In July, two companies announced a collaboration aimed at helping to decarbonize maritime fuel technology. The companies, Brooklyn-based Amogy and Osaka-based Yanmar, say they plan to combine their respective areas of expertise to develop power plants for ships that use Amogy’s advanced technology for cracking ammonia to produce hydrogen fuel for Yanmar’s hydrogen internal combustion engines.

This partnership responds directly to the maritime industry’s ambitious goals to significantly reduce greenhouse gas emissions. The International Maritime Organization (IMO) has set stringent targets. It is calling for a 40 percent reduction in shipping’s carbon emissions from 2008 levels by 2030. But will the companies have a commercially available reformer-engine unit available in time for shipping fleet owners to launch vessels featuring this technology by the IMO’s deadline? The urgency is there, but so are the technical hurdles that come with new technologies.

Shipping accounts for less than 3 percent of global human-caused CO₂ emissions, but decarbonizing the industry would still have a profound impact on global efforts to combat climate change. According to the IMO’s 2020 Fourth Greenhouse Gas Study, shipping produced 1,056 million tonnes of carbon dioxide in 2018.

Amogy and Yanmar did not respond to IEEE Spectrum‘s requests for comment about the specifics of how they plan to synergize their areas of focus. But John Prousalidis, a professor at the National Technical University of Athens’s School of Naval Architecture and Marine Engineering, spoke with Spectrum to help put the announcement in context.

“We have a long way to go. I don’t mean to sound like a pessimist, but we have to be very cautious.” —John Prousalidis, National Technical University of Athens

Prousalidis is among a group of researchers pushing for electrification of seaport activities as a means of cutting greenhouse gas emissions and reducing the amount of pollutants such as nitrogen oxides and sulfur oxides being spewed into the air by ships at berth and by the cranes, forklifts, and trucks that handle shipping containers in ports. He acknowledged that he hasn’t seen any information specific to Amogy and Yanmar’s technical ideas for using ammonia as ships’ primary fuel source for propulsion, but he has studied maritime sector trends long enough—and helped create standards for the IEEE, the International Electrotechnical Commission (IEC), and the International Organization for Standardization (ISO)—in order to have a strong sense of how things will likely play out.

“We have a long way to go,” Prousalidis says. “I don’t mean to sound like a pessimist, but we have to be very cautious.” He points to NASA’s Artemis project, which is using hydrogen as its primary fuel for its rockets.

“The planned missile launch for a flight to the moon was repeatedly postponed because of a hydrogen leak that could not be well traced,” Prousalidis says. “If such a problem took place with one spaceship that is the singular focus of dozens of people who are paying attention to the most minor detail, imagine what could happen on any of the 100,000 ships sailing across the world?”

What’s more, he says, bold but ultimately unsubstantiated announcements from companies are fairly common. Amogy and Yanmar aren’t the first companies to suggest tapping into ammonia for cargo ships—the industry is no stranger to plans to adopt the fuel to move massive ships across the world’s oceans.

“A couple of big pioneering companies have announced that they’re going to have ammonia-fueled ship propulsion pretty soon,” Prousalidis says. “Originally, they announced that it would be available at the end of 2022. Then they said the end of 2023. Now they’re saying something about 2025.”

Shipping produced 1,056 million tonnes of carbon dioxide in 2018.

Prousalidis adds, “Everybody keeps claiming that ‘in a couple of years’ we’ll have [these alternatives to diesel for marine propulsion] ready. We periodically get these announcements about engines that will be hydrogen-ready or ammonia-ready. But I’m not sure what will happen during real operation. I’m sure that they performed several running tests in their industrial units. But in most cases, according to Murphy’s Law, failures will take place at the worst moment that we can imagine.”

All that notwithstanding, Prousalidis says he believes these technical hurdles will someday be solved, and engines running on alternative fuels will replace their diesel-fueled counterparts eventually. But he says he sees the rollout likely mirroring the introduction of natural gas. At the point when a few machines capable of running on that type of fuel were ready, the rest of the logistics chain was not. “We need to have all these brand-new pieces of equipment, including piping, that must be able to withstand the toxicity and combustibility of these new fuels. This is a big challenge, but it means that all engineers have work to do.”

Spectrum also reached out to researchers at the U.S. Department of Energy’s Office of Energy Efficiency and Renewable Energy with several questions about what Amogy and Yanmar say they are looking to pull off. The DOE’s e-mail response: “Theoretically possible, but we don’t have enough technical details (temperature of coupling engine to cracker, difficulty of manifolding, startup dynamics, controls, etc.) to say for certain and if it is a good idea or not.”

This article was updated on 5 August 2024 to correct global shipping emission data.

When it comes to motorsports, the need for speed isn’t only on the racetrack. Engineers who support race teams also need to work at a breakneck pace to fix problems, and that’s something Aakhilesh Singhania relishes.

Singhania is a senior applications engineer at Bosch Engineering, in Novi, Mich. He develops and supports electronic control systems for hybrid race cars, which feature combustion engines and battery-powered electric motors.

Aakhilesh Singhania

Employer:

Bosch Engineering

Occupation:

Senior applications engineer

Education:

Bachelor’s degree in mechanical engineering, Manipal Institute of Technology, India; master’s degree in automotive engineering, University of Michigan, Ann Arbor

His vehicles compete in two iconic endurance races: the Rolex 24 at Daytona in Daytona Beach, Fla., and the 24 Hours of Le Mans in France. He splits his time between refining the underlying technology and providing trackside support on competition day. Given the relentless pace of the racing calendar and the intense time pressure when cars are on the track, the job is high octane. But Singhania says he wouldn’t have it any other way.

“I’ve done jobs where the work gets repetitive and mundane,” he says. “Here, I’m constantly challenged. Every second counts, and you have to be very quick at making decisions.”

An Early Interest in Motorsports

Growing up in Kolkata, India, Singhania picked up a fascination with automobiles from his father, a car enthusiast.

In 2010, when Singhania began his mechanical engineering studies at India’s Manipal Institute of Technology, he got involved in the Formula Student program, an international engineering competition that challenges teams of university students to design, build, and drive a small race car. The cars typically weigh less than 250 kilograms and can have an engine no larger than 710 cubic centimeters.

“It really hooked me,” he says. “I devoted a lot of my spare time to the program, and the experience really motivated me to dive further into motorsports.”

One incident in particular shaped Singhania’s career trajectory. In 2013, he was leading Manipal’s Formula Student team and was one of the drivers for a competition in Germany. When he tried to start the vehicle, smoke poured out of the battery, and the team had to pull out of the race.

“I asked myself what I could have done differently,” he says. “It was my lack of knowledge of the electrical system of the car that was the problem.” So, he decided to get more experience and education.

Learning About Automotive Electronics

After graduating in 2014, Singhania began working on engine development for Indian car manufacturer Tata Motors in Pune. In 2016, determined to fill the gaps in his knowledge about automotive electronics, he left India to begin a master’s degree program in automotive engineering at the University of Michigan in Ann Arbor.

He took courses in battery management, hybrid controls, and control-system theory, parlaying this background into an internship with Bosch in 2017. After graduation in 2018, he joined Bosch full-time as a calibration engineer, developing technology for hybrid and electric vehicles.

Transitioning into motorsports required perseverance, Singhania says. He became friendly with the Bosch team that worked on electronics for race cars. Then in 2020 he got his big break.

That year, the U.S.-based International Motor Sports Association and the France-based Automobile Club de l’Ouest created standardized rules to allow the same hybrid race cars to compete in both the Sportscar Championship in North America, host of the famous Daytona race, and the global World Endurance Championship, host of Le Mans.

The Bosch motorsports team began preparing a proposal to provide the standardized hybrid system. Singhania, whose job already included creating simulations of how vehicles could be electrified, volunteered to help.

“I’m constantly challenged. Every second counts, and you have to be very quick at making decisions.”

The competition organizers selected Bosch as lead developer of the hybrid system that would be provided to all teams. Bosch engineers would also be required to test the hardware they supplied to each team to ensure none had an advantage.

“The performance of all our parts in all the cars has to fall within 1 percent of each other,” Singhania says.

After Bosch won the contract, Singhania officially became a motorsports calibration engineer, responsible for tweaking the software to fit the idiosyncrasies of each vehicle.

In 2022 he stepped up to his current role: developing software for the hybrid control unit (HCU), which is essentially the brains of the vehicle. The HCU helps coordinate all of the different subsystems such as the engine, battery, and electric motor and is responsible for balancing power requirements among these different components to maximize performance and lifetime.

Bosch’s engineers also designed software known as an equity model, which runs on the HCU. It is based on historical data collected from the operation of the hybrid systems’ various components, and controls their performance in real time to ensure all the teams’ hardware operates at the same level.

In addition, Singhania creates simulations of the race cars, which are used to better understand how the different components interact and how altering their configuration would affect performance.

