Hawaii prepares to close its last coal plant

Utility Dive:

As Hawaii prepares to shutter its last operating coal-fired power plant — the 180 MW AES plant on the island of Oahu — state regulators and its utility have assembled a multi-pronged approach to ensuring grid reliability despite delays to several planned solar and storage projects.

The Oahu coal plant is the single largest generator on Oahu, serving roughly 16% of the island’s peak electricity demand. The plant is set to be retired by September, and, originally, was supposed to be replaced by a series of utility-scale renewable energy projects. However, after many of those projects began experiencing delays — leading to concerns among Hawaii regulators about grid reliability — Hawaiian Electric and state officials have turned to a combination of demand response, distributed energy resources, and other measures to keep the lights on after the coal plant goes offline.

Hawaii was the first state in the country to set a deadline for achieving 100% renewable electricity sales, required by 2045, and crossed the 30% renewable electricity sales threshold in 2020. At the same time, it’s also the country’s most petroleum-dependent state – more than four-fifths of its energy consumption is petroleum-based, according to the U.S. Energy Information Administration, with the electric power sector using about a fifth of all the petroleum consumed by the state.

Hawaii has a more challenging task than many other states when it comes to the clean energy transition, according to Scott Glenn, Hawaii’s chief energy officer, who leads the Hawaii State Energy Office. “We’ve got a harder race to run because we’re taking six standalone grids, in the middle of the ocean, to a 100% renewable energy for electricity — and we’re starting from a high fossil fuel starting point,” Glenn said. 

The AES coal plant isn’t the only fossil fuel-fired facility that Hawaiian Electric is looking to retire in the coming years. The utility also plans to retire the 38 MW oil-fired Kahului plant on Maui, which constitutes roughly 15% of the island’s firm power generation capacity, by the end of 2024. To replace the power that would be lost from the planned retirements, in early 2018, the utility launched the first stage of a competitive solicitation for new renewable projects on Oahu, Maui and Hawaii Island, which resulted in eight “Stage 1” utility-scale solar and storage projects.

The following year, Hawaiian Electric issued another solicitation, which resulted in 12 “Stage 2” projects: nine utility-scale solar-plus-storage facilities, and three standalone storage systems. Half of the 20 projects are sited on Oahu and 18 of them are being built by private developers.

[Kavya Balaraman]

More: Hawaii poised to close the door on coal despite delays to clean energy projects