These new batteries are finding a niche

Lithium-ion batteries have some emerging competition: Sodium-based alternatives are starting to make inroads.

Sodium is more abundant on Earth than lithium, and batteries that use the material could be cheaper in the future. Building a new battery chemistry is difficult, mostly because lithium is so entrenched. But, as I’ve noted before, this new technology has some advantages in nooks and crannies. 

I’ve been following sodium-ion batteries for a few years, and we’re starting to see the chemistry make progress, though not significantly in the big category of electric vehicles. Rather, these new batteries are finding niches where they make sense, especially in smaller electric scooters and large energy storage installations. Let’s talk about what’s new for sodium batteries, and what it’ll take for the chemistry to really break out.

Two years ago, lithium prices were, to put it bluntly, bonkers. The price of lithium hydroxide (an ingredient used to make lithium-ion batteries) went from a little under $10,000 per metric ton in January 2021 to over $76,000 per metric ton in January 2023, according to data from Benchmark Mineral Intelligence.

More expensive lithium drives up the cost of lithium-ion batteries. Price spikes, combined with concerns about potential shortages, pushed a lot of interest in alternatives, including sodium-ion.

I wrote about this swelling interest for a 2023 story, which focused largely on vehicle makers in China and a few US startups that were hoping to get in on the game.

There’s one key point to understand here. Sodium-based batteries will need to be cheaper than lithium-based ones to have a shot at competing, especially for electric vehicles, because they tend to be worse on one key metric: energy density. A sodium-ion battery that’s the same size and weight as a lithium-ion one will store less energy, limiting vehicle range.

The issue is, as we’ve seen since that 2023 story, lithium prices—and the lithium-ion battery market—are moving targets. Prices for precursor materials have come back down since the early 2023 peak, with lithium hydroxide crossing below $9,000 per metric ton recently.

And as more and more battery factories are built, costs for manufactured products come down too, with the average price for a lithium-ion pack in 2024 dropping 20%—the biggest annual decrease since 2017, according to BloombergNEF.

I wrote about this potential difficulty in that 2023 story: “If sodium-ion batteries are breaking into the market because of cost and material availability, declining lithium prices could put them in a tough position.”

One researcher I spoke with at the time suggested that sodium-ion batteries might not compete directly with lithium-ion batteries but could instead find specialized uses where the chemistry made sense. Two years later, I think we’re starting to see what those are.

One growing segment that could be a big win for sodium-ion: electric micromobility vehicles, like scooters and three-wheelers. Since these vehicles tend to travel shorter distances at lower speeds than cars, the lower energy density of sodium-ion batteries might not be as big a deal.

There’s a great BBC story from last week that profiled efforts to put sodium-ion batteries in electric scooters. It focused on one Chinese company called Yadea, which is one of the largest makers of electric two- and three-wheelers in the world. Yadea has brought a handful of sodium-powered models to the market so far, selling about 1,000 of the scooters in the first three months of 2025, according to the company’s statement to the BBC. It’s early days, but it’s interesting to see this market emerging.

Sodium-ion batteries are also seeing significant progress in stationary energy storage installations, including some on the grid. (Again, if you’re not worried about carting the battery around and fitting it into the limited package of a vehicle, energy density isn’t so important.)

The Baochi Energy Storage Station that just opened in Yunnan province, China, is a hybrid system that uses both lithium-ion and sodium-ion batteries and has a capacity of 400 megawatt-hours. And Natron Energy in the US is among those targeting other customers for stationary storage, specifically going after data centers.

While smaller vehicles and stationary installations appear to be the early wins for sodium, some companies aren’t giving up on using the alternative for EVs as well. The Chinese battery giant CATL announced earlier this year that it plans to produce sodium-ion batteries for heavy-duty trucks under the brand name Naxtra Battery.

Ultimately, lithium is the juggernaut of the battery industry, and going head to head is going to be tough for any alternative chemistry. But sticking with niches that make sense could help sodium-ion make progress at a time when I’d argue we need every successful battery type we can get. 

This article is from The Spark, MIT Technology Review’s weekly climate newsletter. To receive it in your inbox every Wednesday, sign up here.

Over $1 billion in federal funding got slashed for this polluting industry

The clean cement industry might be facing the end of the road, before it ever really got rolling. 

