Despite being located on the beautiful Hawaiian island of Oahu, the Kalaeloa Cogeneration Plant had trouble in paradise: Large amounts of ash from #6 low-sulfur fuel oil coated the finned tubes of its heat-recovery steam generators (HRSGs). The fouling added an extra $5 million dollars a year to the plant’s fuel bill. By retrofitting the HRSG with new panels and improved fin design, the plant overcame the fouling problems, stopped tube leaks, and cut fuel costs.
The Kalaeloa facility on the island of Oahu is a 208-MW combined-cycle cogeneration plant that uses low-sulfur fuel oil (LSFO). It is owned by PSEG Global and Harbert Power Corp., operated by Kalaeloa Partners LP, and sells all of its electric energy to the island’s utility, Hawaiian Electric Co. (HECO), under a long-term power purchase agreement. HECO reimburses the facility for energy delivered, assuming predetermined fuel consumption at different loads. If the plant’s fuel efficiency is not as initially assumed, the plant owner is responsible for the added cost of the extra fuel.
In addition, the plant supplies thermal energy in the form of steam to a local refinery, Tesoro Hawaii, one of only two refineries on the island. Kalaeloa provides 90% of the refinery’s thermal requirements and supplies approximately 20% to 25% of the entire island’s electrical generating capacity. The plant’s output is critical for meeting the energy needs of Oahu, the third-largest of the Hawaiian Islands (Figure 1).
1. Ocean-front property. The Kalaeloa Cogeneration Plant is in the foreground, with the Tesoro refinery’s wastewater treatment facility and fuel tanks behind it. Diamond Head and Honolulu are in the far background. Courtesy: Gary Hofheimer
Plant Profile
The cogeneration facility provides a portion of the steam needs for Tesoro (previously Broken Hill Proprietary). An approximate total hourly production of 100,000 pounds of steam at three pressure levels (700 psi, 450 psi, and 235 psi) can be supplied. Tesoro’s steam requirements qualify Kalaeloa as a cogenerator under the Public Utility Regulatory Policies Act of 1978. The 208 MW of firm capacity net electrical power provided to HECO is provided at 138 kV to the HECO grid via the adjacent CEIP substation.
The plant comprises two ABB 85-MW (type 11NM) gas turbines, one ABB 51.5-MW extraction/ condensing steam turbine, two Deltak heat-recovery steam generators (HRSGs), and the balance-of-plant equipment that completes the combined cycle (Figure 2). The primary plant fuel is low-sulfur fuel oil. No. 2 diesel fuel is also used as short-time backup fuel and for start-up and shutdown of each gas turbine. Propane is used for the ignition of each gas turbine.
2. Powering Oahu. The Kalaeloa plant entrance with water demineralization plantand demineralization storage tank on the right; the steam turbine, control room, and administrative building on the left; and both stacks of the two combustion turbines in the background. Courtesy: Gary Hofheimer
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