Kahului Power Plant shutdown plan presented
New switchyard would be built, plant turned into transmission center
Hawaiian Electric has developed a plan to shut down the power generation capability of the 72-year-old oil-fired Kahului Power Plant in 2024, while maintaining some of its power distribution capabilities, and building a new switchyard off Pulehu Road.
The plan was submitted to the state Public Utilities Commission for approval on Oct. 22.
The Kahului Power Plant in the Kahului Harbor area was shut down February 2014 after the utility pledged to retire the four oil-fired, steam generators considered old, inefficient and environmentally dirty. But the utility decided to restart the plant in 2016 with increasing power demands and the shutdown of Hawaiian Commercial & Sugar Co., which provided 4 to 16 megawatts of power.
Now, Hawaiian Electric says it plans to retire the energy generating capabilities of the plant in 2024 due to age, the location of the plant in a tsunami inundation zone, the expiration of a National Pollutant Discharge Elimination permit related to the release of water used for cooling into the ocean, and the need to use more renewable energy, the utility filing with the PUC said.
“Based on extensive review and analysis of different options, the company determined this switchyard/synchronous condenser project is the best-fit and most cost-effective solution to do so,” the PUC filing said.
Hawaiian Electric spokeswoman Shayna Decker pointed out Thursday that “using the existing equipment at KPP to convert into the synchronous condensers compared to building them at a new site came out as the lower cost and most efficient option.”
“Using the current KPP facility also does not require acquiring, permitting and constructing of a new site, which would not be completed in time to retire the KPP units in 2024,” she added.
The system upgrades are estimated to cost about $38.8 million, which the utility is seeking to recover from ratepayers, the filing said. However, Decker said that the project actually will result in a $2.33 monthly bill reduction over the life of the project for the typical residential customer because the cost to operate the power plant will be offset once the generating units are retired.
By 2025, the utility estimates that there will be $4.8 million reduction in operating and maintenance costs at the Kahului Power Plant.
The Kahului Power Plant, put in service in 1948, currently provides power generation and transmission support for more than 13,000 residential and business customers in Central Maui, including Kahului Harbor and county water facilities, the filing said.
“The Switchyard/Synchronous Condenser Project addresses operational issues that will otherwise result from not generating electricity at KPP, thereby increasing the Company’s ability to add more renewable resources and improving Maui’s system reliability,” the filing said.
An analysis of the Kahului Power Plant shutdown identified two major issues: A need to replace the power generation capacity of the plant and transmission issues that arise through the loss of voltage support, inertia and short circuit current.
On the first point, the company said it is working to procure replacement power generation through large-scale renewable energy and battery projects. The utility has two contracts for solar and battery projects in Central and South Maui that have been approved by the PUC and two additional solar and battery projects in Central and West Maui that are being reviewed by regulators.
Hawaiian Electric also is building its own $60 million 40-megawatt, 160-megawatt-hour battery energy storage system near the proposed Waena Switchyard, which will help address the transmission issue with the Kahului Power Plant shutdown.
The switchyard would be located on company-owned property along Pulehu Road near the Central Maui Landfill. It would resemble a substation.
The new switchyard will be essential for transmission, collection and controlling the flow of electricity from other generation power sources when the Kahului Power Plant shuts down. Those sources include renewable energy projects, as well as the company’s Ma’alaea Generating Station and the proposed Waena battery energy storage system.
The Waena Switchyard will interconnect two transmission lines, allowing for greater flexibility for maintaining reliable connections from the Maalaea power plant to Central and Upcountry, Decker said.
She added that having the switchyard near the battery system “enables a cost-efficient, secure connection” and that the site was acquired by the utility to build facilities like the switchyard.
The goal is to have the switchyard operational by December 2022, the filings said.
The conversion of two of four Kahului Power Plant units to nongenerating synchronous condensers involve installation of start-up motors to use the units to control voltage and maintain inertia on the system. The two remaining units would be permanently shut down and no longer able to generate electricity. The current power plant facility would house the synchronous condensers and other equipment used to support the electrical system, the utility said.
The utility would have to modify its current NPDES permit to include the synchronous condenser operations. The synchronous condensers will reuse portions of the existing cooling water system and will require significantly less water than the steam electric generating units, Decker said.
The Kahului Power Plant generator conversion is set to be operational in 2024. The utility asks that the PUC make a decision on the allotment of funds for the project by September to allow for procurement of materials and to start construction by January 2022.
* Lee Imada can be reached at firstname.lastname@example.org.