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Why geothermal has been a non-starter there for decades.
In 1881, King David Kalakaua of Hawaii and his entourage paid a late evening visit to Thomas Edison in New York. The king was unsure about electricity — he didn’t think the technology was reliable enough to light up Honolulu’s streets just yet — but after marveling at a chandelier buzzing with electric light, the group started bantering about how Hawaii could generate power. What about putting boilers atop a volcano? There was enough energy up there, a companion to the king mused, that it could illuminate the entire United States. He appeared to be joking, but Edison took the notion seriously. Nice idea, he told his visitors, but an undersea cable carrying power to the mainland would be far too expensive.
Honolulu got its new streetlights a few months later — powered, in the end, by a hydroelectric dam. The volcano thought would wait a century longer.
In the 1970s, geologists began drilling into the eastern rift of the Big Island’s Kilauea volcano, resulting, in 1993, in Hawaii’s first geothermal power plant, which is today called the Puna Geothermal Venture, or PGV. The 38-megawatt facility straddles the most active rift of Hawaii’s most active volcano and is, to this day, the state’s only geothermal plant, supplying just 3% of the islands’ energy. That status quo puzzles geothermal advocates elsewhere. The obvious comparison is to a volcanic sibling like Iceland, where the Earth’s radiant heat supplies 25% of the country’s consumer electricity needs and more than 70% of its overall energy.
“It’s been talked about for ages that at some point, Hawaii needs to have a reset on geothermal,” Mark Glick, Hawaii’s Chief Energy Officer, told me. “That time is now.” So far, that reset involves the governor’s office directing discretionary COVID relief funds with the aim of getting an essentially moribund industry off the ground. Five million dollars will go toward a drilling program to explore the geology of promising areas of heat, hopefully with results that encourage potential developers to make their own, bigger investments. Site selection is underway, with Maui and the Big Island at the top of the list, and Glick said local outreach will begin in the next few months.
That the vast underground heat resources of a place like Maui are only now getting even basic attention is “mind-boggling,” Glick said. But it’s also a reflection of decades of turmoil over all things geothermal in the state — clashes with neighbors, toxic incidents, failed dreams of grandiose infrastructure. That has to change, he added, if the state is serious about ditching its dirtiest forms of power generation quickly. Hawaii has committed to reaching a 100% clean energy portfolio by 2045, but was still producing as much as 80% of its electricity from burning petroleum by last year.
Like other states endowed with abundant heat, Hawaii was previously inspired to consider geothermal energy during the 1970s oil crisis. The state was dependent on imported fuel, and the regularly lava-spewing Kilauea, in particular, looked like “a no-brainer” for geothermal development, explains Roland Horne, director of the Stanford Geothermal Program and a noted historian of the industry.
Hawaii’s problem is that, in addition to being an island chain, it’s also a chain of separate electric grids. With no power lines connecting the Big Island — home to 14% percent of the state’s population — to any others, Kilauea’s energy was marooned. Initially, the state imagined unifying its disparate grids in parallel with geothermal development. But Edison, it turns out, was right about undersea cables, even relatively short ones. After a decade of planning and testing that included laying prototype wires across the 6,100-feet deep, 30-mile wide ‘Alenuihaha Channel between the Big Island and Maui found that such a project was technically feasible but would be far too expensive.
Meanwhile, oil prices fell, and so did interest in hunting for hot rock elsewhere. Although a statewide survey that began in the 1970s found most of the islands could harbor geothermal resources — even older, geologically colder islands like Oahu and even Kauai — nobody followed up. “It led to almost nothing for three decades,” said Nicole Lautze, a geologist at the University of Hawaii-Manoa who is overseeing the state’s current exploratory projects. Instead, the state remained dependent on imported oil.
Other problems were more island-specific. Drilling into an active volcano is fairly unusual for geothermal prospectors and presents unique challenges, given the proximity of lava and abundance of toxic gasses. The work on Kilauea was controversial from the start, with nearby residents and Native Hawaiian spiritual practitioners calling the project not just unsafe but sacrilegious. A release of hydrogen sulfide during construction in 1991 only added to the controversy.
Toxic emissions, including sulfur, from geothermal facilities are generally minuscule compared with fossil fuel plants—and part of the everyday dangers of living on a volcanic slope, Horne told me. “They were coming out of the ground long before Puna was ever built,” he said. But PGV’s reputation as a danger to the community was hard to shake. When geothermal has made headlines in the state over the years since, the story has generally been PGV’s uneasy relationship with the volcano — most notably during Kilauea’s 2018 eruption, during which the plant was totally surrounded by lava flows. Neighbors remained fiercely opposed to the plant when it reopened two years later.
