This week, two new leaders at the US Food and Drug Administration announced plans to limit access to covid vaccines, arguing that there is not much evidence to support the value of annual shots in healthy people. New vaccines will be made available only to the people who are most vulnerable—namely, those over 65 and others with conditions that make them more susceptible to severe disease.
Anyone else will have to wait. Covid vaccines will soon be required to go through more rigorous trials to ensure that they really are beneficial for people who aren’t at high risk.
The plans have been met with fear and anger in some quarters. But they weren’t all that shocking to me. In the UK, where I live, covid boosters have been offered only to vulnerable groups for a while now. And the immunologists I spoke to agree: The plans make sense.
They are still controversial. Covid hasn’t gone away. And while most people are thought to have some level of immunity to the virus, some of us still stand to get very sick if infected. The threat of long covid lingers, too. Given that people respond differently to both the virus and the vaccine, perhaps individuals should be able to choose whether they get a vaccine or not.
But while many of us have benefited hugely from covid vaccinations in the past, there are questions over how useful continuing annual booster doses might be. That’s the argument being made by FDA head Marty Makary and Vinay Prasad, director of the agency’s Center for Biologics Evaluation and Research.
Makary and Prasad’s plans, which were outlined in the New England Journal of Medicine on Tuesday, don’t include such inflammatory language or unfounded claims, thankfully. In fact, they seem pretty measured: Annual covid booster shots will continue to be approved for vulnerable people but will have to be shown to benefit others before people outside the approved groups can access them.
There are still concerns being raised, though. Let’s address a few of the biggest ones.
Shouldn’t I get an annual covid booster alongside my flu vaccine?
At the moment, a lot of people in the US opt to get a covid vaccination around the time they get their annual flu jab. Each year, a flu vaccine is developed to protect against what scientists predict will be the dominant strain of virus circulating come flu season, which tends to run from October through March.
But covid doesn’t seem to stick to the same seasonal patterns, says Susanna Dunachie, a clinical doctor and professor of infectious diseases at the University of Oxford in the UK. “We seem to be getting waves of covid year-round,” she says.
And an annual shot might not offer the best protection against covid anyway, says Fikadu Tafesse, an immunologist and virologist at Oregon Health & Science University in Portland. His own research suggests that leaving more than a year between booster doses could enhance their effectiveness. “One year is really a random time,” he says. It might be better to wait five or 10 years between doses instead, he adds.
“If you are at risk [of a serious covid infection] you may actually need [a dose] every six months,” says Tafesse. “But for healthy individuals, it’s a very different conversation.”
What about children—shouldn’t we be protecting them?
There are reports that pediatricians are concerned about the impact on children, some of whom can develop serious cases of covid. “If we have safe and effective vaccines that prevent illness, we think they should be available,” James Campbell, vice chair of the committee on infectious diseases at the American Academy of Pediatrics, told STAT.
This question has been on my mind for a while. My two young children, who were born in the UK, have never been eligible for a covid vaccine in this country. I found this incredibly distressing when the virus started tearing through child-care centers—especially given that at the time, the US was vaccinating babies from the age of six months.
My kids were eventually offered a vaccine in the US, when we temporarily moved there a couple of years ago. But by that point, the equation had changed. They’d both had covid by then. I had a better idea of the general risks of the virus to children. I turned it down.
“Of course there are children with health problems who should definitely have it,” says Dunachie. “But for healthy children in healthy households, the benefits probably are quite marginal.”
Shouldn’t healthy people get vaccinated to help protect more vulnerable members of society?
It’s a good argument, says Tafesse. Research suggests that people who are vaccinated against covid-19 are less likely to end up transmitting the infection to the people around them. The degree of protection is not entirely clear, particularly with less-studied—and more contagious—variants of the virus and targeted vaccines. The safest approach is to encourage those at high risk to get the vaccine themselves, says Tafesse.
If the vaccines are safe, shouldn’t I be able to choose to get one?
Tafesse doesn’t buy this argument. “I know they are safe, but even if they’re safe, why do I need to get one?” People should know if they are likely to benefit from a drug they are taking, he says.
Having said that, the cost-benefit calculation will differ between individuals. Even a “mild” covid infection can leave some people bed-bound for a week. For them, it might make total sense to get the vaccine.
Dunachie thinks people should be able to make their own decisions. “Giving people a top-up whether they need it or not is a safe thing to do,” she says.
It is still not entirely clear who will be able to access covid vaccinations under the new plans, and how. Makary and Prasad’s piece includes a list of “medical conditions that increase a person’s risk of severe covid-19,” which includes several disorders, pregnancy, and “physical inactivity.” It covers a lot of people; research suggests that around 25% of Americans are physically inactive.
But I find myself agreeing with Dunachie. Yes, we need up-to-date evidence to support the use of any drugs. But taking vaccines away from people who have experience with them and feel they could benefit from them doesn’t feel like the ideal way to go about it.
This article first appeared in The Checkup, MIT Technology Review’s weekly biotech newsletter. To receive it in your inbox every Thursday, and read articles like this first, sign up here.
Since the Chinese biophysicist He Jiankui was released from prison in 2022, he has sought to make a scientific comeback and to repair his reputation after a three-year incarceration for illegally creating the world’s first gene-edited children.
While he has bounced between cities, jobs, and meetings with investors, one area of visible success on his comeback trail has been his X.com account, @Jiankui_He, which has become his main way of spreading his ideas to the world. Starting in September 2022, when he joined the platform, the account stuck to the scientist’s main themes, including promisinga more careful approach to his dream of creating more gene-edited children. “I will do it, only after society has accepted it,” he posted in August 2024. He also shared mundane images of his daily life, including golf games and his family.
Last month, in reply to MIT Technology Review’s questions about who was responsible for the account’s transformation into a font of clever memes, He emailed us back: “It’s thanks to Cathy Tie.”
You may not be familiar with Tie, but she’s no stranger to the public spotlight. A former Thiel fellow, she is a partner in the attention-grabbing Los Angeles Project, which promised to create glow-in-the-dark pets. Over the past several weeks, though, the 29-year-old Canadian entrepreneur has started to get more and more attention as the new wife to (and apparent social media mastermind behind) He Jiankui. On April 15, He announced a new venture, Cathy Medicine, that would take up his mission of editing human embryos to create people resistant to diseases like Alzheimer’s or cancer. Just a few days later, on April 18, He and Tie announced that they had married, posting pictures of themselves in traditional Chinese wedding attire.
But now Tie says that just a month after she married “the most controversial scientist in the world,” her plans to relocate from Los Angeles to Beijing to be with He are in disarray; she says she’s been denied entry to China and the two “may never see each other again,” as He’s passport is being held by Chinese authorities and he can’t leave the country.
Reached by phone in Manila, Tie said authorities in the Philippines had intercepted her during a layover on May 17 and told her she couldn’t board a plane to China, where she was born and where she says she has a valid 10-year visa. She claims they didn’t say why but told her she is likely “on a watch list.” (MIT Technology Review could not independently confirm Tie’s account.)
“While I’m concerned about my marriage, I am more concerned about what this means for humanity and the future of science,” Tie posted to her own X account.
A match made in gene-editing heaven
The romance between He and Tie has been playing out in public over the past several weeks through a series of reveals on He’s X feed, which had already started going viral late last year thanks to his style of posting awkward selfies alongside maxims about the untapped potential of heritable gene editing, which involves changing people’s DNA when they’re just embryos in an IVF dish.
“Human [sic] will no longer be controlled by Darwin’s evolution,” He wrote in March. That post, which showed him standing in an empty lab, gazing into the distance, garnered 9.7 million views. And then, a week later, he collected 13.3 million for this one: “Ethics is holding back scientific innovation and progress.”
In April, the feed started to change even more drastically.
This shift coincided with the development of his romance with Tie. Tie told us she has visited China three times this year, including a three-week stint in April when she and He got married after a whirlwind romance. She bought him a silver wedding ring made up of intertwined DNA strands.
The odd behavior on He’s X feed and the sudden marriage have left followers wondering if they are watching a love story, a new kind of business venture, or performance art. It might be all three.
A wedding photo posted by Tie on the Chinese social media platform Rednote shows the couple sitting at a table in a banquet hall, with a small number of guests. MIT Technology Review has been able to identify several people who attended: Cai Xilei, He’s criminal attorney; Liu Haiyan, an investor and former business partner of He; and Darren Zhu, an artist and Thiel fellow who is making a “speculative” documentary about the biophysicist that will blur the boundaries of fiction and reality.
In the phone interview, Tie declined to say if she and He are legally married. She also confirmed she celebrated a wedding less than one year ago with someone else in California, in July of 2024, but said they broke up after a few months; she also declined to describe the legal status of that marriage. In the phone call, Tie emphasized that her relationship with He is genuine: “I wouldn’t marry him if I wasn’t in love with him.”
An up-and-comer
Years before Tie got into a relationship with He, she was getting plenty of attention in her own right.She became a Thiel fellow in 2015, when she was just 18. That program, started by the billionaire Peter Thiel, gave her a grant of $100,000 to drop out of the University of Toronto and start a gene testing company, Ranomics.
Soon, she began appearing on the entrepreneur circuit as a “wunderkind” who was featured on a Forbes “30 Under 30” list in 2018 and presented as an up-and-coming venture capitalist on CNN that same year. In 2020, she started her second company, Locke Bio, which focuses on online telemedicine.
Like Thiel, Tie has staked out contrarian positions. She’s called mainstream genomics a scam and described entrepreneurship as a way to escape the hidebound practices of academia and bioethics. “Starting companies is my preferred form of art,” she posted in 2022, linking to an interview on CNBC.
By February 2025, Tie was ready to announce another new venture: the Los Angeles Project, a stealth company she had incorporated in 2023 under her legal name, Cheng Cheng Tie. The company, started with the Texas-based biohacker and artist Josie Zayner, says it will try to modify animal embryos; one goal is to make fluorescent glow-in-the-dark rabbits as pets.
The Los Angeles Project revels in explicitly transgressive aims for embryo editing, including a plan to add horn genes to horse embryos to make a unicorn. That’s consistent with Zayner’s past stunts, which include injecting herself with CRISPR during a livestream. “This is a company that should not exist,” Zayner said in announcing the newly public project.
Although the Los Angeles Project has only a tiny staff with uncertain qualifications, it did raise $1 million from the 1517 Fund, a venture group that supports “dropouts” and whose managers previously ran the Thiel Fellowship.
