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Inside Climeworks’ big experiment to wrest carbon from the air

In the spring of 2021, the world’s leading authority on energy published a “roadmap” for preventing the most catastrophic climate change scenarios. One of its conclusions was particularly daunting. Getting energy-related emissions down to net zero by 2050, the International Energy Agency said, would require “huge leaps in innovation.”
Existing technologies would be mostly sufficient to carry us down the carbon curve over the next decade. But after that, nearly half of the remaining work would have to come from solutions that, for all intents and purposes, did not exist yet. Some would only require retooling existing industries, like developing electric long-haul trucks and carbon-free steel. But others would have to be built from almost nothing and brought to market in record time.
What will it take to rapidly develop new solutions, especially those that involve costly physical infrastructure and which have essentially no commercial value today?
That’s the challenge facing Climeworks, the Swiss company developing machines to wrest carbon dioxide molecules directly from the air. In September 2021, a few months after the IEA’s landmark report came out, Climeworks switched on its first commercial-scale “direct air capture” facility, a feat of engineering it dubbed “Orca,” in Iceland.
The technology behind Orca is one of the top candidates to clean up the carbon already blanketing the Earth. It could also be used to balance out any stubborn, residual sources of greenhouse gases in the future, such as from agriculture or air travel, providing the “net” in net-zero. If we manage to scale up technologies like Orca to the point where we remove more carbon than we release, we could even begin cooling the planet.
As the largest carbon removal plant operating in the world, Orca is either trivial or one of the most important climate projects built in the last decade, depending on how you look at it. It was designed to capture approximately 4,000 metric tons of carbon from the air per year, which, as one climate scientist, David Ho, put it, is the equivalent of rolling back the clock on just 3 seconds of global emissions. But the learnings gleaned from Orca could surpass any quantitative assessment of its impact. How well do these “direct air capture” machines work in the real world? How much does it really cost to run them? And can they get better?
The company — and its funders — are betting they can. Climeworks has made major deals with banks, insurers, and other companies trying to go green to eventually remove carbon from the atmosphere on their behalf. Last year, the company raised $650 million in equity that will “unlock the next phase of its growth,” scaling the technology “up to multi-million-ton capacity … as carbon removal becomes a trillion-dollar market.” And just last month, the U.S. Department of Energy selected Climeworks, along with another carbon removal company, Heirloom, to receive up to $600 million to build a direct air capture “hub” in Louisiana, with the goal of removing one million tons of carbon annually.
Two years after powering up Orca, Climeworks has yet to reveal how effective the technology has proven to be. But in extensive interviews, top executives painted a picture of innovation in progress.
Chief marketing officer Julie Gosalvez told me that Orca is small and climatically insignificant on purpose. The goal is not to make a dent in climate change — yet — but to maximize learning at minimal cost. “You want to learn when you're small, right?” Gosalvez said. “It’s really de-risking the technology. It’s not like Tesla doing EVs when we have been building cars for 70 years and the margin of learning and risk is much smaller. It’s completely new.”
From the ground, Orca looks sort of like a warehouse or a server farm with a massive air conditioning system out back. The plant consists of eight shipping container-sized boxes arranged in a U-shape around a central building, each one equipped with an array of fans. When the plant is running, which is more or less all the time, the fans suck air into the containers where it makes contact with a porous filter known as a “sorbent” which attracts CO2 molecules.

When the filters become totally saturated with CO2, the vents on the containers snap shut, and the containers are heated to more than 212 degrees Fahrenheit. This releases the CO2, which is then delivered through a pipe to a secondary process called “liquefaction,” where it is compressed into a liquid. Finally, the liquid CO2 is piped into basalt rock formations underground, where it slowly mineralizes into stone. The process requires a little bit of electricity and a lot of heat, all of which comes from a carbon-free source — a geothermal power plant nearby.
