2001 Hyundai Accent Spark Lightning under Engine

I noticed about 3 Months ago, that my vehicle make a frequent clicking noise, around every 15 Seconds when engine was runing. I opend the hood and it sounded like a static discharge, but you couldnt see it and I didnt feel anything beside that noise. During the months the noise starts to come more frequent and it got louder. So we opend the hood and checked it again, seeing a blue lightning spark coming from the tensinor of the AC belt, every 8 seconds. The Compressor is disconnected due its broken, there is no need for it right now anyways, so the tensioner is not connected to anything right now. This Thursday it was getting so loud that you could hear it even with the hood closed, so we checked it again. We figured out a second location right under the engine in the middle between the oil pan and the harmonic balancer, no cables, just steel there, with the same frequence. My friend and me fix everything on it, but we have no clue about this electrical problem. I dont feel anything though, its driving normal and the electric is working as it should. Help is really apprechiated.