Rylee Brooke Kamahele helped forge a landmark legal settlement requiring Hawai‘i to eliminate carbon emissions from the state’s transportation system in the next 20 years, including cars on all islands, ships and airplanes used for interisland flights.

Now, Kamahele and other plaintiffs in the historic Navahine settlement are pushing back against a major element of the Hawaiʻi Department of Transportation’s plan for reaching the goal. The issue: the department’s proposal to use what’s known as sustainable aviation fuel or SAF— essentially the airplane equivalent of biodiesel — for interisland flights. 

The department’s proposed plan to use the fuel aligns with the view of the aviation industry and fuel producers — as well as a local grower of oily plants that can be converted into sustainable aviation fuel — that SAF is the most practical choice to reduce emissions.

But the plaintiffs have a different view.

“The bottom line is to be completely carbon or 100% emission free by 2045: that’s just the bottom line,” said Kamahele, a 17-year-old activist, entrepreneur and actor from Mililani. 

SAF, she said, is “not 100% carbon free, which is what we’re looking for.”

An alternative solution: “I’m very interested in fully electric planes,” she said.

The Department of Transportation says that’s not an option. 

For zero-emission airplanes to replace jet fuel in 20 years, the department says, “there would need to be a very fast scale-up of electric battery aircraft technology for larger jets” carrying at least 100 passengers.

Given the nascent nature of electric aircraft, the department expects that by 2045, electric planes could make up only 10% of interisland flights. 

The impasse underscores the challenge Hawaiʻi faces as it tries to keep the promises it made to the young plaintiffs.

Major Source Of Emissions

It’s one thing to electrify cars, trucks and boats and charge them using wind and solar power. Airplanes are different. Electric airplanes exist, but experts say they’re not big enough to transport the thousands of people who fly between Hawaiʻi’s islands each day. 

The interisland flights are Hawaiʻi’s biggest transportation carbon producer. They make up more than half of all emissions related to civilian transportation in Hawaiʻi — and about 30% more than all forms of ground transportation combined. 

Jeff Mikulina, a renewable energy consultant who helped craft Hawaiʻi’s energy policy, said the aviation component is “the biggest crux of this zero emissions goal.”

He said SAF is an attractive interim solution but the state needs to work toward electric planes while it pivots to SAF.

“Electrification of airplanes is going to be a winner,” he said.

“The young people are going to now be going to engineering school … and they’re going to realize that these are not simple solutions.”

Gov. Josh Green

Gov. Josh Green is less sanguine about electric planes.

In an interview, Green praised the young plaintiffs but said not all proposed solutions can meet what he called a “purity test.”

“This is a long game, when we’re talking about climate change, the Navahine settlement,” he said.

It’s going to take years, Green said, before technology exists to use electric aircraft to replace traditional planes for interisland flights.

“It’s going to have to be a lot of partners, and the young people are going to now be going to engineering school,” Green said, “and they’re going to come back, and they’re going to realize that these are not simple solutions.”

Final Plan To Be Released Wednesday

The state’s aviation challenge dates back to 2022, when a dozen teenagers, including Kamahele, sued the state Department of Transportation and then-Gov. David Ige, citing their state constitutional right to a clean and healthful environment.

They were represented by lawyers from Earthjustice’s Hawaiʻi office and Our Children’s Trust, an Oregon-based nonprofit organization that brings climate change suits on behalf of young people.

The complaint included allegations that climate change was damaging the lives of each of the plaintiffs. It also noted how a previously mandated zero emissions transportation target required the Department of Transportation to “take any actions necessary” to achieve zero emissions across all transportation modes, including interisland flights. 

The plaintiffs argued the state was headed in the opposite direction.

Green settled in June 2024, essentially requiring the state to follow the law. The settlement lays out interim targets for 2030, 2035 and 2040 to ensure the state eliminates all emissions from transportation by 2045.

In June, the department issued a draft plan for how it would meet the milestones and sought public comments. 

The final plan is expected to be released Wednesday. The department declined interview requests for this story.

The plan will likely include responses from the department to comments from Earthjustice and Our Children’s Trust. A fundamental flaw, the plaintiffs say, is the plan’s repeated reference to “net-zero emissions.” That would allow cars, boats and planes to continue generating carbon and for the state to offset the emissions by doing things like planting trees. 

Kamahele noted the statute requires “real zero” emissions, not net zero.

“Net zero means that we just keep burning fossil fuels and we hide it with offsets,” she said. “That doesn’t protect future generations.

Settlement Envisions SAF As Interim Solution

The use of SAF is another issue.

The settlement actually envisions using SAF to meet the interim targets. It says the Department of Transportation must, “Support adoption by private stakeholders of zero emissions vehicles, sustainable aviation fuel, and other technologies.”