Troubleshooting Problems on Race Day

Technology development is only part of Singhania’s job. On race days, he works as a support engineer, helping troubleshoot problems with the hybrid system as they crop up. Singhania and his colleagues monitor each team’s hardware using computers on Bosch’s race-day trailer, a mobile nerve center hardwired to the organizers’ control center on the race track.

“We are continuously looking at all the telemetry data coming from the hybrid system and analyzing [the system’s] health and performance,” he says.

If the Bosch engineers spot an issue or a team notifies them of a problem, they rush to the pit stall to retrieve a USB stick from the vehicle, which contains detailed data to help them diagnose and fix the issue.

After the race, the Bosch engineers analyze the telemetry data to identify ways to boost the standardized hybrid system’s performance for all the teams. In motorsports, where the difference between winning and losing can come down to fractions of a second, that kind of continual improvement is crucial.

Customers “put lots of money into this program, and they are there to win,” Singhania says.

Breaking Into Motorsports Engineering

Many engineers dream about working in the fast-paced and exciting world of motorsports, but it’s not easy breaking in. The biggest lesson Singhania learned is that if you don’t ask, you don’t get invited.

“Keep pursuing them because nobody’s going to come to you with an offer,” he says. “You have to keep talking to people and be ready when the opportunity presents itself.”

Demonstrating that you have experience contributing to challenging projects is a big help. Many of the engineers Bosch hires have been involved in Formula Student or similar automotive-engineering programs, such as the EcoCAR EV Challenge, says Singhania.

The job isn’t for everyone, though, he says. It’s demanding and requires a lot of travel and working on weekends during race season. But if you thrive under pressure and have a knack for problem solving, there are few more exciting careers.

When it comes to addressing climate change, the “in unity there’s strength” adage certainly applies.

To support IEEE’s climate change initiative, which highlights innovative solutions and approaches to the climate crisis, IEEE’s TryEngineering program has created a collection of lesson plans, activities, and events that cover electric vehicles, solar and wind power systems, and more.

TryEngineering, a program within IEEE Educational Activities, aims to foster the next generation of technology innovators by providing preuniversity educators and students with resources.

To help bring the climate collection to more students, TryEngineering has partnered with the Museum of Science in Boston. The museum, one of the world’s largest science centers, reaches nearly 5 million people annually through its physical location, nearby classrooms, and online platforms.

TryEngineering worked with the museum to distribute a nearly four-minute educational video created by Moment Factory, a multimedia studio specializing in immersive experiences. Using age-appropriate language, the video, which is posted on TryEngineering’s climate change page, explores the issue through visual models and scientific explanations.

“Since the industrial revolution, humans have been digging up fossil fuels and burning them, which releases CO2 into the atmosphere in unprecedented quantities,” the video says. It notes that in the past 60 years, atmospheric carbon dioxide increased at a rate 100 times faster than previous natural changes.

“We are committed to energizing students around important issues like climate change and helping them understand how engineering can make a difference.”

The video explains the impact of pollutants such as lead and ash, and it adds that “when we work together, we can change the global environment.” The video encourages students to contribute to a global solution by making small, personal changes.

“We’re thrilled to contribute to the IEEE climate change initiative by providing IEEE volunteers and educators access to TryEngineering’s collection, so they have resources to use with students,” says Debra Gulick, director of IEEE student and academic education programs.

“We are excited to partner with the Museum of Science to bring even more awareness and exposure of this important issue to the school setting,” Gulick says. “Working with prominent partners like the museum, we are committed to energizing students around important issues like climate change and helping them understand how engineering can make a difference.”

Earlier this month, China announced that it is pouring 6 billion yuan (about US $826 million) into a fund meant to spur the development of solid-state batteries by the nation’s leading battery manufacturers. Solid-state batteries use electrolytes of either glass, ceramic, or solid polymer material instead of the liquid lithium salts that are in the vast majority of today’s electric vehicle (EV) batteries. They’re greatly anticipated because they will have three or four times as much energy density as batteries with liquid electrolytes, offer more charge-discharge cycles over their lifetimes, and be far less susceptible to the thermal runaway reaction that occasionally causes lithium batteries to catch fire.

But China’s investment in the future of batteries won’t likely speed up the timetable for mass production and use in production vehicles. As IEEE Spectrum pointed out in January, it’s not realistic to look for solid-state batteries in production vehicles anytime soon. Experts Spectrum consulted at the time “noted a pointed skepticism toward the technical merits of these announcements. None could isolate anything on the horizon indicating that solid-state technology can escape the engineering and ‘production hell’ that lies ahead.”

“To state at this point that any one battery and any one country’s investments in battery R&D will dominate in the future is simply incorrect.” —Steve W. Martin, Iowa State University

Reaching scale production of solid-state batteries for EVs will first require validating existing solid-state battery technologies—now being used for other, less demanding applications—in terms of performance, life-span, and relative cost for vehicle propulsion. Researchers must still determine how those batteries take and hold a charge and deliver power as they age. They’ll also need to provide proof that a glass or ceramic battery can stand up to the jarring that comes with driving on bumpy roads and certify that it can withstand the occasional fender bender.

Here Come Semi-Solid-State Batteries

Meanwhile, as the world waits for solid electrolytes to shove liquids aside, Chinese EV manufacturer Nio and battery maker WeLion New Energy Technology Co. have partnered to stake a claim on the market for a third option that splits the difference: semi-solid-state batteries, with gel electrolytes.

CarNewsChina.com reported in April that the WeLion cells have an energy density of 360 watt-hours per kilogram. Fully packaged, the battery’s density rating is 260 Wh/kg. That’s still a significant improvement over lithium iron phosphate batteries, whose density tops out at 160 Wh/kg. In tests conducted last month with Nio’s EVs in Shanghai, Chengdu, and several other cities, the WeLion battery packs delivered more than 1,000 kilometers of driving range on a single charge. Nio says it plans to roll out the new battery type across its vehicle lineup beginning this month.

But the Beijing government’s largesse and the Nio-WeLion partnership’s attempt to be first to get semi-solid-state batteries into production vehicles shouldn’t be a temptation to call the EV propulsion game prematurely in China’s favor.

So says Steve W. Martin, a professor of materials science and engineering at Iowa State University, in Ames. Martin, whose research areas include glassy solid electrolytes for solid-state lithium batteries and high-capacity reversible anodes for lithium batteries, believes that solid-state batteries are the future and that hybrid semi-solid batteries will likely be a transition between liquid and solid-state batteries. However, he says, “to state at this point that any one battery and any one country’s investments in battery R&D will dominate in the future is simply incorrect.” Martin explains that “there are too many different kinds of solid-state batteries being developed right now and no one of these has a clear technological lead.”

The Advantages of Semi-Solid-State Batteries

The main innovation that gives semi-solid-state batteries an advantage over conventional batteries is the semisolid electrolyte from which they get their name. The gel electrolyte contains ionic conductors such as lithium salts just as liquid electrolytes do, but the way they are suspended in the gel matrix supports much more efficient ion conductivity. Enhanced transport of ions from one side of the battery to the other boosts the flow of current in the opposite direction that makes a complete circuit. This is important during the charging phase because the process happens more rapidly than it can in a battery with a liquid electrolyte. The gel’s structure also resists the formation of dendrites, the needlelike structures that can form on the anode during charging and cause short circuits. Additionally, gels are less volatile than liquid electrolytes and are therefore less prone to catching fire.

Though semi-solid-state batteries won’t reach the energy densities and life-spans that are expected from those with solid electrolytes, they’re at an advantage in the short term because they can be made on conventional lithium-ion battery production lines. Just as important, they have been tested and are available now rather than at some as yet unknown date.

Semi-solid-state batteries can be made on conventional lithium-ion battery production lines.

Several companies besides WeLion are actively developing semi-solid-state batteries. China’s prominent battery manufacturers, including CATL, BYD, and the state-owned automakers FAW Group and SAIC Group are, like WeLion, beneficiaries of Beijing’s plans to advance next-generation battery technology domestically. Separately, the startup Farasis Energy, founded in Ganzhou, China, in 2009, is collaborating with Mercedes-Benz to commercialize advanced batteries.

The Road Forward to Solid-State Batteries

U.S. startup QuantumScape says the solid-state lithium metal batteries it’s developing will offer energy density of around 400 Wh/kg. The company notes that its cells eliminate the charging bottleneck that occurs in conventional lithium-ion cells, where lithium must diffuse into the carbon particles. QuantumScape’s advanced batteries will therefore allow fast charging from 10 to 80 percent in 15 minutes. That’s a ways off, but the Silicon Valley–based company announced in March that it had begun shipping its prototype Alpha-2 semi-solid-state cells to manufacturers for testing.

