North-South 400kV Interconnection Development Final Re-evaluation Report April 2013 Part Funded by the EU-TEN-E Initiative North-South 400 kV Interconnection Development Final Re-evaluation Report FOREWORD The development of a second interconnector between Ireland and Northern Ireland is fundamental to the delivery of a sustainable, competitive and secure electricity supply to homes, businesses and industries across the island. The publication of this Final Re-evaluation Report is an important step in the planning and delivery process for the project in Ireland. The report captures the key findings of EirGrid and its consultants on a range of technical, environmental and other matters related to the project. In reaching its conclusions, EirGrid has considered responses and feedback frrom stakeholders at all stages of the project to date, including the consultation period which followed the publication of a Preliminnary Re-evaluation Report on the project in May 2011. During this perriod, EirGrid requested feedbacck on all aspects of the project, including the identified study area, the route options and the preferred technical options for the project. EirGrid’s response to this important feedback is included as an appendix to this Final Re-evaluation Report. Separate to EirGrid’s re-evaluation, the Government appointed an Independent Expert Commission to investigate the case for, and cost of undergrounding the second interconnector. Following the publication of a report by the Independent Expert Commission in January 2012,, a significant period of consultation took place between all stakehollders on the findings of the report. EirGrid fully participated and enggaged in this consultation and our response to matters raised is also included in this report. In July 2012 a “Government Energy Policy Statement on the Strategic Importance of Transmission and Other Energy Infrastructure” was published. EirGrid is fully supportive of this policy statement and is committed to comprehensive public and stakeholder engagement on all asspects of the second Interconnnector as the project proceeds througgh the planning process. A period of six weeks is now provided to alllow for feedback on the findings of thhis Final Re-evaluation Report. EirGrid welcomes any feedback received and will consider this feedback in the preparation of a Preferred Project Solution Report which will be published for further consultation in due course. April 2013 North-South 400 kV Interconnection Development Final Re-evaluation Report TABLE OF CONTENTS FOREWORD EXECUTIVE SUMMARY ......................................................................................................................... 1 1 INTRODUCTION AND CONTEXT ............................................................................................. 5 1.1 Background .................................................................................................................... 5 1.2 The Purpose and Scope of this Re-evaluation Process ................................................ 7 1.2.1 Review of the Previous Application for Statutory Approval ........................................... 8 1.2.2 Report of the International Expert Commission ............................................................. 8 1.2.3 Report of the Joint Oireachtas Committee ..................................................................... 9 1.2.4 Government Policy Statement ..................................................................................... 10 1.2.5 The Grid25 IP 2011-2016 and SEA ............................................................................. 11 1.3 The Consultation Process ............................................................................................ 14 1.3.1 EirGrid’s Project Development and Consultation Roadmap ........................................ 14 1.3.2 Consultation and the Re-evaluation Process ............................................................... 17 1.4 Scope and Methodology of this Re-evaluation Report ................................................ 22 1.5 Conclusions .................................................................................................................. 25 2 STRATEGIC NEED, RATIONALE, JUSTIFICATION FOR AND BENEFITS OF THE INTERCONNECTION DEVELOPMENT ................................................................................... 27 2.1 Introduction .................................................................................................................. 27 2.2 Strategic Need and Benefits of an Additional Interconnector ...................................... 27 2.3 Implications of the Economic Downturn ....................................................................... 31 2.4 Security of Supply in the North-East ............................................................................ 32 2.5 Consideration of Third Party Suggestions for Delay of the North-South Interconnector .............................................................................................................. 33 2.5.1 Up-rating of the Existing 275 kV Louth-Tandragee Circuits ........................................ 34 2.5.2 Up-rating of the Existing 220 kV Circuits in the North-East Corridor ........................... 35 2.6 Conclusions .................................................................................................................. 36 3 TECHNOLOGY OPTIONS........................................................................................................ 37 3.1 Project Objectives/Design Criteria ............................................................................... 37 3.2 Review by the International Expert Commission (August – November 2011) ............. 38 3.3 DC Technology as an Alternative to AC Technology ................................................... 39 3.3.1 Overall Conclusion on a DC Circuit as an Alternative to a Standard AC Circuit ......... 44 3.4 Undergrounding the Entire Interconnector using AC UGC .......................................... 46 3.5 High voltage AC XLPE UGC and Extent of its Use ..................................................... 47 3.6 Update on Reliability Statistics for High Voltage AC UGC and OHL ........................... 49 3.7 Update on the World’s Longest High Voltage AC XLPE Cable Circuits ...................... 50 3.8 Update on the Cost Comparison of AC Underground Cable and AC Overhead Line . 53 3.8.1 Capital Costs ................................................................................................................ 53 3.8.2 Life Cycle Costs ........................................................................................................... 53 April 2013 i North-South 400 kV Interconnection Development Final Re-evaluation Report 3.9 Consideration of a Hybrid AC Overhead Line/AC Underground Cable Option ........... 54 3.9.1 The Hybrid Option - Environmental Issues .................................................................. 55 3.9.2 The Hybrid Option - Technical Issues .......................................................................... 56 3.9.3 The Hybrid Option - Cost Issues .................................................................................. 57 3.9.4 Conclusion on Hybrid UGC/OHL Option for the Proposed North-South Interconnector ............................................................................................................. 58 3.10 Alternative Overhead Line Support Structures ............................................................ 58 3.11 Conclusions .................................................................................................................. 61 4 IDENTIFICATION OF PROJECT STUDY AREA ..................................................................... 62 4.1 Introduction .................................................................................................................. 62 4.2 Appropriate Points of Connection to the Existing Transmission Network .................... 63 4.3 Identification of the Study Area of the Planned North-South 400 KV Interconnection Development ...................................................................................... 69 4.4 Description of the Study Area ...................................................................................... 70 4.4.1 The Cavan – Monaghan Study Area (CMSA) .............................................................. 71 4.4.2 The Meath Study Area (MSA) ...................................................................................... 73 4.5 Conclusions .................................................................................................................. 74 5 IDENTIFICATION OF ENVIRONMENTAL AND OTHER CONSTRAINTS WITHIN THE PROJECT STUDY AREA ......................................................................................................... 75 5.1 Background to the Identification of Constraints ........................................................... 75 5.1.1 Re-evaluation Parameters and Considerations ........................................................... 76 5.1.2 Constraints Mapping .................................................................................................... 77 5.2 Identification of Constraints .......................................................................................... 78 5.2.1 Natural Constraints (Naturally Occurring Landscapes and Features) ......................... 80 5.2.2 Artificial Constraints (Forming