A day at Orca begins with the morning huddle. The total number on the team is often in flux, but it typically has a staff of about 15 people, Climeworks’ head of operations Benjamin Keusch told me. Ten work in a virtual control room 1,600 miles away in Zurich, taking turns monitoring the plant on a laptop and managing its operations remotely. The remainder work on site, taking orders from the control room, repairing equipment, and helping to run tests.
During the huddle, the team discusses any maintenance that needs to be done. If there’s an issue, the control room will shut down part of the plant while the on-site workers investigate. So far, they’ve dealt with snow piling up around the plant that had to be shoveled, broken and corroded equipment that had to be replaced, and sediment build-up that had to be removed.

The air is more humid and sulfurous at the site in Iceland than in Switzerland, where Climeworks had built an earlier, smaller-scale model, so the team is also learning how to optimize the technology for different weather. Within all this troubleshooting, there’s additional trade-offs to explore and lessons to learn. If a part keeps breaking, does it make more sense to plan to replace it periodically, or to redesign it? How do supply chain constraints play into that calculus?
The company is also performing tests regularly, said Keusch. For example, the team has tested new component designs at Orca that it now plans to incorporate into Climeworks’ next project from the start. (Last year, the company began construction on “Mammoth,” a new plant that will be nine times larger than Orca, on a neighboring site.) At a summit that Climeworks hosted in June, co-founder Jan Wurzbacher said the company believes that over the next decade, it will be able to make its direct air capture system twice as small and cut its energy consumption in half.
“In innovation lingo, the jargon is we haven’t converged on a dominant design,” Gregory Nemet, a professor at the University of Wisconsin who studies technological development, told me. For example, in the wind industry, turbines with three blades, upwind design, and a horizontal axis, are now standard. “There were lots of other experiments before that convergence happened in the late 1980s,” he said. “So that’s kind of where we are with direct air capture. There’s lots of different ways that are being tried right now, even within a company like Climeworks."
Although Climeworks was willing to tell me about the goings-on at Orca over the last two years, the company declined to share how much carbon it has captured or how much energy, on average, the process has used.
Gosalvez told me that the plant’s performance has improved month after month, and that more detailed information was shared with investors. But she was hesitant to make the data public, concerned that it could be misinterpreted, because tests and maintenance at Orca require the plant to shut down regularly.
“Expectations are not in line with the stage of the technology development we are at. People expect this to be turnkey,” she said. “What does success look like? Is it the absolute numbers, or the learnings and ability to scale?”
Danny Cullenward, a climate economist and consultant who has studied the integrity of various carbon removal methods, did not find the company’s reluctance to share data especially concerning. “For these earliest demonstration facilities, you might expect people to hit roadblocks or to have to shut the plant down for a couple of weeks, or do all sorts of things that are going to make it hard to transparently report the efficiency of your process, the number of tons you’re getting at different times,” he told me.
But he acknowledged that there was an inherent tension to the stance, because ultimately, Climeworks’ business model — and the technology’s effectiveness as a climate solution — depend entirely on the ability to make precise, transparent, carbon accounting claims.
Nemet was also of two minds about it. Carbon removal needs to go from almost nothing today to something like a billion tons of carbon removed per year in just three decades, he said. That’s a pace on the upper end of what’s been observed historically with other technologies, like solar panels. So it’s important to understand whether Climeworks’ tech has any chance of meeting the moment. Especially since the company faces competition from a number of others developing direct air capture technologies, like Heirloom and Occidental Petroleum, that may be able to do it cheaper, or faster.
However, Nemet was also sympathetic to the position the company was in. “It’s relatively incremental how these technologies develop,” he said. “I have heard this criticism that this is not a real technology because we haven’t built it at scale, so we shouldn’t depend on it. Or that one of these plants not doing the removal that it said it would do shows that it doesn’t work and that we therefore shouldn’t plan on having it available. To me, that’s a pretty high bar to cross with a climate mitigation technology that could be really useful.”
More data on Orca is coming. Climeworks recently announced that it will work with the company Puro.Earth to certify every ton of CO2 that it removes from the atmosphere and stores underground, in order to sell carbon credits based on this service. The credits will be listed on a public registry.