On Friday, the US Department of Energy announced that it was canceling $3.7 billion in funding for 24 projects related to energy and industry. That included nearly $1.3 billion for cement-related projects.

Cement is a massive climate problem, accounting for roughly 7% of global greenhouse-gas emissions. What’s more, it’s a difficult industry to clean up, with huge traditional players and expensive equipment and infrastructure to replace. This funding was supposed to help address those difficulties, by supporting projects on the cusp of commercialization. Now companies will need to fill in the gap left by these cancellations, and it’s a big one. 

First up on the list for cuts is Sublime Systems, a company you’re probably familiar with if you’ve been reading this newsletter for a while. I did a deep dive last year, and the company was on our list of Climate Tech Companies to Watch in both 2023 and 2024.

The startup’s approach is to make cement using electricity. The conventional process requires high temperatures typically achieved by burning fossil fuels, so avoiding that could prevent a lot of emissions. 

In 2024, Sublime received an $87 million grant from the DOE to construct a commercial demonstration plant in Holyoke, Massachusetts. That grant would have covered roughly half the construction costs for the facility, which is scheduled to open in 2026 and produce up to 30,000 metric tons of cement each year. 

“We were certainly surprised and disappointed about the development,” says Joe Hicken, Sublime’s senior VP of business development and policy. Customers are excited by the company’s technology, Hicken adds, pointing to Sublime’s recently announced deal with Microsoft, which plans to buy up to 622,500 metric tons of cement from the company. 

Another big name, Brimstone, also saw its funding affected. That award totaled $189 million for a commercial demonstration plant, which was expected to produce over 100,000 metric tons of cement annually. 

In a statement, a Brimstone representative said the company believes the cancellation was a “misunderstanding.” The statement pointed out that the planned facility would make not only cement but also alumina, supporting US-based aluminum production. (Aluminum is classified as a critical mineral by the US Geological Survey, meaning it’s considered crucial to the US economy and national security.) 

An award to Heidelberg Materials for up to $500 million for a planned Indiana facility was also axed. The idea there was to integrate carbon capture and storage to clean up emissions from the plant, which would have made it the first cement plant in the US to demonstrate that technology. In a written statement, a representative said the decision can be appealed, and the company is considering that option.

And National Cement’s funding for the Lebec Net-Zero Project, another $500 million award, was canceled. That facility planned to make carbon-neutral cement through a combination of strategies: reducing the polluting ingredients needed, using alternative fuels like biomass, and capturing the plant’s remaining emissions. 

“We want to emphasize that this project will expand domestic manufacturing capacity for a critical industrial sector, while also integrating new technologies to keep American cement competitive,” said a company spokesperson in a written statement. 

There’s a sentiment here that’s echoed in all the responses I received: While these awards were designed to cut emissions, these companies argue that they can fit into the new administration’s priorities. They’re emphasizing phrases like “critical minerals,” “American jobs,” and “domestic supply chains.” 

“We’ve heard loud and clear from the Trump administration the desire to displace foreign imports of things that can be made here in America,” Sublime’s Hicken says. “At the end of the day, what we deliver is what the policymakers in DC are looking for.” 

But this administration is showing that it’s not supporting climate efforts—often even those that also advance its stated goals of energy abundance and American competitiveness. 

On Monday, my colleague James Temple published a new story about cuts to climate research, including tens of millions of dollars in grants from the National Science Foundation. Researchers at Harvard were particularly hard hit. 

Even as there’s interest in advancing the position of the US on the world’s stage, these cuts are making it hard for researchers and companies alike to do the crucial work of understanding our climate and developing and deploying new technologies. 

This article is from The Spark, MIT Technology Review’s weekly climate newsletter. To receive it in your inbox every Wednesday, sign up here.

What will power AI’s growth?

It’s been a little over a week since we published Power Hungry, a package that takes a hard look at the expected energy demands of AI. Last week in this newsletter, I broke down the centerpiece of that package, an analysis I did with my colleague James O’Donnell. (In case you’re still looking for an intro, you can check out this Roundtable discussion with James and our editor in chief Mat Honan, or this short segment I did on Science Friday.)

