Maui Joint Venture spokesman Simon King said today from Wellington that gas production constraints following Tuesday's outage had finally been overcome from 11.30pm last night and normal production had resumed.

Tuesday's gas production from New Zealand's largest energy resource was constrained to around 50% of normal system deliverability, pending repairs to damaged turbine generators on the A platform.

Repairs to the three turbine generators had started, although it would be several weeks before full system redundancy was again available. In the interim, auxiliary generators and heat recovery systems mobilised to the platform would be sufficient to meet normal gas supply requirements.

During the latest of three unplanned, emergency shutdowns at Maui A, Methanex had to completely close its Taranaki methanol plants, Genesis Power switched its 1000MW Huntly station to coal, while Contact Energy shut its Otahuhu, Auckland, stations, although it managed to keep the New Plymouth station idling. NGC wound back electricity production at the Stratford TCC plant, which uses Maui and Tawn (Tariki, Ahuroa, Waihapa and Ngaere) gas. Spot prices on the electricity market more than doubled, soaring to as much as $NZ525 per megawatt hour.

King said investigations into the root cause of turbine generator failure were continuing and noted that the problems which resulted in turbine generator damage had never previously occurred in the 23-year production history of the Maui facilities.