Suviana accident, what could have happened in the Bargi power plant: the possible scenarios

Credits: Fire Brigade.

The toll from the tragic accident which occurred around 2.30pm on 9 April 2024 at Bargi hydroelectric power station on the artificial lake of Suviana, in the province of Bologna. During scheduled maintenance, the first testimonies speak of a violent “explosion” at one of the two turbines of the power plant, approximately 40 meters deep compared to the lake level, and of a fire. Following the damage, an attic collapsed and the -9 floor of the power plant was flooded, along with part of the -8 floor, making the search and rescue activities of the Fire Brigade very complex. In this video we try to describe the most probable dynamics of the accident based on the – little – information we have available.

The Bargi hydroelectric power plant, managed by Enel Green Poweris a well power plant, which transforms the potential energy of the water arriving from the nearby Lake Brasimone (about 5 km away and at a higher altitude than 375 meters) into electricity. Basically, the water arrives via two large pipes that feed the same number turbines connected through mechanical shafts to two alternators that generate electrical energy. The central one, high 54 metersdevelops three quarters below the surface of the water and is divided into two main parts: higher up (i.e. closer to the water surface) there are the two alternators, while lower down we find the two turbines (on the floors –8 and –9).

well hydroelectric power plant diagram with track group
Diagram of a well hydroelectric power station with binary group (alternator+turbine) like the one in Bargi.

So we have the part down hydraulics of the power plant and on the side electric. This is important because the turbine area is predominantly mechanical and therefore there is very little that can explode. So it is not certain that there was technically an explosion: a mechanical problem with the turbine may have caused a large “bang” which was later mistaken for an explosion.

The fire, however, could have occurred on the higher floors of the power plant, in the alternator area: for example, the damage to the turbine, spreading through the shaft, it could have caused a short circuit in the alternator which in turn would have started the fire. In fact, we would like to remind you that the confirmed victims and the rubble were found in the lower part of the power plant. The damage to the turbine would also have caused the breakage of some refrigeration pipes, thus causing the flooding of the lower floors of the power plant.

A'alternative hypothesis it is that the explosion directly involved the alternator. In fact, one of the rescuers declared that “the alternator on floor (minus) 8 exploded”, but -8 should be the floor where the turbine is located, while the alternator would be higher up.

We reiterate that at the moment we are not certain that the dynamics was actually the one we reconstructed. This is a possibility scenario with a technical-scientific logic that at the moment seems more likely as it is compatible both with the information disseminated and with the structure of the exchange. The truth about what happened will only emerge with the official investigations, which have already been prepared.

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