@struth Blaenau Ffestiniog is a nice place if you can ever take the grandkids. Apart from the hydropower station there is the slatemines and a zipline.
Llandudno is great to visit. Snowdonia has the largest hydropower which as you say would be interesting to see. Apart from all the other atractions it is also home to velocity 2 the worlds fastest zip line 100mph but we will say no more on that lol