Toyota is among a group of companies not looking to hedge their bets. The automaker, ignoring naysayers, aims to commercialize solid-state batteries by 2027 that it says will give an EV a range of 1,200 km on a single charge and allow 10-minute fast charging. It attributes its optimism to breakthroughs addressing durability issues. And for companies like Solid Power, it’s also solid-state or bust. Solid Power, which aims to commercialize a lithium battery with a proprietary sulfide-based solid electrolyte, has partnered with major automakers Ford and BMW. ProLogium Technology, which is also forging ahead with preparations for a solid-state battery rollout, claims that it will start delivering batteries this year that combine a ceramic oxide electrolyte with a lithium-free soft cathode (for energy density exceeding 500 Wh/kg). The company, which has teamed up with Mercedes-Benz, demonstrated confidence in its timetable by opening the world’s first giga-level solid-state lithium ceramic battery factory earlier this year in Taoyuan, Taiwan.

Inside a shipping container in an industrial area of Venice, the Italian startup 9-Tech is taking a crack at a looming global problem: how to responsibly recycle the 54 million to 160 million tonnes of solar modules that are expected to reach the end of their productive lives by 2050. Recovering the materials won’t be easy. Solar panels are built to withstand any environment on Earth for 20 to 30 years, and even after sitting in the sun for three decades, the hardware is difficult to dismantle. In fact, most recycling facilities trash the silicon, silver, and copper—the most valuable but least accessible materials in old solar panels—and recover only the aluminum frames and glass panes.

The startup 9-Tech operates its pilot plant out of a modified shipping container housed at the Green Propulsion Laboratory in the industrial port of Marghera in Venice.Luigi Avantaggiato

The need for recycling will only grow as the world increasingly deploys solar power. More than 1.2 terawatts of solar power has already been deployed globally. Solar panels are currently being distributed at a rate of more than 400 gigawatts per year, and the rate is expected to increase to a whopping 3 TW per year by 2030, according to a literature analysis by researchers at the National Renewable Energy Laboratory (NREL).

In an attempt to stop a mountain of photovoltaic garbage from accumulating, researchers are pursuing better recycling methods. The most advanced methods proposed so far can recover at least 90 percent of the copper, silver, silicon, glass, and aluminum in a crystalline silicon PV module. But these processes are expensive and often involve toxic chemicals. No recycling method has proven to be as cheap as landfilling, and very few operate on an industrial scale, says Garvin Heath, principal environmental engineer at NREL, who manages a group of international experts assigned by the International Energy Agency to analyze PV sustainability.

The founders of 9-Tech say they have a better way. Their process is a noisy one involving a combustion furnace, an ultrasound bath, and mechanical sorting, the vibrations of which shake the floor of the modest freight container where they have been testing their operation for nearly two years. The company uses no toxic chemicals, releases no pollutants into the environment, and recovers up to 90 percent of the materials in a solar panel, says Francesco Miserocchi, chief technology officer at 9-Tech.

Bits of silicon and glass are separated from the rest of the panel. Luigi Avantaggiato

How to Recycle Solar Panels

After the frame, glass, and junction box are removed from a PV panel, the inner, bendable layers of silicon, polymers, and metal conductors remain. Workers cut the inner layers into large sections in preparation for the oven.Luigi Avantaggiato

The company tailors its process to crystalline silicon solar panels, which make up 97 percent of the global PV market. The panels typically consist of an array of silicon wafers doped with boron and phosphorus, and topped with an antireflective coating of silicon nitride. Silver conductors are screen printed onto the wafer surface, and copper conductors are soldered onto the array in a grid pattern. To protect the materials from moisture and damage, manufacturers laminate the entire array in adhesive polymers—usually ethylene-vinyl acetate. Then they encase the laminated array in sheets of tempered glass, frame the whole thing in aluminum, seal the edges, and attach a junction box on the back.

When it’s time to recycle a panel, one of the most challenging steps is removing the polymers, which stick to everything. “It’s not just the edges or a couple of dots of glue. It’s an entire surface—several square feet—of polymer,” says Heath. The polymer can be burned off, but this releases carbon monoxide, hydrofluoric acid, and other harmful pollutants. Separating the silver conductors also proves challenging because they’re applied in a very thin layer–about 10 to 20 micrometers–that is strongly attached to the silicon. Removing them typically involves toxic reagents such as hydrofluoric acid, nitric acid, or sodium hydroxide.

The team at 9-Tech addresses these challenges in two ways. They recover the silver using ultrasound rather than toxic chemicals, and although they burn the polymers, they capture the pollutants emitted.

Layers of silicon and polymer are fed into a continuous combustion furnace, which heats the materials to over 400 °C, vaporizing the polymers. 9-Tech

The process at the company’s pilot plant starts with workers manually removing the aluminum frame, junction box, and tempered glass. This leaves a sandwich of polymers, silicon wafers, and metal conductors. Without the frame or glass, the sandwich layers bend, shattering the fragile silicon into small pieces. Workers crack the tempered glass and then send all the materials, which are mostly still in place because of the polymers, into a continuous combustion furnace. Heated to over 400 °C, the polymers vaporize, and a filter captures the pollutants. The system also captures the heat from the furnace and reuses it for energy efficiency.

A mechanical roller separates the copper grid after the PV materials exit the furnace.Luigi Avantaggiato

After the materials exit the oven, mechanical sieves separate the copper, glass, and silicon. Top: Luigi Avantaggiato; Bottom: 9-Tech

As the remaining material exits the furnace, a roller mechanically strips out the copper. A series of sieves sort the broken bits of glass and silicon based on thickness. The silicon pieces, still laced with silver, are immersed in a bath of organic acid and treated with ultrasound to loosen the bonds between the elements. The ultrasound works by propagating sound waves into the acid bath, resulting in alternating high- and low-pressure cycles. If the waves are intense enough, they create cavitation bubbles that mechanically interact with the material, causing the silver to dislodge from the silicon, explains Pietrogiovanni Cerchier, CEO at 9-Tech.

Finally, workers remove the silicon fragments from the ultrasound bath with a mesh net. This leaves a fine silver dust in the solution, which can be recovered by filtration or centrifuge. All told, Cerchier says, 9-Tech’s pilot plant can recover 90 percent of the silver, 95 percent of the silicon, and 99 percent or more of the copper, aluminum, and glass from a PV module. What’s more, the material is considered highly pure, which increases the types of applications for which it can be reused.

Workers at 9-Tech immerse silver-laced silicon pieces in a bath of organic acid and treat it with ultrasound to loosen the bonds between the elements. 9-Tech

The startup’s recycling process is more expensive than existing methods that recover only aluminum and glass. But the extraction of high-purity silicon, silver, and copper should offset the extra cost, Miserocchi says. Plus, it’s more efficient than mining for virgin elements. You can extract about 500 grams of silver from a tonne of solar panels, but only 165 grams of silver from a tonne of ore, he says. “A photovoltaic panel at the end of its life still has a lot to give,” says Miserocchi. “It can be considered a small mine of precious elements.”

Silver emerges from the silicon bath in a fine dust. 9-Tech

Dozens of New Ways to Recycle PV Panels

High-purity copper, glass, and silicon are recovered from 9-Tech’s PV-panel recycling process.Luigi Avantaggiato

The 9-Tech team will know more about the profitability of their method after they build a larger demonstration facility over the next 18 months. That plant, to be located in the same industrial district of Venice as the shipping container, will be able to handle up to 800 solar modules a day. Their pilot plant processes only about seven modules a day.

The company’s approach is one of many recycling methods for crystalline silicon PV panels in development. A comprehensive review published in April in the Journal of Cleaner Production identified dozens of other efforts globally, including thermal, chemical, mechanical, and optical approaches. The most common method involves grinding the silicon, metal, and polymer layers into small pieces, separating them by density, and recovering the silicon and metal with a thermal or chemical process. Other processes include laser irradiation, high-voltage pulses, optical sorting, pyrolysis, chemical solvents, etching, and delaminating with a hot knife.

Driving this innovation, in part, are regulations adopted by the European Union in 2012. The rules require all PV panel manufacturers in the EU to run take-back or recycling programs, or partner with other recycling schemes. As a result, Germany, which has the most solar power capacity in Europe, has one of the largest PV recycling systems in the world.

“A photovoltaic panel at the end of its life still has a lot to give,” says Miserocchi. “It can be considered a small mine of precious elements.”

But recycling is a high-volume business, and aside from catastrophic weather events that wipe out solar power stations, spent solar modules reach recyclers at a relative trickle. And then there’s the challenge of finding a second life for the materials after they are recovered—a supply chain that’s not well developed.

