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Enegix Base One Green Hydrogen Plant will produce renewable hydrogen via electrolysis in Ceara, Brazil, leveraging 3.4 GW baseload renewables, offshore wind, and hydro to scale clean energy, storage, and export logistics.

Key Points

A $5.4bn Ceara, Brazil project to produce 600m kg of green hydrogen annually using 3.4 GW of baseload renewables.

✅ 3.4 GW baseload from hydro and offshore wind pipelines

✅ Targets 600m kg green hydrogen per year via electrolysis

✅ Focus on storage, transport, and export supply chains

In March, Enegix Energy announced some of the most ambitious hydrogen plans the world has ever seen. The company signed a memorandum of understanding (MOU) with the government of the Brazilian state of Ceará to build the world’s largest green hydrogen plant in the state on the country’s north-eastern coast, and the figures are staggering.

The Base One facility will produce more than 600 million kilograms of green hydrogen annually from 3.4GW of baseload renewable energy, and receive $5.4bn in investment to get the project off the ground and producing within four years.

Green hydrogen, hydrogen produced by electrolysis that is powered by renewables, has significant potential as a clean energy source. Already seeing increased usage in the transport sector, the power source boasts the energy efficiency and the environmental viability to be a cornerstone of the world’s energy mix.

Yet practical challenges have often derailed large-scale green hydrogen projects, from the inherent obstacle of requiring separate renewable power facilities to the logistical and technological challenges of storing and transporting hydrogen. Could vast investment, clever planning, and supportive governments and programs like the DOE’s hydrogen hubs initiative help Enegix to deliver on green hydrogen’s oft-touted potential?

Brazilian billions
The Base One project is exceptional not only for its huge scale, but the timing of its construction, with demand for hydrogen set to increase dramatically over the next few decades. Figures from Wood Mackenzie suggest that hydrogen could account for 1.4 billion tonnes of energy demand by 2050, one-tenth of the world’s supply, with green hydrogen set to be the majority of this figure.

Yet considering that, prior to the announcement of the Enegix project, global green hydrogen capacity was just 94MW, advances in offshore green hydrogen and the development of a project of this size and scope could scale up the role of green hydrogen by orders of magnitude.

“We really need to [advance clean energy] without any emissions on a completely clean, carbon neutral and net-zero framework, and so we needed access to a large amount of green energy projects,” explains Wesley Cooke, founder and CEO of Enegix, a goal aligned with analyses that zero-emissions electricity by 2035 is possible, discussing the motivation behind the vast project.

With these ambitious goals in mind, the company needed to find a region with a particular combination of political will and environmental traits to enable such a project to take off.

“When we looked at all of these key things: pipeline for renewables, access to water, cost of renewables, and appetite for renewables, Brazil really stood out to us,” Cooke continues. “The state of Ceará, that we’ve got an MOU with the government in at the moment, ticks all of these boxes.”

Ceará’s own clean energy plans align with Enegix’s, at least in terms of their ambition and desire for short-term development. Last October, the state announced that it plans to add 5GW of new offshore wind capacity in the next five years. With BI Energia alone providing $2.5bn in investment for its 1.2GW Camocim wind facility, there is significant financial muscle behind these lofty ambitions.

“One thing I should add is that Brazil is very blessed when it comes to baseload renewables,” says Cooke. “They have an incredibly high percentage of their country-wide energy that comes from renewable sources and a lot of this is in part due to the vast hydro schemes that they have for hydro dams. Not a lot of countries have that, and specifically when you’re trying to produce hydrogen, having access to vast amounts of renewables [is vital].”

Changing perceptions and tackling challenges
This combination of vast investment and integration with the existing renewable power infrastructure of Ceará could have cultural impacts too. The combination of state support for and private investment in clean energy offsets many of the narratives emerging from Brazil concerning its energy policies and environmental protections, even as debates over clean energy's trade-offs persist in Brazil and beyond, from the infamous Brumadinho disaster to widespread allegations of illegal deforestation and gold mining.

“I can’t speak for the whole of Brazil, but if we look at Ceará specifically, and even from what we’ve seen from a federal government standpoint, they have been talking about a hydrogen roadmap for Brazil for quite some time now,” says Cooke, highlighting the state’s long-standing support for green hydrogen. “I think we came in at the perfect time with a very solid plan for what we wanted to do, [and] we’ve had nothing but great cooperation, and even further than just cooperation, excitement around the MOU.”

This narrative shift could help overcome one of the key challenges facing many hydrogen projects, the idea that its practical difficulties render it fundamentally unsuitable for baseload power generation. By establishing a large-scale green hydrogen facility in a country that has recently struggled to present itself as one that is invested in renewables, the Base One facility could be the ultimate proof that such clean hydrogen projects are viable.

