Hydrogen bikes are struggling to gain traction in China

If you are in China and looking to ride a shared bike in the city, you might find something on the bike that looks a little different: a water-bottle-size hydrogen tank.

At least a dozen cities in China now have some kind of hydrogen-powered shared bikes for their residents. They offer an easier ride than traditional bikes and a safer energy source than lithium batteries. One Chinese company is betting that this will be the next big thing in public transportation, while others are riding on a national trend toward government policies that encourage the development of the hydrogen industry.

Yet the reception has been mixed. Riders have reported unsatisfactory experiences with current hydrogen bikes, and energy experts doubt whether it makes economic sense to replace e-bikes with hydrogen-powered ones. Even though hydrogen could be a great power source for long-distance transportation in the future, it may not be suitable for urban biking, a completely different task.

While there are companies in other countries that are working on hydrogen-powered bikes—and one French company already has a mature product—China stands out for putting these bikes to use as public transportation. Bike-sharing became hugely popular in the country during the 2010s tech boom. With support from deep-pocketed companies like Alibaba and Meituan, standardized, internet-connected shared bikes have filled urban streets since, sometimes resulting in incredible waste

Youon, a Chinese company with over 1 million bikes on the streets of over 300 cities, is one of the main players in the bike-sharing industry. Facing fierce domestic competition, the company has chosen to differentiate its brand by investing in hydrogen bikes since 2018, with four models now available to buy or rent.

A hydrogen bike is not very different in concept from an e-bike. The difference is in whether the energy is stored in a lithium-ion battery or a hydrogen tank.

Each of Youon’s hydrogen bikes stores 20 grams of hydrogen in the form of metal powders, which can absorb and release the gas in a tank at low pressures (less than 10 bar). When the rider starts pedaling, the hydrogen is fed to a fuel cell under the seat, where a chemical reaction takes place to produce electricity. At its peak, a hydrogen bike can go as fast as 23 kilometers (14 miles) per hour. One tank of hydrogen lasts 40 to 60 kilometers (25 to 37 miles), and replacing the tank takes a few seconds.

Why hydrogen?

E-bikes have existed in China for a long time. According to the official figures, there are around 350 million in China today, and they are commonly used by everyday commuters and professional delivery workers. 

However, many of China’s largest cities have shied away from commissioning e-bikes as part of the public transportation network or even banned them, because lithium batteries pose a fire risk. In 2023, Chinese fire departments received a total of 21,000 reports of e-bikes catching fire, a 17.4% increase from the previous year. 

That created a supply vacuum for Youon. It’s positioned itself as a safer alternative thanks to its use of hydrogen. The hydrogen is stored in a low-pressure state, and if there’s any leak, it will dissipate quickly without causing an explosion, the company says on its website.

It’s a strategy that’s worked: These bikes have been more readily accepted by local governments. In 2022, Youon sold 2,000 of its hydrogen bikes to Lingang, a new high-tech district in Shanghai; in 2023, the company sold 500 hydrogen bikes to the Daxing district of Beijing. Today, its hydrogen bikes can be found in over six Chinese cities. 

Youon has since doubled down on its investment in hydrogen. The company has launched a product that lets users generate hydrogen at home with solar power and water. It also worked with the local government of Jiangsu, where its headquarters are, to publish a set of industry standards covering safety requirements, hydrogen tanks, and more. “Hydrogen energy is also an essential pathway to achieving carbon neutrality,” said Sun Jisheng, the CEO of Youon, at an industry conference in June.

The problem

However, that’s about where the advantage of hydrogen bikes ends.

David Fishman, a China-based senior manager of the Lantou Group, an energy consultancy, says he struggles to see the advantage. “Maybe the safety angle is a relevant factor for someone who doesn’t like carrying around lithium-ion batteries and storing them in their house,” he says. Other than that, hydrogen bikes are less energy-efficient than battery-powered bikes, and it costs more to produce hydrogen in the first place.

The main advantage of hydrogen as an energy source is that it has much higher energy density, meaning a hydrogen tank with the same weight as a lithium battery would produce more energy and power the vehicles to go farther. However, that advantage only kicks in for trips over 800 kilometers, says Mark Z. Jacobson, a professor of civil and environmental engineering at Stanford University.

That means hydrogen is a more economical choice for long-distance transportation like ships, planes, and trucks. Bikes, however, are almost on the exact opposite end of the transportation spectrum. Few people would bike for long distances, let alone those who are only renting a public bike for a short time. For anything shorter than 800 km, battery-powered vehicles are more energy efficient, says Jacobson. He estimates that a battery-powered bike consumes only 40% of the energy of a hydrogen-powered equivalent and also takes up less space.

On top of that, the company’s hydrogen bikes have failed to impress many of the early adopters. 

a row of blue Yuoun hydrogen bikes for rent in the city

VIA YOUONBIKESHARE.COM

Gu, a resident of Lingang who only wishes to use his last name for this story, tells MIT Technology Review that he tried the bikes several times and they never felt effort-saving to him. Instead, the bike, along with the hydrogen tank and fuel-cell-powered motors, felt heavy and hard to maneuver. As a user, he has no idea whether the bike was running as expected or if the difficulty he encountered was due to its running out of hydrogen, although the company is supposed to block any bike with low hydrogen reserves from being unlocked.

Another common complaint is the inconvenience of finding and returning the bikes because there are only a limited number in the city and they have to be returned to specific locations for easy retrieval or tank replenishment. 

“The bike has to be returned to a designated spot. But even if I put the bike at that very location, there’s GPS drifting, and I’d be charged a very high fee for them to move the bike,” Gu says.

On social media, hydrogen-bike users have complained a lot about similar experiences. Youon has found itself caught up in headlines at least a couple of times recently, with stories where users question whether their bikes are really useful for their daily commutes. 

Youon didn’t respond to questions sent by MIT Technology Review.

The future of hydrogen bikes

Despite all these issues, there are at least half a dozen more companies in China working to launch hydrogen-powered shared bikes. These are often startups operating small-scale pilot projects in cities that have sizable hydrogen industries, like Foshan or Xiaoyi. 

Many of these cities have even bigger plans—they are vying to become the hub of the hydrogen economy in China, which is increasingly betting on it as the future of clean energy. 

This year, for the first time, hydrogen energy was mentioned in an annual official report from Beijing, which summarizes government work. The Chinese government said it vows to “accelerate the development of hydrogen energy … after enforcing the lead in smart, connected new energy vehicles.” The mention injected a boost of confidence into the hydrogen industry in China, which already produces more hydrogen every year than any other country.

Not all of this is good news for the environment. About 80% of hydrogen produced in China actually comes from burning coal or natural gas, and some of the fiercest government support for hydrogen comes from coal-mining cities looking to transition. While the country is moving in the direction of green hydrogen (hydrogen generated with renewable energy and water), the fuel will remain polluting for a long time.

When a technology is still in the early stages, finding the best use case for it is key. There are plenty of companies in China working on developing hydrogen-powered trucks and other long-distance forms of transportation, but considering the size of the bike-sharing market in the country, it’s no surprise that turning their attention to bikes seems like a profitable idea to some. 

However, if there’s no way to dramatically improve the performance or economics of hydrogen bikes, it’s hard to imagine the current batch of experiments lasting for long. As companies move from piloting their new products to seeking adoption and profits, they will have some serious questions to answer.

Why investors care about climate tech’s green premium

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

Talking about money can be difficult, but it’s a crucial piece of the puzzle when it comes to climate tech. 

