Key Takeaways
- The EPA partially rejected Hawaiʻi’s 2024 Regional Haze State Implementation Plan (SIP), blocking the state’s main strategy to shut down two aging Hawaiian Electric Co. (HECO) oil‑fired units by 2028.
- The decision hinges on concerns that forced plant closures could threaten grid reliability and constitute a “total regulatory taking” under the Takings Clause of the U.S. Constitution.
- Environmental advocates argue the move undermines the Clean Air Act’s protection of Class I areas (Hawaiʻi Volcanoes and Haleakalā National Parks) and creates a loophole for polluters to evade haze‑reduction requirements.
- HECO says it still intends to retire the plants but needs more renewable generation, storage, and biofuel capacity before the 2028 deadline, citing permitting delays, tax‑credit cuts, and supply‑chain issues.
- The EPA says it will work with Hawaiʻi to revise the SIP, but critics warn the legal reasoning could be used to weaken other Clean Air Act programs nationwide.
The U.S. Environmental Protection Agency’s recent action has stalled a long‑running effort to improve visibility and reduce fine‑particulate pollution in two of Hawaiʻi’s most treasured national parks. On Friday the EPA announced a partial denial of Hawaiʻi’s 2024 Regional Haze State Implementation Plan, a document that outlines how the state intends to meet the visibility‑protection mandates of the federal Clean Air Act. The plan specifically targeted Hawaiʻi Volcanoes National Park on the Big Island and Haleakalā National Park on Maui, both designated as “Class I” areas that receive the highest level of air‑quality protection under the law.
At the heart of the SIP was a commitment to retire at least two of Hawaiian Electric Co.’s oldest oil‑fired generating units—the Kahului plant (commissioned in 1948) and a unit at the Kanoelehua‑Hill facility—by the end of 2028. State officials and environmental groups viewed these closures as a cost‑effective way to cut sulfur dioxide, nitrogen oxides, and particulate emissions that contribute to regional haze, while also avoiding expensive retrofits.
The EPA, however, objected to the “unconsented” nature of those retirements. In a press release the agency argued that forcing HECO to shut down the units could jeopardize grid reliability on Hawaiʻi’s small, isolated island systems and might amount to a taking of private property without just compensation, invoking the Fifth Amendment’s Takings Clause. The agency cited a similar rejection of a Colorado haze plan that sought to close a coal plant, framing the decision as part of EPA Administrator Lee Zeldin’s broader push to enact President Donald Trump’s “energy dominance” agenda.
Environmental advocates, led by Earthjustice’s Mid‑Pacific office and a coalition of national groups, condemned the move as a major setback. They contend that the Clean Air Act already allows for contingency plans when renewable energy is not yet available, and that HECO had previously agreed to retire the three oldest units (including the Māʻalaea plant) in lieu of costly upgrades. Isaac Moriwake, Earthjustice’s managing attorney, called the EPA’s action “one of the biggest bombs to drop in Hawaiʻi so far.” The advocates warn that the EPA’s legal reasoning—labeling the retirements a “total regulatory taking”—creates a loophole that could let facilities sidestep Regional Haze Program requirements altogether and potentially undermine other Clean Air Act initiatives such as the National Ambient Air Quality Standards Program.
HECO’s vice president of power supply, Mike DeCaprio, acknowledged the tension between reliability and emissions reductions. He said the utility still plans to retire the aging plants but must first secure additional biofuel capacity, solar farms, and battery storage to replace the lost generation. DeCaprio emphasized that island grids lack the inherent stability of larger interconnected systems, making reliability a paramount concern. The company has already filed a request with the Public Utilities Commission to raise customer rates by roughly $45 million annually to fund the transition and cover costs associated with the plant closures.
The EPA’s decision also reignited debate over how to separate human‑caused pollution from natural volcanic emissions, known locally as vog. While volcanic eruptions from Kīlauea inject sulfur dioxide and fine particulates into the air—particularly on the southern side of the Big Island—the EPA’s February proposal asserted that no existing methodology can fully screen out volcanic impacts to isolate anthropogenic haze. Environmental groups dismissed this claim as “arbitrary and capricious,” arguing that previous EPA administrations successfully used models to account for episodic volcanic events when assessing visibility trends.
The Department of Health, which oversaw the SIP process, noted that HECO’s letter to the EPA requesting a delay in the retirement deadlines was sent without the agency’s involvement, a procedural omission the health department highlighted in its own correspondence to the EPA. Health Director Kenneth Fink warned that the EPA’s response conflicts with the Clean Air Act’s purpose of protecting visibility in national parks and wilderness areas.
Despite the setback, some observers remain optimistic about Hawaiʻi’s renewable future. Jeff Mikulina of Climate Hawai‘i pointed to recent approvals of two solar‑plus‑storage projects on Kauaʻi that could push the island toward 90 % renewable electricity by 2030. He stressed that short‑term policy headwinds—such as federal tariffs and reduced tax credits under the Trump administration—should not obscure the long‑term trend of declining costs for solar, wind, and especially energy storage, which he views as the “secret sauce” for achieving a 100 % renewable grid.
The EPA has said it remains committed to working with Hawaiʻi to revise the SIP so that it both complies with the law and delivers clean air for all residents. However, the legal precedent set by this partial denial could reverberate far beyond the Pacific, influencing how states balance emission‑reduction mandates with grid reliability and property‑rights considerations in the years to come.