Asked for his assessment of Tie, Michael Gibson, a 1517 partner, said in an email that he thinks Tie is “not just exceptional, but profoundly exceptional.” He sent along a list of observations he’d jotted down about Tie before funding her company, which approvingly noted her “hyper-fluent competence” and “low need for social approval,” adding: “Thoughts & actions routinely unconventional.”
A comeback story
He first gained notoriety in 2018, when he and coworkers at the Southern University of Science & Technology in Shenzhen injected the CRISPR gene editor into several viable human embryos and then transferred these into volunteers, leading to the birth of three girls who he claimed would be resistant to HIV. A subsequent Chinese investigation found he’d practiced medicine illegally while “pursuing fame and fortune.” A court later sentenced him to three years in prison.
He has never apologized for his experiments, except to say he acted “too quickly” and to express regret for the trouble he’d caused his former wife and two daughters. (According to a leaked WeChat post by his ex-wife, she divorced him in 2024 “because of a major fault on his side.”)
Since his release from prison, He has sought to restart his research and convince people that he should be recognized as the “Chinese Darwin,” not “China’sFrankenstein,” as the press once dubbed him.
But his comeback has been bumpy. He lost a position at Wuchang University of Technology, a small private university in Hubei province, after some negative press. In February 2024, He posted that his application for funding from the Muscular Dystrophy Association was rejected. Last September, he even posted pictures of his torn shirt—which he said was the result of an assault by jealous rivals.
One area of clear success, though, was the growing reach of his X profile, which today has ballooned to more than 130,000 followers. And as his public profile rose, some started encouraging He to find ways to cash in. Andrew Hessel, a futurist and synthetic biologist active in US ethics debates, says he tried to get He invited to give a TED Talk. “His story is unique, and I wanted to see his story get more widespread attention, if only as a cautionary tale,” Hessel says. “I think he is a lightning rod for a generation of people working in life sciences.”
Later, Hessel says, he sent him information on how to join X’s revenue-sharing program. “I said, ‘You have a powerful voice. Have you looked into monetization?’” Hessel says.
By last fall, He was also welcoming visitors to what he called a new lab in Beijing. One person who took him up on the offer was Steve Hsu, a Michigan State physics professor who has started several genetics companies and was visiting Beijing.
They ended up talking for hours. Hsu says that He expressed a desire to move to the US and start a company, and that he shared his idea for conducting a clinical trial of embryo editing in South Africa, possibly for the prevention of HIV.
Hsu says he later arranged an invitation for He to give a lecture in the United States. “You are a little radioactive, but things are opening up,” Hsu told him. But He declined the offer because the Chinese government is holding his passport—a common tactic it uses to restrict the movement of sensitive or high-profile figures—and won’t return it to him. “He doesn’t even know why. He literally doesn’t know,” says Hsu. “According to the law, they should give it back to him.”
A curious triangle
Despite any plans by He and Tie to advance the idea, creating designer babies is currently illegal in most of the world, including China and the US. Some experts, however, fret that forbidding the technology will only drive it underground and make it attractive to biohackers or scientists outside the mainstream.
That’s one reason Tie’s simultaneous connection to two notable biotech renegades—He and Zayner—is worth watching. “There is clearly a triangle forming in some way,” says Hessel.
With Tie stuck outside China and He being kept inside the country, their new gene-editing venture, Cathy Medicine, faces an uncertain future. Tie posted previously on Rednote that she was “helping Dr. He open up the U.S. market” and was planning to return to the US with him for scientific research. But when we spoke on the phone, she declined to disclose their next steps and said their predicament means the project is “out of the window now.”
Even as the couple remain separated, their social media game is stronger than ever. As she waited in Manila, Tie sought help from friends, followers, and the entire internet. She blasted out a tweet to “crypto people,” calling them “too pussy to stand up for things when it matters.” Within hours, someone had created a memecoin called $GENE as a way for the public to support the couple.
This week, we published Power Hungry, a package all about AI and energy. At the center of this package is the most comprehensive look yet at AI’s growing power demand, if I do say so myself.
This data-heavy story is the result of over six months of reporting by me and my colleague James O’Donnell (and the work of many others on our team). Over that time, with the help of leading researchers, we quantified the energy and emissions impacts of individual queries to AI models and tallied what it all adds up to, both right now and for the years ahead.
There’s a lot of data to dig through, and I hope you’ll take the time to explore the whole story. But in the meantime, here are three of my biggest takeaways from working on this project.
1. The energy demands of AI are anything but constant.
If you’ve heard estimates of AI’s toll, it’s probably a single number associated with a query, likely to OpenAI’s ChatGPT. One popular estimate is that writing an email with ChatGPT uses 500 milliliters (or roughly a bottle) of water. But as we started reporting, I was surprised to learn just how much the details of a query can affect its energy demand. No two queries are the same—for several reasons, including their complexity and the particulars of the model being queried.
One key caveat here is that we don’t know much about “closed source” models—for these, companies hold back the details of how they work. (OpenAI’s ChatGPT and Google’s Gemini are examples.) Instead, we worked with researchers who measured the energy it takes to run open-source AI models, for which the source code is publicly available.
But using open-source models, it’s possible to directly measure the energy used to respond to a query rather than just guess. We worked with researchers who generated text, images, and video and measured the energy required for the chips the models are based on to perform the task.
Even just within the text responses, there was a pretty large range of energy needs. A complicated travel itinerary consumed nearly 10 times as much energy as a simple request for a few jokes, for example. An even bigger difference comes from the size of the model used. Larger models with more parameters used up to 70 times more energy than smaller ones for the same prompts.
As you might imagine, there’s also a big difference between text, images, or video. Videos generally took hundreds of times more energy to generate than text responses.
2. What’s powering the grid will greatly affect the climate toll of AI’s energy use.
As the resident climate reporter on this project, I was excited to take the expected energy toll and translate it into an expected emissions burden.
Powering a data center with a nuclear reactor or a whole bunch of solar panels and batteries will not affect our planet the same way as burning mountains of coal. To quantify this idea, we used a figure called carbon intensity, a measure of how dirty a unit of electricity is on a given grid.
We found that the same exact query, with the same exact energy demand, will have a very different climate impact depending on what the data center is powered by, and that depends on the location and the time of day. For example, querying a data center in West Virginia could cause nearly twice the emissions of querying one in California, according to calculations based on average data from 2024.
This point shows why it matters where tech giants are building data centers, what the grid looks like in their chosen locations, and how that might change with more demand from the new infrastructure.
3. There is still so much that we don’t know when it comes to AI and energy.
Our reporting resulted in estimates that are some of the most specific and comprehensive out there. But ultimately, we still have no idea what many of the biggest, most influential models are adding up to in terms of energy and emissions. None of the companies we reached out to were willing to provide numbers during our reporting. Not one.
Adding up our estimates can only go so far, in part because AI is increasingly everywhere. While today you might generally have to go to a dedicated site and type in questions, in the future AI could be stitched into the fabric of our interactions with technology. (See my colleague Will Douglas Heaven’s new story on Google’s I/O showcase: “By putting AI into everything, Google wants to make it invisible.”)
AI could be one of the major forces that shape our society, our work, and our power grid. Knowing more about its consequences could be crucial to planning our future.
In 2003, engineers from Germany and Switzerland began building a bridge across the Rhine River simultaneously from both sides. Months into construction, they found that the two sides did not meet. The German side hovered 54 centimeters above the Swiss side.
The misalignment occurred because the German engineers had measured elevation with a historic level of the North Sea as its zero point, while the Swiss ones had used the Mediterranean Sea, which was 27 centimeters lower. We may speak colloquially of elevations with respect to “sea level,” but Earth’s seas are actually not level. “The sea level is varying from location to location,” says Laura Sanchez, a geodesist at the Technical University of Munich in Germany. (Geodesists study our planet’s shape, orientation, and gravitational field.) While the two teams knew about the 27-centimeter difference, they mixed up which side was higher. Ultimately, Germany lowered its side to complete the bridge.
To prevent such costly construction errors, in 2015 scientists in the International Association of Geodesy voted to adopt the International Height Reference Frame, or IHRF, a worldwide standard for elevation. It’s the third-dimensional counterpart to latitude and longitude, says Sanchez, who helps coordinate the standardization effort.
Now, a decade after its adoption, geodesists are looking to update the standard—by using the most precise clock ever to fly in space.
That clock, called the Atomic Clock Ensemble in Space, or ACES, launched into orbit from Florida last month, bound for the International Space Station. ACES, which was built by the European Space Agency, consists of two connected atomic clocks, one containing cesium atoms and the other containing hydrogen, combined to produce a single set of ticks with higher precision than either clock alone.
Pendulum clocks are only accurate to about a second per day, as the rate at which a pendulum swings can vary with humidity, temperature, and the weight of extra dust. Atomic clocks in current GPS satellites will lose or gain a second on average every 3,000 years. ACES, on the other hand, “will not lose or gain a second in 300 million years,” says Luigi Cacciapuoti, an ESA physicist who helped build and launch the device. (In 2022, China installed a potentially stabler clock on its space station, but the Chinese government has not publicly shared the clock’s performance after launch, according to Cacciapuoti.)
From space, ACES will link to some of the most accurate clocks on Earth to create a synchronized clock network, which will support its main purpose: to perform tests of fundamental physics.
But it’s of special interest for geodesists because it can be used to make gravitational measurements that will help establish a more precise zero point from which to measure elevation across the world.
Alignment over this “zero point” (basically where you stick the end of the tape measure to measure elevation) is important for international collaboration. It makes it easier, for example, to monitor and compare sea-level changes around the world. It is especially useful for building infrastructure involving flowing water, such as dams and canals. In 2020, the international height standard even resolved a long-standing dispute between China and Nepal over Mount Everest’s height. For years, China said the mountain was 8,844.43 meters; Nepal measured it at 8,848. Using the IHRF, the two countries finally agreed that the mountain was 8,848.86 meters.
A worker performs tests on ACES at a cleanroom at the Kennedy Space Center in Florida.
ESA-T. PEIGNIER
To create a standard zero point, geodesists create a model of Earth known as a geoid. Every point on the surface of this lumpy, potato-shaped model experiences the same gravity, which means that if you dug a canal at the height of the geoid, the water within the canal would be level and would not flow. Distance from the geoid establishes a global system for altitude.
However, the current model lacks precision, particularly in Africa and South America, says Sanchez. Today’s geoid has been built using instruments that directly measure Earth’s gravity. These have been carried on satellites, which excel at getting a global but low-resolution view, and have also been used to get finer details via expensive ground- and airplane-based surveys. But geodesists have not had the funding to survey Africa and South America as extensively as other parts of the world, particularly in difficult terrain such as the Amazon rainforest and Sahara Desert.