I’ve been thinking more about the financial piece of climate innovation since my colleague James Temple sat down for a chat with Mike Schroepfer, former CTO of Meta and a current climate tech investor. They talked about Schroepfer’s philanthropic work as well as his climate-tech venture firm, Gigascale Capital. (I’d highly recommend reading the full Q&A here.) 

In their conversation, Schroepfer spoke about investing in companies not solely because of their climate promises, but because they can deliver a cheaper, better product that happens to have benefits for climate action too. 

This all got me thinking about what we can expect from new technologies financially. What do they need to do to compete, and how quickly can they do so? 

Look through the portfolio of a climate-focused venture capital firm or walk around a climate-tech conference, and you’ll be struck by the creativity and straight-up brilliance of some of the proposed technologies.

But in order to survive, they need a lot more than a good idea, as my colleague David Rotman pointed out in a story from December outlining six takeaways from this century’s first boom in climate tech. Countless companies rose to stardom with shiny new ideas starting around 2006 before crashing and failing by 2013.

As David put it, there are lessons in that rise and fall for today’s boom in climate technology: “The brilliance of many new climate technologies is evident, and we desperately need them. But none of that will ensure success. Venture-backed startups will need to survive on the basis of economics and financial advantages, not good intentions.”

Often, companies looking to help address climate change with new products are competing with an established industry. These newcomers must contend with what Bill Gates has called the “green premium.”

The green premium is the cost difference between a cheaper product that increases pollution and a more expensive alternative that offers climate benefits. In order to get people on board with new technologies, we need to close that gap. 

As Gates has outlined in his writings on this topic, there are basically two ways to do this: We need to find ways to either increase the cost of polluting products or cut the cost of the version that causes little to no climate pollution.

Some policies aim to go after the first of these options—the European Union has put a price on carbon, raising the cost of fossil-fuel-based products, for example. But relying on policy can leave companies at the whims of political winds in markets like the US. 

So that leaves the other option: New technology needs to get cheaper. 

As Schroepfer explained in his chat with James, one of the focuses at his venture firm, Gigascale Capital, is picking companies that can compete on economics or offer other benefits to customers. As he put it, a company should basically be saying: “Hey, this is a better product. [whispers] By the way, it’s better for the environment.”

It’s unrealistic to expect companies to have better, cheaper products right out of the gate, Schroepfer acknowledges. But he says that the team is looking for companies that can—over the course of a relatively short, roughly five-to-10-year period—grow to compete on cost, or even gain a cost advantage over the alternatives.

Schroepfer points to batteries and solar power as examples of technologies that are competitive today. When it’s available, electricity produced with solar panels is the cheapest on the planet. Batteries are 90% less expensive than they were just 15 years ago.

But these cases reveal the tricky thing about the green premium: Many new technologies can eventually make up the gap, but it can take much longer than businesses and investors are willing to wait. Solar panels and lithium-ion batteries were available commercially in the 1990s, but it’s taken until now to get to the point where they’re cheap and widespread.

Some technologies just getting started today could be the batteries and solar power of the 2040s, if we’re willing to invest the time and money to get them there. And I already see a few instances where people are willing to pay more for climate-friendly products today, in part because of hopes for their future.  

One example that comes to mind is low-emissions steel. H2 Green Steel, a Swedish company working to make steel without fossil fuels, says it has customers who have agreed to pay 20% to 30% more for its products than metal made with fossil fuels. But that’s just the price today: Some reports predict that these technologies will be able to compete on cost by 2040 or 2050

Most new technologies designed to address climate change will need to make a case for themselves in the market. The question for the rest of us: How much support and time are we willing to put in to give them the best shot of getting there?


Now read the rest of The Spark

Related reading

For more on what the former Meta CTO has been up to in climate, read the full Q&A here. There’s a whole lot more to unpack, including work on glacier stabilization, ocean-based carbon removal, and even solar geoengineering. 

For more on the lessons that companies can take away from the first cleantech boom, give this story from my colleague David Rotman a read.

Another thing

The US Department of Energy is putting $33 million into nine concentrating solar projects, as my colleague James Temple reported exclusively last week. 

Concentrating solar power uses mirrors to direct sunlight, which heats up some target material. It’s not a new technology, and the DOE has been funding efforts to get it going since the 1970s. But it could be useful in industries from food and beverages to low-carbon fuels. Read the full story here

Keeping up with climate  

Western battery startups could be in big trouble. While new chemistries and alternative architectures attracted a lot of investor attention a few years ago, the companies are now facing the reality of competing with massive existing manufacturers. (The Information)

California’s largest wildfire of the year has burned well over 300,000 acres so far. Climate change has helped create the conditions that supercharge blazes. (Inside Climate News)

The UAE has been trying to juice up rainfall with high-tech cloud seeding operations. But the whole thing may be more about the show than the science—check out this great deep dive for more. (Wired)

Congestion pricing plans—like the one recently proposed and then abandoned in New York City—can be unpopular with voters. Yet people generally come around once they start to see the benefits. Here’s an in-depth look at how attitudes toward these plans change over time. (Grist)

Air New Zealand backed down from a goal to cut its emissions nearly 30% by the end of the decade. The first major airline to walk back such a promise, the company points to a lack of supply for alternative fuels, as well as delays in new aircraft deliveries. (BBC)

Global methane emissions are climbing at the quickest pace in decades. The powerful greenhouse gas is responsible for over half the warming we’ve experienced so far. (The Guardian

Demand for air conditioning is swelling in Africa. But the industry isn’t well regulated, and some residents are struggling to get reliable systems and keep harmful refrigerant gases from leaking. (Associated Press)

Southeast Asia is home to a fleet of relatively new coal power plants. Pulling these facilities off the grid early could be a major step to cutting emissions from global electricity production. (Cipher News)

Correction: an earlier version of this story misstated the name of Mike Schroepfer’s firm. It is Gigascale Capital.

Five ways to make music streaming better for the climate

This story first appeared in China Report, MIT Technology Review’s newsletter about technology in China. Sign up to receive it in your inbox every Tuesday.

This week, we are taking a short break from China and turning to its neighbor South Korea instead. As K-pop sweeps the world and accumulates a massive, devout fan base, these fans have been turning their power into action. Today, I published a story about Kpop4planet, a group of volunteers who are using K-pop’s influence to hold large corporations accountable for their carbon footprints.

One of the most interesting (and also successful) campaigns Kpop4planet has organized shines a light on the carbon footprint of music streaming. Aware that K-pop fans stream significantly more than average (sometimes over five hours a day!) to support their favorite artists, the group successfully campaigned to get Korea’s largest domestic streaming platform to pledge to use 100% renewable energy by 2030.

I have to admit, before working on this story, it didn’t really cross my mind that streaming music could be so polluting. Streaming an album more than 27 times uses more energy than it takes to produce a CD, according to researchers, but it’s surprisingly hard to draw a conclusive answer on whether streaming is more polluting than CDs or records overall. What we do know is that since the carbon emissions associated with streaming are produced in faraway data centers and through invisible data transmissions, the problem is harder to pin down.

During my reporting, I talked to several experts about how to correctly understand the climate impact of music streaming, and one thing became clear: It all comes down to how we stream—the content, the device, the length, etc. They also recommended a bunch of things that any music streaming user can do to leave a smaller carbon footprint.

So here are the things you can do if you are a heavy music streamer:

1. Use small devices instead of big TVs. 

A major part of streaming’s carbon footprint comes from the device that’s used to play the music or video. And some are much more power hungry than others. A 50-inch LED TV consumes 100 times more electricity than a smartphone when used for streaming, according to the International Energy Agency. It also consumes more electricity if the screen stays on, displaying videos or lyrics, rather than just playing the audio. So using a smartphone to stream cuts energy consumption to a minimum.