First Solar, a global PV manufacturer based in Tempe, Ariz., addressed both of these issues on a large scale by building an in-house recycling program with seven facilities in five countries. The company makes cadmium telluride thin-film solar panels that buyers can purchase with the recycling price built in. At the end of the panels’ lives, buyers send them back to First Solar for recycling into new products. The semiconductor material can be recycled up to 41 times, giving it a life-span of more than 1,200 years, according to the company. But the glass isn’t pure enough to be reused in solar modules, so the company plans to supply it to float-glass manufacturers for use in windows and doors.

The challenges with recycling have inspired researchers to rethink the way crystalline solar panels are made. For example, some manufacturers are trying to reduce or eliminate the difficult-to-recover silver, replacing it with other conductive metals. And a team at NREL demonstrated in February a way to eliminate polymers in PV panels by laser welding the glass panes instead, which may do a better job sealing out moisture. That technique may lend itself to perovskite solar modules, a promising technology that is particularly susceptible to moisture and corrosion.

“Recycling shouldn’t be the only strategy,” says Heath. People should consider alternative ways to repair or reuse solar panels to extend their lives before resorting to recycling, he says.

Additional reporting by Luigi Avantaggiato

When Yifeng Chen was a teenager in Shantou, China, in the early 2000s, he saw a TV program that amazed him. The show highlighted rooftop solar panels in Germany, explaining that the panels generated electricity to power the buildings and even earned the owners money by letting them sell extra energy back to the electricity company.

Yifeng Chen

Employer

Trina Solar

Title

Assistant vice president of technology

Member Grade

Member

Alma Maters

Sun Yat-sen University, in Guangzhou, China, and Leibniz University Hannover, in Germany

An incredulous Chen marveled at not only the technology but also the economics. A power authority would pay its customers?

It sounded like magic: useful and valuable electricity extracted from simple sunlight. The wonder of it all has fueled his dreams ever since.

In 2013 Chen earned a Ph.D. in photovoltaic sciences and technologies, and today he’s assistant vice president of technology at China’s Trina Solar, a Changzhou-based company that is one of the largest PV manufacturers in the world. He leads the company’s R&D group, whose efforts have set more than two dozen world records for solar power efficiency and output.

For Chen’s contributions to the science and technology of photovoltaic energy conversion, the IEEE member received the 2023 IEEE Stuart R. Wenham Young Professional Award from the IEEE Electron Devices Society.

“I was quite surprised and so grateful” to receive the Wenham Award, Chen says. “It’s a very high-level recognition, and there are so many deserving experts from around the world.”

Trina Solar’s push for more efficient hardware

Today’s commercial solar panels typically achieve about 20 percent efficiency: They can turn one-fifth of captured sunlight into electricity. Chen’s group is trying to make the panels more efficient.

The group is focusing on optimizing solar cell designs, including the passivated emitter and rear cell (PERC), which is the industry standard for commodity solar panels.

Invented in 1983, PERCs are used today in nearly 90 percent of solar panels on the market. They incorporate coatings on the front and back to capture sunlight more effectively and to avoid losing energy, both at the surfaces and as the sunlight travels through the cell. The coatings, known as passivation layers, are made from materials such as silicon nitride, silicon dioxide, and aluminum oxide. The layers keep negatively charged free electrons and positively charged electron holes apart, preventing them from combining at the surface of the solar cell and wasting energy.

Chen and his team have developed several ways to boost the performance of PERC panels, hitting a record of 24.5 percent efficiency in 2022. One of the technologies is a multilayer antireflective coating that helps solar panels trap more light. They also created extremely fine metallization fingers—narrow lines on solar cells’ surfaces—to collect and transport the electric current and help capture more sunlight. And they developed an advanced method for laying the strips of conductive metal that run across the solar cell, known as bus bars.

Experts predict the maximum efficiency of PERC technology will be reached soon, topping out at about 25 percent.

IEEE Member Yifeng Chen displays an i-TOPCon solar module, which has a production efficiency of more than 23 percent and a power output of up to 720 watts.Trina Solar

“So the question is: How do we get solar cells even more efficient?” Chen says.

During the past few years he and his group have been working on tunnel oxide passivated contact (TOPCon) technology. A TOPCon cell uses a thin layer of “tunneling oxide” insulating material—typically silicon dioxide—which is applied to the solar cell’s surface. Similar to the passivation layers on PERC cells, the tunnel oxide stops free electrons and electron holes from combining and wasting energy.

In 2022 Trina created a TOPCon-type panel with a record 25.5 percent efficiency, and two months ago the company announced it had achieved a record 740.6 watts for a mass-produced TOPCon solar module. The latter was the 26th record Trina set for solar power–related efficiencies and outputs.

To achieve that record-breaking performance for their TOPCon panels, Chen and his team optimized the company’s manufacturing processes including laser-induced firing, in which a laser heats part of the solar cell and creates bonds between the metal contacts and the silicon wafer. The resulting connections are stronger and better aligned, enhancing efficiency.

“We’re trying to keep improving things to trap just a little bit more sunlight,” Chen says. “Gaining 1 or 2 percent more efficiency is huge. These may sound like very tiny increases, but at scale these small improvements create a lot of value in terms of economics, sustainability, and value to society.”

As the efficiency of solar cells rises and prices drop, Chen says, he expects solar power to continue to grow around the world. China currently leads the world in installed solar power capacity, accounting for about 40 percent of global capacity. The United States is a distant second, with 12 percent, according to a 2023 Rystad Energy report. The report predicts that China’s 500 gigawatts of solar capacity in 2023 is likely to exceed 1 terawatt by 2026.

“I’m inspired by using science to create something useful for human beings, and then driven by the pursuit for excellence,” Chen says. “We can always learn something new to make that change, improve that piece of technology, and get just that little bit better.”

Trained by solar-power pioneers

Chen attended Sun Yat-sen University in Guangzhou, China, earning a bachelor’s degree in optics sciences and technologies in 2008. He stayed on to pursue a Ph.D. in photovoltaics sciences and technologies. His research was on high-efficiency solar cells made from wafer-based crystalline silicon. His adviser was Hui Shen, a leading PV professor and founder of the university’s Institute for Solar Energy Systems. Chen calls him “the first of three very important figures in my scientific career.”

In 2011 Chen spent a year as a Ph.D. student at Leibniz University Hannover, in Germany. There he studied under Pietro P. Altermatt, the second influential figure in his career.

Altermatt—a prominent silicon solar-cell expert who would later become principal scientist at Trina—advised Chen on his computational techniques for modeling and analyzing the behavior of 2D and 3D solar cells. The models play a key role in designing solar cells to optimize their output.

“Gaining 1 or 2 percent more efficiency is huge. These may sound like very tiny increases, but at scale, these small improvements create a lot of value in terms of economics, sustainability, and value to society.”

“Dr. Altermatt changed how I look at things,” Chen says. “In Germany, they really focus on device physics.”

After completing his Ph.D., Chen became a technical assistant at Trina, where he met the third highly influential person in his career: Pierre Verlinden, a pioneering photovoltaic researcher who was the company’s chief scientist.

At Trina, Chen quickly ascended through R&D roles. He has been the company’s assistant vice president of technology since 2023.

IEEE’s “treasure” trove of research

Chen joined IEEE as a student because he wanted to attend the IEEE Photovoltaic Specialists Conference, the longest-running event dedicated to photovoltaics, solar cells, and solar power.

The membership was particularly beneficial during his Ph.D. studies, he says, because he used the IEEE Xplore Digital Library to access archival papers.

“My work has certainly been inspired by papers I found via IEEE,” Chen says. “Plus, you end up clicking around and reading other work that isn’t related to your field but is so interesting.

“The publication repository is a treasure. It’s eye-opening to see what’s going on inside and outside of your industry, with new discoveries happening all the time.”

Nearly 400 exhibitors representing the boldest energy innovations in the United States came together last week at the annual ARPA-E Energy Innovation Summit. The conference, hosted in Dallas by the U.S. Advanced Research Projects Agency–Energy (ARPA-E), showcased the agency’s bets on early-stage energy technologies that can disrupt the status quo. U.S. Secretary of Energy Jennifer Granholm spoke at the summit. “The people in this room are America’s best hope” in the race to unleash the power of clean energy, she said. “The technologies you create will decide whether we win that race. But no pressure,” she quipped. IEEE Spectrum spent three days meandering the aisles of the showcase. Here are five of our favorite demonstrations.

Gas Li-ion batteries thwart extreme cold

South 8 Technologies demonstrates the cold tolerance of its Li-ion battery by burying it in ice at the 2024 ARPA-E Energy Innovation Summit. Emily Waltz

Made with a liquified gas electrolyte instead of the standard liquid solvent, a new kind of lithium-ion battery that stands up to extreme cold, made by South 8 Technologies in San Diego, won’t freeze until temps drop below –80 °C. That’s a big improvement on conventional Li-ion batteries, which start to degrade when temps reach 0 °C and shut down at about –20 °C. “You lose about half of your range in an electric vehicle if you drive it in the middle of winter in Michigan,” says Cyrus Rustomji, cofounder of South 8. To prove the company’s point, Rustomji and his team set out a bucket of dry ice at nearly –80 °C at their booth at the ARPA-E summit and put flashlights in it—one powered by a South 8 battery and one powered by a conventional Li-ion cell. The latter flashlight went out after about 10 minutes, and South 8’s kept going for the next 15 hours. Rustomji says he expects EV batteries made with South 8’s technology to maintain nearly full range at –40 °C, and gradually degrade in temperatures lower than that.