In 2014, when Lautze was tapped for a new survey of that state’s geothermal resources, the word “geothermal” was so taboo that she was reluctant to tell anyone locally her line of work. But she had funding from the U.S. Department of Energy, thanks to the federal government’s resurgent interest in geothermal as a source of clean, firm energy. Popular perception in Hawaii held that the Earth’s heat could only be tapped on the Big Island, where magma was breaching the surface, but Lautze was intrigued by the possibility of finding resources on islands that are less geologically volatile and home to more people. She set about developing new simulations for subsurface heat across the state, followed by on-the-ground experiments.
On islands like Lanai and Maui, Lautze said her team received a warmer welcome than expected. Certain benefits of geothermal had become much more clear amidst the state’s rush to adopt renewable energy — among them, that geothermal power would take a fraction of the land required to produce the same electricity from wind turbines or solar panels, in addition to providing continuous power, regardless of the weather. “Hawaii is realizing that they’re not going to get to 100 percent renewable from solar and wind alone,” said Lautze. Plus, she added, “the cost of energy is going up and up and up.”
The next step toward tapping that heat is what’s known as “slim hole” drilling, using bits less than 7 inches wide to descend more than a kilometer down. Even promising hotspots can be duds, and developers are often hesitant even in well-mapped places, which Hawaii isn’t. Before the state tries to sell geothermal companies on the idea of coming to Hawaii, officials want to be sure of what they’re selling. “There’s an absolute dearth of information on the volcanically older islands,” Lautze said.
Mike Kaleikini, head of Hawaii affairs for Ormat, which owns PGV, told me he’s been heartened to see the state turning its attention to basic research. Developers could very well get excited about places like Maui, he said, with some initial exploration already done and if they feel they can navigate permitting and potential concerns from the public. “Hawaii is not the easiest place to do business,” he added.
Among the better prospects for new development is on Big Island land owned by the Department of Hawaiian Home Lands, an agency that works to redistribute homes and land to Native Hawaiians. Located on the more docile slopes of Mauna Kea, the project’s backers say it could both power DHHL’s housing developments and generate royalties that help finance more home building.
Whatever heat developers strike there will remain marooned on the Big Island, at least for now. Channeling the dream of near-endless volcanic energy, Glick’s office proposed tying the Big Island’s geothermal production to a regional hydrogen hub so that the energy could be shipped offshore, but the DOE ultimately passed on funding the plan. Lautze still dreams of wires strung across the unruly Hawaiian channels. People still talk about the idea, she noted, even if it elicits smirks and eyerolls from people who lived through its past failures. The state is still a far cry from achieving the king’s dream. But the only way to get there is to start drilling.
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On Alaska’s permitting overhaul, HALEU winners, and Heatmap’s Climate 101
Current conditions: Kansas, Oklahoma, and Arkansas brace for up to a foot of rain • Tropical Storm Juliette, still located well west of Mexico, is moving northward and bringing rain to parts of Southern California • Heat and dryness are raising the risk of wildfire in South Africa.
The Trump administration has started the process to roll back logging protections from more than 44 million acres of national forest land. On Wednesday, U.S. Secretary of Agriculture Brooke Rollins proposed undoing a 25-year-old rule that banned building roads or harvesting timber on federally controlled forest land, much of which is located in Alaska. “Today marks a critical step forward in President Trump’s commitment to restoring local decision-making to federal land managers to empower them to do what’s necessary to protect America’s forests and communities from devastating destruction from fires,” Rollins said in a statement. “This administration is dedicated to removing burdensome, outdated, one-size-fits-all regulations that not only put people and livelihoods at risk but also stifle economic growth in rural America.”
Environmental groups slammed the proposal for jeopardizing wildlife habitats and putting waterways at risk. “Communities depend on clear water filtered by roadless areas, animals depend on the unfragmented habitat that can only exist where there are no roads, and anglers depend on clean water in the streams where trout and salmon swim,” Ellen Montgomery, the director of Environment America’s great outdoors campaign, said in a press release. “We cannot let these essential forests be carved up by roads, obliterated by chainsaws, and contaminated by mines.”
