More than 8,000 Big Island customers lost power Tuesday night after Hawaiian Electric enacted several rolling blackouts.
Following the shutdown of a pair of large generators - one for repairs and one because of unexpected damage - Hawaiian Electric advised customers to conserve power Tuesday from 5 p.m. to 9 p.m. to make up for an 80 megawatt power shortfall.
Despite the advisory, Hawaiian Electric announced shortly before 7 p.m. Tuesday that it would conduct 30-minute rolling outages starting in the areas of Ainaloa and Pahoa, Captain Cook to Honaunau, and Halaula along Akoni Pule Highway from Iole Road to Niuli Place.
"The brief emergency outages will be initiated in various areas around the island to protect the electric system and prevent loss of power to an even greater number of customers,"according to the announcement.
At 9:30 p.m., Hawaiian Electric said in statement an estimated 8,580 customers were impacted by the blackouts, which began at 7:20 p.m. and ended at 8:06 p.m.
Hawaiian Electric spokeswoman Kristen Okinaka stated via email on Wednesday that conservation efforts by residents and business owners helped reduce the strain on the power grid, but noted that the lack of wind on a hot day caused both a higher use of air conditioning and a lack of wind-generated power to bolster the grid's capacity.
Okinaka wrote that Hawaiian Electric's systems operations team determined the sites of the blackouts based on several factors.
"Our system operations team manages the island's electric grid and determines whether we will have sufficient generation to meet the evening peak, which is when electricity use is the highest," Okinaka wrote. "The peak is from 5 p.m. to 9 p.m. The impacted areas and the timing of the outages are based on the amount of electric demand that needs to be reduced in real time. The areas also are rotated so different areas are selected for this type of emergency outage."
Okinaka wrote that the need for further conservation efforts or outages has passed for now.
One of the two generators that shut down Tuesday - called Hamakua Energy - failed unexpectedly when a pair of transmission lines tripped, which caused damage that took several hours to repair, but those repairs were completed Tuesday evening and the generator is back online.