South 8 Technologies

Conventional Li-ion batteries use liquid solvents, such as ethylene and dimethyl carbonate, as the electrolyte. The electrolyte serves as a medium through which lithium salt moves from one electrode to the other in the battery, shuttling electricity. When it’s cold, the carbonates thicken, which lowers the power of the battery. They can also freeze, which shuts down all conductivity. South 8 swapped out the carbonate for some industrial liquified gases with low freezing points (a recipe the company won’t disclose).

Using liquified gases also reduces fire risk because the gas very quickly evaporates from a damaged battery cell, removing fuel that could burn and cause the battery to catch fire. If a conventional Li-ion battery gets damaged, it can short-circuit and quickly become hot—like over 800 °C hot. This causes the liquid electrolyte to heat adjacent cells and potentially start a fire.

There’s another benefit to this battery, and this one will make EV drivers very happy: It will take only 10 minutes to reach an 80 percent charge in EVs powered by these batteries, Rustomji estimates. That’s because liquified gas has a lower viscosity than carbonate-based electrolytes, which allows the lithium salt to move from one electrode to the other at a faster rate, shortening the time it takes to recharge the battery.

South 8’s latest improvement is a high-voltage cathode that reduces material costs and could enable fast charging down to 5 minutes for a full charge. “We have the world record for a high-voltage, low-temperature cathode,” says Rustomji.

Liquid cooling won’t leak on servers

Chilldyne guarantees that its liquid-cooling system won’t leak even if tubes get hacked in half, as IEEE Spectrum editor Emily Waltz demonstrates at the 2024 ARPA-E Energy Innovation Summit. Emily Waltz

Data centers need serious cooling technologies to keep servers from overheating, and sometimes air-conditioning just isn’t enough. In fact, the latest Blackwell chips from Nvidia require liquid cooling, which is more energy efficient than air. But liquid cooling tends to make data-center operators nervous. “A bomb won’t do as much damage as a leaky liquid-cooling system,” says Steve Harrington, CEO of Chilldyne. His company, based in Carlsbad, Calif., offers liquid cooling that’s guaranteed not to leak, even if the coolant lines get chopped in half. (They aren’t kidding: Chilldyne brought an axe to its demonstration at ARPA-E and let Spectrum try it out. Watch the blue cooling liquid immediately disappear from the tube after it’s chopped.)

Chilldyne

The system is leakproof because Chilldyne’s negative-pressure system pulls rather than pushes liquid coolant through tubes, like a vacuum. The tubes wind through servers, absorbing heat through cold plates, and return the warmed liquid to tanks in a cooling distribution unit. This unit transfers the heat outside and supplies cooled liquid back to the servers. If a component anywhere in the cooling loop breaks, the liquid is immediately sucked back into the tanks before it can leak. Key to the technology: low-thermal-resistance cold plates attached to each server’s processors, such as the CPUs or GPUs. The cold plates absorb heat by convection, transferring the heat to the coolant tube that runs through it. Chilldyne optimized the cold plate using corkscrew-shaped metal channels, called turbulators, that force water around them “like little tornadoes,” maximizing the heat absorbed, says Harrington. The company developed the cold plate under an ARPA-E grant and is now measuring the energy savings of liquid cooling through an ARPA-E program.

Salvaged mining waste also sequesters CO₂

Phoenix Tailings’ senior research scientist Rita Silbernagel explains how mining waste contains useful metals and rare earth elements and can also be used as a place to store carbon dioxide.Emily Waltz

Mining leaves behind piles of waste after the commercially viable material is extracted. This waste, known as tailings, can contain rare earth elements and valuable metals that are too difficult to extract with conventional mining techniques. Phoenix Tailings—a startup based in Woburn, Mass.—extracts metals and rare earth elements from tailings in a process that leaves behind no waste and creates no direct carbon dioxide emissions. The company’s process starts with a hydrometallurgical treatment that separates rare earth elements from the tailings, which contain iron, aluminum, and other common elements. Next the company uses a novel solvent extraction method to separate the rare earth elements from one another and purify the desired element in the form of an oxide. The rare earth oxide then undergoes a molten-salt electrolysis process that converts it into a solid metal form. Phoenix Tailings focuses on extracting neodymium, neodymium-praseodymium alloy, dysprosium, and ferro dysprosium alloy, which are rare earth metals used in permanent magnets for EVs, wind turbines, jet engines, and other applications. The company is evaluating several tailings sites in the United States, including in upstate New York.

The company has also developed a process to extract metals such as nickel, copper, and cobalt from mining tailings while simultaneously sequestering carbon dioxide. The approach involves injecting CO₂ into the tailings, where it reacts with minerals, transforming them into carbonates—compounds that contain the carbonate ion, which contains three oxygen atoms and one carbon atom. After the mineral carbonation process, the nickel or other metals are selectively leached from the mixture, yielding high-quality nickel that can be used by EV-battery and stainless-steel industries.

Better still, this whole process, says Rita Silbernagel, senior research scientist at Phoenix Tailings, absorbs more CO₂ than it emits.

Hydrokinetic turbines: a new business model

Emrgy adjusts the height of its hydrokinetic turbines at the 2024 ARPA-E Energy Innovation Summit. The company plans to install them in old irrigation channels to generate renewable energy and new revenue streams for rural communities. Emily Waltz

These hydrokinetic turbines run in irrigation channels, generating electricity and revenue for rural communities. Developed by Emrgy in Atlanta, the turbines can change in height and blade pitch based on the flow of the water. The company plans to put them in irrigation channels that were built to bring water from snowmelt in the Rocky Mountains to agricultural areas in the western United States. Emrgy estimates that there are more than 160,000 kilometers of these waterways in the country. The system is aging and losing water, but it’s hard for water districts to justify the cost of repairing them, says Tom Cuthbert, chief technology officer at Emrgy. The company’s solution is to place its hydrokinetic turbines throughout these waterways as a way to generate renewable electricity and pay for upgrades to the irrigation channels.

The concept of placing hydrokinetic turbines in waterways isn’t new, but until recent years, connecting them to the grid wasn’t practical. Emrgy’s timing takes advantage of the groundwork laid by the solar power industry. The company has five pilot projects in the works in the United States and New Zealand. “We found that existing water infrastructure is a massive overlooked real estate segment that is ripe for renewable energy development,” says Emily Morris, CEO and founder of Emrgy.

Pressurized water stores energy deep underground

Quidnet Energy brought a wellhead to the 2024 ARPA-E Energy Innovation Summit to demonstrate its geoengineered energy-storage system.Emily Waltz

Quidnet Energy brought a whole wellhead to the ARPA-E summit to demonstrate its underground pumped hydro storage technique. The Houston-based company’s geoengineered system stores energy as pressurized water deep underground. It consists of a surface-level pond, a deep well, an underground reservoir at the end of the well, and a pump system that moves pressurized water from the pond to the underground reservoir and back. The design doesn’t require an elevation change like traditional pumped storage hydropower.

Quidnet’s system consists of a surface-level pond, a deep well, an underground reservoir at the end of the well, and a pump system that moves pressurized water from the pond to the underground reservoir and back.Quidnet Energy

It works like this: Electricity from renewable sources powers a pump that sends water from the surface pond into a wellhead and down a well that’s about 300 meters deep. At the end of the well, the pressure from the pumped water flows into a previously engineered fracture in the rock, creating a reservoir that’s hundreds of meters wide and sits beneath the weight of the whole column of rock above it, says Bunker Hill, vice president of engineering at Quidnet. The wellhead then closes and the water remains under high pressure, keeping energy stored in the reservoir for days if necessary. When electricity is needed, the well is opened, letting the pressurized water run up the same well. Above ground, the water passes through a hydroelectric turbine, generating 2 to 8 megawatts of electricity. The spent water then returns to the surface pond, ready for the next cycle. “The hard part is making sure the underground reservoir doesn’t lose water,” says Hill. To that end, the company developed customized sealing solutions that get injected into the fracture, sealing in the water.

Solar panels are built to last 25 years or more in all kinds of weather. Key to this longevity is a tight seal of the photovoltaic materials. Manufacturers achieve the seal by laminating a panel’s silicon cells with polymer sheets between glass panes. But the sticky polymer is hard to separate from the silicon cells at the end of a solar panel’s life, making recycling the materials more difficult.