Nevertheless, practical challenges remain, as is the case with any energy project of this scale. Cooke mentions a number of solutions to two of the obstacles facing hydrogen production around the world: renewable energy storage and transportation of the material.

“We were looking at compressed hydrogen via specialised tankers [and] we were looking at liquefied hydrogen, [as] you have to get liquefied hydrogen very cool to around -253°, and you can use 30% to 40% of your total energy that you started with just to get it down to that temperature,” Cooke explains.

“The other aspect is that if you’re transporting this internationally, you really have to think about the supply chain. If you land in a country like Indonesia, that’s wonderful, but how do you get it from Indonesia to the customers that need it? What is the supply chain? What does that look like? Does it exist today?”

The future of green hydrogen
These practical challenges present something of a chicken and egg problem for the future of green hydrogen: considerable up-front investment is required for functions such as storage and transport, but the difficulties of these functions can scare off investors and make such investments uncommon.

Yet with the world’s environmental situation increasingly dire, more dramatic, and indeed risky, moves are needed to alter its energy mix, and Enegix is one company taking responsibility and accepting these risks.

“We need to have the renewables to match the dirty fuel types,” Cooke says. “This [investment] will really come from the decisions that are being made right now by large-scale companies, multi-billion-euro-per-year revenue companies, committing to building out large scale factories in Europe and Asia, to support PEM [hydrolysis].”

This idea of large-scale green hydrogen is also highly ambitious, considering the current state of the energy source. The International Renewable Energy Agency reports that around 95% of hydrogen comes from fossil fuels, so hydrogen has a long ways to go to clean up its own carbon footprint before going on to displace fossil fuel-driven industries.

Yet this displacement is exactly what Enegix is targeting. Cooke notes that the ultimate goal of Enegix is not simply to increase hydrogen production for use in a single industry, such as clean vehicles. Instead, the idea is to develop green hydrogen infrastructure to the point where it can replace coal and oil as a source of baseload power, leapfrogging other renewables to form the bedrock of the world’s future energy mix.

“The problem with [renewable] baseload is that they’re intermittent; the wind’s not always blowing and the sun’s not always shining and batteries are still very expensive, although that is changing. When you put those projects together and look at the levelised cost of energy, this creates a chasm, really, for baseload.

“And for us, this is really where we believe that hydrogen needs to be thought of in more detail and this is what we’re really evangelising about at the moment.”

A more hydrogen-reliant energy mix could also bring social benefits, with Cooke suggesting that the same traits that make hydrogen unwieldy in countries with established energy infrastructures could make hydrogen more practically viable in other parts of the world.

“When you look at emerging markets and developing markets at the moment, the power infrastructure in some cases can be quite messy,” Cooke says. “You’ve got the potential for either paying for the power or extending your transmission grid, but rarely being able to do both of those.

“I think being able to do that last mile piece, utilising liquid organic hydrogen carrier as an energy vector that’s very cost-effective, very scalable, non-toxic, and non-flammable; [you can] get that power where you need it.

“We believe hydrogen has the potential to be very cost-effective at scale, supporting a vision of cheap, abundant electricity over time, but also very modular and usable in many different use cases.”

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American-Made Solar Prize Round 3 accelerates DOE-backed solar innovation, empowering entrepreneurs and domestic manufacturing with photovoltaics and grid integration support via National Laboratories, incubators, and investors to validate products, secure funding, and deploy backup power.

Key Points

A DOE challenge fast-tracking solar innovation to market readiness, boosting US manufacturing and grid integration.

✅ $50,000 awards to 20 teams for prototype validation

✅ Access to National Labs, incubators, investors, and mentors

✅ Focus on PV advances and grid integration solutions

The U.S. Department of Energy (DOE) announced the 20 competitors who have been invited to advance to the next phase of the American-Made Solar Prize Round 3, a competition designed to incentivize the nation’s entrepreneurs to strengthen American leadership in solar energy innovation and domestic manufacturing, a key front in the clean energy race today.

The American-Made Solar Prize is designed to help more American entrepreneurs thrive in the competitive global energy market. Each round of the prize brings new technologies to pre-commercial readiness in less than a year, ensuring new ideas enter the marketplace. As part of the competition, teams will have access to a network of DOE National Laboratories, technology incubators and accelerators, and related DOE efforts like next-generation building upgrades, venture capital firms, angel investors, and industry. This American-Made Network will help these competitors raise private funding, validate early-stage products, or test technologies in the field.

