Rolling blackouts could end Friday

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Guam residents experienced rolling blackouts Tuesday and Wednesday evening after the 55-megawatt Cabras 2 generator, which returned to service only a month ago after a $4.9 million overhaul, broke down Tuesday with boiler tube leaks.

One-hour rolling blackouts affected customers between 6 and 9 p.m. Tuesday and 6:48 p.m. to 9 p.m. Wednesday.

The first haul of heavy power plant modules is transported from Cabras Island in Piti to the Guam Ukudu Combined Cycle Power Plant in Dededo, Feb. 4, 2023. Guam remains vulnerable to power outages until the 198-megawatt power plant starts operating next year. Residents this week experienced two evenings of rolling blackouts.

The Cabras 1 generator was shut down for maintenance at the time, and the loss of the Cabras 2 generator, combined with limited generating capacity by the 44-megawatt Piti 9 generator, left GPA with a maximum generating capacity of only 221 megawatts Tuesday evening. That is about 30 megawatts short of the peak power demand.

The Cabras 1 generator, which has been down for scheduled repairs, is scheduled to be back online by Friday, according to the Guam Power Authority.

It's unclear how long it might take to repair the Cabras 2 boiler tube leaks and return that generator to service.

Rolling blackouts still were possible Thursday evening, according to the power agency, which stated the Guam Waterworks Authority switched its wells and pump stations to standby generators to reduce the power demand. Large power customers, including the Navy, also have been asked to switch to generator power during peak demand hours, according to GPA.

GPA's legal counsel has said the decades-old Cabras generators are unreliable, even after expensive overhauls. The Cabras generators burn oil to heat water for steam turbines. The generators have miles of boiler tubes.

"What seems to happen, because the units are almost 50 years old, … three months later, four months later, the boiler is leaking. It's just never going to get better," GPA legal counsel Graham Botha told the Public Utilities Commission in April 2022, when the commission approved the Cabras 2 overhaul.

Botha said the overhaul was necessary, however, to prevent turbine blade failure, which could put the generator out of commission even longer.

The island will remain vulnerable to blackouts until the new 198-megawatt Ukudu power plant starts operating next year, according to GPA.

Guam residents also experienced rolling power outages last August when the Cabras 2 generator and the Piti 8 generator broke down while the Piti 9 generator was out of service for a scheduled overhaul to convert it to diesel fuel.

Cabras 1 and Cabras 2 are scheduled to be decommissioned in late 2024, after the Ukudu power plant is operating, to comply with federal clean air regulations.

GPA wants to continue to operate the Piti 8 and Piti 9 generators, which now burn ultra-low-sulfur diesel, until 2029.

A project to build a 41-megawatt reserve diesel power plant in Piti recently was canceled due to excessive cost.

Reach reporter Steve Limtiaco at

[email protected].

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