But this week, I want to talk about another story that I also wrote for that package, which focused on nuclear energy. I thought this was an important addition to the mix of stories we put together, because I’ve seen a lot of promises about nuclear power as a saving grace in the face of AI’s energy demand. My reporting on the industry over the past few years has left me a little skeptical. 

As I discovered while I continued that line of reporting, building new nuclear plants isn’t so simple or so fast. And as my colleague David Rotman lays out in his story for the package, the AI boom could wind up relying on another energy source: fossil fuels. So what’s going to power AI? Let’s get into it. 

When we started talking about this big project on AI and energy demand, we had a lot of conversations about what to include. And from the beginning, the climate team was really focused on examining what, exactly, was going to be providing the electricity needed to run data centers powering AI models. As we wrote in the main story: 

“A data center humming away isn’t necessarily a bad thing. If all data centers were hooked up to solar panels and ran only when the sun was shining, the world would be talking a lot less about AI’s energy consumption.” 

But a lot of AI data centers need to be available constantly. Those that are used to train models can arguably be more responsive to the changing availability of renewables, since that work can happen in bursts, any time. Once a model is being pinged with questions from the public, though, there needs to be computing power ready to run all the time. Google, for example, would likely not be too keen on having people be able to use its new AI Mode only during daylight hours.

Solar and wind power, then, would seem not to be a great fit for a lot of AI electricity demand, unless they’re paired with energy storage—and that increases costs. Nuclear power plants, on the other hand, tend to run constantly, outputting a steady source of power for the grid. 

As you might imagine, though, it can take a long time to get a nuclear power plant up and running. 

Large tech companies can help support plans to reopen shuttered plants or existing plants’ efforts to extend their operating lifetimes. There are also some existing plants that can make small upgrades to improve their output. I just saw this news story from the Tri-City Herald about plans to upgrade the Columbia Generating Station in eastern Washington—with tweaks over the next few years, it could produce an additional 162 megawatts of power, over 10% of the plant’s current capacity. 

But all that isn’t going to be nearly enough to meet the demand that big tech companies are claiming will materialize in the future. (For more on the numbers here and why new tech isn’t going to come online fast enough, check out my full story.) 

Instead, natural gas has become the default to meet soaring demand from data centers, as David lays out in his story. And since the lifetime of plants built today is about 30 years, those new plants could be running past 2050, the date the world needs to bring greenhouse-gas emissions to net zero to meet the goals set out in the Paris climate agreement. 

One of the bits I found most interesting in David’s story is that there’s potential for a different future here: Big tech companies, with their power and influence, could actually use this moment to push for improvements. If they reduced their usage during peak hours, even for less than 1% of the year, it could greatly reduce the amount of new energy infrastructure required. Or they could, at the very least, push power plant owners and operators to install carbon capture technology, or ensure that methane doesn’t leak from the supply chain.

AI’s energy demand is a big deal, but for climate change, how we choose to meet it is potentially an even bigger one. 

Three takeaways about AI’s energy use and climate impacts

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. 

To dig into our reporting, give the main story a read. And if you’re looking for more details on how we came up with our numbers, you can check out this behind-the-scenes piece.

There are also some great related stories in this package, including one from James Temple on the data center boom in the Nevada desert, one from David Rotman about how AI’s rise could entrench natural gas, and one from Will Douglas Heaven on a few technical innovations that could help make AI more efficient. Oh, and I also have a piece on why nuclear isn’t the easy answer some think it is. 

Find them, and the rest of the stories in the package, here. 

This article is from The Spark, MIT Technology Review’s weekly climate newsletter. To receive it in your inbox every Wednesday, sign up here.

How US research cuts are threatening crucial climate data

Over the last few months, and especially the last few weeks, there’s been an explosion of news about proposed budget cuts to science in the US. One trend I’ve noticed: Researchers and civil servants are sounding the alarm that those cuts mean we might lose key data that helps us understand our world and how climate change is affecting it.

My colleague James Temple has a new story out today about researchers who are attempting to measure the temperature of mountain snowpack across the western US. Snow that melts in the spring is a major water source across the region, and monitoring the temperature far below the top layer of snow could help scientists more accurately predict how fast water will flow down the mountains, allowing farmers, businesses, and residents to plan accordingly.