Each team will receive a $50,000 cash prize and become eligible to compete in the next phase of the competition. Through a rigorous evaluation process, teams were chosen based on the novelty of their ideas and how their solutions address a critical need of the solar industry. The teams were selected from 120 submissions and represent 11 states. These projects will tackle challenges related to new solar applications, like farming, as well as show how solar can be used to provide backup power when the grid goes down, aided by increasingly affordable batteries now reaching scale. Nine teams will advance solar photovoltaic technologies, and 11 will address challenges related to how solar integrates with the grid. The projects are as follows:

Photovoltaics:

• Durable Antireflective and Self-Cleaning Glass (Pittsburgh, PA)
• Pursuit Solar - More Power, Less Hassle (Denver, NC)
• PV WaRD (San Diego, CA)
• Remotely Deployed Solar Arrays (Charlottesville, VA)
• Robotics Changing the Landscape for Solar Farms (San Antonio, TX)
• TrackerSled (Chicago, IL)
• Transparent Polymer Barrier Films for PV (Bristol, PA)
• Solar for Snow (Duluth, MN)
• SolarWall Power Tower (Buffalo, NY)

Systems Integration:

• Affordable Local Solar Storage via Utility Virtual Power Plants (Parker, TX)
• Allbrand Solar Monitor (Detroit, MI)
• Beyond Monitoring – Next Gen Software and Hardware (Atlanta, GA)
• Democratizing Solar with Artificial Intelligence Energy Management (Houston, TX)
• Embedded, Multi-Function Maximum Power Point Tracker for Smart Modules (Las Vegas, NV)
• Evergrid: Keep Solar Flowing When the Grid Is Down (Livermore, CA)
• Inverter Health Scan (San Jose, CA)
• JuiceBox: Integrated Solar Electricity for Americans Transitioning out of Homelessness and Recovering from Natural Disasters (Claremont, CA)
• Low-Cost Parallel-Connected DC Power Optimizer (Blacksburg, VA)
• Powerfly: A Plug-and-Play Solar Monitoring Device (Berkeley, CA)
• Simple-Assembly Storage Kit (San Antonio, TX)

Read the descriptions of the projects to see how they contribute to efforts to improve solar and wind power worldwide.

Over the next six months, these teams will fast-track their efforts to identify, develop, and test disruptive solutions amid record solar and storage growth projected nationwide. During a national demonstration day at Solar Power International in September 2020, a panel of judges will select two final winners who will receive a $500,000 prize. Learn more at the American-Made Solar Prize webpage.

The American-Made Challenges incentivize the nation's entrepreneurs to strengthen American leadership in energy innovation and domestic manufacturing. These new challenges seek to lower the barriers U.S.-based innovators face in reaching manufacturing scale by accelerating the cycles of learning from years to weeks while helping to create partnerships that connect entrepreneurs to the private sector and the network of DOE’s National Laboratories across the nation, alongside recent wind energy awards that complement solar innovation.

Go here to learn how this work aligns with a tenfold solar expansion being discussed nationally.

https://www.energy.gov/eere/solar/solar-energy-technologies-office

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Canada EV Tariffs weigh protectionism, import duties, and trade policy against affordable electric vehicles, climate goals, and consumer costs, balancing domestic manufacturing, critical minerals, battery supply chains, and China relations amid US-EU actions.

Key Points

Canada EV Tariffs are proposed duties on Chinese EV imports to protect jobs vs. prices, climate goals, and trade risks.

✅ Shield domestic automakers; counter subsidies

✅ Raise EV prices; slow adoption, climate targets

✅ Spark China retaliation; hit exports, supply chains

Canada, a rising star in critical EV battery minerals, finds itself at a crossroads. The question: should they follow the US and EU and impose tariffs on Chinese electric vehicles (EVs), after the U.S. 100% tariff on Chinese EVs set a precedent?

The Allure of Protectionism

Proponents see tariffs as a shield for Canada's auto industry, supported by recent EV assembly deals that put Canada in the race, a vital job creator. They argue that cheaper Chinese EVs, potentially boosted by government subsidies, threaten Canadian manufacturers. Tariffs, they believe, would level the playing field.

Consumer Concerns and Environmental Impact

Opponents fear tariffs will translate to higher prices, deterring Canadians from buying EVs, especially amid EV shortages and wait times already affecting the market. This could slow down Canada's transition to cleaner transportation, crucial for meeting climate goals. A slower EV adoption could also impact Canada's potential as an EV leader.

