HECO retiring 35% of firm generators on Maui by 2028, replacing with renewable energy

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Hawaiian Electric Companyʻs Māʻalaea power plant. (Sept. 2022) PC: Wendy Osher

Hawaiian Electric is gearing up for a transformative decade on Maui, as the utility company plans to retire 88 megawatts (MW) of its fossil fuel firm generators, or roughly 35% of the firm generator capacity on Maui. This major overhaul is driven by state environmental regulations and difficulties in sourcing parts for aging generators, many of which have become obsolete.

Between 2028 and 2030, Hawaiian Electric Company (HECO) plans to lose 50MW from diesel engines at the Māʻalaea Power Plant and another 38MW from the closure of the Kahului Power Plant. At a Public Utilities Commission meeting on Tuesday, Vice President of Power Supply Mike DeCaprio highlighted the challenges ahead, saying, “For years, we have stated concerns with the energy margins on Maui. Today, that is temporarily resolved with the commercial operation of the Kūihelani Solar Storage project. But by 2028, it’s going to be challenging.”

Part of the challenge stems from pandemic-induced setbacks that saw four renewable energy projects scheduled for 2027-2028—intended to comprise 66% of Maui’s capacity—drop out due to supply chain issues, permitting delays, and the high cost of doing business during COVID-19. This left only the Kūihelani and Waena Storage projects moving forward.

Despite the setbacks, HECO has remained committed to meeting the state’s Renewable Portfolio Standards (RPS), which mandates achieving 100% renewable energy by 2045. In 2023, HECO reported 35.4% renewable energy (renewable mix: 19.1% customer-sited solar, 15.7% wind, 0.6% grid scale solar) on Maui County.

Compliance YearRPS Requirement (% of Generation)
Hawaiʻi Renewable Portfolio Standards by year.
County comparison of meeting State RPS benchmarks. PC: State of Hawaiʻi Public Utilities Commission

Currently, Maui’s power grid comprises a mix of firm and variable (as-available) power sources, totaling 253MW. At Māʻalaea Power Plant, which has a capacity of 212MW, the diesel generators and combustion turbines, which are “essentially jet engines that produce power” will start phasing out between 2028 and 2030. Mitsubishi, the engine manufacturer, will no longer supply parts for these engines, rendering them obsolete.


Similarly, the 38MW Kahului Power Plant, which relies on steam turbines and industrial fuel oil, must retire by the end of 2027 due to conditions in its air permit. The Clean Air Act requires states to restore natural visibility in national parks, necessitating the plant’s closure. However, HECO has secured a one-year extension from the State Department of Health, allowing the plant to operate until the end of 2028 if necessary.

Maui’s renewable energy landscape includes privately-owned wind farms like Kaheawa I (30MW), Kaheawa II (21MW), and Auwahi (21MW), as well as Hawaiʻi’s largest solar farm, AES Kūihelani (60MW), and SMRR (2.87MW). Additionally, private rooftop solar systems contribute over 100MW—more than half the peak load on Maui—according to HECO.

Hawaiian Electric Company presentation screenshot at the Maui grid update hosted by Public Utilities Commission on Tuesday, July 2, 2024. PC: Hawaiian Electric

Looking forward, HECO is progressing with the 40MW Waena Battery Energy Storage System (BESS), set for completion in November 2026. They have also selected an independent power producer to create a 40MW firm renewable generator at the Waena site, which DeCaprio emphasized is crucial for retiring fossil fuel generators.

In December 2023 and January 2024, HECO selected five more projects to bolster Maui’s renewable capacity, including AES Kūihelani Phase 2 Solar, Terraform’s Kaheawa Wind 1, Longroad’s Pūlehu Solar & Storage, and Ameresco’s ‘Ūkiu Energy biofuel project. These projects include a community benefits package that allocates $3,000 per MW (capped at a minimum of $200,000 per year) to host communities.

Are Hawaiian Electric’s wildfire mitigation techniques enough?

PSPS Map for Maui County. PC: Hawaiian Electric Company

Public Safety Power Shutoff (PSPS) launched July 1. A PSPS is a process electric utilities use to deactivate power in high-risk conditions for safety purposes. It could affect the approximate 26,100 Maui County customers in outage zones.


Since electric equipment requires visible inspection by employees, known as spotters, before re-energizing the system, PSPS “will cause more frequent and longer outages,” said Mat McNeff, Hawaiian Electric director for Maui, Molokaʻi and Lānaʻi.

A concern for some at the Public Utilities Commission (PUC) meeting on Tuesday, community members Mark Johnson and Joseph Stewart called for more radical changes, such as underground power lines.

“Running lines in the air is outdated technology, from like the Victorian Era. We can run ground lines, and then we don’t have half of these problems that cause infrastructure issues,” said Stewart.

In a conversation with Maui Now, Jim Kelly, HECO vice president of government and community relations and corporate communications, noted that nearly half of distribution lines on Maui are already underground, but that they’re aware that more undergrounding is what the community wants. “It’s absolutely something that we are looking at. We’ve applied for some federal funding that we hope might be used to help pay for that because it’s very expensive to underground lines,” Kelly added.

No new lines have been undergrounded on Maui since the fire unless it was in a new development, in which case it was paid for by the developer, Kelly said. “We are working with the Lahaina community and the County to develop planning for utility restoration, including undergrounding.”


Moving power lines underground can reduce the risk of wildfire ignition by 98%, according to California’s largest utility company, Pacific Gas & Electric (PG&E). Undergrounding electric power lines are associated with high costs, wherein raising capital for undergrounding in California led to customers paying 13% more on their electric bill on average.

On Hawaiian Electric’s website, the utility says it buries lines when “installed cost of an underground line is comparable to costs for an overhead line” and if “the requester pays the difference.”

Kelly emphasized that “you don’t necessarily have to underground everything to make it safer, as we found from California utilities.”

HECO plans to use a combination of techniques, such as covered conductors, fast-trip settings, spark-less fuses, fire-resistant poles and crossarms, enhanced weather monitoring, and vegetation management. The utility says PSPS is a “last-resort measure.”

“In other words, we want to use all of these techniques strategically – no one size fits all,” Kelly said.

While PSPS events lower the risk of wildfires, they can have their own serious consequences. On average, households in California have lost power for 48 hours during the outages, according to PSE Health Energy. That’s enough time for food and medication to spoil in refrigerators, people to miss work or school, and those who rely on electrical-powered medical devices to suffer.

JD Pells
JD is a news reporter for Maui Now. He has contributed stories to TCU 360, Fort Worth Report and the Pulitzer Center on Crisis Reporting. JD interned at Maui Now in 2021. He graduated from the Bob Schieffer College of Communication at Texas Christian University, with a bachelor's in journalism and business in 2022, before coming back home to Maui with the purpose of serving his community. He can be reached at jdpells@pmghawaii.com.
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