But long-running government programs that monitor the snowpack across the West are among those being threatened by cuts across the US federal government. Also potentially in trouble: carbon dioxide measurements in Hawaii, hurricane forecasting tools, and a database that tracks the economic impact of natural disasters. It’s all got me thinking: What do we lose when data is in danger?

Take for example the work at Mauna Loa Observatory, which sits on the northern side of the world’s largest active volcano. In this Hawaii facility, researchers have been measuring the concentration of carbon dioxide in the atmosphere since 1958.

The resulting graph, called the Keeling Curve (after Charles David Keeling, the scientist who kicked off the effort) is a pillar of climate research. It shows that carbon dioxide, the main greenhouse gas warming the planet, has increased in the atmosphere from around 313 parts per million in 1958 to over 420 parts per million today.

Proposed cuts to the National Oceanic and Atmospheric Administration (NOAA) jeopardize the Keeling Curve’s future. As Ralph Keeling (current steward of the curve and Keeling’s son) put it in a new piece for Wired, “If successful, this loss will be a nightmare scenario for climate science, not just in the United States, but the world.”

This story has echoes across the climate world right now. A lab at Princeton that produces what some consider the top-of-the-line climate models used to make hurricane forecasts could be in trouble because of NOAA budget cuts. And last week, NOAA announced it would no longer track the economic impact of the biggest natural disasters in the US.

Some of the largest-scale climate efforts will feel the effects of these cuts, and as James’s new story shows, they could also seep into all sorts of specialized fields. Even seemingly niche work can have a huge impact not just on research, but on people.

The frozen reservoir of the Sierra snowpack provides about a third of California’s groundwater, as well as the majority used by towns and cities in northwest Nevada. Researchers there are hoping to help officials better forecast the timing of potential water supplies across the region.

This story brought to mind my visit to El Paso, Texas, a few years ago. I spoke with farmers there who rely on water coming down the Rio Grande, alongside dwindling groundwater, to support their crops. There, water comes down from the mountains in Colorado and New Mexico in the spring and is held in the Elephant Butte Reservoir. One farmer I met showed me pages and pages of notes of reservoir records, which he had meticulously copied by hand. Those crinkled pages were a clear sign: Publicly available data was crucial to his work.

The endeavor of scientific research, particularly when it involves patiently gathering data, isn’t always exciting. Its importance is often overlooked. But as cuts continue, we’re keeping a lookout, because losing data could harm our ability to track, address, and adapt to our changing climate. 

This article is from The Spark, MIT Technology Review’s weekly climate newsletter. To receive it in your inbox every Wednesday, sign up here.

Did solar power cause Spain’s blackout?

At roughly midday on Monday, April 28, the lights went out in Spain. The grid blackout, which extended into parts of Portugal and France, affected tens of millions of people—flights were grounded, cell networks went down, and businesses closed for the day.

Over a week later, officials still aren’t entirely sure what happened, but some (including the US energy secretary, Chris Wright) have suggested that renewables may have played a role, because just before the outage happened, wind and solar accounted for about 70% of electricity generation. Others, including Spanish government officials, insisted that it’s too early to assign blame.

It’ll take weeks to get the full report, but we do know a few things about what happened. And even as we wait for the bigger picture, there are a few takeaways that could help our future grid.

Let’s start with what we know so far about what happened, according to the Spanish grid operator Red Eléctrica:

• A disruption in electricity generation took place a little after 12:30 p.m. This may have been a power plant flipping off or some transmission equipment going down.
• A little over a second later, the grid lost another bit of generation.
• A few seconds after that, the main interconnector between Spain and southwestern France got disconnected as a result of grid instability.
• Immediately after, virtually all of Spain’s electricity generation tripped offline.

One of the theories floating around is that things went wrong because the grid diverged from its normal frequency. (All power grids have a set frequency: In Europe the standard is 50 hertz, which means the current switches directions 50 times per second.) The frequency needs to be constant across the grid to keep things running smoothly.

There are signs that the outage could be frequency-related. Some experts pointed out that strange oscillations in the grid frequency occurred shortly before the blackout.

Normally, our grid can handle small problems like an oscillation in frequency or a drop that comes from a power plant going offline. But some of the grid’s ability to stabilize itself is tied up in old ways of generating electricity.