To understand the discrepancy in precision, imagine a bridge that spans Africa from the Mediterranean coast to Cape Town, South Africa. If it’s built using the current geoid, the two ends of the bridge will be misaligned by tens of centimeters. In comparison, you’d be off by at most five centimeters if you were building a bridge spanning North America.
To improve the geoid’s precision, geodesists want to create a worldwide network of clocks, synchronized from space. The idea works according to Einstein’s theory of general relativity, which states that the stronger the gravitational field, the more slowly time passes. The 2014 sci-fi movie Interstellar illustrates an extreme version of this so-called time dilation: Two astronauts spend a few hours in extreme gravity near a black hole to return to a shipmate who has aged more than two decades. Similarly, Earth’s gravity grows weaker the higher in elevation you are. Your feet, for example, experience slightly stronger gravity than your head when you’re standing. Assuming you live to be about 80 years old, over a lifetime your head will age tens of billionths of a second more than your feet.
A clock network would allow geodesists to compare the ticking of clocks all over the world. They could then use the variations in time to map Earth’s gravitational field much more precisely, and consequently create a more precise geoid. The most accurate clocks today are precise enough to measure variations in time that map onto centimeter-level differences in elevation.
“We want to have the accuracy level at the one-centimeter or sub-centimeter level,” says Jürgen Müller, a geodesist at Leibniz University Hannover in Germany. Specifically, geodesists would use the clock measurements to validate their geoid model, which they currently do with ground- and plane-based surveying techniques. They think that a clock network should be considerably less expensive.
ACES is just a first step. It is capable of measuring altitudes at various points around Earth with 10-centimeter precision, says Cacciapuoti. But the point of ACES is to prototype the clock network. It will demonstrate the optical and microwave technology needed to use a clock in space to connect some of the most advanced ground-based clocks together. In the next year or so, Müller plans to use ACES to connect to clocks on the ground, starting with three in Germany. Müller’s team could then make more precise measurements at the location of those clocks.
These early studies will pave the way for work connecting even more precise clocks than ACES to the network, ultimately leading to an improved geoid. The best clocks today are some 50 times more precise than ACES. “The exciting thing is that clocks are getting even stabler,” says Michael Bevis, a geodesist at Ohio State University, who was not involved with the project. A more precise geoid would allow engineers, for example, to build a canal with better control of its depth and flow, he says. However, he points out that in order for geodesists to take advantage of the clocks’ precision, they will also have to improve their mathematical models of Earth’s gravitational field.
Even starting to build this clock network has required decades of dedicated work by scientists and engineers. It took ESA three decades to make a clock as small as ACES that is suitable for space, says Cacciapuoti. This meant miniaturizing a clock the size of a laboratory into the size of a small fridge. “It was a huge engineering effort,” says Cacciapuoti, who has been working on the project since he began at ESA 20 years ago.
Geodesists expect they’ll need at least another decade to develop the clock network and launch more clocks into space. One possibility would be to slot the clocks onto GPS satellites. The timeline depends on the success of the ACES mission and the willingness of government agencies to invest, says Sanchez. But whatever the specifics, mapping the world takes time.
Anthropic has announced two new AI models that it claims represent a major step toward making AI agents truly useful.
AI agents trained on Claude Opus 4, the company’s most powerful model to date, raise the bar for what such systems are capable of by tackling difficult tasks over extended periods of time and responding more usefully to user instructions, the company says.
Claude Opus 4 has been built to execute complex tasks that involve completing thousands of steps over several hours. For example, it created a guide for the video game Pokémon Red while playing it for more than 24 hours straight. The company’s previously most powerful model, Claude 3.7 Sonnet, was capable of playing for just 45 minutes, says Dianne Penn, product lead for research at Anthropic.
Similarly, the company says that one of its customers, the Japanese technology company Rakuten, recently deployed Claude Opus 4 to code autonomously for close to seven hours on a complicated open-source project.
Anthropic achieved these advances by improving the model’s ability to create and maintain “memory files” to store key information. This enhanced ability to “remember” makes the model better at completing longer tasks.
“We see this model generation leap as going from an assistant to a true agent,” says Penn. “While you still have to give a lot of real-time feedback and make all of the key decisions for AI assistants, an agent can make those key decisions itself. It allows humans to act more like a delegator or a judge, rather than having to hold these systems’ hands through every step.”
While Claude Opus 4 will be limited to paying Anthropic customers, a second model, Claude Sonnet 4, will be available for both paid and free tiers of users. Opus 4 is being marketed as a powerful, large model for complex challenges, while Sonnet 4 is described as a smart, efficient model for everyday use.
Both of the new models are hybrid, meaning they can offer a swift reply or a deeper, more reasoned response depending on the nature of a request. While they calculate a response, both models can search the web or use other tools to improve their output.
AI companies are currently locked in a race to create truly useful AI agents that are able to plan, reason, and execute complex tasks both reliably and free from human supervision, says Stefano Albrecht, director of AI at the startup DeepFlow and coauthor of Multi-Agent Reinforcement Learning: Foundations and Modern Approaches. Often this involves autonomously using the internet or other tools. There are still safety and security obstacles to overcome. AI agents powered by large language models can act erratically and perform unintended actions—which becomes even more of a problem when they’re trusted to act without human supervision.
“The more agents are able to go ahead and do something over extended periods of time, the more helpful they will be, if I have to intervene less and less,” he says. “The new models’ ability to use tools in parallel is interesting—that could save some time along the way, so that’s going to be useful.”
As an example of the sorts of safety issues AI companies are still tackling, agents can end up taking unexpected shortcuts or exploiting loopholes to reach the goals they’ve been given. For example, they might book every seat on a plane to ensure that their user gets a seat, or resort to creative cheating to win a chess game. Anthropic says it managed to reduce this behavior, known as reward hacking, in both new models by 65% relative to Claude Sonnet 3.7. It achieved this by more closely monitoring problematic behaviors during training, and improving both the AI’s training environment and the evaluation methods.
The thousands of sprawling acres in rural northeast Louisiana had gone unwanted for nearly two decades. Louisiana authorities bought the land in Richland Parish in 2006 to promote economic development in one of the poorest regions in the state. For years, they marketed the former agricultural fields as the Franklin Farm mega site, first to auto manufacturers (no takers) and after that to other industries that might want to occupy more than a thousand acres just off the interstate.
This story is a part of MIT Technology Review’s series “Power Hungry: AI and our energy future,” on the energy demands and carbon costs of the artificial-intelligence revolution.
So it’s no wonder that state and local politicians were exuberant when Meta showed up. In December, the company announced plans to build a massive $10 billion data center for training its artificial-intelligence models at the site, with operations to begin in 2028. “A game changer,” declared Governor Jeff Landry, citing 5,000 construction jobs and 500 jobs at the data center that are expected to be created and calling it the largest private capital investment in the state’s history. From a rural backwater to the heart of the booming AI revolution!
The AI data center also promises to transform the state’s energy future. Stretching in length for more than a mile, it will be Meta’s largest in the world, and it will have an enormous appetite for electricity, requiring two gigawatts for computation alone (the electricity for cooling and other building needs will add to that). When it’s up and running, it will be the equivalent of suddenly adding a decent-size city to the region’s grid—one that never sleeps and needs a steady, uninterrupted flow of electricity.
To power the data center, Entergy aims to spend $3.2 billion to build three large natural-gas power plants with a total capacity of 2.3 gigawatts and upgrade the grid to accommodate the huge jump in anticipated demand. In its filing to the state’s power regulatory agency, Entergy acknowledged that natural-gas plants “emit significant amounts of CO2” but said the energy source was the only affordable choice given the need to quickly meet the 24-7 electricity demand from the huge data center.
Meta said it will work with Entergy to eventually bring online at least 1.5 gigawatts of new renewables, including solar, but that it had not yet decided which specific projects to fund or when those investments will be made. Meanwhile, the new natural-gas plants, which are scheduled to be up and running starting in 2028 and will have a typical lifetime of around 30 years, will further lock in the state’s commitment to the fossil fuel.
The development has sparked interest from the US Congress; last week, Sheldon Whitehouse, the ranking member of the Senate Committee on Environment and Public Works issued a letter to Meta that called out the company’s plan to power its data center with “new and unabated natural gas generation” and said its promises to offset the resulting emissions “by funding carbon capture and a solar project are vague and offer little reassurance.”
The choice of natural gas as the go-to solution to meet the growing demand for power from AI is not unique to Louisiana. The fossil fuel is already the country’s chief source of electricity generation, and large natural-gas plants are being built around the country to feed electricity to new and planned AI data centers. While some climate advocates have hoped that cleaner renewable power would soon overtake it, the booming power demand from data centers is all but wiping out any prospect that the US will wean itself off natural gas anytime soon.
The reality on the ground is that natural gas is “the default” to meet the exploding power demand from AI data centers, says David Victor, a political scientist at the University of California, San Diego, and co-director of its Deep Decarbonization Project. “The natural-gas plant is the thing that you know how to build, you know what it’s going to cost (more or less), and you know how to scale it and get it approved,” says Victor. “Even for [AI] companies that want to have low emissions profiles and who are big pushers of low or zero carbon, they won’t have a choice but to use gas.”
The preference for natural gas is particularly pronounced in the American South, where plans for multiple large gas-fired plants are in the works in states such as Virginia, North Carolina, South Carolina, and Georgia. Utilities in those states alone are planning some 20 gigawatts of new natural-gas power plants over the next 15 years, according to a recent report. And much of the new demand—particularly in Virginia, South Carolina and Georgia—is coming from data centers; in those 3 states data centers account for around 65 to 85% of projected load growth.
“It’s a long-term commitment in absolutely the wrong direction,” says Greg Buppert, a senior attorney at the Southern Environmental Law Center in Charlottesville, Virginia. If all the proposed gas plants get built in the South over the next 15 years, he says, “we’ll just have to accept that we won’t meet emissions reduction goals.”
But even as it looks more and more likely that natural gas will remain a sizable part of our energy future, questions abound over just what its continued dominance will look like.
For one thing, no one is sure exactly how much electricity AI data centers will need in the future and how large an appetite companies will have for natural gas. Demand for AI could fizzle. Or AI companies could make a concerted effort to shift to renewable energy or nuclear power. Such possibilities mean that the US could be on a path to overbuild natural-gas capacity, which would leave regions saddled with unneeded and polluting fossil-fuel dinosaurs—and residents footing soaring electricity bills to pay off today’s investments.
The good news is that such risks could likely be managed over the next few years, if—and it’s a big if—AI companies are more transparent about how flexible they can be in their seemingly insatiable energy demands.