But the plaintiffs don’t see it as a long-term solution. 

“Sustainable Aviation Fuel (‘SAF’) is often made from corn ethanol, which increases carbon dioxide, air pollution, consumes a significant amount of land area, and must be shipped to Hawaiʻi, and is thus a non-solution for zero emissions transportation,” Earthjustice and Our Children’s Trust wrote in response to the department’s plan. 

In addition, they wrote, the plan calls for the continued use of SAF well past 2045. The idea that zero-emission planes will make up only 10% of interisland flights by 2045 is “contrary to the Navahine Settlement, which commits to 100% zero emissions for interisland flights by 2045.”

Airline industry experts say there’s no other practical option.

Alana James is the sustainability innovation director for Alaska and Hawaiian airlines. The airline industry’s goal, she says, is to achieve net zero emissions by 2050; Alaska Air Group, which includes Hawaiian, is aiming for 2040.

The plan includes operating more efficiently, using next-generation airplanes and using carbon offsets. 

But SAF is the most promising technology, James said. It can reduce carbon emissions by 50%-80% when blended with standard aviation fuel, she said. Plus, it’s ready to use now: airlines are already using SAF blends with existing engines and infrastructure.

One problem is capacity. There’s not that much SAF being produced. Alaska has agreements to buy SAF from West Coast refineries but still only consumed about 1% of its total aviation fuel from SAF last year, James said.

Another issue is price. SAF costs two to five times what conventional jet fuel costs. James couldn’t say what that would mean for someone traveling from, say, Oʻahu to Maui. But she estimated using SAF blends would mean a 25% increase in fuel prices, which would significantly impact ticket prices.

“I think across the airline industry, we are aligned that scaling the supply of cost-competitive, sustainable aviation fuel is going to be the key to addressing aviation carbon emissions,” James said.

Plan Calls For SAF Production Incentive

A key to driving down costs is support from state and federal taxpayers, similar to other green energies like solar, James said.

“SAF is going to require incentives to help reduce that cost gap to conventional fuels,” she said.

States like Washington, Minnesota and Illinois offer tax credits to support SAF. While the Hawaiʻi Legislature has yet to get on board, part of the Department of Transportation’s proposed plan is to create a SAF tax credit.

The bottom line: SAF will cost Hawaiʻi residents, in the form of tax incentives or higher interisland plane fares.

Hawaiʻi’s only refinery, Par Hawaii, already is betting big on SAF. In July, Par Hawaii announced a deal with Mitsubishi Corporation and ENEOS Corporation, which contributed $100 million for a 35.6% stake in a new joint venture, Hawaii Renewables, focused on producing renewable fuels at Par’s Kapolei refinery. By the end of this year, Hawaii Renewables expects to be able to produce 61 million gallons of SAF and other renewable fuels.

“We are slowly getting off the ground,” said Par Hawaii’s president, Eric Wright. “We do still have a long way to go.”

Par Hawaii is also working with Pono Pacific, a land conservation company that wants to ramp up production of a plant called camelina, whose oily seeds can be processed into SAF. The idea is to grow at least some SAF feedstock in Hawaiʻi rather than importing it.

“For the state to meet its goals, we’re really going to have to all work together on this,” Wright said.

Electric airplanes aren’t an option, James of Hawaiian Airlines, said. 

Hawaiian now flies about 150 interisland flights with 128-seat airplanes. Current electric airplanes aren’t nearly that big. 

Hawaiian has made an equity investment in REGENT Craft Inc., developer of what it calls an all-electric Seaglider, designed to fly on a cushion of air just above the ocean’s surface. The company says it has raised more than $90 million from other big-name investors, including Japan Airlines, Mesa Air Group, Thiel Capital, Mark Cuban and Lockheed Martin, and has orders for more than 600 Seagliders valued at more than $9 billion.

The company is targeting its 12-passenger plane, which is regulated as a maritime vessel, to enter service in 2026 or 2027 and a larger 50- to 100-passenger plane by the end of the decade.

Such technology is promising, James said, but added, “It’s going to take time before they’re going to really be able to make a dent” in reducing carbon emissions for interisland flights.

For the plaintiffs, meanwhile, SAF also won’t fly.

“It pollutes when you grow it,” Kamahele said. “It pollutes when you refine it. It pollutes again when you ship it to get to Hawai‘i, and then when you burn it here in Hawai‘i, it pollutes even more. Hawai‘i deserves real clean energy, not greenwashing.”

Civil Beat’s coverage of climate change and the environment is supported by The Healy Foundation, the Marisla Fund of the Hawai‘i Community Foundation and the Frost Family Foundation.