But even if Orca eventually runs at full capacity, Climeworks will never be able to sell 4,000 carbon credits per year from the plant. Gosalvez clarified that 4,000 tons is the amount of carbon the plant is designed to suck up annually, but the more important number is the amount of “net” carbon removal it can produce. “That might be the first bit of education you need to get out there,” she said, “because it really invites everyone to look at what are the key drivers to be paid attention to.”
She walked me through a chart that illustrated the various ways in which some of Orca’s potential to remove carbon can be lost. First, there’s the question of availability — how often does the plant have to shut down due to maintenance or power shortages? Climeworks aims to limit those losses to 10%. Next, there’s the recovery stage, where the CO2 is separated from the sorbent, purified, and liquified. Gosalvez said it’s basically impossible to do this without losing some CO2. At best, the company hopes to limit that to 5%.
Finally, the company also takes into account “gray emissions,” or the carbon footprint associated with the business, like the materials, the construction, and the eventual decommissioning of the plant and restoration of the site to its former state. If one of Climeworks’ plants ever uses energy from fossil fuels (which the company has said it does not plan to do) it would incorporate any emissions from that energy. Climeworks aims to limit gray emissions to 15%.
In the end, Orca’s net annual carbon removal capacity — the amount Climeworks can sell to customers — is really closer to 3,000 tons. Gosalvez hopes other carbon removal companies adopt the same approach. “Ultimately what counts is your net impact on the planet and the atmosphere,” she said.
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Despite being a first-of-its-kind demonstration plant — and an active research site — Orca is also a commercial project. In fact, Gosalvez told me that Orca’s entire estimated capacity for carbon removal, over the 12 years that the plant is expected to run, sold out shortly after it began operating. The company is now selling carbon removal services from its yet-to-be-built Mammoth plant.
In January, Climeworks announced that Orca had officially fulfilled orders from Microsoft, Stripe, and Shopify. Those companies have collectively asked Climeworks to remove more than 16,000 tons of carbon, according to the deal-tracking site cdr.fyi, but it’s unclear what portion of that was delivered. The achievement was verified by a third party, but the total amount removed was not made public.
Climeworks has also not disclosed how much it has charged companies per ton of carbon, a metric that will eventually be an important indicator of whether the technology can scale to a climate-relevant level. But it has provided rough estimates of how much it expects each ton of carbon removal to cost as the technology scales — expectations which seem to have shifted after two years of operating Orca.
In 2021, Climeworks co-founder Jan Wurzbacher said the company aimed to get the cost down to $200 to $300 per ton removed by the end of the decade, with steeper declines in subsequent years. But at the summit in June, he presented a new cost curve chart showing that the price was currently more than $1,000, and that by the end of the decade, it would fall to somewhere between $400 to $700. The range was so large because the cost of labor, energy, and storing the CO2 varied widely by location, he said. The company aims to get the price down to $100 to $300 per ton by 2050, when the technology has significantly matured.
Critics of carbon removal technologies often point to the vast sums flowing into direct air capture tech like Orca, which are unlikely to make a meaningful difference in climate change for decades to come. During a time when worsening disasters make action feel increasingly urgent, many are skeptical of the value of investing limited funds and political energy into these future solutions. Carbon removal won’t make much of a difference if the world doesn’t deploy the tools already available to reduce emissions as rapidly as possible — and there’s certainly not enough money or effort going into that yet.
But we’ll never have the option to fully halt climate change, let alone begin reversing it, if we don’t develop solutions like Orca. In September, the International Energy Agency released an update to its seminal net-zero report. The new analysis said that in the last two years, the world had, in fact, made significant progress on innovation. Now, some 65% of emission reductions after 2030 could be accounted for with technologies that had reached market uptake. It even included a line about the launch of Orca, noting that Climeworks’ direct air capture technology had moved from the prototype to the demonstration stage.
But it cautioned that DAC needs “to be scaled up dramatically to play the role envisaged,” in the net zero scenario. Climeworks’ experience with Orca offers a glimpse of how much work is yet to be done.