Power plants like those that run on coal and natural gas have massive rotating generators. If there are brief issues on the grid that upset the balance, those physical bits of equipment have inertia: They’ll keep moving at least for a few seconds, providing some time for other power sources to respond and pick up the slack. (I’m simplifying here—for more details I’d highly recommend this report from the National Renewable Energy Laboratory.)

Solar panels don’t have inertia—they rely on inverters to change electricity into a form that’s compatible with the grid and matches its frequency. Generally, these inverters are “grid-following,” meaning if frequency is dropping, they follow that drop.

In the case of the blackout in Spain, it’s possible that having a lot of power on the grid coming from sources without inertia made it more possible for a small problem to become a much bigger one.

Some key questions here are still unanswered. The order matters, for example. During that drop in generation, did wind and solar plants go offline first? Or did everything go down together?

Whether or not solar and wind contributed to the blackout as a root cause, we do know that wind and solar don’t contribute to grid stability in the same way that some other power sources do, says Seaver Wang, climate lead of the Breakthrough Institute, an environmental research organization. Regardless of whether renewables are to blame, more capability to stabilize the grid would only help, he adds.

It’s not that a renewable-heavy grid is doomed to fail. As Wang put it in an analysis he wrote last week: “This blackout is not the inevitable outcome of running an electricity system with substantial amounts of wind and solar power.”

One solution: We can make sure the grid includes enough equipment that does provide inertia, like nuclear power and hydropower. Reversing a plan to shut down Spain’s nuclear reactors beginning in 2027 would be helpful, Wang says. Other options include building massive machines that lend physical inertia and using inverters that are “grid-forming,” meaning they can actively help regulate frequency and provide a sort of synthetic inertia.

Inertia isn’t everything, though. Grid operators can also rely on installing a lot of batteries that can respond quickly when problems arise. (Spain has much less grid storage than other places with a high level of renewable penetration, like Texas and California.)

Ultimately, if there’s one takeaway here, it’s that as the grid evolves, our methods to keep it reliable and stable will need to evolve too.

If you’re curious to hear more on this story, I’d recommend this Q&A from Carbon Brief about the event and its aftermath and this piece from Heatmap about inertia, renewables, and the blackout.

This article is from The Spark, MIT Technology Review’s weekly climate newsletter. To receive it in your inbox every Wednesday, sign up here.

A long-abandoned US nuclear technology is making a comeback in China

China has once again beat everyone else to a clean energy milestone—its new nuclear reactor is reportedly one of the first to use thorium instead of uranium as a fuel and the first of its kind that can be refueled while it’s running.

It’s an interesting (if decidedly experimental) development out of a country that’s edging toward becoming the world leader in nuclear energy. China has now surpassed France in terms of generation, though not capacity; it still lags behind the US in both categories. But one recurring theme in media coverage about the reactor struck me, because it’s so familiar: This technology was invented decades ago, and then abandoned.

You can basically copy and paste that line into countless stories about today’s advanced reactor technology. Molten-salt cooling systems? Invented in the mid-20th century but never commercialized. Same for several alternative fuels, like TRISO. And, of course, there’s thorium.

This one research reactor in China running with an alternative fuel says a lot about this moment for nuclear energy technology: Many groups are looking into the past for technologies, with a new appetite for building them.

First, it’s important to note that China is the hot spot for nuclear energy right now. While the US still has the most operational reactors in the world, China is catching up quickly. The country is building reactors at a remarkable clip and currently has more reactors under construction than any other country by far. Just this week, China approved 10 new reactors, totaling over $27 billion in investment.

China is also leading the way for some advanced reactor technologies (that category includes basically anything that deviates from the standard blueprint of what’s on the grid today: large reactors that use enriched uranium for fuel and high-pressure water to keep the reactor cool). High-temperature reactors that use gas as a coolant are one major area of focus for China—a few reactors that use this technology have recently started up, and more are in the planning stages or under construction.

Now, Chinese state media is reporting that scientists in the country reached a milestone with a thorium-based reactor. The reactor came online in June 2024, but researchers say it recently went through refueling without shutting down. (Conventional reactors generally need to be stopped to replenish the fuel supply.) The project’s lead scientists shared the results during a closed meeting at the Chinese Academy of Sciences.

I’ll emphasize here that this isn’t some massive power plant: This reactor is tiny. It generates just two megawatts of heat—less than the research reactor on MIT’s campus, which rings in at six megawatts. (To be fair, MIT’s is one of the largest university research reactors in the US, but still … it’s small.)

