand and by the flows across be traversed consists of one or more lines. In some countries lower voltage interconnections with other systems. of the following: lines have been placed underground EirGrid has calculated that, based ■ A built-up urban area where but, for the reasons given above, no on its vision of 2025, a significant there is no space for support country has adopted a policy of increase in grid capacity will be structures; undergrounding high voltage lines. required. The following sections ■ An area with a multiplicity of discuss the technical options for Reasons for building at 400 kV existing overhead power lines; delivery of the necessary capability A 400 kV line typically provides three and the research and development ■ A relatively wide expanse of times more capacity than a 220 kV line initiatives that EirGrid is undertaking deep water; and will meet long-term needs more to ensure that best practice is used. ■ An area of unique natural beauty. effectively. Therefore one way of There are two main reasons why reducing the number of new lines in the Overhead and underground underground cables are used so rarely long-term is to use the 400 kV voltage. electricity lines at transmission voltages (110 kV, 220 Power flow on a 400 kV line Overhead lines are the standard kV and 400 kV). Firstly the capital cost experiences much lower losses than form of transmission throughout the of installing a cable is many times that the equivalent flow on a 220 kV line. world. Lines are made up of three of an equivalent overhead line and Building at 400 kV therefore supports conductors that carry the power from secondly the operating performance of the EU and the Government’s generators to loads and in many cases an underground cable is not as good as common objective of increasing two earth wires that help protect the that of an overhead line. The higher the energy efficiency. circuit from lightning faults. These operating voltage the stronger will be Upgrading an existing 220 kV line to wires are supported on either wood the case in favour of an overhead line. 400 kV can achieve similar efficiency pole or steel mast structures. While some lines are placed under- and capacity gains. However, this High voltage (HV) circuits can only ground internationally, this is only a would involve taking the existing 220 be laid underground using special small proportion of the amount in place. kV line out of service and dismantling HV cables designed specifically for Statistics from the 23 European it and building a new 400 kV line on underground use. The conductors countries that make up the Union for the same route. The system could not in underground HV cables must be the Co-ordination of Transmission of operate without one 220 kV line for an heavily insulated to avoid a short Electricity (UCTE) show that in 2006 extended period, it could not operate circuit between the conductor and only 1.7% of their combined Extra with a number of lines out of service the ground around the cable. As a High Voltage grids (i.e., 220 kV and simultaneously as would be the case result, the installation costs for an above) consisted of underground if all 220 kV lines were upgraded to underground cable are far higher cable. The comparable figure for the 400 kV by 2025. than for a simple overhead line. Republic of Ireland was 4.7%. By Overhead lines cost significantly contrast at transmission voltages Up-rating existing circuits less to construct than underground below 220 kV the level of usage of In recent years, a number of factors, cables. They are easier to pinpoint underground cable in Ireland is lower including financial constraints and faults on and quicker to repair and so than our European neighbours. It is difficulties obtaining planning provide a cheaper and more reliable therefore at this voltage, 110 kV, that permissions for new infrastructure, alternative to underground cables. EirGrid can give greater consideration have intensified interest in increasing While they do have an impact on to the use of cable. the ability of existing circuits to carry the local visual environment, this When considering a transmission higher levels of power. is minimised as far as possible project in isolation however, neither a A transmission line’s ability to carry in construction and planning. technical nor an economic case can power depends largely on the type of

44 A Strategy for the Development of Ireland’s Electricity Grid New 220 kV line design

conductor used, the height of the infrastructure and line routes so as to The electricity that is generated by conductor above ground and the minimise new build where possible. this country’s power stations is also operating voltage. Up-rating is a As part of the process a rigorous AC. The link between the power process where the current carrying examination of new technologies that stations and the distribution network capacity of existing high voltage can be employed will be initiated. is provided by the high voltage lines is increased by using various Such opportunities may present Transmission Grid. Therefore the strategies or techniques. themselves in the form of new Transmission Grid also operates There are a number of different up- conductor types or in utilising with AC electricity. rating scenarios that can be applied monitoring techniques which enable If a transmission grid was to be to the Irish situation. existing circuits to carry more power. operated with direct current (DC) it Some transmission lines can be would be necessary to install an up-rated by simply raising some of Tower design AC/DC converter station at every the support structures so that more Transmission tower design has been power station and at every point of power can be transmitted through evolving over the last 70 years from connection to the distribution the conductors without infringing the early double wood pole lines still network. Such AC/DC converter electrical ground clearances. This in operation today to the steel lattice stations typically cost many tens of method will be limited by the capacity and monopole designs. millions of Euro. Although the cost per of that particular conductor to carry For all new projects, efficient and km of HVDC underground cable and the required power. optimally designed towers are being overhead line is cheaper that their AC To overcome this conductor capacity developed, where the main feature equivalents the excessive cost of the limit, up-rating can be carried out by of these towers is the reduced visual converter stations makes the replacing the existing conductors with impact due to lower towers, a lower widespread use of HVDC unattractive, higher capacity conductors and by number of steel struts in the structure other than for bulk transfers over long strengthening and/or raising the or new slimline monopole structures, distances where the savings in line or support structures. There are an all in various shapes and sizes. cable outweigh the additional costs of increasing number of conductor types With the availability of modern converter stations. available, each with different current materials there are now numerous The need of the power system to carrying capabilities, costs and service options available for the internal respond instantaneously to increases experience. It is our intention to use configurations, size, materials, colour in supply and demand, mean that new high-capacity conductors where and finish of each structure whilst HVDC technology is not feasible for a appropriate and affordable. having regard to the environmental, main grid system, although it may In the case that raising structures planning and practical consequences have a role in a few limited and replacing conductors will not of each option. circumstances: meet requirements, further increases As part of all new developments ■ An AC to DC to AC connection in power transfer capability can be an investigation into the appropriate can be used when two achieved by replacing an existing structure design taking into account independent AC networks are transmission line with a higher voltage all current and emerging designs will to be linked together and the line along the same route. Replacing take place so as to minimise the respective operators want their a 110 kV line with a 220 kV line will impact on the existing environment. systems to continue to operate normally mean using steel lattice The objective is to limit any impact at different frequencies. The towers in place of wood pole structures. of new transmission infrastructure on operator of the converter station Opportunities also become the landscape by combining tower would have complete control available to up-rate existing design and robust route selection. over the quantity and direction transmission lines during of flow of electrical power refurbishment programmes where High Voltage Direct Current (HVDC) transferred between the two extensive work would have to be In Ireland, like in all other countries of systems. An example of this carried out in any case on these lines. the world, the electricity that is would be EirGrid’s planned Our policy is to examine all up- distributed to electricity consumers is East-West Interconnector rating opportunities using existing of the alternating current (AC) variety. between Ireland and Wales.