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Generate Capital, CalSTRS, and the Rhodium Group have teamed up on a new Transition Acceleration Framework to measure and assess emissions impacts.
The most common way to judge whether a company or project is helping to tackle climate change is to measure emissions. Has the company reduced its carbon footprint? Will the project add fewer greenhouse gas emissions to the atmosphere than alternatives?
It’s a useful metric, but a limited one. One company might be doing more to advance the energy transition than another — by investing in an expensive, early-stage solution such as geothermal power, for example — but a comparison of their carbon footprints won’t necessarily show it. At the project level, a solar farm in Mississippi, where solar deployment has lagged, will do more to decarbonize the U.S. power grid than one of equal size in California, even though both projects emit zero carbon.
This presents a challenge for climate-minded investors like Jonah Goldman, the chief strategy officer of Generate Capital, who are trying to figure out where their dollars can make the biggest difference. To solve it, Goldman worked with colleagues at the California State Teachers Retirement System, which backs Generate’s investments, and a team at the Rhodium Group to develop a new way for investors to assess where to put their money.
“The question that most of the frameworks out there ask is, what are your carbon emissions today, and can your carbon emissions be lowered?” Goldman told me. “The Transition Acceleration Framework asks, how can you apply capital that has the best chance of getting to decarbonization over a reasonable time frame?
“It sounds like a similar question. It sounds like semantics. But it’s actually quite different,” he said.
At a high level, the Transition Acceleration Framework measures how much additional decarbonization a given investment can deliver beyond what would likely have occurred anyway. It can also be used to evaluate policy interventions and procurement decisions, such as where to get power for a data center. The Rhodium Group published a white paper describing the methodology on Thursday, as well as an accompanying report using it to evaluate options for powering data centers in the U.S.
The Transition Acceleration Framework has three components: transition potential, transition efficiency, and acceleration factor.
Transition potential is “the size of the emissions-reduction opportunity,” the white paper says — it measures the gap between the current trajectory for a given technology and its potential deployment in a deeply decarbonized world. Some of the solutions with the highest transition potential scores, per Rhodium’s analysis, include light duty electric vehicles and utility-scale solar.
Transition efficiency measures how effective a dollar spent on that technology can be at closing the gap, based on an estimate of the total capital expenditure required to realize the potential. There, more nascent solutions like low-carbon cement and geothermal power score higher than EVs and solar.
Rhodium combines these two complementary metrics into a single “technology factor,” a score on a scale from one to ten that can help identify the highest-leverage sectors to invest in. (The project is similar in spirit to Heatmap’s Decarbonize Your Life series, in which we tried to determine the highest-leverage actions a given individual could take to cut emissions. If you missed it, check it out.)
While the transition potential and efficiency metrics provide a high-level view into how transformative different types of investments can be, the third component of the framework — the acceleration factor — helps distinguish between specific projects.
This starts with an assessment of five “acceleration attributes” — cost reduction, capital availability, new markets, infrastructure and supply chains, and political economy — that represent different mechanisms by which a single investment can help move an entire technology category forward.
For cost reduction, for example, an investor might ask how likely it is that the project will reduce the cost of future deployments through learning by doing or economies of scale. If it’s a first-of-a-kind project, the answer is likely yes. For capital availability, they might look at whether the investment will de-risk the technology. Goldman praised Amazon’s early investment in Rivian delivery vans — not just because it took gas-powered Amazon vans off the road, but because it also spurred other automakers and major shippers such as Walmart and GM to follow suit.
“While the Amazon-Rivian deal wasn’t 100% responsible for it, it certainly was a huge signal to the market that there was safety in solving this last mile delivery problem,” he said.
The Rhodium report outlines a method investors can use to score and weight the various attributes and combine them with the technology factor score to reach a final “acceleration factor” score.