2. Wait longer to buy a new phone. 

Yes, smartphones are designed to be pretty energy-efficient to use, but manufacturing them is another story. “In the life-cycle analysis of a phone, 85% to 90% of its lifetime energy occurs in its production,” says Laura Marks, a professor in media art and philosophy at Simon Fraser University. The manufacturing process usually involves fossil fuels, plastics, and minerals that could pollute the environment.

“So if I were to make a couple of recommendations, one of them would be to keep your devices for as long as possible, because that’s a huge, huge component of streaming that’s often overlooked,” she says.

3. Return to digital downloads, and only use streaming in selected situations.

While few people still download music files today, experts have agreed that one of the most climate-friendly ways to listen to music is to keep a digital file of your favorite song and return to it repeatedly. 

We also need to change our mindset about treating streaming as the only way to listen to music, says Joe Steinhardt, an assistant professor in the music industry program at Drexel University. “The first and the easiest [suggestion] is to think about streaming music like Styrofoam plates or plastic forks. It doesn’t mean I never use those; it’s just that I don’t eat every meal off of them,” he says. If you are listening to a large variety of music, maybe streaming is the best choice; if you are listening to a few songs repeatedly, go for a digital download or even an old-fashioned CD.

4. Push for streaming platforms to do their part.

Climate action is not just about individual responsibility—it also means pushing corporations to do better. Just as Kpop4planet chased after Melon, Korea’s largest domestic music streaming service, you can also hold your favorite music streaming service accountable. 

A big part of that is figuring out where the platforms’ data centers are, as these can account for a third to a half of streaming’s carbon footprint, according to Marks. These gigantic facilities draw significant amounts of electricity. If they can switch to using renewable energy, that will be much more meaningful than any action one individual can take. It’s also important not to fall for empty promises, and to seek specific plans on where and how they plan to source renewable energy.

5. Cherish music and resist overconsumption.

Many experts mention the Jevons paradox, which states that increasing the efficiency with which a resource is used can lead to more total consumption. In the case of streaming, this means that even if the technology can become more energy-efficient on a per-song basis, the business model and the sheer convenience often encourage users to listen to more and more songs without considering the climate consequences.

To resist that mindset, Marks suggests, we should cherish listening to music more. “Instead of streaming all day, it could mean really enjoying the performance of a song—just listening to it a couple of times and then talking with your friends about it,” she says.

My conclusion? It’s never too late to become aware of the climate impact of music streaming and think about what we can do to make it even just a little greener. 

What’s your relationship with music streaming? Tell me more about it at zeyi@technologyreview.com.


Now read the rest of China Report

Catch up with China

1. CATL, the world’s largest EV battery maker, is flush with cash. But China’s strict control of capital means it has to seek external investment to build up its supply chain outside the country. (Financial Times $)

2. China is asking the World Trade Organization to settle its dispute with the US about EV tariffs. (Reuters $)

3. US-China trade conflicts are spreading to the mattress market, where US retailers say the domestic market is being flooded by Chinese products. (Wall Street Journal $)

4. A new movie in China used AI face-swapping technology to make Jackie Chan look decades younger. Critics hated it. (South China Morning Post $)

5. The failed assassination attempt at a Trump rally not only boosted support for the former president but also caused the price of a Chinese stock to soar—all because the name of the company sounds like “Trump Wins Big” in Chinese. (Bloomberg $)

6. China denies it’s building a naval base in Cambodia. Satellite images show that it is. (New York Times $)

7. Claw-machine arcades are cropping up in Hong Kong—but it’s a result of the failing retail market and low demand for commercial property. (Nikkei Asia $)

Lost in translation

Morowali, a remote, agricultural community in Indonesia, has been transformed into a hub for heavy industry by the entrance of a Chinese company, according to the Chinese magazine Sanlian Lifeweek. Tsingshan Holding Group, a Chinese steel and nickel company, was instrumental in investing in and setting up the Indonesia Morowali Industrial Park (IMIP), where a rich local reserve of nickel ore is converted into high-purity nickel sulfate that’s essential for electric vehicle batteries. 

IMIP has created at least 100,000 jobs and contributed significantly to Indonesia’s economy, but it has also led to environmental and health challenges for local communities. Concerns about air and water pollution, garbage disposal, and worker safety have intensified following an explosion in 2023 that killed eight Chinese workers and 13 Indonesian workers. Now, local workers are organizing to sit down with management and push for changes in worker welfare.

One more thing

If you want a guaranteed sighting of a UFO, come to Shenzhen. Last week, a Chinese company tested an electric helicopter that looks just like a UFO. Flying at a low height and able to land on water, the vehicle is designed for transporting tourists and displaying ads in the future.

How fish-safe hydropower technology could keep more renewables on the grid

Hydropower is the world’s leading source of renewable electricity, generating more power in 2022 than all other renewables combined. But while hydropower is helping clean up our electrical grid, it’s not always a positive force for fish.

Dams that create reservoirs on rivers can change habitats. And for some species, especially those that migrate long distances, hydropower facilities can create dangerous or insurmountable barriers. In some parts of the world, including the US, Canada, and Europe, governments have put protections in place to protect ecosystems from hydropower’s potential harms.

New environmental regulations can leave older facilities facing costly renovations or force them to shutter entirely. That’s a big problem, because pulling hydropower plants off the grid eliminates a flexible, low-emissions power source that can contribute to progress in fighting climate change. New technologies, including fish-safe turbines, could help utilities and regulators come closer to striking a balance between the health of river ecosystems and global climate goals. 

That’s where companies like Natel Energy come in. The company started with two big goals: high performance and fish survival, says Gia Schneider, Natel’s cofounder and chief commercial officer.

The company is making new designs for the turbines that generate electricity in hydropower plants as water rushes through equipment and moves their blades. Conventional turbine blades can move as fast as 30 meters per second, or about 60 to 70 miles per hour, Schneider says. When straight, thin edges are moving that quickly and striking fish, “it’s fairly obvious why that’s not a good outcome,” she says.

Natel’s turbine design focuses on preventing fast-moving equipment from making fatal contact with fish. The blades have a thicker leading edge that pushes water out in front of it, creating a stagnation zone, or “basically an airbag for fish,” Schneider says. The blades are also curved, so even if fish are struck, they don’t take a direct hit.

The company has tested its turbines with a range of species, including American eels, alewife, and rainbow trout. In the case of one recent study with American eels, scientists found that over 99% of eels survived after 48 hours of passing through Natel’s equipment. In comparison, one 2010 study found that just 40% of tagged European eels were able to pass through the turbines of a hydropower plant, though survival depended a lot on the size of both the eel and equipment in question.  

Changing turbine designs won’t help fish survive all power plants: at some of the biggest plants with the tallest dams, rapid changes in water pressure can kill fish. But Schneider says that the company’s technology could be slotted into up to half of the existing US hydropower fleet to make plants more fish-safe.

Hydropower is one of the world’s older renewable energy sources. By 2030, more than 20% of the global fleet’s generating units will be more than 55 years old, according to the International Energy Agency. The average age of a hydropower plant in the US today is roughly 65 years.  

In the US, privately held hydropower plants are licensed by an agency called the Federal Energy Regulatory Commission for a term of up to 50 years. Roughly 17 gigawatts’ worth of hydropower facilities (enough to power 13 million homes) are up for relicensing by 2035, according to the National Hydropower Association.