Around 2016, natural gas overtook coal as the main fuel for electricity generation in the US. And today—despite the rapid rise of solar and wind power, and well-deserved enthusiasm for the falling price of such renewables—natural gas is still king, accounting for around 40% of electricity generated in the US. In Louisiana, which is also a big producer, that share is some 72%, according to a recent audit.
Natural gas burns much cleaner than coal, producing roughly half as much carbon dioxide. In the early days of the gas revolution, many environmental activists and progressive politicians touted it as a valuable “bridge” to renewables and other sources of clean energy. And by some calculations, natural gas has fulfilled that promise. The power sector has been one of the few success stories in lowering US emissions, thanks to its use of natural gas as a replacement for coal.
But natural gas still produces a lot of carbon dioxide when it is burned in conventionally equipped power plants. And fracking causes local air and water pollution. Perhaps most worrisome, drilling and pipelines are releasing substantial amounts of methane, the main ingredient in natural gas, both accidentally and by intentional venting. Methane is a far more potent greenhouse gas than carbon dioxide, and the emissions are a growing concern to climate scientists, albeit one that’s difficult to quantify.
Still, carbon emissions from the power sector will likely continue to drop as coal is further squeezed out and more renewables get built, according to the Rhodium Group, a research consultancy. But Rhodium also projects that if electricity demand from data centers remains high and natural-gas prices low, the fossil fuel will remain the dominant source of power generation at least through 2035 and the transition to cleaner electricity will be much delayed. Rhodium estimates that the continued reign of natural gas will lead to an additional 278 million metric tons of annual US carbon emissions by 2035 (roughly equivalent to the emissions from a large US state such as Florida), relative to a future in which the use of fossil fuel gradually winds down.
Our addiction to natural gas, however, doesn’t have to be a total climate disaster, at least over the longer term. Large AI companies could use their vast leverage to insist that utilities install carbon capture and sequestration (CCS) at power plants and use natural gas sourced with limited methane emissions.
Entergy, for one, says its new gas turbines will be able to incorporate CCS through future upgrades. And Meta says it will help to fund the installation of CCS equipment at one of Entergy’s existing natural-gas power plants in southern Louisiana to help prove out the technology.
But the transition to clean natural gas is a hope that will take decades to realize. Meanwhile, utilities across the country are facing a more imminent and practical challenge: how to meet the sudden demand for gigawatts more power in the next few years without inadvertently building far too much capacity. For many, adding more natural-gas power plants might seem like the safe bet. But what if the explosion in AI demand doesn’t show up?
Times of stress
AI companies tout the need for massive, power-hungry data centers. But estimates for just how much energy it will actually take to train and run AI models vary wildly. And the technology keeps changing, sometimes seemingly overnight. DeepSeek, the new Chinese model that debuted in January, may or may not signal a future of new energy-efficient AI, but it certainly raises the possibility that such advances are possible. Maybe we will find ways to use far more energy-efficient hardware. Or maybe the AI revolution will peter out and many of the massive data centers that companies think they’ll need will never get built. There are already signs that too many have been constructed in China and clues that it might be beginning to happen in the US.
Despite the uncertainty, power providers have the task of drawing up long-term plans for investments to accommodate projected demand. Too little capacity and their customers face blackouts; too much and those customers face outsize electricity bills to fund investments in unneeded power.
There could be a way to lessen the risk of overbuilding natural-gas power, however. Plenty of power is available on average around the country and on most regional grids. Most utilities typically use only about 53% of their available capacity on average during the year, according to a Duke study. The problem is that utilities must be prepared for the few hours when demand spikes—say, because of severe winter weather or a summer heat wave.
The soaring demand from AI data centers is prompting many power providers to plan new capacity to make sure they have plenty of what Tyler Norris, a fellow at Duke’s Nicholas School of the Environment, and his colleagues call “headroom,” to meet any spikes in demand. But after analyzing data from power systems across the country, Norris and his coauthors found that if large AI facilities cut back their electricity use during hours of peak demand, many regional power grids could accommodate those AI customers without adding new generation capacity.
Even a moderate level of flexibility would make a huge difference. The Duke researchers estimate that if data centers cut their electricity use by roughly half for just a few hours during the year, it will allow utilities to handle some additional 76 gigawatts of new demand. That means power providers could effectively absorb the 65 or so additional gigawatts that, according to some predictions, data centers will likely need by 2029.
“The prevailing assumption is that data centers are 100% inflexible,” says Norris. That is, that they need to run at full power all the time. But Norris says AI data centers, particularly ones that are training large foundation models (such as Meta’s facility in Richland Parish), can avoid running at full capacity or shift their computation loads to other data centers around the country—or even ramp up their own backup power—during times when a grid is under stress.
The increased flexibility could allow companies to get AI data centers up and running faster, without waiting for new power plants and upgrades to transmission lines—which can take years to get approved and built. It could also, Norris noted in testimony to the US Congress in early March, provide at least a short-term reprieve on the rush to build more natural-gas power, buying time for utilities to develop and plan for cleaner technologies such as advanced nuclear and enhanced geothermal. It could, he testified, prevent “a hasty overbuild of natural-gas infrastructure.”
AI companies have expressed some interest in their ability to shift around demand for power. But there are still plenty of technology questions around how to make it happen. Late last year, EPRI (the Electric Power Research Institute), a nonprofit R&D group, started a three-year collaboration with power providers, grid operators, and AI companies including Meta and Google, to figure it out. “The potential is very large,” says David Porter, the EPRI vice president who runs the project, but we must show it works “beyond just something on a piece of paper or a computer screen.”
Porter estimates that there are typically 80 to 90 hours a year when a local grid is under stress and it would help for a data center to reduce its energy use. But, he says, AI data centers still need to figure out how to throttle back at those times, and grid operators need to learn how to suddenly subtract and then add back hundreds of megawatts of electricity without disrupting their systems. “There’s still a lot of work to be done so that it’s seamless for the continuous operation of the data centers and seamless for the continuous operation of the grid,” he says.
Footing the bill
Ultimately, getting AI data centers to be more flexible in their power demands will require more than a technological fix. It will require a shift in how AI companies work with utilities and local communities, providing them with more information and insights into actual electricity needs. And it will take aggressive regulators to make sure utilities are rigorously evaluating the power requirements of data centers rather than just reflexively building more natural-gas plants.
“The most important climate policymakers in the country right now are not in Washington. They’re in state capitals, and these are public utility commissioners,” says Costa Samaras, the director of Carnegie Mellon University’s Scott Institute for Energy Innovation.
In Louisiana, those policymakers are the elected officials at the Louisiana Public Service Commission, who are expected to rule later this year on Entergy’s proposed new gas plants and grid upgrades. The LPSC commissioners will decide whether Entergy’s arguments about the huge energy requirements of Meta’s data center and need for full 24/7 power leave no alternative to natural gas.
In the application it filed last fall with LPSC, Entergy said natural-gas power was essential for it to meet demand “throughout the day and night.” Teaming up solar power with battery storage could work “in theory” but would be “prohibitively costly.” Entergy also ruled out nuclear, saying it would take too long and cost too much.
Others are not satisfied with the utility’s judgment. In February, the New Orleans–based Alliance for Affordable Energy and the Union of Concerned Scientists filed a motion with the Louisiana regulators arguing that Entergy did not do a rigorous market evaluation of its options, as required by the commission’s rules. Part of the problem, the groups said, is that Entergy relied on “unsubstantiated assertions” from Meta on its load needs and timeline.
“Entergy is saying [Meta] needs around-the-clock power,” says Paul Arbaje, an analyst for the climate and energy program at the Union of Concerned Scientists. “But we’re just being asked to take [Entergy’s] word for it. Regulators need to be asking tough questions and not just assume that these data centers need to be operated at essentially full capacity all the time.” And, he suggests, if the utility had “started to poke holes at the assumptions that are sometimes taken as a given,” it “would have found other cleaner options.”
In an email response to MIT Technology Review, Entergy said that it has discussed the operational aspects of the facility with Meta, but “as with all customers, Entergy Louisiana will not discuss sensitive matters on behalf of their customers.” In a letter filed with the state’s regulators in early April, Meta said Entergy’s understanding of its energy needs is, in fact, accurate.
The February motion also raised concern over who will end up paying for the new gas plants. Entergy says Meta has signed a 15-year supply contract for the electricity that is meant to help cover the costs of building and running the power plants but didn’t respond to requests by MIT Technology Review for further details of the deal, including what happens if Meta wants to terminate the contract early.
Meta referred MIT Technology Review’s questions about the contract to Entergy but says its policy is to cover the full cost that utilities incur to serve its data centers, including grid upgrades. It also says it is spending over $200 million to support the Richland Parish data centers with new infrastructure, including roads and water systems.
Not everyone is convinced. The Alliance for Affordable Energy, which works on behalf of Louisiana residents, says that the large investments in new gas turbines could mean future rate hikes, in a state where residents already have high electricity bills and suffer from one of country’s most unreliable grids. Of special concern is what happens after the 15 years.
“Our biggest long-term concern is that in 15 years, residential ratepayers [and] small businesses in Louisiana will be left holding the bag for three large gas generators,” says Logan Burke, the alliance’s executive director.
Indeed, consumers across the country have good reasons to fear that their electricity bills will go up as utilities look to meet the increased demand from AI data centers by building new generation capacity. In a paper posted in March, researchers at Harvard Law School argued that utilities “are now forcing the public to pay for infrastructure designed to supply a handful of exceedingly wealthy corporations.”
The Harvard authors write, “Utilities tell [public utility commissions] what they want to hear: that the deals for Big Tech isolate data center energy costs from other ratepayers’ bills and won’t increase consumers’ power prices.” But the complexity of the utilities’ payment data and lack of transparency in the accounting, they say, make verifying this claim “all but impossible.”
The boom in AI data centers is making Big Tech a player in our energy infrastructure and electricity future in a way unimaginable just a few years ago. At their best, AI companies could greatly facilitate the move to cleaner energy by acting as reliable and well-paying customers that provide funding that utilities can use to invest in a more robust and flexible electricity grid. This change can happen without burdening other electricity customers with additional risks and costs. But it will take AI companies committed to that vision. And it will take state regulators who ask tough questions and don’t get carried away by the potential investments being dangled by AI companies.
Huge new AI data centers like the one in Richland Parish could in fact be a huge economic boon by providing new jobs, but residents deserve transparency and input into the negotiations. This is, after all, public infrastructure. Meta may come and go, but Louisiana’s residents will have to live with—and possibly pay for—the changes in the decades to come.