Heatmap’s new Climate 101 series aims, as Heatmap deputy editor Jillian Goodman explained, to be “a primer on some of the key technologies of the energy transition.” That includes “everything from what makes silicon a perfect material for solar panels (and computer chips), to what’s going on inside a lithium-ion battery, to the difference between advanced and enhanced geothermal.”
This might be especially helpful for those still trying to find their way into the climate conversation, but we hope there’s something here for everyone. For instance, did you know that contemporary readers might have understood Don Quixote’s “tilting at windmills” to be an expression of NIMBYism? Well, now you do!
The federal Permitting Council signed a first-of-a-kind memorandum of understanding to work together with Alaska’s government to streamline permitting on critical infrastructure projects across the state. First established in 2015, the agency was designed to improve transparency and speed up the greenlighting of infrastructure approvals. But it had yet to forge such a close pact with an individual state. “Our team is ready to work with Governor Dunleavy to bring Alaska back into the energy spotlight, ending the neglect of the Biden Administration and bringing Alaska’s incredible natural resources to the rest of the world,” Emily Domenech, the Permitting Council’s executive director, said in a statement.
Domenech — a former staffer for House Speakers Kevin McCarthy and Mike Johnson who went on to serve as a senior vice president at Boundary Stone, a firm founded by alumni of the Obama-era Department of Energy — acted as something of a Republican sage for the clean energy industry. In an interview with Heatmap’s Matthew Zeitlin after last November’s election, she urged the industry to forge closer relationships with members of the current congressional majority. “If you ask Republicans to be for or against the IRA as a whole, they’ll be against it,” Domenech said, “But Republicans think about energy as a regional issue. So instead of forcing this one size fits all approach, IRA advocates would be smart to give people room to support only the policies that make the most sense for their state or region.”
The Department of Energy selected another three companies to receive a special kind of nuclear fuel from its growing stockpile. HALEU — pronounced HAY-loo, an acronym for high assay low enriched uranium — is a reactor fuel enriched up to four times as much as traditional reactor fuel. The fuel is needed for all kinds of novel reactor designs, particularly those that use coolants other than water. Until recently, however, Russia’s state-owned Rosatom had enjoyed a virtual monopoly over its global supply. The Biden administration set aside billions for HALEU production. In April, the Trump administration selected five companies to receive some of the government-procured supply, including Westinghouse, Bill Gates’ TerraPower, and the Google-backed Kairos Power. Now the agency has picked another three:
Two firefighters battling the Bear Gulch fire on Washington’s Olympic Peninsula were arrested by federal law enforcement Wednesday. The reason for the arrests is unclear, according to the Seattle Times. Over three hours, federal agents from Border Patrol carried out an “operation on the fire,” demanding identification from members of two private contractor crews who were among the 400 firefighters battling Washington state’s largest active blaze. The Incident Management Team from the National Interagency Fire Center suggested that the action did not interfere with the efforts to tamp down the flames.
The American West is primed for wildfires right now. Following a lull in June and July, Heatmap’s Jeva Lange wrote that “the forecast for the Pacific Northwest for ‘Dirty August’ and ‘Snaptember,’ historically the two worst months of the year in the region for wildfires,” was full of warning signs, including low precipitation and abnormally high temperatures.
Living, gnawing weedwackers.Vesper Energy
The 1.36 million solar panels at Vesper Energy’s Hornet Solar farm in Swisher County, Texas, one of the United States' largest single-phase solar projects, were overgrown with vegetation. So naturally, the company brought in sheep. More than 2,000 white, wooly ovines arrived this month and were allowed to roam the facility’s six square miles. “As Texas continues to lead the nation in solar energy growth, solar grazing highlights how innovation can support rural economies, preserve farmland, and strengthen the state’s reliable energy future,” Vesper said.
Here at Heatmap, we write a lot about decarbonization — that is, the process of transitioning the global economy away from fossil fuels and toward long-term sustainable technologies for generating energy. What we don’t usually write about is what those technologies actually do. Sure, solar panels convert energy from the sun into electricity — but how, exactly? Why do wind turbines have to be that tall? What’s the difference between carbon capture, carbon offsets, and carbon removal, and why does it matter?
So today, we’re bringing you Climate 101, a primer on some of the key technologies of the energy transition. In this series, we’ll cover everything from what makes silicon a perfect material for solar panels (and computer chips), to what’s going on inside a lithium-ion battery, to the difference between advanced and enhanced geothermal.