Since many of those facilities were started up, there have been significant changes to environmental requirements, and some plants may face high costs and difficult engineering work as they try to adhere to new rules and stay in operation. Adding screens to basically filter fish out of the intake for hydropower plants is one potential solution in some cases, but both installation and maintenance of such a system can add significant cost. In these facilities, Natel’s technology represents an alternative, Schneider says.

Natel has installed several projects in Maine, Oregon, and Austria. They all involve relatively small turbines, but the company is on the way to undertaking bigger projects and recently won a bid process with a manufacturing partner to supply a larger turbine that’s three meters in diameter to an existing plant, Schnieder says. The company is also licensing its fish-safe turbine designs to existing manufacturers.

Whether utilities move to adopt fish-safe design could depend on how it affects efficiency, or the amount of energy that can be captured by a given water flow. Natel’s turbine designs will, in some cases, be slightly less efficient than today’s conventional ones, Schneider says, though the difference is marginal, and they likely still represent an improvement over older designs. 

While there’s sometimes a trade-off between fish-safe design and efficiency, that’s not the case with all novel turbines in all cases. A 2019 study from the US Army Corps of Engineers found that one new design improved fish safety while also producing more power.

Slotting new turbines into hydropower plants won’t solve all the environmental challenges associated with the technology, though. For example, the new equipment would only be relevant for downstream migration, like when eels move from freshwater rivers out into the ocean to reproduce. Other solutions would still be needed to allow a path for upstream migration.

Ideally, the best solution for many plants would likely be natural bypasses or ramps, which allow free passage of many species in both directions, says Ana T. Silva, a senior research scientist at the Norwegian Institute for Nature Research. However, because of space requirements, these can’t always be installed or used. 

Natel CTO Abe Schneider holds a large trout used in fish passage testing at the Monroe Hydro Plant in Madras, Oregon.
NATEL

People have been trying to improve fish passage for a long time, says Michael Milstein, a senior public affairs officer at NOAA Fisheries, part of the US National Oceanic and Atmospheric Administration. The solutions in place today include fish ladders, where fish swim or hop up into successively taller pools to pass dams. Other dams are too tall for that, and fish are captured and loaded onto trucks to go around them.

The challenge, Milstein says, is that “every river is different, and every dam is different.” Solutions need to be adapted to each individual situation, he adds; fish-safe turbines would be most important when there’s no bypass and going through a facility is the only option fish have.

The issue of protecting ecosystems and providing safe passage for fish has sparked fierce debates over existing hydropower projects across the western US and around the world. 

Even with the current state-of-the-art technology, “it’s not always possible to provide sufficient passage,” Milstein says. Several dams are currently being removed from the Klamath River in Oregon and Northern California because of the effects on local ecosystems.  The dams drastically changed the river, wiping out habitat for local salmon, steelhead, and lamprey and creating ideal conditions for parasites to decimate fish populations. 

But while hydropower facilities can have negative environmental impacts, climate change can also be extremely harmful to wildlife, Natel’s Schneider points out. If too many hydropower plants are shut down, it could leave a gap that keeps more fossil fuels on the grid, hampering efforts to address climate change.  

Reducing hydropower plants’ impact on local environments could help ensure that more of them can stay online, generating renewable electricity that plays an important role in our electrical grid. “Fish-safe turbines won’t solve everything—there are many, many problems in our rivers,” Schneider says. “But we need to start tackling all of them, so this is one tool.”

A US push to use ethanol as aviation fuel raises major climate concerns

Eliminating carbon pollution from aviation is one of the most challenging parts of the climate puzzle, simply because large commercial airlines are too heavy and need too much power during takeoff for today’s batteries to do the job. 

But one way that companies and governments are striving to make some progress is through the use of various types of sustainable aviation fuels (SAFs), which are derived from non-petroleum sources and promise to be less polluting than standard jet fuel.

This week, the US announced a push to help its biggest commercial crop, corn, become a major feedstock for SAFs. 

Federal guidelines announced on April 30 provide a pathway for ethanol producers to earn SAF tax credits within the Inflation Reduction Act, President Biden’s signature climate law, when the fuel is produced from corn or soy grown on farms that adopt certain sustainable agricultural practices.

It’s a limited pilot program, since the subsidy itself expires at the end of this year. But it could set the template for programs in the future that may help ethanol producers generate more and more SAFs, as the nation strives to produce billions of gallons of those fuels per year by 2030. 

Consequently, the so-called Climate Smart Agricultural program has already sounded alarm bells among some observers, who fear that the federal government is both overestimating the emissions benefits of ethanol and assigning too much credit to the agricultural practices in question. Those include cover crops, no-till techniques that minimize soil disturbances, and use of “enhanced-efficiency fertilizers,” which are designed to increase uptake by plants and thus reduce runoff into the environment.

The IRA offers a tax credit of $1.25 per gallon for SAFs that are 50% lower in emissions than standard jet fuel, and as much as 50 cents per gallon more for sustainable fuels that are cleaner still. The new program can help corn- or soy-based ethanol meet that threshold when the source crops are produced using some or all of those agricultural practices.

Since the vast majority of US ethanol is produced from corn, let’s focus on the issues around that crop. To get technical, the program allows ethanol producers to subtract 10 grams of carbon dioxide per megajoule of energy, a measure of carbon intensity, from the life-cycle emissions of the fuel when it’s generated from corn produced with all three of the practices mentioned. That’s about an eighth to a tenth of the carbon intensity of gasoline.

Ethanol’s questionable climate footprint

Today, US-generated ethanol is mainly mixed with gasoline. But ethanol producers are eager to develop new markets for the product as electric vehicles make up a larger share of the cars and trucks on the road. Not surprisingly, then, industry trade groups applauded the announcement this week.

The first concern with the new program, however, is that the emissions benefits of corn-based ethanol have been hotly debated for decades.

Corn, like any plant that uses photosynthesis to produce food, sucks up carbon dioxide from the air. But using corn for fuel rather than food also creates pressure to clear more land for farming, a process that releases carbon dioxide from plants and soil. In addition, planting, fertilizing, and harvesting corn produce climate pollution as well, and the same is true of refining, distributing, and burning ethanol. 

For its analyses under the new program, the Treasury Department intends to use an updated version of the so-called GREET model to evaluate the life-cycle emissions of SAFs, which was developed by the Department of Energy’s Argonne National Lab. A 2021 study from the lab, relying on that model, concluded that US corn ethanol produced as much as 52% less greenhouse gas than gasoline. 

But some researchers and nonprofits have criticized the tool for accepting low estimates of the emissions impacts of land-use changes, among other issues. Other assessments of ethanol emissions have been far more damning.

A 2022 EPA analysis surveyed the findings from a variety of models that estimate the life-cycle emissions of corn-based ethanol and found that in seven out of 20 cases, they exceeded 80% of the climate pollution from gasoline and diesel.

Moreover, the three most recent estimates from those models found ethanol emissions surpassed even the higher-end estimates for gasoline or diesel, Alison Cullen, chair of the EPA’s science advisory board, noted in a 2023 letter to the administrator of the agency.

“Thus, corn starch ethanol may not meet the definition of a renewable fuel” under the federal law that mandates the use of biofuels in the market, she wrote. If so, it’s then well short of the 50% threshold required by the IRA, and some say it’s not clear that the farming practices laid out this week could close the gap.

Agricultural practices

Nikita Pavlenko, who leads the fuels team at the International Council on Clean Transportation, a nonprofit research group, asserted in an email that the climate-smart agricultural provisions “are extremely sloppy” and “are not substantiated.” 