for a Sustainable and Competitive Future 45 APPENDIX A TECHNICAL OPTIONS FOR GRID DEVELOPMENT

■ DC transmission is more • ‘Smart Grid’ concepts; and use of smart meters in system suitable than AC when a large • Underground cable technology operation will be monitored and amount of power is to be and use. introduced as technology solutions transferred over a very long when appropriate. Dynamic monitoring of line loading distance on a radial (i.e., not Underground cable technology involves installing devices to monitor meshed) circuit. HVDC overhead and use will be kept under review. the loading of a line and the climatic lines would typically be used to In partnership with NIE, EirGrid has environment. Combining dynamic move 1,000 MW or more over commissioned a technical study into knowledge of the environment, the distances in excess of 650 km. the possible application of HVDC line design and the system conditions HVDC underground or sub- circuits on the island of Ireland. may enable an existing circuit to carry marine cables are typically EirGrid is participating in work being more power. EirGrid has selected a used to move 250 MW or more carried out through the international specific line and is implementing a over distances in excess of organisation CIGRE on cables in pilot project. tens of kilometres. A long power systems. New technologies facilitate the sub-sea crossing, such as that development of new conductor types. proposed for the East-West High capacity lightweight conductor Interconnector, would be an types are being developed. With example of where this lightweight and reduced thermal would arise. expansion properties, it may be EirGrid always investigates possible to install such conductors and stays up to date on all new on existing structures and gain technologies. EirGrid can see potential increased capacity without visual for HVDC in transmitting the bulk changes to a line or additional energy generated by clusters of rights-of-way. The availability and renewable energy generators from the applicability of such technologies remote areas where they are normally to the Irish Grid will be examined. located and where one would expect Investigation into the appropriate the existing Transmission Grid to be structure design, taking into account weak to areas where the existing the emerging and current designs will Transmission Grid is already strong. take place so that each development As a result EirGrid, in partnership uses the appropriate structure to with Northern Ireland Electricity (NIE), minimise the impact on the existing has commissioned a technical study environment. The ability to convert into the possible application of HVDC existing 220 kV structures to 400 kV circuits on the island of Ireland. operation will also be explored. The ‘Smart Grid’ concept is a term Research & development used to refer to grids that use robust The technology options available to two-way communications and implement GRID25 will increase as intelligent equipment and support Research and Development is carried greater participation of users of the out. EirGrid will be undertaking Grid in contributing to the efficiency, initiatives in the following areas which reliability and safety of the operation will facilitate implementing the Strategy of the Grid and power delivery. Smart taking account of best practice: Grids includes electronic control • Dynamic monitoring of measures such as SCADA and remote line loading; control switching which have been in • Conductor types; effective operation in Ireland for decades. Further developments in • Tower design; Smart Grids such as the integration

46 A Strategy for the Development of Ireland’s Electricity Grid APPENDIX B GLOSSARY

A H AC HVAC Alternating current High Voltage Alternating Current – the standard for electricity generation, AC/DC converter transmission and distribution An interface between AC and DC worldwide. systems comprising electronic equipment that rectifies AC current HVDC to DC or inverts DC current to AC High Voltage Direct Current

C O Circuit Overhead line An electrical circuit is a closed path A circuit comprising conductors and formed by the interconnection of tower or pole support structures. electrical components, such as an overhead line or transformer, through R which an electric current can flow. Renewable Generation Generation from renewable energy Conductor sources such as wind, wave, tidal, A metal wire capable of carrying biomass and photovoltaic cells. electrical current. S Conventional Generation Smart Grid Types of generation technologies in A transformed electricity transmission existence prior to emergence of and distribution network or renewable energy generators “Grid” that uses robust two-way communications, advanced sensors E and distributed computers to improve EirGrid the efficiency, reliability and safety A state-owned company, EirGrid is the of power delivery and use. independent electricity Transmission System Operator (TSO) in Ireland T and the Market Operator (MO) in the Transmission System wholesale electricity trading system. See “Grid”

G U Grid Underground cable The transmission system is a meshed A reinforced insulated electricity network of high voltage lines and conductor placed underground. cables (400 kV, 220 kV and 110 kV) for the transmission of bulk electricity Up-rating supply around Ireland. The Grid, Changing the conductor, the towers electricity transmission network or the voltage of an overhead line to and transmission system are used increase its power-carrying capability interchangeably in this document

for a Sustainable and Competitive Future 47 48 designed by the design house / +353 1 6604700 EIRGRID Plc The Oval 160 Shelbourne Road Ballsbridge Dublin 4 telephone +353 (0)1 677 1700 fax +353 (0)1 661 5375 [email protected] www.eirgrid.com