Researchers at the U.S. National Renewable Energy Lab (NREL) in Golden, Colo., say they’ve found a better way to seal solar modules. Using a femtosecond laser, the researchers welded together solar panel glass without the use of polymers such as ethylene vinyl acetate. These glass-to-glass precision welds are strong enough for outdoor solar panels, and are better at keeping out corrosive moisture, the researchers say.

A femtosecond laser welds a small piece of test glass.NREL

“Solar panels are not easily recycled,” says David Young, a senior scientist at NREL. “There are companies that are doing it now, but it’s a tricky play between cost and benefit, and most of the problem is with the polymers.” With no adhesive polymers involved, recycling facilities can more easily separate and reuse the valuable materials in solar panels such as silicon, silver, copper, and glass.

Because of the polymer problem, many recycling facilities just trash the polymer-covered silicon cells and recover only the aluminum frames and glass encasements, says Silvana Ovaitt, a photovoltaic (PV) analyst at NREL. This partial recycling wastes the most valuable materials in the modules.

“At some point there’s going to be a huge amount of spent panels out there, and we want to get it right, and make it easy to recycle.” —David Young, NREL

Finding cost-effective ways to recycle all the materials in solar panels will become increasingly important. Manufacturers globally are deploying enough solar panels to produce an additional 240 gigawatts each year. That rate is projected to increase to 3 terawatts by 2030, Ovaitt says. By 2050, anywhere from 54 to 160 million tonnes of PV panels will have reached the end of their life-spans, she says.

“At some point there’s going to be a huge amount of spent panels out there, and we want to get it right, and make it easy to recycle,” says Young. “There’s no reason not to.” A change in manufacturing could help alleviate the problem—although not for at least another 25 years, when panels constructed with the new technique would be due to be retired.

In NREL’s technique, the glass that encases the solar cells in a PV panel is welded together by precision melting. The precision melting is accomplished with femtosecond lasers, which pack a tremendous number of photons into a very short time scale--about 1 millionth of 1 billionth of a second. The number of photons emitted per second from the laser is so intense that it changes the optical absorption process in the glass, says Young. The process changes from linear (normal absorption) to nonlinear, which allows the glass to absorb energy from the photons that it would normally not absorb, he says.

The intense beam, focused near the interface of the two sheets of glass, generates a small plasma of ionized glass atoms. This plasma allows the glass to absorb most of the photons from the laser and locally melt the two glass sheets to form a weld. Because there’s no open surface, there is no evaporation of the molten glass during the welding process. The lack of evaporation from the molten pool allows the glass to cool in a stress-free state, leaving a very strong weld.

A femtosecond laser creates precision welds between two glass plates.David Young/NREL

In stress tests conducted by the NREL group, the welds proved almost as strong as the glass itself, as if there were no weld at all. Young and his colleagues described their proof-of-concept technique in a paper published 21 February in the IEEE Journal of Photovoltaics.

This is the first time a femtosecond laser has been used to test glass-to-glass welds for solar modules, the authors say. The cost of such lasers has declined over the last few years, so researchers are finding uses for them in a wide range of applications. For example, femtosecond lasers have been used to create 3D midair plasma displays and to turn tellurite glass into a semiconductor crystal. They’ve also been used to weld glass in medical devices.

Prior to femtosecond lasers, research groups attempted to weld solar panel glass with nanosecond lasers. But those lasers, with pulses a million times as long as those of a femtosecond laser, couldn’t create a glass-to-glass weld. Researchers tried using a filler material called glass frit in the weld, but the bonds of the dissimilar materials proved too brittle and weak for outdoor solar panel designs, Young says.

In addition to making recycling easier, NREL’s design may make solar panels last longer. Polymers are poor barriers to moisture compared with glass, and the material degrades over time. This lets moisture into the solar cells, and eventually leads to corrosion. “Current solar modules aren’t watertight,” says Young. That will be a problem for perovskite cells, a leading next-generation solar technology that is extremely sensitive to moisture and oxygen.

“If we can provide a different kind of seal where we can eliminate the polymers, not only do we get a better module that lasts longer, but also one that is much easier to recycle,” says Young.

A consortium of U.S. federal agencies has pooled their funds and wide array of expertise to reinvent the emergency vehicle. The hybrid electric box truck they’ve come up with is carbon neutral. And in the aftermath of a natural disaster like a tornado or wildfire, the vehicle, called H2Rescue, can supply electric power and potable water to survivors while acting as a temperature-controlled command center for rescue personnel.

The agencies that funded and developed it from an idea on paper to a functional Class 7 emergency vehicle prototype say they are pleased with the outcome of the project, which is now being used for further research and development.

“Any time the fuel cell is producing energy to move the vehicle or to export power, it’s generating water.” –Nicholas Josefik, U.S. Army Corps of Engineers Construction Research Lab

Commercial truck and locomotive engine maker Cummins, which has pledged to make all its heavy-duty road and rail vehicles zero-emission by 2050, won a $1 million competitive award to build the H2Rescue, which gets its power from a hydrogen fuel cell that charges its lithium-ion batteries. In demonstrations, including one last summer at National Renewable Energy Lab facilities in Colorado, the truck proved capable of driving 290-kilometers, then taking on the roles of power plant, mobile command center, and (courtesy of the truck’s “exhaust”) supplier of clean drinking water.

A hydrogen tank system located behind the 15,000-kilogram truck’s cab holds 175 kg of fuel at 70 megapascals (700 bars) of pressure. Civilian anthropology researcher Lance Larkin at the U.S. Army Corps of Engineers’ Construction Engineering Research Laboratory (CERL) in Champaign, Ill., told IEEE Spectrum that that’s enough fuel for the fuel cell to generate 1,800 kilowatt-hours of energy. Or enough, he says, to keep the lights on in 15 to 20 average U.S. homes for about three days.

The fuel cell can provide energy directly to the truck’s powertrain. However, it mainly charges two battery packs with a total capacity of 155-kilowatt-hours because batteries are better than fuel cells at handling the variable power demands that come with vehicle propulsion. When the truck is at a disaster site, the fuel cell can automatically turn itself on and off to keep the batteries charged up while they are exporting electric power to buildings that would otherwise be in the dark. “If it’s called upon to export, say, 3 kilowatts to keep a few computers running, the fuel in its tanks could keep them powered for weeks,” says Nicholas Josefik, an industrial engineer at CERL.

As if that weren’t enough, an onboard storage tank captures the water that is the byproduct of the electrochemical reactions in the fuel cell. “Any time the fuel cell is producing energy to move the vehicle or to export power, it’s generating water,” says Josefik. The result: roughly 1,500 liters of clean water available any place where municipal or well water supplies are unavailable or unsafe.

“When the H2Rescue drives to a location, you won’t need to pull that generator behind you, because the truck itself is a generator.” —Nicholas Josefik, U.S. Army Corps of Engineers Construction Research Lab

Just as important as what it can do, Josefik notes, is what it won’t do: “In a traditional emergency situation, you send in a diesel truck and that diesel truck is pulling a diesel-powered generator, so you can provide power to the site,” he says. “And another diesel truck is pulling in a fuel tank to fuel that diesel generator. A third truck might pull a trailer with a water tank on it.

“But when the H2Rescue drives to a location,” he continues, “You won’t need to pull that generator behind you, because the truck itself is a generator. You don’t have to drag a trailer full of water, because you know that while you’re on site, H2Rescue will be your water source.” He adds that H2Rescue will not only allow first responders to eliminate a few pieces of equipment but will also eliminate the air pollution and noise that come standard with diesel-powered vehicles and generators.

Larkin recalls that the impetus for developing the zero-emission emergency vehicle came in 2019, when a series of natural disasters across the United States, including wildfires and hurricanes, spurred action. “The organizations that funded this project were observing this and saw a need for an alternative emergency support,” he says. They asked themselves, Larkin notes, “‘What can we do to help our first responders take on these natural disasters?’ The rest, as they say, is history.”

Asked when we’ll see the Federal Emergency Management Agency, which is typically in charge of disaster response anywhere in the 50 U.S. states, dispatch the H2Rescue truck to the aftermath of, say, a hurricane, Josefik says, “This is still a research unit. We’re working on trying to build a version 2.0 that could go and support responders to an emergency.” That next version, he says, would be the result of some optimizations suggested by Cummins as it was putting the H2Rescue together. “Because this was a one-off build, [Cummins] identified a number of areas for improvement, like how they would do the wiring and the piping differently, so it’s more compact in the unit.” The aim for the second iteration, Larkin says, is “a turnkey unit, ready to operate without all the extra gauges and monitoring equipment that you wouldn’t want in a vehicle that you would turn over to somebody.”

There is no timetable for when the new and improved H2Rescue will go into production. The agencies that allocated the funds for the prototype have not yet put up the money to create its successor.