He said the Department of Energy and Department of Agriculture especially “put their thumbs on the scale” on the question of land-use changes, using estimates of soy and corn emissions that were 33% to 55% lower than those produced for a program associated with the UN’s International Civil Aviation Organization.

He finds that ethanol sourced from farms using these agriculture practices will still come up short of the IRA’s 50% threshold, and that producers may have to take additional steps to curtail emissions, potentially including adding carbon capture and storage to ethanol facilities or running operations on renewables like wind or solar.

Freya Chay, a program lead at CarbonPlan, which evaluates the scientific integrity of carbon removal methods and other climate actions, says that these sorts of agricultural practices can provide important benefits, including improving soil health, reducing erosion, and lowering the cost of farming. But she and others have stressed that confidently determining when certain practices actually and durably increase carbon in soil is “exceedingly complex” and varies widely depending on soil type, local climate conditions, past practices, and other variables.

One recent study of no-till practices found that the carbon benefits quickly fade away over time and reach nearly zero in 14 years. If so, this technique would do little to help counter carbon emissions from fuel combustion, which can persist in the atmosphere for centuries or more.

“US policy has a long history of asking how to continue justifying investment in ethanol rather than taking a clear-eyed approach to evaluating whether or not ethanol helps us reach our climate goals,” Chay wrote in an email. “In this case, I think scrutiny is warranted around the choice to lean on agricultural practices with uncertain and variable benefits in a way that could unlock the next tranche of public funding for corn ethanol.”

There are many other paths for producing SAFs that are or could be less polluting than ethanol. For example, they can be made from animal fats, agriculture waste, forest trimmings, or non-food plants that grow on land unsuitable for commercial crops. Other companies are developing various types of synthetic fuels, including electrofuels produced by capturing carbon from plants or the air and then combining it with cleanly sourced hydrogen. 

But all these methods are much more expensive than extracting and refining fossil fuels, and most of the alternative fuels will still produce more emissions when they’re used than the amount that was pulled out of the atmosphere by the plants or processes in the first place. 

The best way to think of these fuels is arguably as a stopgap, a possible way to make some climate progress while smart people strive to develop and build fully emissions-free ways of quickly, safely, and reliably moving things and people around the globe.

The inadvertent geoengineering experiment that the world is now shutting off

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

Usually when we talk about climate change, the focus is squarely on the role that greenhouse-gas emissions play in driving up global temperatures, and rightly so. But another important, less-known phenomenon is also heating up the planet: reductions in other types of pollution.

In particular, the world’s power plants, factories, and ships are pumping much less sulfur dioxide into the air, thanks to an increasingly strict set of global pollution regulations. Sulfur dioxide creates aerosol particles in the atmosphere that can directly reflect sunlight back into space or act as the “condensation nuclei” around which cloud droplets form. More or thicker clouds, in turn, also cast away more sunlight. So when we clean up pollution, we also ease this cooling effect. 

Before we go any further, let me stress: cutting air pollution is smart public policy that has unequivocally saved lives and prevented terrible suffering. 

The fine particulate matter produced by burning coal, gas, wood, and other biomatter is responsible for millions of premature deaths every year through cardiovascular disease, respiratory illnesses, and various forms of cancer, studies consistently show. Sulfur dioxide causes asthma and other respiratory problems, contributes to acid rain, and depletes the protective ozone layer. 

But as the world rapidly warms, it’s critical to understand the impact of pollution-fighting regulations on the global thermostat as well. Scientists have baked the drop-off of this cooling effect into net warming projections for the coming decades, but they’re also striving to obtain a clearer picture of just how big a role declining pollution will play.

A new study found that reductions in emissions of sulfur dioxide and other pollutants are responsible for about 38%, as a middle estimate, of the increased “radiative forcing” observed on the planet between 2001 and 2019. 

An increase in radiative forcing means that more energy is entering the atmosphere than leaving it, as Kerry Emanuel, a professor of atmospheric science at MIT, lays out in a handy explainer here. As that balance has shifted in recent decades, the difference has been absorbed by the oceans and atmosphere, which is what is warming up the planet. 

The remainder of the increase is “mainly” attributable to continued rising emissions of heat-trapping greenhouse gases, says Øivind Hodnebrog, a researcher at the Center for International Climate and Environment Research in Norway and lead author of the paper, which relied on climate models, sea-surface temperature readings, and satellite observations.

The study underscores the fact that as carbon dioxide, methane, and other gases continue to drive up temperature​​s, parallel reductions in air pollution are revealing more of that additional warming, says Zeke Hausfather, a scientist at the independent research organization Berkeley Earth. And it’s happening at a point when, by most accounts, global warming is about to begin accelerating or has already started to do so. (There’s ongoing debate over whether researchers can yet detect that acceleration and whether the world is now warming faster than researchers had expected.)

Because of the cutoff date, the study did not capture a more recent contributor to these trends. Starting in 2020, under new regulations from the International Maritime Organization, commercial shipping vessels have also had to steeply reduce the sulfur content in fuels. Studies have already detected a decrease in the formation of “ship tracks,” or the lines of clouds that often form above busy shipping routes. 

Again, this is a good thing in the most important way: maritime pollution alone is responsible for tens of thousands of early deaths every year. But even so, I have seen and heard of suggestions that perhaps we should slow down or alter the implementation of some of these pollution policies, given the declining cooling effect.

A 2013 study explored one way to potentially balance the harms and benefits. The researchers simulated a scenario in which the maritime industry would be required to use very low-sulfur fuels around coastlines, where the pollution has the biggest effect on mortality and health. But then the vessels would double the fuel’s sulfur content when crossing the open ocean. 

In that hypothetical world, the cooling effect was a bit stronger and premature deaths declined by 69% with respect to figures at the time, delivering a considerable public health improvement. But notably, under a scenario in which low-sulfur fuels were required across the board, mortality declined by 96%, a difference of more than 13,000 preventable deaths every year.

Now that the rules are in place and the industry is running on low-sulfur fuels, intentionally reintroducing pollution over the oceans would be a far more controversial matter.

While society basically accepted for well over a century that ships were inadvertently emitting sulfur dioxide into the air, flipping those emissions back on for the purpose of easing global warming would amount to a form of solar geoengineering, a deliberate effort to tweak the climate system.

Many think such planetary interventions are far too powerful and unpredictable for us to muck around with. And to be sure, this particular approach would be one of the more ineffective, dangerous, and expensive ways to carry out solar geoengineering, if the world ever decided it should be done at all. The far more commonly studied concept is emitting sulfur dioxide high in the stratosphere, where it would persist for longer and, as a bonus, not be inhaled by humans. 

On an episode of the Energy vs. Climate podcast last fall, David Keith, a professor at the University of Chicago who has closely studied the topic, said that it may be possible to slowly implement solar geoengineering in the stratosphere as a means of balancing out the reduced cooling occurring from sulfur dioxide emissions in the troposphere.

“The kind of solar geoengineering ideas that people are talking about seriously would be a thin wedge that would, for example, start replacing what was happening with the added warming we have from unmasking the aerosol cooling from shipping,” he said. 

Positioning the use of solar geoengineering as a means of merely replacing a cruder form that the world was shutting down offers a somewhat different mental framing for the concept—though certainly not one that would address all the deep concerns and fierce criticisms.


Now read the rest of The Spark 

Read more from MIT Technology Review’s archive: 

Back in 2018, I wrote a piece about the maritime rules that were then in the works and the likelihood that they would fuel additional global warming, noting that we were “about to kill a massive, unintentional” experiment in solar geoengineering.

