This year, Kapalua Bay Beach on Maui topped a closely list as the country’s best beach.
But Hawai‘i also tops another not-so-glamourous list, according to the U.S. Energy Information Administration—as the state with the most expensive electricity prices.
But maybe not for long: In 2015, Hawai‘i’s Governor David Ige signed the country’s first state law mandating 100% of its electricity come from renewable energy sources by the year 2045. One such renewable is geothermal. But the very thing that makes geothermal an attractive source of clean energy in Hawai‘i just shut down the only geothermal power plant in the state—Kīlauea volcano.
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Before the most active volcano in the world started erupting on May 3rd in the lower East Rift Zone—smack dab in the middle of a housing subdivision and a scant few miles from the power plant—Puna Geothermal Ventures (PGV), owned by Nevada’s Ormat Technologies, contributed approximately 25 percent of Hawaii Island’s electricity.
Now, after just passing the one-month mark, Kīlauea’s eruptions show no signs of slowing. The U.S. Geological Survey estimates lava has covered 7.7 square miles of land to date. Over the past couple weekends, more than 500 earthquakes were recorded at the summit; a lake was filled with lava, its water boiled off; a half-mile wide lava flow made its ocean entry. Additionally, two buildings at PGV were destroyed.
However, officials say the plant’s loss won’t affect the island utility’s ability to provide electricity to residents.
“Hawai‘i Island has a diverse portfolio of generation, including fossil-fueled generation, solar, wind, and hydropower,” Rhea Lee-Moku, spokesperson with Hawai‘i Electric Light Co. (HELCO), told The Daily Beast. “Since PGV shut down, we have relied on other generating units to provide the island’s electricity. We currently have sufficient generation to cover the island’s electricity needs.”
At its simplest, geothermal energy is generated from the natural warmth of the Earth. In Hawai‘i, where magma bubbles up from a hotspot in the Earth’s crust, it makes perfect sense to tap geothermal as a source of renewable energy. Currently, the United States leads the world in geothermal energy production. However, the loss of PGV is already impacting both Hawai‘i residents and might pose a glitch in Hawai‘i’s push for 100 percent renewables.
Lee-Moku reported the loss of PGV would add about $2.60 to the June bill of a typical residential customer on Hawai‘i Island who uses an average 500 kilowatt-hours per month. What’s more, “Without PGV, Hawai‘i Island will go from 57 percent renewable to 37 percent renewable,” Lee-Moku said.
According to Donald Thomas, director of the University of Hawai‘i at Hilo’s Center for the Study of Active Volcanoes, the geothermal water comes from a naturally occurring network of underground fractures that are already present in the Earth. “It’s a bit complex,” Thomas said. PGV started generating electricity in 1993. It’s the first and only geothermal power plant in Hawai‘i.
“The process involves extracting steam from deep wells and directing it to a conventional steam turbine,” Thomas explained. “The exhaust steam from the turbine is directed into a heat exchanger where the steam is condensed as it heats a binary fluid—pentane.”
Pentane is a highly flammable liquid that’s attractive in geothermal use. Its low boiling point allows it to extract significantly more energy from the produced geothermal steam than would be possible with a conventional steam turbine alone.
“The pentane vapor,” Thomas continued, “Is directed to a second turbine that uses the energy of the pentane turbine to also drive the electrical generator.”
The exhaust from the pentane turbine is then cooled back to its liquid state and gets cycled through the system again—boiled to create more vapor to drive the pentane turbine.
Key to the design at PGV is that everything that comes out of the ground goes back into the ground with the exception of some of the heat used to produce electricity. “All spent fluids are injected at a greater depth than those drawn from the production zone. It has the effect of replenishing and replacing fluids withdrawn from the reservoir.”
But a geothermal plant located on an active volcanic rift zone doesn’t come without risk. In emergency proceedings soon after the first fissure erupted in early May, PGV officials scrambled to remove the pentane from their facility. As lava marched ever closer, raising fears of many in the surrounding community, workers then went about plugging PGV’s 11 geothermal wells to prevent the possible release of toxic gases in case lava breached the facility. Lava did eventually destroy numerous buildings—two as recent as this weekend—and covered an access road. Lava also engulfed three of 11 geothermal wells; however no explosive emission of hydrogen sulfide or other gases resulted.
At the other end of the Hawaiian Island chain, Kaua‘i’s utility company operates as a not-for-profit cooperative owned by the members it serves. Kaua‘i Island Utility Cooperative (KIUC) has set its own goal to produce at least 70 percent of the island’s electricity by 2030. They’re relying on solar, biomass, and hydropower to do so—but not geothermal.
“The tragedy for communities on Kīlauea's East Rift Zone will doubtless generate caution in discussion of future geothermal uses, but there are several islands with geothermal potential that are not in active volcanic zones,” Jan TenBruggencate, a retired science writer for the Honolulu Advertiser, said. “Maui and the Big Island have the greatest availability of high-temperature resources, but all the main islands have some geothermally-warmed ground water, which could play a role in energy or other applications.”
TenBruggencate, who also happens to be an elected board member of KIUC but was not speaking on their behalf, acknowledged inherent risks with geothermal, adding, “But it is not clear to me that risks of geothermal are significantly higher than those, for example, of wind and corrosion in solar power, biofouling in marine power applications like wave energy, or the various risks in industrial biomass systems. Not to make light of this, but if a volcano erupts under you, there is no safe haven—not for any human endeavor nor any energy resource.”
As long as the hotspot in the Earth’s mantle continues to burp magma, there will likely be geothermal opportunities in Hawai‘i. The question at this point is whether the Puna plant will return to contributing to Hawai‘i’s goal of 100% renewable energy resources by 2045.
“It’s premature to make a decision for what the future holds,” Mike Kaleikini, a spokesperson for Puna Geothermal Ventures said. “But we’re not giving up. We’re committed to providing electricity to HELCO.”
According to Thomas, the plant is still intact. “The wells—for which the pads were covered—should be recoverable and operable,” he said. “Some of the support infrastructure was lost, but the essential components of the power plant have, so far, survived pretty well unharmed. It will take some time to replace the infrastructure but the capital costs won't be excessive. All this assumes that the eruption will run out of magma in the reasonably foreseeable future—and I'm afraid we don't have much of a track record for the duration of these events.”