You can’t see, hear, taste, feel, or smell it, but software is everywhere around us. It underpins modern civilization even while consuming more energy, wealth, and time than it needs to and burping out a significant amount of carbon dioxide into the atmosphere. The software industry and the code it ships need to be much more efficient in order to minimize the emissions attributable to programs running in data centers and over transmission networks. Two approaches to software development featured in Spectrum‘s April 2024 issue can help us get there.

In “Why Bloat Is Still Software’s Biggest Vulnerability,” Bert Hubert pays homage to the famed computer scientist and inventor of Pascal, Niklaus Wirth, whose influential essay “A Plea for Lean Software” appeared in IEEE Computer in 1995. Wirth’s essay built on a methodology first conceived by Spectrum contributing editor Robert N. Charette, who in the early 1990s adapted the Toyota Production System for software development.

Hubert points out that bloated code offers giant attack surfaces for bad actors. Malicious hacks and ransomware attacks, not to mention run-of-the-mill software failures, are like the weather now: partly cloudy with a 50 percent chance of your app crashing or your personal information being circulated on the Dark Web. Back in the day, limited compute resources forced programmers to write lean code. Now, with much more robust resources at hand, coders are writing millions of lines of code for relatively simple apps that call on hundreds of libraries of, as Hubert says, “unknown provenance.”

“There’s an already existing large segment of the software-development ecosystem that cares about this space—they just haven’t known what to do.” —Asim Hussain, Green Web Foundation

Among other things, he argues for legislation along the lines of what the European Union is trying to enforce: “NIS2 for important services; the Cyber Resilience Act for almost all commercial software and electronic devices; and a revamped Product Liability Directive that also extends to software.” Hubert, a software developer himself, walks the lean walk: His 3-megabyte image-sharing program Trifecta does the same job as other programs that use hundreds of megabytes of code.

Lean software should, in theory, be green software. In other words, it should run so efficiently that it reduces the amount of energy used in data centers and transmission networks. Overall, the IT and communications sectors are estimated to account for 2 to 4 percent of global greenhouse gas emissions and, according to one 2018 study, could by 2040 reach 14 percent. And that study came out prior to the explosion in AI applications, whose insatiable hunger for computing resources and the power required to feed the algorithms exacerbates an already complicated problem.

Thankfully, several groups are working on solutions, including the Green Web Foundation. The GWF was spun up almost 20 years ago to figure out how the Internet is powered, and now has a goal of a fossil-free Internet by 2030.

There are three main ways to achieve that objective, according to the foundation’s chair and executive director Asim Hussain: Use less energy, use fewer physical resources, and use energy more prudently—by, for instance, having your apps do more when there’s power from wind and solar available and less when there’s not.

“There’s an already existing large segment of the software-development ecosystem that cares about this space—they just haven’t known what to do,” Hussain told Spectrum contributing editor Rina Diane Caballar. They do now, thanks to Caballar’s extensive reporting and the handy how-to guide she includes in “We Need to Decarbonize Software.” Programmers have the tools to make software leaner and greener. Now it’s up to them, and as we’ve seen in the EU, their legislators, to make sustainable and secure code their top priority. Software doesn’t have to suck.

Diesel cars are a popular choice for those looking to buy a used vehicle in Asia, Europe, and elsewhere. After all, diesel cars cost less to maintain, burn less fuel, and have a longer engine life. Although the pollutant emissions of a diesel engine are less than those of a gasoline one, it still emits carcinogens, nitrous oxides, and soot. Older models don’t even have the emission-control features that newer ones do.

To reduce emissions, diesel vehicles use filters that catch exhaust particles and other contaminants. The filters can cost thousands of dollars to replace, however, because they’re made with precious metals.

Looking to make replacement filters more environmentally friendly and affordable, a team of engineering students from the Bangladesh University of Engineering and Technology, in Dhaka, designed a carbon-based version with bamboo. The Green Warriors idea won the US $300 prize for best impact in the IEEE Women in Engineering Big Idea Pitch competition. The contest’s goal is to encourage female engineering students and researchers to become more entrepreneurial as a way to boost the number of technical startups led by women.

“We found that old diesel cars are a significant contributor to CO₂ emissions, and we wanted to do something about that,” team leader Tasmiah Afrin said in an email interview.

“Our groundbreaking activated-carbon-based filter represents a significant leap forward in environmental and economic efficiency,” the electrical engineering student added. “The filters can rapidly and effectively capture carbon-based gases from vehicle emissions, contributing to immediate improvements in air quality and reduced carbon emissions.”

A carbon-based particulate filter

Diesel engines produce more polluting particulate matter than gas engines. Because the particles are so small, they can pass easily through a catalytic converter, which is designed to reduce a vehicle’s toxic emissions. Diesel particulate filters therefore are installed in the exhaust system, generally at the exit of the catalytic converter. The most popular type of catalytic converter forces the exhaust through a ceramic honeycomb structure coated with a thin layer containing a precious metal such as platinum, palladium, or rhodium.

“Our project,” Afrin says, “is based on a modified air filter for incoming air into the catalytic converter.”

The Green Warriors’ prototype filter is made from bamboo and uses carbon granules to further reduce emissions.

Activated carbon granules in an absorption chamber and metallic mesh form the filters, Afrin says. Gases pass through either double or multiple chambers. Their prototype is more aerodynamic and lightweight than existing designs used for carbon filters, Afrin says.

“These filters offer a remarkable 5 to 7 percent cost efficiency improvement compared to existing filters, making them a more cost-effective solution for carbon capture in vehicle exhaust systems,” she says. “Not only are they cost-efficient, but they also boast an impressive absorption speed. This means the filters can rapidly and effectively capture carbon-based greenhouse gases from vehicle emissions, contribute to immediate improvements in air quality and reduce carbon emissions.”

She says she believes the team’s diesel particulate filter would cost less than a current filter, which because of its precious-metal content can cost a few thousand U.S. dollars.

A system for replacing filters

The filters are just one part of the team’s vision for reducing auto emissions. The students’ pitch also included a transport-management system they would build called CarGreenTech and its accompanying smartphone app. Using the app, owners of older diesel cars could purchase the replacement filter or arrange for one to be installed. Another option would be for CarGreenTech to buy the older car, outfit it with a new filter, and resell the vehicle. The goal is to extend the life of these older vehicles, Afrin says.

“CarGreenTech is a platform to make existing vehicles more climate-positive—which provides an all-in-one solution,” Afrin says. “It captures carbon from the diesel engine exhaust by utilizing layered active carbon filters, upcycling older car parts through a car buying/selling/upgrading business-to-business and business-to-consumer solution.” A motivator for student-led startups

The team also includes Ishman Tasnim, Fahmida Sultana Naznin, and Nusrat Subah Shakhawat. Tasnim is studying industrial and production engineering, and Naznin is pursuing a degree in computer science and engineering. Shakhawat recently graduated from the university with a degree in electrical engineering.

The team’s mentor was IEEE Member Toufiqur Rahman Shuvo, a lecturer at the university.

The students are all members of the IEEE student branch at the Bangladesh University of Engineering and Technology.

“IEEE WIE has a great impact on giving motivation to student startups like us,” Afrin says. “Entering the IEEE WIE pitch competition was one of our best decisions. We were greatly motivated by the judges and getting an award for our work.”

This article was updated on 4 March 2024.

Twenty homes scattered across Canada and the northern United States are keeping warm this winter using prototypes of the latest iteration in residential heating systems: cold-climate heat pumps.

Heat pumps aren’t common in homes at this latitude, because historically they haven’t worked well in subzero temperatures. But heat-pump manufacturers say they now have the technology to heat homes just as efficiently in bitter cold as they do in milder winter temperatures.

To prove it, eight manufacturers are publicly testing their prototypes in the Cold-Climate Heat Pump Technology Challenge, hosted by the U.S. Department of Energy in partnership with Natural Resources Canada. The companies’ task is to demonstrate a high-efficiency, residential air-source heat pump that can perform at 100 percent capacity at -15 °C. Companies can choose to further test their machines down to -26 °C.

Heat-pump manufacturers Bosch, Carrier, Daikin, Johnson Controls, Lennox, Midea, Rheem, and Trane Technologies have each passed the laboratory phase of the challenge, according to the DOE. They are now field-testing their prototypes in homes in 10 northern U.S. states and two Canadian provinces, where furnaces and boilers burning fossil gas, fuel oil, or propane are more commonly used.

Companies that complete the challenge won’t receive cash prizes. But the DOE will help them expand into cold-climate markets by engaging with stakeholders in those regions, a DOE spokesperson told IEEE Spectrum. The challenge will conclude later this year, and prototypes will likely be ready for commercialization in 2025.