With seemingly no limit to the demand for artificial intelligence, everyone in the energy, AI, and climate fields is justifiably worried. Will there be enough clean electricity to power AI and enough water to cool the data centers that support this technology? These are important questions with serious implications for communities, the economy, and the environment.
This story is a part of MIT Technology Review’s series “Power Hungry: AI and our energy future,” on the energy demands and carbon costs of the artificial-intelligence revolution.
But the question about AI’s energy usage portends even bigger issues about what we need to do in addressing climate change for the next several decades. If we can’t work out how to handle this, we won’t be able to handle broader electrification of the economy, and the climate risks we face will increase.
Innovation in IT got us to this point. Graphics processing units (GPUs) that power the computing behind AI have fallen in cost by 99% since 2006. There was similar concern about the energy use of data centers in the early 2010s, with wild projections of growth in electricity demand. But gains in computing power and energy efficiency not only proved these projections wrong but enabled a 550% increase in global computing capability from 2010 to 2018 with only minimal increases in energy use.
In the late 2010s, however, the trends that had saved us began to break. As the accuracy of AI models dramatically improved, the electricity needed for data centers also started increasing faster; they now account for 4.4% of total demand, up from 1.9% in 2018. Data centers consume more than 10% of the electricity supply in six US states. In Virginia, which has emerged as a hub of data center activity, that figure is 25%.
Projections about the future demand for energy to power AI are uncertain and range widely, but in one study, Lawrence Berkeley National Laboratory estimated that data centers could represent 6% to 12% of total US electricity use by 2028. Communities and companies will notice this type of rapid growth in electricity demand. It will put pressure on energy prices and on ecosystems. The projections have resulted in calls to build lots of new fossil-fired power plants or bring older ones out of retirement. In many parts of the US, the demand will likely result in a surge of natural-gas-powered plants.
It’s a daunting situation. Yet when we zoom out, the projected electricity use from AI is still pretty small. The US generated about 4,300 billion kilowatt-hours last year. We’ll likely need another 1,000 billion to 1,200 billion or more in the next decade—a 24% to 29% increase. Almost half the additional electricity demand will be from electrified vehicles. Another 30% is expected to be from electrified technologies in buildings and industry. Innovation in vehicle and building electrification also advanced in the last decade, and this shift will be good news for the climate, for communities, and for energy costs.
We also need to understand what the energy consumption and carbon emissions associated with AI are buying us. While the impacts from producing semiconductors and powering AI data centers are important, they are likely small compared with the positive or negative effects AI may have on applications such as the electricity grid, the transportation system, buildings and factories, or consumer behavior. Companies could use AI to develop new materials or batteries that would better integrate renewable energy into the grid. But they could also use AI to make it easier to find more fossil fuels. The claims about potential benefits for the climate are exciting, but they need to be continuously verified and will need support to be realized.
This isn’t the first time we’ve faced challenges coping with growth in electricity demand. In the 1960s, US electricity demand was growing at more than 7% per year. In the 1970s that growth was nearly 5%, and in the 1980s and 1990s it was more than 2% per year. Then, starting in 2005, we basically had a decade and a half of flat electricity growth. Most projections for the next decade put our expected growth in electricity demand at around 2% again—but this time we’ll have to do things differently.
To manage these new energy demands, we need a “Grid New Deal” that leverages public and private capital to rebuild the electricity system for AI with enough capacity and intelligence for decarbonization. New clean energy supplies, investment in transmission and distribution, and strategies for virtual demand management can cut emissions, lower prices, and increase resilience. Data centers bringing clean electricity and distribution system upgrades could be given a fast lane to connect to the grid. Infrastructure banks could fund new transmission lines or pay to upgrade existing ones. Direct investment or tax incentives could encourage clean computing standards, workforce development in the clean energy sector, and open data transparency from data center operators about their energy use so that communities can understand and measure the impacts.
In 2022, the White House released a Blueprint for an AI Bill of Rights that provided principles to protect the public’s rights, opportunities, and access to critical resources from being restricted by AI systems. To the AI Bill of Rights, we humbly offer a climate amendment, because ethical AI must be climate-safe AI. It’s a starting point to ensure that the growth of AI works for everyone—that it doesn’t raise people’s energy bills, adds more clean power to the grid than it uses, increases investment in the power system’s infrastructure, and benefits communities while driving innovation.
By grounding the conversation about AI and energy in context about what is needed to tackle climate change, we can deliver better outcomes for communities, ecosystems, and the economy. The growth of electricity demand for AI and data centers is a test case for how society will respond to the demands and challenges of broader electrification. If we get this wrong, the likelihood of meeting our climate targets will be extremely low. This is what we mean when we say the energy and climate impacts from data centers are small, but they are also huge.
Costa Samaras is the Trustee Professor of Civil and Environmental Engineering and director of the Scott Institute for Energy Innovation at Carnegie Mellon University.
Emma Strubell is the Raj Reddy Assistant Professor in the Language Technologies Institute in the School of Computer Science at Carnegie Mellon University.
Ramayya Krishnan is dean of the Heinz College of Information Systems and Public Policy and the William W. and Ruth F. Cooper Professor of Management Science and Information Systems at Carnegie Mellon University.
In the high desert east of Reno, Nevada, construction crews are flattening the golden foothills of the Virginia Range, laying the foundations of a data center city.
Google, Tract, Switch, EdgeCore, Novva, Vantage, and PowerHouse are all operating, building, or expanding huge facilities within the Tahoe Reno Industrial Center, a business park bigger than the city of Detroit.
This story is a part of MIT Technology Review’s series “Power Hungry: AI and our energy future,” on the energy demands and carbon costs of the artificial-intelligence revolution.
Meanwhile, Microsoft acquired more than 225 acres of undeveloped property within the center and an even larger plot in nearby Silver Springs, Nevada. Apple is expanding its data center, located just across the Truckee River from the industrial park. OpenAI has said it’s considering building a data center in Nevada as well.
The corporate race to amass computing resources to train and run artificial intelligence models and store information in the cloud has sparked a data center boom in the desert—just far enough away from Nevada’s communities to elude wide notice and, some fear, adequate scrutiny.
Switch, a data center company based in Las Vegas, says the full build-out of its campus at the Tahoe Reno Industrial Center could exceed seven million square feet.
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The full scale and potential environmental impacts of the developments aren’t known, because the footprint, energy needs, and water requirements are often closely guarded corporate secrets. Most of the companies didn’t respond to inquiries from MIT Technology Review, or declined to provide additional information about the projects.
But there’s “a whole lot of construction going on,” says Kris Thompson, who served as the longtime project manager for the industrial center before stepping down late last year. “The last number I heard was 13 million square feet under construction right now, which is massive.”
Indeed, it’s the equivalent of almost five Empire State Buildings laid out flat. In addition, public filings from NV Energy, the state’s near-monopoly utility, reveal that a dozen data-center projects, mostly in this area, have requested nearly six gigawatts of electricity capacity within the next decade.
That would make the greater Reno area—the biggest little city in the world—one of the largest data-center markets around the globe.
It would also require expanding the state’s power sector by about 40%, all for a single industry in an explosive growth stage that may, or may not, prove sustainable. The energy needs, in turn, suggest those projects could consume billions of gallons of water per year, according to an analysis conducted for this story.
Construction crews are busy building data centers throughout the Tahoe Reno Industrial Center.
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The build-out of a dense cluster of energy and water-hungry data centers in a small stretch of the nation’s driest state, where climate change is driving up temperatures faster than anywhere else in the country, has begun to raise alarms among water experts, environmental groups, and residents. That includes members of the Pyramid Lake Paiute Tribe, whose namesake water body lies within their reservation and marks the end point of the Truckee River, the region’s main source of water.
Much of Nevada has suffered through severe drought conditions for years, farmers and communities are drawing down many of the state’s groundwater reservoirs faster than they can be refilled, and global warming is sucking more and more moisture out of the region’s streams, shrubs, and soils.
“Telling entities that they can come in and stick more straws in the ground for data centers is raising a lot of questions about sound management,” says Kyle Roerink, executive director of the Great Basin Water Network, a nonprofit that works to protect water resources throughout Nevada and Utah.
“We just don’t want to be in a situation where the tail is wagging the dog,” he later added, “where this demand for data centers is driving water policy.”
Luring data centers
In the late 1850s, the mountains southeast of Reno began enticing prospectors from across the country, who hoped to strike silver or gold in the famed Comstock Lode. But Storey County had few residents or economic prospects by the late 1990s, around the time when Don Roger Norman, a media-shy real estate speculator, spotted a new opportunity in the sagebrush-covered hills.
He began buying up tens of thousands of acres of land for tens of millions of dollars and lining up development approvals to lure industrial projects to what became the Tahoe Reno Industrial Center. His partners included Lance Gilman, a cowboy-hat-wearing real estate broker, who later bought the nearby Mustang Ranch brothel and won a seat as a county commissioner.
In 1999, the county passed an ordinance that preapproves companies to develop most types of commercial and industrial projects across the business park, cutting months to years off the development process. That helped cinch deals with a flock of tenants looking to build big projects fast, including Walmart, Tesla, and Redwood Materials. Now the promise of fast permits is helping to draw data centers by the gigawatt.
On a clear, cool January afternoon, Brian Armon, a commercial real estate broker who leads the industrial practices group at NAI Alliance, takes me on a tour of the projects around the region, which mostly entails driving around the business center.
Lance Gilman, a local real estate broker, helped to develop the Tahoe Reno Industrial Center and land some of its largest tenants.
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After pulling off Interstate 80 onto USA Parkway, he points out the cranes, earthmovers, and riprap foundations, where a variety of data centers are under construction. Deeper into the industrial park, Armon pulls up near Switch’s long, low, arched-roof facility, which sits on a terrace above cement walls and security gates. The Las Vegas–based company says the first phase of its data center campus encompasses more than a million square feet, and that the full build-out will cover seven times that space.
Over the next hill, we turn around in Google’s parking lot. Cranes, tents, framing, and construction equipment extend behind the company’s existing data center, filling much of the 1,210-acre lot that the search engine giant acquired in 2017.
Last August, during an event at the University of Nevada, Reno, the company announced it would spend $400 million to expand the data center campus along with another one in Las Vegas.
Thompson says that the development company, Tahoe Reno Industrial LLC, has now sold off every parcel of developable land within the park (although several lots are available for resale following the failed gamble of one crypto tenant).
