Power was down for nearly five hours, which led to a considerable drop in temperature in the electrolysis cells and production had to be stopped. There were no injuries or uncontrolled emissions.

The reason for the power outage was unclear as of Tuesday morning. The outage affected the connection to the national grid in Qatar and Qatalum’s own power station.

Although power supplies resumed, the electrolyte in most of the 444 affected cells had cooled to the point that it began to solidify, and these cells must be prepared for a restart. The remaining 260 cells will be started up as originally planned.

Qatalum planned to reach full production by the end of 2010. This will be delayed as a result of the power outage. Qatalum is now preparing a revised start-up plan.

Qatalum will investigate the cause of the outage in cooperation with the authorities in Qatar.

Qatalum is a 50-50 joint venture between Norsk Hydro ASA and Qatar Petroleum. Qatalum has a total annual production capacity of 585,000 tonnes of primary aluminium.