How heat pumps beat the cold

Advances in the technology came primarily through improvements in one key heat-pump component: the compressor. Heat pumps work by moving and compressing fluids. In the winter, the systems draw heat from outside the home, most commonly from the air. (There is heat in the air even in subzero temperatures.) An outdoor heat exchanger, or coil, absorbs the heat into the heat-pump system.

The outdoor air passes over a heat exchanger containing a fluid, or refrigerant, that has a very low boiling point. A common refrigerant, called R410a, boils at -48.5 °C. The refrigerant boils and evaporates into a vapor, and a compressor increases its temperature and pressure. The superheated vapor then moves through an indoor coil, where fans blow air across it, moving heat into the home. In the summer, the system reverses, moving heat from inside the building to the outside, and cooling the home.

“They couldn’t get the lab any colder than [-30 °C], so we had to cut the power to get the heat pump to turn off.” —Katie Davis, Trane Technologies

The colder the temperature outside, the harder heat pumps must work to extract and move enough heat to maintain the home’s temperature. At about 4 °C, most air-source heat pumps currently on the market start operating at less than their full capacity, and at some point (usually around -15 °C), they can no longer do the job at all. At that point, an auxiliary heat source kicks on, which is less efficient.

But advancements in compressor technology over the past five years have addressed that issue. By controlling the compressor motor’s speed, and improving the timing of when vapor is injected into the compressor, engineers have made heat pumps more efficient in colder temperatures.

For example, Trane Technologies, headquartered in Dublin, “played with the vapor compression cycle” so that it gets an extra injection of refrigerant, says Katie Davis, vice president of engineering and technology in Trane’s residential business. “It’s works a little like fuel injection,” she says. When the system begins to lose its capacity to heat, the system injects refrigerant to give it a boost, she says.

In the lab portion of the DOE’s heat pump challenge, Trane’s unit operated at 100 percent capacity at -15 °C and kept running even as the lab’s temperature dropped to -30 °C, although no longer at full capacity. “They couldn’t get the lab any colder than that, so we had to cut the power to get the heat pump to turn off,” Davis says.

Vapor-injection compressor technology has been around for years, but until recently, had not been optimized for heat pumps, Davis says. That, plus the introduction of smart systems that enable the indoor and outdoor units to communicate with each other and the thermostat, has enabled heat pumps to take on colder weather.

Heat pumps can reduce emissions and cut energy costs

The DOE is pushing for wider adoption of heat pumps because of their potential to reduce greenhouse gas emissions. Such systems run on electricity rather than fossil fuels, and when the electricity comes from renewable sources, the greenhouse gas savings are substantial, the DOE says. Because heat pumps transfer heat rather than generate it, they are significantly more efficient than traditional heating systems, the agency says.

A two-year study published 12 February in the journal Joule supports the DOE’s claim. The study found that if every heated home in the United States switched to a heat pump, home energy use would drop by 31 to 47 percent on average, and national carbon dioxide emissions would fall by 5 to 9 percent, depending on how much electricity is provided by renewable energy. Those figures are based on heat pumps that draw heat from an air source (rather than ground or water) and includes both homes that pull heat through ductwork, and homes that are ductless.

The energy savings should lower bills for 62 to 95 percent of homeowners, depending on the efficiency and cold-climate performance of the heat pump being installed. How well a home is insulated and the type of heating system being replaced also makes a big difference in energy bills, the study found. For households that are currently heating with electric resistance heat, fuel oil, or propane, heat pumps could save thousands of dollars annually. For natural gas, the savings are less and depend on the price of natural gas in the local area.

Some homeowners are hesitant to switch to heat pumps because of what’s known as “temperature anxiety.”

Cold-climate heat pumps will likely boost energy savings for homeowners, but will require higher up-front costs, says Eric Wilson, a senior research engineer at the National Renewable Energy Laboratory in Golden, Colo., and an author of the paper. “It’s generally well known that heat pumps can save money, but there’s a lot of confusion around whether they’re a good idea in all climates,” he says. His study and the DOE’s cold-climate heat pump challenge will help provide a clearer picture, he says.

The DOE is one of several government entities trying to expedite adoption of residential high-efficiency heat pumps. Nine U.S. states earlier this month pledged to accelerate heat-pump sales. Their pledge builds on an announcement in September from 25 governors, who vowed to quadruple heat-pump installation in their states by 2030. The U.S. federal government also offers tax credits and states will be rolling out rebates to offset the cost of installation.

So far, the efforts seem to be working. In the U.S., heat pumps outsold furnaces for a second year in a row in 2023, according to data released 9 February by the Air-Conditioning, Heating, and Refrigeration Institute, in Arlington, Va.

Europe is making a similar push. The European Commission has called for expedited deployment of heat pumps, and recommended that member states phase out the use of fossil-fuel heating systems in all buildings by 2035. Many European countries are subsidizing residential heat pump installation by offering grants to homeowners.

But some homeowners are hesitant to switch to heat pumps because of what’s known as “temperature anxiety.” It’s like electric-vehicle range anxiety: Homeowners are concerned about getting stuck in a cold house.

And some just like the feel of old fashioned heat. “Folks who have furnaces say they really like the way that hot heat feels when it’s coming out,” says Davis at Trane. “Heat pumps put out warm heat and it’s going to do a good job heating your home, but it’s not that hot heat that comes out of a furnace.”

Trane’s cold-climate heat pump—the one entered into the DOE’s challenge—is currently heating the home of a family in Boise, Idaho, Davis says. “We’ve had excellent feedback from our customer there, who said their energy bills went down,” she says.

Heat Pump Challenge Specs

To pass the DOE’s field test, heat pumps must operate at -15 °C with the following specifications:

• Operate at 100 percent heating capacity without relying on backup electrical resistance heat
• Demonstrate 40 percent greater efficiency than current heat pumps on the market
• Function in homes that distribute air through ductwork
• Draw heat from the air (rather than the ground or water)

According to the Intergovernmental Panel on Climate Change, approximately 15 percent of net anthropogenic greenhouse gas emissions come from the transportation sector. To meet global climate targets, we must devise ways to get people and goods from point A to point B without burning fossil fuels.

In this month’s special report on the greening of transportation, we examine a moonshot idea for powering electric vehicles, the biggest change in aviation since the jet engine, and cargo ships with a battle-tested mode of generation.

Internal combustion engines (ICEs) in cars and vans accounted for almost half of all carbon dioxide emissions attributable to the transportation sector in 2022, according to Statista. And the world is waking up to the staggering challenges of going electric, as Contributing Editor Robert N. Charette pointed out last year in the IEEE Spectrum series “The EV Transition Explained.”

During his reporting for that series, Charette ran across a startup called Influit Energy that is trying to commercialize a new type of flow battery. Flow batteries are typically used in stationary applications like power-grid storage,but as Charette notes in our cover story, “Can Flow Batteries Finally Beat Lithium?” Influit’s battery circulates an energy-dense nanoelectrofuel to store 15 to 25 times as much energy as a similarly sized conventional flow battery. The Influit battery also compares favorably to lithium-based batteries in terms of safety and stability, and it could provide the range of an ICE vehicle. Cars and trucks with these kinds of batteries could fill up with the nanoelectrofuel at the pump, perhaps taking advantage of the existing infrastructure built for gas-guzzlers.

“We are in the early stages of a key transition: Electrification could be the first fundamental change in airplane propulsion systems since the advent of the jet engine.”–Amy Jankovsky, Christine Andrews, and Bill Rogers

The second article in our report looks at how recent innovations in power electronics, electric motors, and batteries for the car industry are beginning to find applications in airplane design. In one effort, GE Aerospace and Boeing’s Aurora Flight Sciences are working together on a hybrid-electric propulsion system for a 150-to-180-seat airplane. The project, described by Amy Jankovsky, Christine Andrews, and Bill Rogers in “Fly the Hybrid Skies,” started in 2021 and aims to modify a Saab 340 aircraft using two GE CT7 engines combined with electric propulsion units for a megawatt-class system. As the authors note, “We are in the early stages of a key transition: Electrification could be the first fundamental change in airplane propulsion systems since the advent of the jet engine.”

The maritime industry needs a similar fundamental advance, reports Prachi Patel in “Merchant Shipping’s Nuclear Option.” Almost all of the world’s commercial fleets still run on diesel fuel. The industry needs to move much faster if it’s to reach the target of net-zero emissions by 2050 set by the United Nations’ International Maritime Organization.

One way to meet this goal is to go nuclear. Some 160 nuclear-powered vessels ply the high seas today, though almost all are navy ships and submarines. Next-generation small modular reactors (SMRs) could be a game changer for commercial cargo ships. Patel describes several efforts around the world to adapt SMRs to the marine environment. In theory, the small reactors should be safer and simpler to operate than conventional nuclear reactors.

It’s easy to look at the challenges posed by climate change and sigh. Or cry. The engineers you’ll find in this issue don’t have time for despair. They’re too busy working the problem.