When I ask Armon what’s attracting all the data centers here, he starts with the fast approvals but cites a list of other lures as well: The inexpensive land. NV Energy’s willingness to strike deals to supply relatively low-cost electricity. Cool nighttime and winter temperatures, as far as American deserts go, which reduce the energy and water needs. The proximity to tech hubs such as Silicon Valley, which cuts latency for applications in which milliseconds matter. And the lack of natural disasters that could shut down the facilities, at least for the most part.
“We are high in seismic activity,” he says. “But everything else is good. We’re not going to have a tornado or flood or a devastating wildfire.”
Then there’s the generous tax policies.
In 2023, Novva, a Utah-based data center company, announced plans to build a 300,000-square-foot facility within the industrial business park.
Nevada doesn’t charge corporate income tax, and it has also enacted deep tax cuts specifically for data centers that set up shop in the state. That includes abatements of up to 75% on property tax for a decade or two—and nearly as much of a bargain on the sales and use taxes applied to equipment purchased for the facilities.
Data centers don’t require many permanent workers to run the operations, but the projects have created thousands of construction jobs. They’re also helping to diversify the region’s economy beyond casinos and generating tax windfalls for the state, counties, and cities, says Jeff Sutich, executive director of the Northern Nevada Development Authority. Indeed, just three data-center projects, developed by Apple, Google, and Vantage, will produce nearly half a billion dollars in tax revenue for Nevada, even with those generous abatements, according to the Nevada Governor’s Office of Economic Development.
The question is whether the benefits of data centers are worth the tradeoffs for Nevadans, given the public health costs, greenhouse-gas emissions, energy demands, and water strains.
The rain shadow
The Sierra Nevada’s granite peaks trace the eastern edge of California, forcing Pacific Ocean winds to rise and cool. That converts water vapor in the air into the rain and snow that fill the range’s tributaries, rivers, and lakes.
But the same meteorological phenomenon casts a rain shadow over much of neighboring Nevada, forming an arid expanse known as the Great Basin Desert. The state receives about 10 inches of precipitation a year, about a third of the national average.
The Truckee River draws from the melting Sierra snowpack at the edge of Lake Tahoe, cascades down the range, and snakes through the flatlands of Reno and Sparks. It forks at the Derby Dam, a Reclamation Act project a few miles from the Tahoe Reno Industrial Center, which diverts water to a farming region further east while allowing the rest to continue north toward Pyramid Lake.
Along the way, an engineered system of reservoirs, canals, and treatment plants divert, store, and release water from the river, supplying businesses, cities, towns, and native tribes across the region. But Nevada’s population and economy are expanding, creating more demands on these resources even as they become more constrained.
The Truckee River, which originates at Lake Tahoe and terminates at Pyramid Lake, is the major water source for cities, towns, and farms across northwestern Nevada.
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Throughout much of the 2020s the state has suffered through one of the hottest and most widespread droughts on record, extending two decades of abnormally dry conditions across the American West. Some scientists fear it may constitute an emerging megadrought.
About 50% of Nevada currently faces moderate to exceptional drought conditions. In addition, more than half of the state’s hundreds of groundwater basins are already “over-appropriated,” meaning the water rights on paper exceed the levels believed to be underground.
It’s not clear if climate change will increase or decrease the state’s rainfall levels, on balance. But precipitation patterns are expected to become more erratic, whiplashing between short periods of intense rainfall and more-frequent, extended, or severe droughts.
In addition, more precipitation will fall as rain rather than snow, shortening the Sierra snow season by weeks to months over the coming decades.
“In the extreme case, at the end of the century, that’s pretty much all of winter,” says Sean McKenna, executive director of hydrologic sciences at the Desert Research Institute, a research division of the Nevada System of Higher Education.
That loss will undermine an essential function of the Sierra snowpack: reliably delivering water to farmers and cities when it’s most needed in the spring and summer, across both Nevada and California.
These shifting conditions will require the region to develop better ways to store, preserve, and recycle the water it does get, McKenna says. Northern Nevada’s cities, towns, and agencies will also need to carefully evaluate and plan for the collective impacts of continuing growth and development on the interconnected water system, particularly when it comes to water-hungry projects like data centers, he adds.
“We can’t consider each of these as a one-off, without considering that there may be tens or dozens of these in the next 15 years,” McKenna says.
Thirsty data centers
Data centers suck up water in two main ways.
As giant rooms of server racks process information and consume energy, they generate heat that must be shunted away to prevent malfunctions and damage to the equipment. The processing units optimized for training and running AI models often draw more electricity and, in turn, produce more heat.
To keep things cool, more and more data centers have turned to liquid cooling systems that don’t need as much electricity as fan cooling or air-conditioning.
These often rely on water to absorb heat and transfer it to outdoor cooling towers, where much of the moisture evaporates. Microsoft’s US data centers, for instance, could have directly evaporated nearly 185,000 gallons of “clean freshwater” in the course of training OpenAI’s GPT-3 large language model, according to a 2023 preprint study led by researchers at the University of California, Riverside. (The research has since been peer-reviewed and is awaiting publication.)
What’s less appreciated, however, is that the larger data-center drain on water generally occurs indirectly, at the power plants generating extra electricity for the turbocharged AI sector. These facilities, in turn, require more water to cool down equipment, among other purposes.
You have to add up both uses “to reflect the true water cost of data centers,” says Shaolei Ren, an associate professor of electrical and computer engineering at UC Riverside and coauthor of the study.
Ren estimates that the 12 data-center projects listed in NV Energy’s report would directly consume between 860 million gallons and 5.7 billion gallons a year, based on the requested electricity capacity. (“Consumed” here means the water is evaporated, not merely withdrawn and returned to the engineered water system.) The indirect water drain associated with electricity generation for those operations could add up to 15.5 billion gallons, based on the average consumption of the regional grid.
The exact water figures would depend on shifting climate conditions, the type of cooling systems each data center uses, and the mix of power sources that supply the facilities.
Solar power, which provides roughly a quarter of Nevada’s power, requires relatively little water to operate, for instance. But natural-gas plants, which generate about 56%, withdraw 2,803 gallons per megawatt-hour on average, according to the Energy Information Administration.
Geothermal plants, which produce about 10% of the state’s electricity by cycling water through hot rocks, generally consume less water than fossil fuel plants do but often require more water than other renewables, according to some research.
But here too, the water usage varies depending on the type of geothermal plant in question. Google has lined upseveral deals to partially power its data centers through Fervo Energy, which has helped to commercialize an emerging approach that injects water under high pressure to fracture rock and form wells deep below the surface.
The company stresses that it doesn’t evaporate water for cooling and that it relies on brackish groundwater, not fresh water, to develop and run its plants. In a recent post, Fervo noted that its facilities consume significantly less water per megawatt-hour than coal, nuclear, or natural-gas plants do.
Part of NV Energy’s proposed plan to meet growing electricity demands in Nevada includes developing several natural-gas peaking units, adding more than one gigawatt of solar power and installing another gigawatt of battery storage. It’s also forging ahead with a more than $4 billion transmission project.
But the company didn’t respond to questions concerning how it will supply all of the gigawatts of additional electricity requested by data centers, if the construction of those power plants will increase consumer rates, or how much water those facilities are expected to consume.
NV Energy operates a transmission line, substation, and power plant in or around the Tahoe Reno Industrial Center.
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“NV Energy teams work diligently on our long-term planning to make investments in our infrastructure to serve new customers and the continued growth in the state without putting existing customers at risk,” the company said in a statement.
An added challenge is that data centers need to run around the clock. That will often compel utilities to develop new electricity-generating sources that can run nonstop as well, as natural-gas, geothermal, or nuclear plants do, says Emily Grubert, an associate professor of sustainable energy policy at the University of Notre Dame, who has studied the relative water consumption of electricity sources.
“You end up with the water-intensive resources looking more important,” she adds.
Even if NV Energy and the companies developing data centers do strive to power them through sources with relatively low water needs, “we only have so much ability to add six gigawatts to Nevada’s grid,” Grubert explains. “What you do will never be system-neutral, because it’s such a big number.”
Securing supplies
On a mid-February morning, I meet TRI’s Thompson and Don Gilman, Lance Gilman’s son, at the Storey County offices, located within the industrial center.
“I’m just a country boy who sells dirt,” Gilman, also a real estate broker, says by way of introduction.
We climb into his large SUV and drive to a reservoir in the heart of the industrial park, filled nearly to the lip.
Thompson explains that much of the water comes from an on-site treatment facility that filters waste fluids from companies in the park. In addition, tens of millions of gallons of treated effluent will also likely flow into the tank this year from the Truckee Meadows Water Authority Reclamation Facility, near the border of Reno and Sparks. That’s thanks to a 16-mile pipeline that the developers, the water authority, several tenants, and various local cities and agencies partnered to build, through a project that began in 2021.
“Our general improvement district is furnishing that water to tech companies here in the park as we speak,” Thompson says. “That helps preserve the precious groundwater, so that is an environmental feather in the cap for these data centers. They are focused on environmental excellence.”
The reservoir within the industrial business park provides water to data centers and other tenants.
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But data centers often need drinking-quality water—not wastewater merely treated to irrigation standards—for evaporative cooling, “to avoid pipe clogs and/or bacterial growth,” the UC Riverside study notes. For instance, Google says its data centers withdrew about 7.7 billion gallons of water in 2023, and nearly 6 billion of those gallons were potable.
Tenants in the industrial park can potentially obtain access to water from the ground and the Truckee River, as well. From early on, the master developers worked hard to secure permits to water sources, since they are nearly as precious as development entitlements to companies hoping to build projects in the desert.
Initially, the development company controlled a private business, the TRI Water and Sewer Company, that provided those services to the business park’s tenants, according to public documents. The company set up wells, a water tank, distribution lines, and a sewer disposal system.
But in 2000, the board of county commissioners established a general improvement district, a legal mechanism for providing municipal services in certain parts of the state, to manage electricity and then water within the center. It, in turn, hired TRI Water and Sewer as the operating company.
As of its 2020 service plan, the general improvement district held permits for nearly 5,300 acre-feet of groundwater, “which can be pumped from well fields within the service area and used for new growth as it occurs.” The document lists another 2,000 acre-feet per year available from the on-site treatment facility, 1,000 from the Truckee River, and 4,000 more from the effluent pipeline.
Those figures haven’t budged much since, according to Shari Whalen, general manager of the TRI General Improvement District. All told, they add up to more than 4 billion gallons of water per year for all the needs of the industrial park and the tenants there, data centers and otherwise.
Whalen says that the amount and quality of water required for any given data center depends on its design, and that those matters are worked out on a case-by-case basis.
When asked if the general improvement district is confident that it has adequate water resources to supply the needs of all the data centers under development, as well as other tenants at the industrial center, she says: “They can’t just show up and build unless they have water resources designated for their projects. We wouldn’t approve a project if it didn’t have those water resources.”