There’s something here for everyone, whether you’re already an industry expert or merely climate curious. For instance, did you know that contemporary 17th century readers might have understood Don Quixote’s famous “tilting at windmills” to be an expression of NIMYBism? I sure didn’t! But I do now that I’ve read Jeva Lange’s 101 guide to wind energy.
That said, I’d like to extend an especial welcome to those who’ve come here feeling lost in the climate conversation and looking for a way to make sense of it. All of us at Heatmap have been there at some point or another, and we know how confusing — even scary — it can be. The constant drumbeat of news about heatwaves and floods and net-zero this and parts per million that is a lot to take in. We hope this information will help you start to see the bigger picture — because the sooner you do, the sooner you can join the transition, yourself.
Without further ado, here’s your Climate 101 syllabus:
Once you feel ready to go deeper, here are some more Heatmap stories to check out:
The basics on the world’s fastest-growing source of renewable energy.
Solar power is already the backbone of the energy transition. But while the basic technology has been around for decades, in more recent years, installations have proceeded at a record pace. In the United States, solar capacity has grown at an average annual rate of 28% over the past decade. Over a longer timeline, the growth is even more extraordinary — from an stalled capacity base of under 1 gigawatt with virtually no utility-scale solar in 2010, to over 60 gigawatts of utility-scale solar in 2020, and almost 175 gigawatts today. Solar is the fastest-growing source of renewable energy in both the U.S. and the world.
There are some drawbacks to solar, of course. The sun, famously, does not always shine, nor does it illuminate all places on Earth to an equal extent. Placing solar where it’s sunniest can sometimes mean more expense and complexity to connect to the grid. But combined with batteries — especially as energy storage systems develop beyond the four hours of storage offered by existing lithium-ion technology — solar power could be the core of a decarbonized grid.
Solar power can be thought of as a kind of cousin of the semiconductors that power all digital technology. As Princeton energy systems professor and Heatmap contributor Jesse Jenkins has explained, certain materials allow for electrons to flow more easily between molecules, carrying an electrical charge. On one end of the spectrum are your classic conductors, like copper, which are used in transmission lines; on the other end are insulators, like rubber, which limit electrical charges.
In between on that spectrum are semiconductors, which require some amount of energy to be used as a conductor. In the computing context these are used to make transistors, and in the energy context they’re used to make — you guessed it — solar panels.
In a solar panel, the semiconductor material absorbs heat and light from the sun, allowing electrons to flow. The best materials for solar panels, explained Jenkins, have just the right properties so that when they absorb light, all of that energy is used to get the electrons flowing and not turned into wasteful heat. Silicon fits the bill.
When you layer silicon with other materials, you can force the electrons to flow in a single direction consistently; add on a conductive material to siphon off those subatomic particles, and voilà, you’ve got direct current. Combine a bunch of these layers, and you’ve got a photovoltaic panel.
Globally, solar generation capacity stood at over 2,100 terawatt-hours in 2024, according to Our World in Data and the Energy Institute, growing by more than a quarter from the previous year. A huge portion of that growth has been in China, which has almost half of the world’s total installed solar capacity. Installations there have grown at around 40% per year in the past decade.
Solar is still a relatively small share of total electricity generation, however, let alone all energy usage, which includes sectors like transportation and industry. Solar is the sixth largest producer of electricity in the world, behind coal, gas, hydropower, nuclear power, and wind. It’s the fourth largest non-carbon-emitting generation source and the third largest renewable power source, after wind and hydropower.
Solar has taken off in the United States, too, where utility-scale installations make up almost 4% of all electricity generated.
While that doesn’t seem like much, overall growth in generation has been tremendous. In 2024, solar hit just over 300 terawatt-hours of generation in the U.S., compared to about 240 terawatt-hours in 2023 and just under 30 in 2014.
Looking forward, there’s even more solar installation planned. Developers plan to add some 63 gigawatts of capacity to the grid this year, following an additional 30 gigawatts in 2024, making up just over half of the total planned capacity additions, according to Energy information Administration.
Solar is cheap compared to other energy sources, and especially other renewable sources. The world has a lot of practice dealing with silicon at industrial scale, and China especially has rapidly advanced manufacturing processes for photovoltaic cells. Once the solar panel is manufactured, it’s relatively simple to install compared to a wind turbine. And compared to a gas- or coal-fired power plant, the fuel is free.