In an accompanying report, Rhodium researchers used the framework to compare a number of different options for powering data centers in the U.S. It’s a high-level assessment — i.e. it doesn’t consider project-specific acceleration attributes — but it provides a rough hierarchy of the arrangements that accelerate the energy transition the most against those that do the most harm. At the top of the list is a grid-connected data center that signs a power purchase agreement with a clean, firm generator, such as a nuclear or geothermal plant. At the bottom, with a negative score indicating it would actually hinder progress relative to a regular grid connection, is an off-grid data center powered entirely by natural gas.
Of course, hyperscalers prioritizing speed to power are unlikely to wait around for a nuclear plant to get built. But there are plenty of options between that and behind the meter gas. An off-grid data center that builds enough renewables and batteries for 95% of its electricity needs and relies on gas backup scores higher than a grid-connected project that buys spot market renewable energy certificates.
“Different data center power configurations can have a meaningfully different impact on the transition, even if you’re looking at things that might on the surface seem relatively similar,” Michael Delgado, a partner at Rhodium, told me.
For now, the Transition Acceleration Framework is just that — a framework. Rhodium is piloting it with Generate and CalSTRS, as well as some additional partners, conducting bespoke assessments or their portfolios and projects. The hope is that it could eventually inform not just individual investment decisions or portfolio analyses but regulations and policy packages.
“This is an open method that we’re trying to put out there and get feedback on from the investment and philanthropic and policy world,” Delgado said.
The question is whether he still has a choice.
The United States has resumed bombing Iran, the U.S. military’s regional command announced on Wednesday. The United States also bombed more than 80 sites on Tuesday, including radar and air defense facilities, but the new set of targets is more expansive.
President Trump declared on Wednesday that the ceasefire between the two countries is dead. Yet he also suggested that an extended war isn’t on the table. “We’re not looking for long term,” he said at the NATO Summit in Turkey. “Anything that happens is going to be over very quickly … and will only make it safer, including for oil.”
Such a statement surely reflects the president’s awareness that his war isn’t very popular among Americans. But does he have any leverage anymore over how long the war lasts? When Trump okayed the interim Iran ceasefire in June, he said that Iran would not toll oil and gas tankers passing through the Strait of Hormuz. Since then, Iran and Oman have started setting up the infrastructure to do just that. That discrepancy may have been the ceasefire’s doom: The truce broke down after Iran fired missiles at oil and natural gas tankers that were allegedly not using its approved route through the strait. (Iran has said that its preferred route through the waterway is the “only safe passage.”)
American officials have said that restoring freedom of navigation through the Strait of Hormuz is one of their goals in ending — and now, resuming — the war. But the strait was open to all before the war began; Iran only shuttered it after the United States and Israel began bombing in February. Yet now that Iran has learned how easily it can close the strait and keep it closed, it has a new weapon to wield over the American and European economies.
And what of the country’s nuclear program? Back in March, it allegedly didn’t play into the calculus, partly because President Trump claimed the U.S. had destroyed the program in 2025. Instead, Secretary of State Marco Rubio said that the president had no choice but to enter the new conflict because Israel was already going to bomb Iran, and since the Islamic Republic would respond by targeting American bases in the Middle East, the United States might as well strike first. A day later, President Trump changed the story, saying that Iran was already planning to bomb U.S. military bases, which forced pre-emptive action on America and Israel’s part.
Yet by April 1, the president had justified the war to the American people by citing Iran’s nuclear program more than 20 times. “For years, everyone has said that Iran cannot have nuclear weapons. But in the end, those are just words, if you’re not willing to take action when the time comes,” he said. The new conflict had obliterated the country’s navy, defense industrial base, and ability to produce missiles, he said. Yet Iran — partly thanks to its small, cheap drones — was able to keep the strait closed for another two months.
What does all of this mean for energy and decarbonization? More expensive fossil fuels. The global crude benchmark Brent surged to $80 a barrel today, while West Texas Intermediate surpassed $74, bringing both to roughly the same level as when the June ceasefire was first announced. Researchers at Brown University estimate that Americans have paid $60 billion — or roughly $500 per household — more for gasoline and diesel than they would have had the conflict never happened.