Regardless, progress is progress for thorium reactors, as the world has been entirely focused on uranium for the last 50 years or so.

Much of the original research on thorium came out of the US, which pumped resources into all sorts of different reactor technologies in the 1950s and ’60s. A reactor at Oak Ridge National Laboratory in Tennessee that ran in the 1960s used Uranium-233 fuel (which can be generated when thorium is bombarded with radiation).

Eventually, though, the world more or less settled on a blueprint for nuclear reactors, focusing on those that use Uranium-238 as fuel and are cooled by water at a high pressure. One reason for the focus on uranium for energy tech? The research could also be applied to nuclear weapons.

But now there’s a renewed interest in alternative nuclear technologies, and the thorium-fueled reactor is just one of several examples. A prominent one we’ve covered before: Kairos Power is building reactors that use molten salt as a coolant for small nuclear reactors, also a technology invented and developed in the 1950s and ’60s before being abandoned. 

Another old-but-new concept is using high-temperature gas to cool reactors, as X-energy is aiming to do in its proposed power station at a chemical plant in Texas. (That reactor will be able to be refueled while it’s running, like the new thorium reactor.) 

Some problems from decades ago that contributed to technologies being abandoned will still need to be dealt with today. In the case of molten-salt reactors, for example, it can be tricky to find materials that can withstand the corrosive properties of super-hot salt. For thorium reactors, the process of transforming thorium into U-233 fuel has historically been one of the hurdles. 

But as early progress shows, the archives could provide fodder for new commercial reactors, and revisiting these old ideas could give the nuclear industry a much-needed boost. 

This article is from The Spark, MIT Technology Review’s weekly climate newsletter. To receive it in your inbox every Wednesday, sign up here.

The vibes are shifting for US climate tech

The past few years have been an almost nonstop parade of good news for climate tech in the US. Headlines about billion-dollar grants from the government, massive private funding rounds, and labs churning out advance after advance have been routine. Now, though, things are starting to shift.  

About $8 billion worth of US climate tech projects have been canceled or downsized so far in 2025. (You can see a map of those projects in my latest story here.) 

There are still projects moving forward, but these cancellations definitely aren’t a good sign. And now we have tariffs to think about, adding additional layers of expense and, worse, uncertainty. (Businesses, especially those whose plans require gobs of money, really don’t like uncertainty.) Honestly, I’m still getting used to an environment that isn’t such a positive one for climate technology. How worried should we be? Let’s get into the context.

Sometimes, one piece of news can really drive home a much larger trend. For example, I’ve read a bazillion studies about extreme weather and global warming, but every time a hurricane comes close to my mom’s home in Florida, the threat of climate-fueled extreme weather becomes much more real for me. A recent announcement about climate tech hit me in much the same fashion.

In February, Aspen Aerogels announced it was abandoning plans for a Georgia factory that would have made materials that can suppress battery fires. The news struck me, because just a few months before, in October, I had written about the Department of Energy’s $670 million loan commitment for the project. It was a really fun story, both because I found the tech fascinating and because MIT Technology Review got the exclusive access to cover it first.

And now, suddenly, that plan is just dead. Aspen said it will shift some of its production to a factory in Rhode Island and send some overseas. (I reached out to the company with questions for my story last week, but they didn’t get back to me.)

One example doesn’t always mean there’s a trend; I got food poisoning at a sushi restaurant once, but I haven’t cut out sashimi permanently. The bad news, though, is that Aspen’s cancellation is just one of many. Over a dozen major projects in climate technology have gotten killed so far this year, as the nonprofit E2 tallied up in a new report last week. That’s far from typical.

I got some additional context from Jay Turner, who runs Big Green Machine, a database that also tracks investments in the climate-tech supply chain. That project includes some data that E2 doesn’t account for: news about when projects are delayed or take steps forward. On Monday, the Big Green Machine team released a new update, one that Turner called “concerning.”

Since Donald Trump took office on January 20, about $10.5 billion worth of investment in climate tech projects has progressed in some way. That basically means 26 projects were announced, secured new funding, increased in scale, or started construction or production.

