Mr. Garrett Blaney:

I will try my best. We gave the background in the presentation so that the committee could understand the context of the need for the second interconnector. In terms of the technical issue, I will attempt a layman's description of it, but Deputy Colreavy would probably need to go back to EirGrid if he wants to get a detailed technical analysis of his proposal. My understanding is that the problem is length. With AC, one can only do a certain length underground before one hits technical problems, and at lengths beyond that one must use DC. Clearly, if one were to put the two converter stations beside each other at the Border, one would still have long lines underground and the same technical problems. I would refer the Deputy to EirGrid if he wants to get into more of the technical detail, but it is not possible or practical to have the two converter stations beside each other. It would preclude the need for them in the first place. One would end up with everything underground, and it would not work.

With regard to the sterile area, this is because one cannot connect DC lines to the electricity system; only AC lines can be connected. If standard pylons go through an area, it is relatively easy to take the cables from the pylon down into a substation and back up onto the pylons. When the connector is underground as a DC cable, a converter station is needed, and once we go beyond a converter station at each end, the complexity becomes much more significant. DC systems are much more difficult to run and there are some fundamentals, such as whether one can switch the current on and off, that one can do easily with AC but that become a major problem with DC. I apologise, as I am not the technical expert here. I am trying to give a layman's view of the process. If Deputy Colreavy has any further questions, I suggest that EirGrid would be able to explain it more efficiently for him.