If this stage of the war doesn’t go “long term,” as Trump hopes, then at least the world will have a little more oil than anticipated to work with, as stockpiles have risen in recent days. But a new and extended phase of the war threatens a return to the prices seen earlier in the spring — or prices that go even higher, should China decline to tap its reserves this time. One potential early pain point is diesel, which is already expensive because of Ukraine’s strikes on Russian refineries. Costlier fuel will keep encouraging more EV sales in Europe, Asia, and even the United States; high diesel prices in particular will provide a tailwind to the shockingly rapid electrification of China’s trucking sector.
Of course, the war will bring much more besides — more squandered time, more military spending, more human misery. It is the first that Trump might regret most. A conflict the White House joined without much public debate — and once forecast would last “four to six weeks” — now looks likely to eat much of his second term.
Pollution from peaker plants combined with heat and smoke can push summer air quality into the danger zone.
If you ever have to pick a day to stay inside, pick July 5. In cities across the United States, the Fourth of July’s pyrotechnic revelries make the wee hours after Independence Day consistently one of the worst of the year for air quality. Just look at Washington, D.C., which briefly held the distinction of having the world’s most polluted air this past Sunday morning following one of the largest firework displays in history.
But if you have to pick a second day to stay inside, shoot for one during the second half of July, which is the hottest period of the year in the United States. For one thing, it’s just plain miserable out. For another, the country’s 1,000 or so peaking power plants, or “peakers,” are more likely to be operating to meet the energy demands of heavy air-conditioning use, emitting disproportionately high levels of pollution for the electricity they generate.
Peakers are the backup power sources operators run only when demand is at its highest, such as during a heat wave. Peakers are also “probably the dirtiest and most expensive energy on the grid,” Abbe Ramanan, who leads the Phase Out Peakers project at the nonprofit Clean Energy Group, told me. “They tend to burn dirtier fuels, such as oil, and typically have older and less efficient emissions control systems.”
Some 63 million Americans live within a three-mile radius of a peaker, according to a 2023 Clean Energy Group report, where they face health conditions including “significant … increases in estimated rates of hospitalization for asthma, acute respiratory infection, and chronic obstructive pulmonary disease,” all conditions associated with proximity to fossil fuel-fired plants. On top of that, historic redlining practices mean two-thirds of peakers are located in communities with a higher percentage of low-income households than the national average, according to the group’s reporting. And yet peakers also provide life-saving power and AC when a blackout could mean death, such as during last week’s heat wave on the East Coast, making them simultaneously a menace and necessity to maintaining public health, at least with our current grid.
What exactly is peaker plant pollution? How does it appear in the Air Quality Index you might see on your phone? And how do local regulators consider pollution when issuing air quality forecasts? I set out to get answers.
To understand peaker plant pollution, let’s start with a refresher on how air quality alerts work.
The AQI scale runs from 0 to 500 and reflects the local concentrations of five major pollutants: particulate matter, ozone, carbon monoxide, sulfur dioxide, and nitrogen dioxide. Each pollutant has an Environmental Protection Agency-regulated benchmark for what is safe (many of which are set at levels clean air advocates argue are too lax). As concentrations increase, the overall AQI rises to warn first “sensitive groups” and then the general public when to take precautions, such as limiting outdoor activity or wearing a mask. (To learn more about the AQI scale, read my colleague Emily Pontecorvo’s explainer here.)
As do all fossil fuel power plants, peakers release planet-warming carbon dioxide as a byproduct of combustion, along with nitrogen oxides, particulate matter, volatile organic compounds, and other trace toxins that aren’t captured in the AQI, such as heavy metals. Oil and coal-fired power plants also release sulfur dioxide, which creates acid rain; natural gas-fired plants, on the other hand, emit comparatively little.