Meanwhile, $12.2 billion across 14 projects has slowed down in some way. This covers projects that were canceled, were delayed significantly, or lost funding, as well as companies that went bankrupt. So by total investment, there’s been more bad news in climate tech than good news, according to Turner’s tracking.

It’s tempting to look for the silver lining here. The projects still moving forward are certainly positive, and we’ll hopefully continue to see some companies making progress even as we head into even more uncertain times. But the signs don’t look good.

One question that I have going forward is how a seemingly inevitable US slowdown on climate technology will ripple around the rest of the world. Several experts I’ve spoken with seem to agree that this will be a great thing for China, which has aggressively and consistently worked to establish itself as a global superpower in industries like EVs and batteries.

In other words, the energy transition is rolling on. Will the US get left behind? 

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These four charts sum up the state of AI and energy

While it’s rare to look at the news without finding some headline related to AI and energy, a lot of us are stuck waving our hands when it comes to what it all means.

Sure, you’ve probably read that AI will drive an increase in electricity demand. But how that fits into the context of the current and future grid can feel less clear from the headlines. That’s true even for people working in the field. 

A new report from the International Energy Agency digs into the details of energy and AI, and I think it’s worth looking at some of the data to help clear things up. Here are four charts from the report that sum up the crucial points about AI and energy demand.

1. AI is power hungry, and the world will need to ramp up electricity supply to meet demand. 

This point is the most obvious, but it bears repeating: AI is exploding, and it’s going to lead to higher energy demand from data centers. “AI has gone from an academic pursuit to an industry with trillions of dollars at stake,” as the IEA report’s executive summary puts it.

Data centers used less than 300 terawatt-hours of electricity in 2020. That could increase to nearly 1,000 terawatt-hours in the next five years, which is more than Japan’s total electricity consumption today.

Today, the US has about 45% of the world’s data center capacity, followed by China. Those two countries will continue to represent the overwhelming majority of capacity through 2035.  

2. The electricity needed to power data centers will largely come from fossil fuels like coal and natural gas in the near term, but nuclear and renewables could play a key role, especially after 2030.

The IEA report is relatively optimistic on the potential for renewables to power data centers, projecting that nearly half of global growth by 2035 will be met with renewables like wind and solar. (In Europe, the IEA projects, renewables will meet 85% of new demand.)

In the near term, though, natural gas and coal will also expand. An additional 175 terawatt-hours from gas will help meet demand in the next decade, largely in the US, according to the IEA’s projections. Another report, published this week by the energy consultancy BloombergNEF, suggests that fossil fuels will play an even larger role than the IEA projects, accounting for two-thirds of additional electricity generation between now and 2035.

Nuclear energy, a favorite of big tech companies looking to power operations without generating massive emissions, could start to make a dent after 2030, according to the IEA data.

3. Data centers are just a small piece of expected electricity demand growth this decade.

We should be talking more about appliances, industry, and EVs when we talk about energy! Electricity demand is on the rise from a whole host of sources: Electric vehicles, air-conditioning, and appliances will each drive more electricity demand than data centers between now and the end of the decade. In total, data centers make up a little over 8% of electricity demand expected between now and 2030.

There are interesting regional effects here, though. Growing economies will see more demand from the likes of air-conditioning than from data centers. On the other hand, the US has seen relatively flat electricity demand from consumers and industry for years, so newly rising demand from high-performance computing will make up a larger chunk. 

4. Data centers tend to be clustered together and close to population centers, making them a unique challenge for the power grid.  

The grid is no stranger to facilities that use huge amounts of energy: Cement plants, aluminum smelters, and coal mines all pull a lot of power in one place. However, data centers are a unique sort of beast.

First, they tend to be closely clustered together. Globally, data centers make up about 1.5% of total electricity demand. However, in Ireland, that number is 20%, and in Virginia, it’s 25%. That trend looks likely to continue, too: Half of data centers under development in the US are in preexisting clusters.

Data centers also tend to be closer to urban areas than other energy-intensive facilities like factories and mines. 

Since data centers are close both to each other and to communities, they could have significant impacts on the regions where they’re situated, whether by bringing on more fossil fuels close to urban centers or by adding strain to the local grid. Or both.

Overall, AI and data centers more broadly are going to be a major driving force for electricity demand. It’s not the whole story, but it’s a unique part of our energy picture to continue watching moving forward. 

