Ethiopia’s energy authorities Friday confirmed that the mega power plant in the country with no dam, which was constructed at a cost of 281 million euros ($407 million), already collapsed.

With an installed capacity of 420 megawatts, Gilgel Gibe II uses water from another dam constructed more than 26kms from it for an earlier commissioned power plant called Gilgel Gibe I, after it generates 180Mw in the older station. The water is then channeled through 25.8kms and 6.3m diameter concrete tunnel bowered through chains of mountains. It generates more power at GII because of the elevation difference created due to the design at the later.

The 1,000m long two metal penstocks at GII, that pour the water from the tunnel in the mid-height of a mountain down to the turbines at the bottom, would increase the turbine circulation.

“Geological incidents in the tunnel caused the closure of the plant,” said Alemayehu Tegenu, Minister of Mines and Energy, at a press briefing on Friday. Present were Meheret Debebe, CEO of Ethiopian Electric Power Corporation (EEPCo), and management of the project contractor and supervisor.

“We are currently investigating the cause of the slit,” Meheret said.

Biggest power plant

Financed by Italy, Gibe II is the Horn of African state’s biggest power plant featuring 4 x 105MW pelton units, the TBM tunnel, penstocks and surface powerhouse. But only one of the four units was operating since inauguration.

Its construction by the Italian giant, Salini Costruttori SpA, had been delayed by more than two years. A high-profile January 13 inauguration of the project was attended by Prime Minister Meles Zenawi and Italian government officials.

About 10 days after the ceremony, the project’s core component, the 25.8 kilometer-long tunnel, collapsed shutting down operations for an extended period. The geological incident has slit the concrete lining 9kms in the tunnel and EEPCo closed the plant three days later. The repair could take months, reports indicate.

Maintenance work is being carried out following the rockfall in the project’s headrace tunnel. According to a statement by project builders, Salini Costruttori, an unforeseen geological event provoked a rockfall involving about 15m of the 25.8km long headrace tunnel.

Salini said maintenance will be carried out over the next two months to recover full operational capability at the 420MW project.

Over 2,100 Ethiopians and foreigners took part in the construction of GII plant, located 250kms south-west of Addis Ababa on the Omo valley.