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| 38 kV line that carries power to Kilcullen. © Eugene Brennan |
Today was a busy day! First I had to scoff my dinner quickly (well half of it!) to be up at Dún Ailinne by 1:30 for the site tour. There was an open day today at which archaeologist Dr Susan Johnston of George Washington University gave us an update on what work had been done so far this summer. Dr Johnston has been investigating the neolithic and iron age ceremonial site since 2006, alongside a team of archaeology students. On the walk back, I snapped a picture of the pylon near the motorway bridge, that carries the power lines that supply electricity to Kilcullen. Those lines come from a substation adjacent to the turn for the Glen of Imaal on the N81. Electricity is transmitted at 38,000 volts or 38 kV from the Stratford substation in Wicklow, before being dropped to 10 kV for distribution by the transformers in the Kilcullen substation. What's interesting is that all the power for Kilcullen is supplied through three cables, probably not much thicker than a half or three quarter inch rope. In fact if the voltage was much higher, say a few million volts or so, those cables would only have to be the size of the wires on your phone charger. As you may remember from a previous article, Why are Voltages So High for Electricity Transmission?, one of the reasons for using such high voltages is to reduce current and hence power loss in cables. If we need to supply gas or water to a location, pipes have to be physically greater in diameter if we want to transport larger volume flow rates at the same pressure. That's because gas and water are actual stuff or matter. However energy isn't matter or a tangible quantity that takes up space and which one could hold in their hand. It's a property of matter. So it doesn't necessarily need a large conduit for transmission in the same way that water does. In fact in principle, superconductors the thickness of a human hair could supply the power demands of a city.
After having the rest of my dinner, I headed off on a cycle trip to Ballymore to do the 5k loop. I took another snap here of the outflow from the Ballymore Water Treatment Plant, which crosses the trail on the loop and also the river. I think this is the original feed that supplies water to the reservoir at Old Kilcullen. There's at least another main that heads northwards to Dublin. Over 10 years ago, the water mains were upgraded to the reservoir. The new lines operate at a higher pressure, so they can supply a higher flow rate, even though the diameter is smaller than the original line. In fact Kilcullen now actually receives most of its water from the River Barrow, water being pumped from the Srowland Water Treatment Plant near Ardscull to the reservoir at Old Kilcullen, where it's mixed with Liffey water. The tank is so cavernous that lorries were being driven around inside it during construction, or so I'm told.
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| Water mains from Ballymore Water Treatment Plant. © Eugene Brennan |
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| © Eugene Brennan |