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Tariffs are bad news for batteries

Update: Since this story was first published in The Spark, our weekly climate newsletter, the White House announced that most reciprocal tariffs would be paused for 90 days. That pause does not apply to China, which will see an increased tariff rate of 125%.

Today, new tariffs go into effect for goods imported into the US from basically every country on the planet.

Since Donald Trump announced his plans for sweeping tariffs last week, the vibes have been, in a word, chaotic. Markets have seen one of the quickest drops in the last century, and it’s widely anticipated that the global economic order may be forever changed.  

While many try not to look at the effects on their savings and retirement accounts, experts are scrambling to understand what these tariffs might mean for various industries. As my colleague James Temple wrote in a new story last week, anxieties are especially high in climate technology.

These tariffs could be particularly rough on the battery industry. China dominates the entire supply chain and is subject to monster tariff rates, and even US battery makers won’t escape the effects.   

First, in case you need it, a super-quick refresher: Tariffs are taxes charged on goods that are imported (in this case, into the US). If I’m a US company selling bracelets, and I typically buy my beads and string from another country, I’ll now be paying the US government an additional percentage of what those goods cost to import. Under Trump’s plan, that might be 10%, 20%, or upwards of 50%, depending on the country sending them to me. 

In theory, tariffs should help domestic producers, since products from competitors outside the country become more expensive. But since so many of the products we use have supply chains that stretch all over the world, even products made in the USA often have some components that would be tariffed.

In the case of batteries, we could be talking about really high tariff rates, because most batteries and their components currently come from China. As of 2023, the country made more than 75% of the world’s lithium-ion battery cells, according to data from the International Energy Agency.

Trump’s new plan adds a 34% tariff on all Chinese goods, and that stacks on top of a 20% tariff that was already in place, making the total 54%. (Then, as of Wednesday, the White House further raised the tariff on China, making the total 104%.)

But when it comes to batteries, that’s not even the whole story. There was already a 3.5% tariff on all lithium-ion batteries, for example, as well as a 7.5% tariff on batteries from China that’s set to increase to 25% next year.

If we add all those up, lithium-ion batteries from China could have a tariff of 82% in 2026. (Or 132%, with this additional retaliatory tariff.) In any case, that’ll make EVs and grid storage installations a whole lot more expensive, along with phones, laptops, and other rechargeable devices.

The economic effects could be huge. The US still imports the majority of its lithium-ion batteries, and nearly 70% of those imports are from China. The US imported $4 billion worth of lithium-ion batteries from China just during the first four months of 2024.

Although US battery makers could theoretically stand to benefit, there are a limited number of US-based factories. And most of those factories are still purchasing components from China that will be subject to the tariffs, because it’s hard to overstate just how dominant China is in battery supply chains.

While China makes roughly three-quarters of lithium-ion cells, it’s even more dominant in components: 80% of the world’s cathode materials are made in China, along with over 90% of anode materials. (For those who haven’t been subject to my battery ramblings before, the cathode and anode are two of the main components of a battery—basically, the plus and minus ends.)

Even battery makers that work in alternative chemistries don’t seem to be jumping for joy over tariffs. Lyten is a California-based company working to build lithium-sulfur batteries, and most of its components can be sourced in the US. (For more on the company’s approach, check out this story from 2024.) But tariffs could still spell trouble. Lyten has plans for a new factory, scheduled for 2027, that rely on sourcing affordable construction materials. Will that be possible? “We’re not drawing any conclusions quite yet,” Lyten’s chief sustainability officer, Keith Norman, told Heatmap News.

The battery industry in the US was already in a pretty tough spot. Billions of dollars’ worth of factories have been canceled since Trump took office.  Companies making investments that can total hundreds of millions or billions of dollars don’t love uncertainty, and tariffs are certainly adding to an already uncertain environment.

We’ll be digging deeper into what the tariffs mean for climate technology broadly, and specifically some of the industries we cover. If you have questions, or if you have thoughts to share about what this will mean for your area of research or business, I’d love to hear them at casey.crownhart@technologyreview.com. I’m also on Bluesky @caseycrownhart.bsky.social.

This article is from The Spark, MIT Technology Review’s weekly climate newsletter. To receive it in your inbox every Wednesday, sign up here.