I drove my wife's Opel first time after a while and I think there is a weird sound coming from the engine area. I am not a mechanic but I think it sounds like a faulty bearing sound, kind of grinding noise. Please check the following video I captured and let me know what you think?
Sounds like a pulley/tensioner/alternator bearing. If you remove the belt as described above and the noise goes you narrow the problem to a few possibles, the car will run although the alternator light will come on as the alternator is not turning and the battery is not being charged. Does the car have Aircon? You can use a small length of hose and put one end near you ear and the other by each tensioner etc sequentially to narrow down the noise, but don’t get it/you tangled in the belt/fan. The noise is so obvious a garage should suss it in no time if it is not within your diy skills.