Kathleen Lynch (Cork North Central, Labour)
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Question 56: To ask the Minister for Communications, Energy and Natural Resources the position regarding the north south interconnector and the report into overhead versus underground transmission lines which was due for publication in early June 2008; and if he will make a statement on the matter. [28038/08]

Eamon Ryan (Dublin South, Green Party)
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The Independent Study on the Comparative Merits of Overhead Electricity Transmission Lines versus Underground Cables was published yesterday and I have forwarded it to the Joint Oireachtas Committee on Communications, Energy and Natural Resources.

The study was conducted by International consultants Ecofys, in partnership with an expert in underground cable technology, Professor Dr Heinrich Brakelmann of the University of Duisburg-Essen, Germany, and with Golder Associates, a global group specialising in ground engineering and environmental services.

The study examines available electricity transmission technologies, their characterisation, comparisons of techno-economic characteristics and environmental impacts, policy implications and costs. It also includes a review of over 500 stakeholder submissions received by the Department as part of the submissions process, analysis of current international practice and two hypothetical case studies with route lengths of 100km and 50km. The study was completed on a national basis and is not project specific.

The study represents an impartial, independent, technical assessment on the relative merits of overhead electricity lines versus underground cables and provides important further information that can used to facilitate decision making for current and future individual projects.

In its conclusions, the study notes the increasing pressure internationally to place electricity transmission infrastructure underground and the continued technology development in the field of underground cables at high and extra high voltages. The study states however, that the size and number of existing underground cables internationally is limited and that the majority of existing projects do not represent transmission connections in conventional networks. It also notes that underground transmission cables can be expected to have forced outage rates (likelihood of unplanned system breakdowns) which are at least 10 times more frequent than those expected of overhead lines. The consultants describe this as a "severe limitation" for underground cables and that consequently, underground cables do not therefore compare to overhead lines in terms of adequacy of the electricity transmission system and reliability of electricity supply. The consultants describe this finding as "the dominating criterion" when comparing overhead and underground technologies and note that the associated negative impacts cannot compensate for any of the advantages of underground cables.

The study also notes that the cost implications underground cable proposals are difficult to quantify, but would be significant. Based on case studies conducted by the consultants, they state that the cost of underground cables would be approximately five times greater than the capital cost of overhead lines and three times the lifecycle cost. In relation to perceived health impacts, the study notes that EirGrid operates within WHO guidelines and that in practice, the transmission system generally operates at levels that are 80-90% lower than the levels recommended in these guidelines.

I am fully supportive of the Joint Committee's commitment to full and objective debate of all the complex issues and to hear the views of all sides. Ecofys have confirmed their availability to present their report to the Joint Oireachtas Committee when required.

I have no statutory function regarding specific power lines, including the north south interconnector. The planning, development and routing of transmission line infrastructure is a matter for EirGrid, which is the State body responsible for operating the electricity transmission system in Ireland, including the wholesale electricity trading system. I forwarded the Ecofys study on its publication, to EirGrid and to ESB Networks.

Approval of the Transmission System Development Plan, which includes power lines, is a matter for the Commission for Energy Regulation, which is statutorily independent in carrying out its functions. Individual power lines also require permission under the relevant planning process including the Strategic Infrastructure Board where appropriate.