Another thing

Speaking of the concerns about solar geoengineering, late last week I published a deep dive into Harvard’s unsuccessful, decade-long effort to launch a high-altitude balloon to conduct a tiny experiment in the stratosphere. I asked a handful of people who were involved in the project or followed it closely for their insights into what unfolded, the lessons that can be drawn from the episode—and their thoughts on what it means for geoengineering research moving forward.

Keeping up with Climate 

Yup, as the industry predicted (and common sense would suggest), this week’s solar eclipse dramatically cut solar power production across North America. But for the most part, grid operators were able to manage their systems smoothly, minus a few price spikes, thanks in part to a steady buildout of battery banks and the availability of other sources like natural gas and hydropower. (Heatmap)

There’s been a pile-up of bad news for Tesla in recent days. First, the company badly missed analyst expectations for vehicle deliveries during the first quarter. Then, Reuters reported that the EV giant has canceled plans for a low-cost, mass-market car. That may have something to do with the move to “prioritize the development of a robotaxi,” which the Wall Street Journal then wrote about. Over on X, Elon Musk denied the Reuters story, sort ofposting that “Reuters is lying (again).” But there’s a growing sense that his transformation into a “far-right activist” is exacting an increasingly high cost on his personal and business brands. (Wall Street Journal)

In a landmark ruling this week, the European Court of Human Rights determined that by not taking adequate steps to address the dangers of climate change, including increasingly severe heat waves that put the elderly at particular risk, Switzerland had violated the human rights of a group of older Swiss women who had brought a case against the country. Legal experts say the ruling creates a precedent that could unleash many similar cases across Europe. (The Guardian)

How to reopen a nuclear power plant

A shut-down nuclear power plant in Michigan could get a second life thanks to a $1.52 billion loan from the US Department of Energy. If successful, it will be the first time a shuttered nuclear power plant reopens in the US.  

Palisades Power Plant shut down on May 20, 2022, after 50 years of generating low-carbon electricity. But the plant’s new owner thinks economic conditions have improved in the past few years and plans to reopen by the end of 2025.

A successful restart would be a major milestone for the US nuclear fleet, and the reactor’s 800 megawatts of capacity could help inch the country closer to climate goals. But reopening isn’t as simple as flipping on a light switch—there are technical, administrative, and regulatory hurdles ahead before Palisades can start operating again. Here’s what it takes to reopen a nuclear power plant.

Step 1: Stay ready

One of the major reasons Palisades has any shot of restarting is that the site’s new owner has been planning on this for years. “Technically, the stars had all aligned for the plant to stay operating,” says Patrick White, research director at the Nuclear Innovation Alliance, a nonprofit think tank.

Holtec International supplies equipment for nuclear reactors and waste and provides services like decommissioning nuclear plants. Holtec originally purchased Palisades with the intention of shutting it down, taking apart the facilities, and cleaning up the site. The company has decommissioned other recently shuttered nuclear plants, including Indian Point Energy Center in New York. 

Changing economic conditions have made continued operation too expensive to justify for many nuclear power plants, especially smaller ones. Those with a single, relatively small reactor, like Palisades, have been the most vulnerable.  

Once a nuclear power plant shuts down, it can quickly become difficult to start it back up. As with a car left out in the yard, White says, “you expect some degradation.” Maintenance and testing of critical support systems might slow down or stop. Backup diesel generators, for example, would need to be checked and tested regularly while a reactor is online, but they likely wouldn’t be treated the same way after a plant’s shutdown, White says.

Holtec took possession of Palisades in 2022 after the reactor shut down and the fuel was removed. Even then, there were already calls to keep the plant’s low-carbon power on the grid, says Nick Culp, senior manager for government affairs and communications at Holtec.

The company quickly pivoted and decided to try to keep the plant open, so records and maintenance work largely continued. “It looks like it shut down yesterday,” Culp says.

Because of the continued investment of time and resources, starting the plant back up will be more akin to restarting after a regular refueling or maintenance outage than starting a fully defunct plant. After maintenance is finished and fresh fuel loaded in, the Palisades reactor could restart and provide enough electricity for roughly 800,000 homes.

Step 2: Line up money and permission

Support has poured in for Palisades, with the state of Michigan setting aside $300 million in funding for the plant’s restart in the last two years. And now, the Department of Energy has issued a conditional loan commitment for $1.52 billion.

Holtec will need to meet certain technical and legal conditions to get the loan money, which will eventually be repaid with interest. (Holtec and the DOE Loan Programs Office declined to give more information about the loan’s conditions or timeline.)

The state funding and federal loan will help support the fixes and upgrades needed for the plant’s equipment and continue paying the approximately 200 workers who have stayed on since its shutdown. The plant employed about 700 people while it was operating, and the company is now working on rehiring additional workers to help with the restart, Culp says.  

One of the major remaining steps in a possible Palisades restart is getting authorization from regulators, as no plant in the US has restarted operations after shutting down. “We’re breaking new ground here,” says Jacopo Buongiorno, a professor of nuclear engineering at MIT. 

The Nuclear Regulatory Commission oversees nuclear power plants in the US, but the agency doesn’t have a specific regulatory framework for restarting operations at a nuclear power plant that has shut down and entered decommissioning, White says. The NRC created a panel that will oversee reopening efforts.

Palisades effectively gave up the legal right to operate when it shut down and took the fuel out of the reactor. Holtec will need to submit detailed plans to the NRC with information about how it plans to reopen and operate the plant safely. Holtec formally began the process of reauthorizing operations with the NRC in October 2023 and plans to submit the rest of its materials this year.

Step 3: Profit?

If regulators sign off, the plan is to have Palisades up and running again by the end of 2025. The fuel supply is already lined up, and the company has long-term buyers committed for the plant’s full power output, Culp says.

If all goes well, the plant could be generating power until at least 2051, 80 years after it originally began operations.

Expanded support for low-carbon electricity sources, and nuclear in particular, have helped make it possible to extend the life of older plants across the US. “This restart of a nuclear plant represents a sea change in support for clean firm power,” says Julie Kozeracki, a senior advisor for the US Department of Energy’s Loan Programs Office.

As of last year, a majority of Americans (57%) support more nuclear power in the country, up from 43% in 2016, according to a poll from the Pew Research Center. There’s growing funding available for the technology as well, including billions of dollars in tax credits for nuclear and other low-carbon energy included in the Inflation Reduction Act

Growing support and funding, alongside rising electricity prices, contribute to making existing nuclear plants much more valuable than they were just a few years ago, says MIT’s Buongiorno. “Everything has changed,” he adds.   

But even a successful Palisades restart wouldn’t mean that we’ll see a wave of other shuttered nuclear plants reopening around the US. “This is a really rare case where you had someone doing a lot of forward thinking,” White says. For other plants that are nearing decommissioning, it would be cheaper, simpler, and more efficient to extend their operations rather than allowing them to shut down in the first place. 

Update: This story has been updated with additional details regarding how the NRC may reauthorize Palisades Nuclear Plant.

The problem with plug-in hybrids? Their drivers.

Plug-in hybrids are supposed to be the best of both worlds—the convenience of a gas-powered car with the climate benefits of a battery electric vehicle. But new data suggests that some official figures severely underestimate the emissions they produce. 

According to new real-world driving data from the European Commission, plug-in hybrids produce roughly 3.5 times the emissions official estimates suggest. The difference is largely linked to driver habits: people tend to charge plug-in hybrids and drive them in electric mode less than expected.

“The environmental impact of these vehicles is much, much worse than what the official numbers would indicate,” says Jan Dornoff, a research lead at the International Council on Clean Transportation.

