East Oahu Transmission Project
Critical Reliability Concerns
The East Oahu Transmission Project will address critical electric power reliability concerns for the area from downtown to Hawaii Kai and from Kahuku to Makapuu Point. The area comprises 56 percent of the power demand on Oahu and includes downtown, the University of Hawaii at Manoa, Kapiolani Community College and Waikiki as well as Windward Community College, Brigham Young University and countless homes and businesses. The impacted area includes Marine Corps Base Hawaii in Kaneohe, State Civil Defense Headquarters at Diamond Head, Fort Ruger (Hawaii National Guard headquarters), the Honolulu Police Department, and the Prince Kuhio Federal Building that includes FBI Headquarters, all vital to Hawaii’s security needs.
1. Pukele Substation, which delivers electricity to Manoa, Palolo, St. Louis Heights, Kaimuki, McCully/Moiliili, Diamond Head, Kapahulu and Waikiki, is supplied with power by two 138 kV lines that run across the Koolau mountain range from the Koolau Substation in Kaneohe. These lines run through difficult terrain with limited access where they are constantly exposed to high winds and corrosive weather. When one line is removed from service for maintenance, the second line must carry the entire load. If the second line goes out for any reason, there is no back up and an immediate major outage would affect 16 percent of the total Oahu power load, including Waikiki.
2. Three 138 kV lines bring power from the Ewa area to the Koolau Substation in Kaneohe. The Koolau Substation serves the area from Kahuku to Hawaii Kai and into Kahala, an area that uses about 14 percent of the power on Oahu. The Koolau Substation also supplies power to Pukele Substation described above, meaning 30 percent of Oahu’s total power needs flow through Koolau. If one of the three lines is down for maintenance and a second line goes out for any reason, the third line would have to carry all the power. If that line continues to carry excess electricity, it would heat up and begin to sag. To avoid permanent damage to the line, HECO would be forced to take the third line out of service, cutting power to the entire Windward side and the Pukele service area, including Waikiki. Under forecasted load growth, this vulnerability becomes a risk in about 2005.
3. Similarly, three lines and the Honolulu Power Plant serve downtown, supplying 26 percent of power demand on Oahu. Just as on the Windward side, if one is down for maintenance and another goes out, the result would be an overload risking damage to the third line followed by a blackout over much of the area. This becomes an increasing risk by the year 2023. # # #