While NOx is an irritant in its own right, it is, more significantly, a key ingredient in the chemical reaction that creates ozone. When NOx mixes with volatile organic compounds — found in vehicle exhaust, personal care products, and yes, also power plant emissions — on a warm, sunny day, the chemical reaction creates ground-level ozone, which is corrosive enough to scar lung tissue with repeated, prolonged exposure. An expert once helpfully likened it to me as “sunburn on your lungs.” Health researchers have determined that, globally, ozone (also known as smog) causes a million premature deaths every year.
Yes, although it’s not an easy or neat measurement.
Peaker plants are used to rapidly supply electricity to the grid when demand exceeds the baseload capacity. As a result, they run infrequently — only about 5% of the year, or 464 hours per plant, in 2022, per Clean Energy Group’s analysis of 2022 EPA data. Using a stricter definition of peakers, the Government Accountability Office found that the plants represent nearly a fifth of the nation’s potential generating capacity but produce only about a 30th of its overall electricity, mostly due to the time they spend sitting idle.
Power plants use a number of emission control systems to limit emissions of various pollutants. But the EPA has much looser requirements for low-operating peakers, which “may not have effective, if any, emissions control technology,” the GAO writes. When operational, peakers emit an estimated 60 million tons of CO2 per year, with a median NOx emission rate about 6.1 times greater per unit of electricity generated by natural gas-fueled peakers compared to non-peaker gas plants.
“One really big issue with peakers is the emissions control systems are not operating during times when the plant is starting up or shutting down, which means that emissions are just unabated during those times,” Ramanan told me. “And because those plants tend to operate in short bursts, such as during a heat wave, they will start up and shut down more frequently.” Even up to a day beforehand, when the plant is running its test cycle, it might be emitting pollutants even while not actually providing any power.
One 2017 study by University of Wisconsin–Madison researchers found that across the Eastern U.S. from 2007 to 2012, total electricity generation rose by about 4% for every 1-degree Celsius (1.8-degree Fahrenheit) increase in daily summer temperature, with NOx correspondingly up 3.6% and CO2 up 3.3%. Though these numbers aren’t peaker-specific, the plants represent a disproportionate share of the rise since they’re reserved for the hottest, heaviest-load days.
Though the slower rise in NOx suggests “slightly cleaner plants … on average,” the authors write, that is “not completely unexpected, as new natural gas plants are required to have controls installed even as some peaking plants do not.” They note, however, that their data does not fully capture grandfathered-in units, since gas- and oil-fired peakers are allowed non-direct-measurement reporting.
In fact, in Maine and Connecticut, which “use more petroleum for electricity generation than most states in the U.S., primarily as peaking plants deployed on the hottest days,” NOx jumped 33% and 23% per degree Celsius, respectively. Separately, a 2016 study found that peaking plants may have accounted for up to 87% of local particulate matter in the PJM Interconnection during a July 2006 heat wave.
Peaker plant pollution is significant enough that chronic exposure in local communities has measurable health impacts. But how does it factor into summer AQI levels?
My colleague Matthew Zeitlin spoke this week with Margaret LaFarr, the New York State Department of Environmental Conservation’s director of air resources, who told him that peaker plant pollution is “one of the factors we consider” in formulating its air quality forecasts. But because the state’s agency uses modeling to predict when and where air quality will be poor, the granularity of a single peaker just isn’t there. “If we have to have specific information on the emissions, it would not be ready in time for a timely advisory,” LaFarr said.
Ramanan, whose nonprofit has diligently recorded the negative impacts of peakers, concurred that it is “difficult to pinpoint just how much peaker plants contribute to local air pollution because those sorts of studies are just very expensive to do.” Studies that look at disproportionate health impacts, on the other hand, are a little simpler to put together.
Additionally, while the AQI might rise locally near peakers during a heat wave, because of the nature of the scale, it can’t neatly distinguish why. A high ozone reading, for example, might just as easily be due to tailpipe emissions on a hot day; in the New York metro area, vehicles are responsible for an estimated 60% of the air pollution. Meteorological conditions — whether it’s sunny, a key factor in ozone formation, or which way the wind is blowing — obscure the picture. Particulate matter readings could be from a peaker, for example, but they could just as easily be from wildfire smoke.