While conventional hybrid vehicles contain only a small battery to slightly improve fuel economy, plug-in hybrids allow fully electric driving for short distances. These plug-in vehicles typically have a range of roughly 30 to 50 miles (50 to 80 kilometers) in electric driving mode, with a longer additional range when using the secondary fuel, like gasoline or diesel. But drivers appear to be using much more fuel than was estimated.

According to the new European Commission report, drivers in plug-in hybrid vehicles produce about 139.4 grams of carbon dioxide for every kilometer driven, based on measurements of how much fuel vehicles use over time. On the other hand, official estimates from manufacturers, which are determined using laboratory tests, put emissions at 39.6 grams per kilometer driven.

Some of this gap can be explained by differences between the controlled conditions in a lab and real-world driving. Even conventional combustion-engine vehicles tend to have higher real-world emissions than official estimates suggest, though the gap is roughly 20%, not 200% or more as it is for plug-in hybrids.

The major difference comes down to how drivers tend to use plug-in hybrids. Researchers have noticed the problem in previous studies, some of them using crowdsourced data. 

In one study from the ICCT published in 2022, researchers examined real-world driving habits of people in plug-in hybrids. While the method used to determine official emissions values estimated that drivers use electricity to power vehicles 70% to 85% of the time, the real-world driving data suggested that vehicle owners actually used electric mode for 45% to 49% of their driving. And if vehicles were company-provided cars, the average was only 11% to 15%.

The difference between reality and estimates can be a problem for drivers, who may buy plug-in hybrids expecting climate benefits and gas savings. But if drivers are charging less than expected, the benefits might not be as drastic as promised. Trips taken in a plug-in hybrid cut emissions by only 23% relative to trips in a conventional vehicle, rather than the nearly three-quarters reduction predicted by official estimates, according to the new analysis.

“People need to be realistic about what they face,” Dornoff says. Driving the vehicles in electric mode as much as possible can help maximize the financial and environmental benefits, he adds.

It’s important to close the gap between expectations and reality not only for individuals’ sake, but also to ensure that policies aimed at cutting emissions have the intended effects. 

The European Union passed a law last year that will end sales of gas-powered cars in 2035. This is aimed at cutting emissions from transportation, a sector that makes up around one-fifth of global emissions. In the EU, manufacturers are required to have a certain average emissions value for all their vehicles sold. If plug-in hybrids are performing much worse in the real world than expected, it could mean the transportation sector is actually making less progress toward climate goals than it’s getting credit for.

Plug-in hybrids’ failure to meet expectations is also a problem in the US, says Aaron Isenstadt, a senior researcher at the ICCT based in San Francisco. Real-world fuel consumption was about 50% higher than EPA estimates in one ICCT study, for example. The gap between expectations and reality is smaller in the US partly because official emissions estimates are calculated differently, and partly because US drivers have different driving habits and may have better access to charging at home, Isenstadt says.

The Biden administration recently finalized new tailpipe emissions rules, which set guidelines for manufacturers about the emissions their vehicles can produce. The rules aim at ramping down emissions from new vehicles sold, so by 2032, roughly half of new cars sold in the US will need to produce zero emissions in order to meet the standards.

Both the EU and the US have plans to update estimates about how drivers are using plug-in hybrids, which should help policies in both markets better reflect reality. The EU will make an adjustment to estimates about driver behavior beginning in 2025, while the US will do so later, in 2027.

New York City’s plan to stop e-bike battery fires

Walk just a few blocks in New York City and you’ll likely spot an electric bike zipping by.

The vehicles have become increasingly popular in recent years, especially among delivery drivers, tens of thousands of whom weave through New York streets. But the e-bike influx has caused a wave of fires sparked by their batteries, some of them deadly.

Now, the city wants to fight those fires with battery swapping. A pilot program will provide a small number of delivery drivers with alternative options to power up their e-bikes, including swapping stations that supply fully charged batteries on demand. 

Proponents say the program could lay the groundwork for a new mode of powering small electric vehicles in the city, one that’s convenient and could reduce the risk of fires. But the road to fire safety will likely be long and winding given the sheer number of batteries we’re integrating into our daily lives, in e-bikes and beyond.

A swapping solution

The number of fires caused by batteries in New York City increased nearly ninefold between 2019 and 2023, according to reporting from The City. Concern over fires has been steadily growing, and in March 2023 Mayor Eric Adams announced a plan to address the problem that included regulations for e-bikes and their batteries, crackdowns on unsafe charging practices, and outreach for delivery drivers.

While batteries can catch fire for a variety of reasons, many incidents appear to have been caused by e-bike drivers charging their batteries in apartment buildings, including a February blaze that killed one person and injured 22.

The city’s most recent effort, designed to address charging, is a pilot program for delivery drivers who use e-bikes. For six months, 100 drivers will be matched with one of three startups that will provide a charging solution that doesn’t involve plugging in batteries in apartment buildings.

One of the startups, Swiftmile, is building fast charging stations that look like bike racks and can charge an e-bike battery within two hours. The other two participating companies, Popwheels and Swobbee, are proposing a different, even quicker solution: battery swapping. Instead of plugging in a battery and waiting for it to power up, a rider can swap out a dead battery for a fresh one.

Battery swapping is already being used for some electric vehicles, largely across Asia. Chinese automaker Nio operates a network of battery swapping stations that can equip a car with a fresh battery in just under three minutes. Gogoro, one of MIT Technology Review’s 2023 Climate Tech Companies to Watch, has a network of battery swapping stations for electric scooters that can accommodate more than 400,000 swaps each day.

The concept will need to be adjusted for New York and for delivery drivers, says Baruch Herzfeld, co-founder and CEO of Popwheels. “But if we get it right,” he says, “we think everybody in New York will be able to use light electric vehicles.”

Existing battery swap networks like Nio’s have mostly included a single company’s equipment, giving the manufacturer control over the vehicle, battery, and swapping equipment. That’s because one of the keys to making battery swapping work is fleet commonality—a base of many vehicles that can all use the same system.

Fortunately, delivery drivers have formed something of a de facto fleet in New York City, says David Hammer, co-founder and president of Popwheels. Roughly half of the city’s 60,000-plus delivery workers rely on e-bikes, according to city estimates. Many of them use bikes from a brand called Arrow, which include removable batteries.

Convenience is key for delivery drivers working on tight schedules. “For a lot of people, battery charging, battery swapping, it’s just technology. But for [delivery workers], it’s their livelihood,” says Irene Figueroa-Ortiz, a policy advisor at the NYC Department of Transportation.

For the New York pilot, Popwheels is building battery cabinets in several locations throughout the city that will include 16 charging slots for e-bike batteries. Riders will open a cabinet door using a smartphone app, plug in the used battery and take a fresh one from another slot. Based on the company’s modeling, each cabinet should be able to support constant use by 40 to 50 riders, Hammer says.

“Maybe it leads to an even larger vision of battery swapping as a part of an urban future,” Hammer says. “But for now, it’s solving a very real and immediate problem that delivery workers have around how they can work a full day, and earn a reasonable living, and do it without having to put their lives at risk for battery fires.”

A growing problem

Lithium-ion batteries power products from laptops and cellphones to electric vehicles, including cars, trucks, and e-bikes. A major benefit of the battery chemistry is its energy density, or ability to pack a lot of energy into a small container. But all that stored energy can also be dangerous.

Batteries can catch fire during charging or use, and even while being stored. Generally, fires happen when temperatures around the battery rise to unsafe levels or if a physical problem in a battery causes a short circuit, allowing current to flow unchecked. These factors can set in motion a dangerous process called thermal runaway.

