Mr. Peter O'Shea:

All of these technologies will have a part to play but there are limits to what they can achieve. Battery technology is advancing steadily. The energy density of batteries is increasing day by day and week by week and that is what is putting the real emphasis on electrification of transport and electric vehicles. These are limited enough in terms of the actual storage an individual device can provide but when one uses the law of large numbers and put a lot of them together, one starts to get to something that is useful. I told this committee 18 months ago that if we were to store one day's worth of electricity in Ireland in the Turlough Hill-type power plants for when the wind does not blow and the sun does not shine, we would have to build 60 new Turlough Hills. This constitutes massive storage capability but also a level of implementation that is not credible right now. Equally, were we to store one day's worth of electricity in batteries, if one takes the Tesla Powerwell that is currently available commercially and is a 10 kW-hour battery, one would need something like 14 million of them on houses in Ireland so this is six or seven batteries on the side of every house. Again, this says to me that there is something that can certainly contribute but it probably cannot achieve a full day's worth of energy storage. The challenges are real, which is why the we in the ESB would say that when we look at the technologies, we should not discount any of them because the challenge is so big that we have to get to the end of this and all of these technologies have a part to play.