Waterbattles
As the region’s water sources have grown more constrained, lining up supplies has become an increasingly high-stakes and controversial business.
More than a century ago, the US federal government filed a lawsuit against an assortment of parties pulling water from the Truckee River. The suit would eventually establish that the Pyramid Lake Paiute Tribe’s legal rights to water for irrigation superseded other claims. But the tribe has been fighting to protect those rights and increase flows from the river ever since, arguing that increasing strains on the watershed from upstream cities and businesses threaten to draw away water reserved for reservation farming, decrease lake levels, and harm native fish.
The Pyramid Lake Paiute Tribe considers the water body and its fish, including the endangered cui-ui and threatened Lahontan cutthroat trout, to be essential parts of its culture, identity, and way of life. The tribe was originally named Cui-ui Ticutta, which translates to cui-ui eaters. The lake continues to provide sustenance as well as business for the tribe and its members, a number of whom operate boat charters and fishing guide services.
“It’s completely tied into us as a people,” says Steven Wadsworth, chairman of the Pyramid Lake Paiute Tribe.
“That is what has sustained us all this time,” he adds. “It’s just who we are. It’s part of our spiritual well-being.”
Steven Wadsworth, chairman of the Pyramid Lake Paiute Tribe, fears that data centers will divert water that would otherwise reach the tribe’s namesake lake.
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In recent decades, the tribe has sued the Nevada State Engineer, Washoe County, the federal government, and others for overallocating water rights and endangering the lake’s fish. It also protested the TRI General Improvement District’s applications to draw thousands of additional acre‑feet of groundwater from a basin near the business park. In 2019, the State Engineer’s office rejected those requests, concluding that the basin was already fully appropriated.
More recently, the tribe took issue with the plan to build the pipeline and divert effluent that would have flown into the Truckee, securing an agreement that required the Truckee Meadows Water Authority and other parties to add back several thousand acre‑feet of water to the river.
Whalen says she’s sensitive to Wadsworth’s concerns. But she says that the pipeline promises to keep a growing amount of treated wastewater out of the river, where it could otherwise contribute to rising salt levels in the lake.
“I think that the pipeline from [the Truckee Meadows Water Authority] to our system is good for water quality in the river,” she says. “I understand philosophically the concerns about data centers, but the general improvement district is dedicated to working with everyone on the river for regional water-resource planning—and the tribe is no exception.”
Water efficiency
In an email, Thompson added that he has “great respect and admiration,” for the tribe and has visited the reservation several times in an effort to help bring industrial or commercial development there.
He stressed that all of the business park’s groundwater was “validated by the State Water Engineer,” and that the rights to surface water and effluent were purchased “for fair market value.”
During the earlier interview at the industrial center, he and Gilman had both expressed confidence that tenants in the park have adequate water supplies, and that the businesses won’t draw water away from other areas.
“We’re in our own aquifer, our own water basin here,” Thompson said. “You put a straw in the ground here, you’re not going to pull water from Fernley or from Reno or from Silver Springs.”
Gilman also stressed that data-center companies have gotten more water efficient in recent years, echoing a point others made as well.
“With the newer technology, it’s not much of a worry,” says Sutich, of the Northern Nevada Development Authority. “The technology has come a long way in the last 10 years, which is really giving these guys the opportunity to be good stewards of water usage.”
An aerial view of the cooling tower fans at Google’s data center in the Tahoe Reno Industrial Center.
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Indeed, Google’s existing Storey County facility is air-cooled, according to the company’s latest environmental report. The data center withdrew 1.9 million gallons in 2023 but only consumed 200,000 gallons. The rest cycles back into the water system.
Google said all the data centers under construction on its campus will also “utilize air-cooling technology.” The company didn’t respond to a question about the scale of its planned expansion in the Tahoe Reno Industrial Center, and referred a question about indirect water consumption to NV Energy.
The search giant has stressed that it strives to be water efficient across all of its data centers, and decides whether to use air or liquid cooling based on local supply and projected demand, among other variables.
Four years ago, the company set a goal of replenishing more water than it consumes by 2030. Locally, it also committed to provide half a million dollars to the National Forest Foundation to improve the Truckee River watershed and reduce wildfire risks.
Microsoft clearly suggestedin earlier news reports that the Silver Springs land it purchased around the end of 2022 would be used for a data center. NAI Alliance’s market real estate report identifies that lot, as well as the parcel Microsoft purchased within the Tahoe Reno Industrial Center, as data center sites.
But the company now declines to specify what it intends to build in the region.
“While the land purchase is public knowledge, we have not disclosed specific details [of] our plans for the land or potential development timelines,” wrote Donna Whitehead, a Microsoft spokesperson, in an email.
Workers have begun grading land inside a fenced off lot within the Tahoe Reno Industrial Center.
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Microsoft has also scaled down its global data-center ambitions, backing away from several projects in recent months amid shifting economic conditions, according to various reports.
Whatever it ultimately does or doesn’t build, the company stresses that it has made strides to reduce water consumption in its facilities. Late last year, the company announced that it’s using “chip-level cooling solutions” in data centers, which continually circulate water between the servers and chillers through a closed loop that the company claims doesn’t lose any water to evaporation. It says the design requires only a “nominal increase” in energy compared to its data centers that rely on evaporative water cooling.
Others seem to be taking a similar approach. EdgeCore also said its 900,000-square-foot data center at the Tahoe Reno Industrial Center will rely on an “air-cooled closed-loop chiller” that doesn’t require water evaporation for cooling.
But some of the companies seem to have taken steps to ensure access to significant amounts of water. Switch, for instance, took a lead role in developing the effluent pipeline. In addition, Tract, which develops campuses on which third-party data centers can build their own facilities, has said it lined up more than 1,100 acre-feet of water rights, the equivalent of nearly 360 million gallons a year.
Apple, Novva, Switch, Tract, and Vantage didn’t respond to inquiries from MIT Technology Review.
Coming conflicts
The suggestion that companies aren’t straining water supplies when they adopt air cooling is, in many cases, akin to saying they’re not responsible for the greenhouse gas produced through their power use simply because it occurs outside of their facilities. In fact, the additional water used at a power plant to meet the increased electricity needs of air cooling may exceed any gains at the data center, Ren, of UC Riverside, says.
“That’s actually very likely, because it uses a lot more energy,” he adds.
That means that some of the companies developing data centers in and around Storey County may simply hand off their water challenges to other parts of Nevada or neighboring states across the drying American West, depending on where and how the power is generated, Ren says.
Google has said its air-cooled facilities require about 10% more electricity, and its environmental report notes that the Storey County facility is one of its two least-energy-efficient data centers.
Pipes running along Google’s data center campus help the search company cool its servers.
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Some fear there’s also a growing mismatch between what Nevada’s water permits allow, what’s actually in the ground, and what nature will provide as climate conditions shift. Notably, the groundwater committed to all parties from the Tracy Segment basin—a long-fought-over resource that partially supplies the TRI General Improvement District—already exceeds the “perennial yield.” That refers to the maximum amount that can be drawn out every year without depleting the reservoir over the long term.
“If pumping does ultimately exceed the available supply, that means there will be conflict among users,” Roerink, of the Great Basin Water Network, said in an email. “So I have to wonder: Who could be suing whom? Who could be buying out whom? How will the tribe’s rights be defended?”
The Truckee Meadows Water Authority, the community-owned utility that manages the water system for Reno and Sparks, said it is planning carefully for the future and remains confident there will be “sufficient resources for decades to come,” at least within its territory east of the industrial center.
Storey County, the Truckee-Carson Irrigation District, and the State Engineer’s office didn’t respond to questions or accept interview requests.
Open for business
As data center proposals have begun shifting into Northern Nevada’s cities, more local residents and organizations have begun to take notice and express concerns. The regional division of the Sierra Club, for instance, recently sought to overturn the approval of Reno’s first data center, about 20 miles west of the Tahoe Reno Industrial Center.
Olivia Tanager, director of the Sierra Club’s Toiyabe Chapter, says the environmental organization was shocked by the projected electricity demands from data centers highlighted in NV Energy’s filings.
Nevada’s wild horses are a common sight along USA Parkway, the highway cutting through the industrial business park.
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“We have increasing interest in understanding the impact that data centers will have to our climate goals, to our grid as a whole, and certainly to our water resources,” she says. “The demands are extraordinary, and we don’t have that amount of water to toy around with.”
During a city hall hearing in January that stretched late into the evening, she and a line of residents raised concerns about the water, energy, climate, and employment impacts of AI data centers. At the end, though, the city council upheld the planning department’s approval of the project, on a 5-2 vote.
“Welcome to Reno,” Kathleen Taylor, Reno’s vice mayor, said before casting her vote. “We’re open for business.”
Where the river ends
In late March, I walk alongside Chairman Wadsworth, of the Pyramid Lake Paiute Tribe, on the shores of Pyramid Lake, watching a row of fly-fishers in waders cast their lines into the cold waters.
The lake is the largest remnant of Lake Lahontan, an Ice Age inland sea that once stretched across western Nevada and would have submerged present-day Reno. But as the climate warmed, the lapping waters retreated, etching erosional terraces into the mountainsides and exposing tufa deposits around the lake, large formations of porous rock made of calcium-carbonate. That includes the pyramid-shaped island on the eastern shore that inspired the lake’s name.
A lone angler stands along the shores of Pyramid Lake.
In the decades after the US Reclamation Service completed the Derby Dam in 1905, Pyramid Lake declined another 80 feet and nearby Winnemucca Lake dried up entirely.
“We know what happens when water use goes unchecked,” says Wadsworth, gesturing eastward toward the range across the lake, where Winnemucca once filled the next basin over. “Because all we have to do is look over there and see a dry, barren lake bed that used to be full.”
In an earlier interview, Wadsworth acknowledged that the world needs data centers. But he argued they should be spread out across the country, not densely clustered in the middle of the Nevada desert.
Given the fierce competition for resources up to now, he can’t imagine how there could be enough water to meet the demands of data centers, expanding cities, and other growing businesses without straining the limited local supplies that should, by his accounting, flow to Pyramid Lake.
He fears these growing pressures will force the tribe to wage new legal battles to protect their rights and preserve the lake, extending what he refers to as “a century of water wars.”
“We have seen the devastating effects of what happens when you mess with Mother Nature,” Wadsworth says. “Part of our spirit has left us. And that’s why we fight so hard to hold on to what’s left.”
This story is a part of MIT Technology Review’s series “Power Hungry: AI and our energy future,” on the energy demands and carbon costs of the artificial-intelligence revolution.