Most batteries include a battery management system to control charging, which prevents temperatures from spiking and sparking a fire. But if this system malfunctions or if a battery doesn’t include one, charging can lead to fires, says Ben Hoff, who leads fire safety engineering and hardware design at Popwheels.

Some of the delivery drivers who attended a sign-up event for New York’s charging pilot program in late February cited safety as a reason they were looking for alternative solutions for their batteries. “Of course, I worry about that,” Jose Sarmiento, a longtime delivery worker, said at the event. “Even when I’m sleeping, I’m thinking about the battery.”  

Battery swapping could also be a key to safer electric transit, Popwheels’ Hammer says. The company has tight control over the batteries it provides drivers, and its monitoring systems include temperature sensors installed in the charging cabinets. Charging can be shut down immediately if a battery starts to overheat, and an aerosol fire suppression system can slow a fire if one does happen to start inside a cabinet.

The batteries Popwheels provides are also UL-certified, meaning they’re required to pass third-party safety tests. New York City banned the sale of uncertified batteries and e-bikes last year, but many drivers still use them, Hammer says.

Low-quality batteries are more likely to cause fires, a problem that can often be traced to the manufacturing process, says Michael Pecht, a professor at the University of Maryland who studies the reliability and safety of electronic devices.

Battery manufacturing facilities should be as clean as a medical operating room or a semiconductor facility, Pecht explains. Contamination from dust and dirt that wind up in batteries can create problems over time as charging and discharging a battery causes small physical changes. After enough charging cycles, even a tiny dust particle can lead to a short circuit that sparks a fire.

Low-quality manufacturing makes battery fires more likely, but it’s a daunting task to keep tight control over the huge number of cells being made each year. Large manufacturers can produce billions of batteries annually, making the solution to battery fires a complex one, Pecht says: “I think there’s a group who want an easy answer. To me, the answer is not that easy.”

New programs that provide well-manufactured batteries and tightly control charging could make a dent in safety concerns. But real progress will require quick and dramatic scale-up, alongside regulations and continual outreach to communities. 

Popwheels would need to install hundreds of its battery swapping cabinets to support a significant fraction of the city’s delivery drivers. The pilot will help determine whether riders are willing to use new methods of powering their livelihood. As Hammer says, “If they don’t use it, it doesn’t matter.”

Why methane emissions are still a mystery

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

If you follow papers in climate and energy for long enough, you’re bound to recognize some patterns. 

There are a few things I’ll basically always see when I’m sifting through the latest climate and energy research: one study finding that perovskite solar cells are getting even more efficient; another showing that climate change is damaging an ecosystem in some strange and unexpected way. And there’s always some new paper finding that we’re still underestimating methane emissions. 

That last one is what I’ve been thinking about this week, as I’ve been reporting on a new survey of methane leaks from oil and gas operations in the US. (Yes, there are more emissions than we thought there were—get the details in my story here.) But what I find even more interesting than the consistent underestimation of methane is why this gas is so tricky to track down. 

Methane is the second most abundant greenhouse gas in the atmosphere, and it’s responsible for around 30% of global warming so far. The good news is that methane breaks down quickly in the atmosphere. The bad news is that while it’s floating around, it’s a super-powerful greenhouse gas, way more potent than carbon dioxide. (Just how much more potent is a complicated question that depends on what time scale you’re talking about—read more in this Q&A.)

The problem is, it’s difficult to figure out where all this methane is coming from. We can measure the total concentration in the atmosphere, but there are methane emissions from human activities, there are natural methane sources, and there are ecosystems that soak up a portion of all those emissions (these are called methane sinks). 

Narrowing down specific sources can be a challenge, especially in the oil and gas industry, which is responsible for a huge range of methane leaks. Some are small and come from old equipment in remote areas. Other sources are larger, spewing huge amounts of the greenhouse gas into the atmosphere but only for short times. 

A lot of stories about tracking methane have been in the news recently, mostly because of a methane-hunting satellite launched earlier this month. It’s designed to track down methane using tools called spectrometers, which measure how light is reflected and absorbed. 

This is just one of a growing number of satellites that are keeping an eye on the planet for methane emissions. Some take a wide view, spotting which regions have high emissions. Other satellites are hunting for specific sources and can see within a few dozen meters where a leak is coming from. (If you want to read more about why there are so many methane satellites, I recommend this story from Emily Pontecorvo at Heatmap.)

But methane tracking isn’t just a space game. In a new study published in Nature, researchers used nearly a million measurements taken from airplanes flown over oil- and gas-producing regions to estimate total emissions. 

The results are pretty staggering: researchers found that, on average, roughly 3% of oil and gas production at the sites they examined winds up as methane emissions. That’s about three times the official government estimates used by the US Environmental Protection Agency. 

I spoke with one of the authors of the study, Evan Sherwin, who completed the research as a postdoc at Stanford. He compared the challenge of understanding methane leaks to the parable of the blind men and the elephant: there are many pieces of the puzzle (satellites, planes, ground-based detection), and getting the complete story requires fitting them all together. 

“I think we’re really starting to see an elephant,” Sherwin told me. 

That picture will continue to get clearer as MethaneSAT and other surveillance satellites come online and researchers get to sift through the data. And that understanding will be crucial as governments around the world race to keep promises about slashing methane emissions. 


Now read the rest of The Spark

Related reading

For more on how researchers are working to understand methane emissions, give my latest story a read

If you’ve missed the news on methane-hunting satellites, check out this story about MethaneSAT from last month

Pulling methane out of the atmosphere could be a major boost for climate action. Some startups hope that spraying iron particles above the ocean could help, as my colleague James Temple wrote in December

five planes flying out of white puffy clouds at different angles across a blue sky, leaving contrails behind

PHOTO ILLUSTRATION | GETTY IMAGES

Another thing

Making minor changes to airplane routes could put a significant dent in emissions, and a new study found that these changes could be cheap to implement. 

The key is contrails, thin clouds that planes produce when they fly. Minimizing contrails means less warming, and changing flight paths can reduce the amount of contrail formation. Read more about how in the latest from my colleague James Temple

Keeping up with climate  

New rules from the US Securities and Exchange Commission were watered down, cutting off the best chance we’ve had at forcing companies to reckon with the dangers of climate change, as Dara O’Rourke writes in a new opinion piece. (MIT Technology Review)

Yes, heat pumps slash emissions, even if they’re hooked up to a pretty dirty grid. Switching to a heat pump is better than heating with fossil fuels basically everywhere in the US. (Canary Media)

Rivian announced its new R2, a small SUV set to go on sale in 2026. The reveal signals a shift to focusing on mass-market vehicles for the brand. (Heatmap)

Toyota has focused on selling hybrid vehicles instead of fully electric ones, and it’s paying off financially. (New York Times)

→ Here’s why I wrote in December 2022 that EVs wouldn’t be fully replacing hybrids anytime soon. (MIT Technology Review)

Some scientists think we should all pay more attention to tiny aquatic plants called azolla. They can fix their own nitrogen and capture a lot of carbon, making them a good candidate for crops and even biofuels. (Wired)

New York is suing the world’s largest meat company. The company has said it’ll produce meat with no emissions by 2040, a claim that is false and misleading, according to the New York attorney general’s office. (Vox)

A massive fire in Texas has destroyed hundreds of homes. Climate change has fueled dry conditions, and power equipment sparked an intense fire that firefighters struggled to contain. (Grist)

→ Many of the homes destroyed in the blaze are uninsured, creating a tough path ahead for recovery. (Texas Tribune)