From 1975 to 2022, solar module costs fell from over $100 per watt to below $0.50, according to Our World In Data. From 2012 to 2022 alone, costs fell by about 90%, and have fallen by “around 20% every time the global cumulative capacity doubles,” writes OWID analyst Hannah Ritchie. Much of the decline in cost has been attributed to “Wright’s Law,” which says that unit costs fall as production increases.
While construction costs have flat-lined or slightly increased recently due to supply chain issues and overall inflation, the overall trend is one of cost declines, with solar construction costs declining from around $3,700 per kilowatt-hour in 2013, to around $1,600 in 2023.
There are solar panels at extreme latitudes — Alaska, for instance, has seen solar growth in the past few years. But there are obvious challenges with the low amount of sunlight for large stretches of the year. At higher latitudes, irradiance, a measure of how much power is transmitted from the sun to a specific area, is lower (although that also varies based on climate and elevation). Then there are also more day-to-day issues, such as the effect of snow and ice on panels, which can cause issues in turning sunlight into power (they literally block the panel from the sun). High latitudes can see wild swings in solar generation: In Tromso, in northern Norway, solar generation in summer months can be three times as high as the annual average, with a stretch of literally zero production in December and January.
While many Nordic countries have been leaders in decarbonizing their electricity grids, they tend not to rely on solar in that project. In Sweden, nuclear and hydropower are its largest non-carbon-emitting fuel sources for electricity; in Norway, electricity comes almost exclusively from hydropower.
There has been some kind of policy support for solar power since 1978, when the Energy Tax Act provided tax credits for solar power investment. Since then, the investment tax credit has been the workhorse of American solar policy. The tax credit as it was first established was worth 10% of the system’s upfront cost “for business energy property and equipment using energy resources other than oil or natural gas,” according to the Congressional Research Service.
But above that baseline consistency has been a fair amount of higher-level turmoil, especially recently. The Energy Policy Act of 2005 kicked up the value of that credit to 30% through 2007; Congress kept extending that timeline, with the ITC eventually scheduled to come down to 10% for utility-scale and zero for residential projects by 2024.
Then came the 2022 Inflation Reduction Act, which re-instituted the 30% investment tax credit, with bonuses for domestic manufacturing and installing solar in designated “energy communities,” which were supposed to be areas traditionally economically dependent on fossil fuels. The tax then transitioned into a “technology neutral” investment tax credit that applied across non-carbon-emitting energy sources, including solar, beginning in 2024.
This year, Congress overhauled the tax incentives for solar (and wind) yet again. Under the One Big Beautiful Bill Act, signed in July, solar projects have to start construction by July 2026, or complete construction by the end of 2027 to qualify for the tax credit. The Internal Revenue Service later tightened up its definition of what it means for a project to start construction, emphasizing continuing actual physical construction activities as opposed to upfront expenditures, which could imperil future solar development.
At the same time, the Trump administration is applying a vise to renewables projects on public lands and for which the federal government plays a role in permitting. Renewable industry trade groups have said that the highest levels of the Department of Interior are obstructing permitting for solar projects on public lands, which are now subject to a much closer level of review than non-renewable energy projects.
Massachusetts Institute of Technology Researchers attributed the falling cost of solar this century to “scale economies.” Much of this scale has been achieved in China, which dominates the market for solar panel production, especially for export, even though much of the technology was developed in the United States.
At this point, however, the cost of an actual solar system is increasingly made up of “soft costs” like labor and permitting, at least in the United States. According to data from the National Renewables Energy Laboratory, a utility-scale system costs $1.20 per watt, of which soft costs make up a third, $0.40. Ten years ago, a utility-scale system cost $2.90 per watt, of which soft costs was $1.20, or less than half.
Beyond working to make existing technology even cheaper, there are other materials-based advances that promise higher efficiency for solar panels.
The most prominent is “perovskite,” the name for a group of compounds with similar structures that absorb certain frequencies of light particularly well and, when stacked with silicon, can enable more output for a given amount of solar radiation. Perovskite cells have seen measured efficiencies upwards of 34% when combined with silicon, whereas typical solar cells top out around 20%.
The issue with perovskite is that it’s not particularly durable, partially due to weaker chemical bonds within the layers of the cell. It’s also more expensive than existing solar, although much of that comes down inefficient manufacturing processes. If those problems can be solved, perovskite could promise more output for the same level of soft costs as silicon-based solar panels.