Measuring the energy used by an AI model is not like evaluating a car’s fuel economy or an appliance’s energy rating. There’s no agreed-upon method or public database of values. There are no regulators who enforce standards, and consumers don’t get the chance to evaluate one model against another.
Despite the fact that billions of dollars are being poured into reshaping energy infrastructure around the needs of AI, no one has settled on a way to quantify AI’s energy usage. Worse, companies are generally unwilling to disclose their own piece of the puzzle. There are also limitations to estimating the emissions associated with that energy demand, because the grid hosts a complicated, ever-changing mix of energy sources.
It’s a big mess, basically. So, that said, here are the many variables, assumptions, and caveats that we used to calculate the consequences of an AI query. (You can see the full results of our investigation here.)
Measuring the energy a model uses
Companies like OpenAI, dealing in “closed-source” models, generally offer access to their systems through an interface where you input a question and receive an answer. What happens in between—which data center in the world processes your request, the energy it takes to do so, and the carbon intensity of the energy sources used—remains a secret, knowable only to the companies. There are few incentives for them to release this information, and so far, most have not.
That’s why, for our analysis, we looked at open-source models. They serve as a very imperfect proxy but the best one we have. (OpenAI, Microsoft, and Google declined to share specifics on how much energy their closed-source models use.)
The best resources for measuring the energy consumption of open-source AI models are AI Energy Score, ML.Energy, and MLPerf Power. The team behind ML.Energy assisted us with our text and image model calculations, and the team behind AI Energy Score helped with our video model calculations.
Text models
AI models use up energy in two phases: when they initially learn from vast amounts of data, called training, and when they respond to queries, called inference. When ChatGPT was launched a few years ago, training was the focus, as tech companies raced to keep up and build ever-bigger models. But now, inference is where the most energy is used.
The most accurate way to understand how much energy an AI model uses in the inference stage is to directly measure the amount of electricity used by the server handling the request. Servers contain all sorts of components—powerful chips called GPUs that do the bulk of the computing, other chips called CPUs, fans to keep everything cool, and more. Researchers typically measure the amount of power the GPU draws and estimate the rest (more on this shortly).
To do this, we turned to PhD candidate Jae-Won Chung and associate professor Mosharaf Chowdhury at the University of Michigan, who lead the ML.Energy project. Once we collected figures for different models’ GPU energy use from their team, we had to estimate how much energy is used for other processes, like cooling. We examined research literature, including a 2024 paper from Microsoft, to understand how much of a server’s total energy demand GPUs are responsible for. It turns out to be about half. So we took the team’s GPU energy estimate and doubled it to get a sense of total energy demands.
The ML.Energy team uses a batch of 500 prompts from a larger dataset to test models. The hardware is kept the same throughout; the GPU is a popular Nvidia chip called the H100. We decided to focus on models of three sizes from the Meta Llama family: small (8 billion parameters), medium (70 billion), and large (405 billion). We also identified a selection of prompts to test. We compared these with the averages for the entire batch of 500 prompts.
Image models
Stable Diffusion 3 from Stability AI is one of the most commonly used open-source image-generating models, so we made it our focus. Though we tested multiple sizes of the text-based Meta Llama model, we focused on one of the most popular sizes of Stable Diffusion 3, with 2 billion parameters.
The team uses a dataset of example prompts to test a model’s energy requirements. Though the energy used by large language models is determined partially by the prompt, this isn’t true for diffusion models. Diffusion models can be programmed to go through a prescribed number of “denoising steps” when they generate an image or video, with each step being an iteration of the algorithm that adds more detail to the image. For a given step count and model, all images generated have the same energy footprint.
The more steps, the higher quality the end result—but the more energy used. Numbers of steps vary by model and application, but 25 is pretty common, and that’s what we used for our standard quality. For higher quality, we used 50 steps.
We mentioned that GPUs are usually responsible for about half of the energy demands of large language model requests. There is not sufficient research to know how this changes for diffusion models that generate images and videos. In the absence of a better estimate, and after consulting with researchers, we opted to stick with this 50% rule of thumb for images and videos too.
Video models
Chung and Chowdhury do test video models, but only ones that generate short, low-quality GIFs. We don’t think the videos these models produce mirror the fidelity of the AI-generated video that many people are used to seeing.
Instead, we turned to Sasha Luccioni, the AI and climate lead at Hugging Face, who directs the AI Energy Score project. She measures the energy used by the GPU during AI requests. We chose two versions of the CogVideoX model to test: an older, lower-quality version and a newer, higher-quality one.
We asked Luccioni to use her tool, called Code Carbon, to test both and measure the results of a batch of video prompts we selected, using the same hardware as our text and image tests to keep as many variables as possible the same. She reported the GPU energy demands, which we again doubled to estimate total energy demands.
Tracing where that energy comes from
After we understand how much energy it takes to respond to a query, we can translate that into the total emissions impact. Doing so requires looking at the power grid from which data centers draw their electricity.
Nailing down the climate impact of the grid can be complicated, because it’s both interconnected and incredibly local. Imagine the grid as a system of connected canals and pools of water. Power plants add water to the canals, and electricity users, or loads, siphon it out. In the US, grid interconnections stretch all the way across the country. So, in a way, we’re all connected, but we can also break the grid up into its component pieces to get a sense for how energy sources vary across the country.
Understanding carbon intensity
The key metric to understand here is called carbon intensity, which is basically a measure of how many grams of carbon dioxide pollution are released for every kilowatt-hour of electricity that’s produced.
To get carbon intensity figures, we reached out to Electricity Maps, a Danish startup company that gathers data on grids around the world. The team collects information from sources including governments and utilities and uses them to publish historical and real-time estimates of the carbon intensity of the grid. You can find more about their methodology here.
The company shared with us historical data from 2024, both for the entire US and for a few key balancing authorities (more on this in a moment). After discussions with Electricity Maps founder Olivier Corradi and other experts, we made a few decisions about which figures we would use in our calculations.
One way to measure carbon intensity is to simply look at all the power plants that are operating on the grid, add up the pollution they’re producing at the moment, and divide that total by the electricity they’re producing. But that doesn’t account for the emissions that are associated with building and tearing down power plants, which can be significant. So we chose to use carbon intensity figures that account for the whole life cycle of a power plant.
We also chose to use the consumption-based carbon intensity of energy rather than production-based. This figure accounts for imports and exports moving between different parts of the grid and best represents the electricity that’s being used, in real time, within a given region.
For most of the calculations you see in the story, we used the average carbon intensity for the US for 2024, according to Electricity Maps, which is 402.49 grams of carbon dioxide equivalent per kilowatt-hour.
Understanding balancing authorities
While understanding the picture across the entire US can be helpful, the grid can look incredibly different in different locations.
One way we can break things up is by looking at balancing authorities. These are independent bodies responsible for grid balancing in a specific region. They operate mostly independently, though there’s a constant movement of electricity between them as well. There are 66 balancing authorities in the US, and we can calculate a carbon intensity for the part of the grid encompassed by a specific balancing authority.
Electricity Maps provided carbon intensity figures for a few key balancing authorities, and we focused on several that play the largest roles in data center operations. ERCOT (which covers most of Texas) and PJM (a cluster of states on the East Coast, including Virginia, Pennsylvania, and New Jersey) are two of the regions with the largest burden of data centers, according to research from the Harvard School of Public Health.
We added CAISO (in California) because it covers the most populated state in the US. CAISO also manages a grid with a significant number of renewable energy sources, making it a good example of how carbon intensity can change drastically depending on the time of day. (In the middle of the day, solar tends to dominate, while natural gas plays a larger role overnight, for example.)
One key caveat here is that we’re not entirely sure where companies tend to send individual AI inference requests. There are clusters of data centers in the regions we chose as examples, but when you use a tech giant’s AI model, your request could be handled by any number of data centers owned or contracted by the company. One reasonable approximation is location: It’s likely that the data center servicing a request is close to where it’s being made, so a request on the West Coast might be most likely to be routed to a data center on that side of the country.
Explaining what we found
To better contextualize our calculations, we introduced a few comparisons people might be more familiar with than kilowatt-hours and grams of carbon dioxide. In a few places, we took the amount of electricity estimated to be used by a model and calculated how long that electricity would be able to power a standard microwave, as well as how far it might take someone on an e-bike.
In the case of the e-bike, we assumed an efficiency of 25 watt-hours per mile, which falls in the range of frequently cited efficiencies for a pedal-assisted bike. For the microwave, we assumed an 800-watt model, which falls within the average range in the US.
We also introduced a comparison to contextualize greenhouse gas emissions: miles driven in a gas-powered car. For this, we used data from the US Environmental Protection Agency, which puts the weighted average fuel economy of vehicles in the US in 2022 at 393 grams of carbon dioxide equivalent per mile.
Predicting how much energy AI will use in the future
After measuring the energy demand of an individual query and the emissions it generated, it was time to estimate how all of this added up to national demand.
There are two ways to do this. In a bottom-up analysis, you estimate how many individual queries there are, calculate the energy demands of each, and add them up to determine the total. For a top-down look, you estimate how much energy all data centers are using by looking at larger trends.
Bottom-up is particularly difficult, because, once again, closed-source companies do not share such information and declined to talk specifics with us. While we can make some educated guesses to give us a picture of what might be happening right now, looking into the future is perhaps better served by taking a top-down approach.
This data is scarce as well. The most important report was published in December by the Lawrence Berkeley National Laboratory, which is funded by the Department of Energy, and the report authors noted that it’s only the third such report released in the last 20 years. Academic climate and energy researchers we spoke with said it’s a major problem that AI is not considered its own economic sector for emissions measurements, and there aren’t rigorous reporting requirements. As a result, it’s difficult to track AI’s climate toll.
Still, we examined the report’s results, compared them with other findings and estimates, and consulted independent experts about the data. While much of the report was about data centers more broadly, we drew out data points that were specific to the future of AI.
Company goals
We wanted to contrast these figures with the amounts of energy that AI companies themselves say they need. To do so, we collected reports by leading tech and AI companies about their plans for energy and data center expansions, as well as the dollar amounts they promised to invest. Where possible, we fact-checked the promises made in these claims. (Meta and Microsoft’s pledges to use more nuclear power, for example, would indeed reduce the carbon emissions of the companies, but it will take years, if not decades, for these additional nuclear plants to come online.)
Requests to companies
We submitted requests to Microsoft, Google, and OpenAI to have data-driven conversations about their models’ energy demands for AI inference. None of the companies made executives or leadership available for on-the-record interviews about their energy usage.