One way air quality activists like to think about peaker pollution is as a co-occurrence — that is, a compounding pollution on top of already degraded conditions. Hot days tend to be the worst for ozone already, because of the aforementioned tailpipe pollution; peakers, activated to help with the heat-related energy load, then release more ozone-generating emissions at the worst possible time.
While a precise breakdown of the AQI might not be there for peakers, “we know the days that are more conducive to ozone formation generally tend to be those same days where people are cranking up their ACs and there is a higher demand for energy,” LaFarr said.
There is some speculation that cleaner input fuels could help reduce the worst peaker plant emissions. Generally, this is true: The 2017 study by the University of Wisconsin–Madison researchers found that from 1997 to 2015, in Texas, petroleum use in electricity generation dropped 85% and coal dropped 12%, while natural gas increased 57%. As a result, Texas had the lowest level of SO2 sensitivity of any state.
But beyond the existing fuel mixes, fuel switching is not a clean fix for peaker plants. “Burning things like hydrogen and [methane captured from waste processing facilities] don’t actually reduce the air pollution burden in any meaningful way,” Ramanan argued. “Hydrogen in particular tends to actually have extremely high levels of NOx emissions when it’s combusted.”
In Astoria, a neighborhood of New York City, activists opposed retrofitting the local oil-powered peaker plant to run on natural gas because doing so would “lock the state into relying on fossil fuels for decades, fly in the face of the state’s climate law that requires a drastic reduction in carbon emissions by mid-century and continue to pollute in an already overburdened community where many residents are immigrants and live below the poverty line,” Inside Climate News reported. At the same time, doing so would “reduce the state’s greenhouse gas emissions by more than 5 million tons through the year 2035,” per its owner, NRG Energy.
But a third way emerged: New York eventually denied NRG’s permit because it violated the state’s climate law, and the utility subsequently sold the Astoria facility to serve as the converter station for Beacon Wind, a development off the coasts of New York and Massachusetts.
While wind, new transmission, and battery storage all face enormous headwinds in the current political climate — meaning that many peaker plants targeted by activists for retirement are likely to stick around for years yet — advocates remain adamant that a playbook exists for decarbonization. “In terms of replacing one-to-one capacity, we’ve been looking at battery storage even just at peaker plant sites that can be paired with renewables or grid connected batteries,” Ramanan said, adding that “really great work is also being done in terms of virtual power plants and demand reduction — because it’s not just about reducing peak capacity, it’s also reducing the peak overall.”
That raises a final, particularly thorny question: Is air pollution from peaker plants “worth it” if it means being able to run AC?
A 2018 follow-up study by the same team of researchers at the University of Wisconsin–Madison explored a similar question. They found that climate change alone would increase summer mortality related to the smallest airborne particulate pollution by more than 13,500 deaths, and ozone-related mortality by more than 3,500 deaths in a mid-century scenario. AC-driven power sector emissions — full-fleet numbers, albeit disproportionately including peakers — would, on top of that, account for 654 PM 2.5 deaths and 315 ozone deaths, a nearly 5% and 9% increase, respectively, over climate impacts alone.
Researchers credit access to air conditioning in the United States with a 75% decline in deaths, and modeling exercises frequently show that a blackout during a heat wave could realistically result in hundreds of thousands of people needing medical attention. But clean air advocates also point to examples like Astoria, where the denial of a permit to retrofit a peaker plant for slightly better fossil fuels resulted in the grounds being used for a renewable energy source instead.
It’s certainly not an easily replicable process given the current political and economic climate, but it also perhaps suggests a false dichotomy of peakers vs. AC. Affordable power and livable spaces are just two among a host of community needs energy and public health officials must keep in mind.
“It’s not enough to just replace the existing system with renewables and battery storage and have fewer emissions,” Ramanan said. “It also has to be equitable, because otherwise we’re just going to replicate the same issues we’re having now in different ways.”