The Looming Trade War Shadow

Tariffs risk escalating tensions with China, Canada's second-largest trading partner. China might retaliate with tariffs on Canadian exports, jeopardizing sectors like oil and lumber. This could harm the Canadian economy and disrupt critical mineral and battery development, areas where Canada is strategically positioned, even as opportunities to capitalize on the U.S. EV pivot continue to emerge across North America.

Navigating a Charged Path

The Canadian government faces a complex decision. Protecting domestic jobs is important, but so is keeping EVs affordable for a greener future and advancing EV sales regulations that shape the market. Canada must carefully consider the potential benefits of tariffs against the risks of higher consumer costs and a potential trade war.

This path forward could involve exploring alternative solutions. Canada could invest in its domestic EV industry, providing incentives for both consumers and manufacturers. Additionally, collaborating with other countries, including Canada-U.S. collaboration as companies turn to EVs, to address China's alleged unfair trade practices might be a more strategic approach.

Canada's decision on EV tariffs will have far-reaching consequences. Striking a balance between protecting its domestic industry and fostering a robust, environmentally friendly transportation sector, and meeting ambitious EV goals set by policymakers, is crucial. Only time will tell which path Canada chooses, but the stakes are high, impacting not just jobs, but also the environment and Canada's position in the global EV race.

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Electric Vehicle Grid Integration aligns EV charging with grid capacity using smart charging, time-of-use rates, V2G, and demand response to reduce peak load, enable renewable energy, and optimize infrastructure planning.

Key Points

Aligning EV charging with grid needs via smart charging, TOU pricing, and V2G to balance load and support renewables.

✅ Time-of-use rates shift charging to off-peak hours

✅ Smart charging responds to real-time grid signals

✅ V2G turns fleets into distributed energy storage

When Seattle City Light unveiled five new electric vehicle charging stations last month in an industrial neighborhood south of downtown, the electric utility wasn't just offering a new spot for drivers to fuel up. It also was creating a way for the service to figure out how much more power it might need as electric vehicles catch on.

Seattle aims to have nearly a third of its residents driving electric vehicles by 2030. Washington state is No. 3 in the nation in per capita adoption of plug-in cars, behind California and Hawaii. But as Washington and other states urge their residents to buy electric vehicles — a crucial component of efforts to reduce carbon emissions — they also need to make sure the electric grid can handle it amid an accelerating EV boom nationwide.

The average electric vehicle requires 30 kilowatt hours to travel 100 miles — the same amount of electricity an average American home uses each day to run appliances, computers, lights and heating and air conditioning.

An Energy Department study found that increased electrification across all sectors of the economy could boost national consumption by as much as 38 percent by 2050, in large part because of electric vehicles. The environmental benefit of electric cars depends on the electricity being generated by renewables.

So far, states predict they will be able to sufficiently boost power production. But whether electric vehicles will become an asset or a liability to the grid largely depends on when drivers charge their cars.

Electricity demand fluctuates throughout the day; demand is higher during daytime hours, peaking in the early evening. If many people buy electric vehicles and mostly try to charge right when they get home from work — as many now do — the system could get overloaded or force utilities to deliver more electricity than they are capable of producing.

In California, for example, the worry is not so much with the state’s overall power capacity, but rather with the ability to quickly ramp up production and maintain grid stability when demand is high, said Sandy Louey, media relations manager for the California Energy Commission, in an email. About 150,000 electric vehicles were sold in California in 2018 — 8 percent of all state car sales.

The state projects that electric vehicles will consume 5.4 percent of the state’s electricity, or 17,000 gigawatt hours, by 2030.

Responding to the growth in electric vehicles will present unique challenges for each state. A team of researchers from the University of Texas at Austin estimated the amount of electricity that would be required if every car on the road transitioned to electric. Wyoming, for instance, would need to nudge up its electricity production only 17 percent, while Maine would have to produce 55 percent more.

Efficiency Maine, a state trust that oversees energy efficiency and greenhouse gas reduction programs, offers rebates for the purchase of electric vehicles, part of state efforts to incentivize growth.

“We’re certainly mindful that if those projections are right, then there will need to be more supply,” said Michael Stoddard, the program’s executive director. “But it’s going to unfold over a period of the next 20 years. If we put our minds to it and plan for it, then we should be able to do it.”

A November report sponsored by the Energy Department found that there has been almost no increase in electricity demand nationwide over the past 10 years, while capacity has grown an average of 12 gigawatts per year (1 GW can power more than a half-million homes). That means energy production could climb at a similar rate and still meet even the most aggressive increase in electric vehicles, with proper planning.

Charging during off-peak hours would allow not only many electric vehicles to be added to the roads but also utilities to get more use out of power plants that run only during the limited peak times through improved grid coordination and flexible demand.

Seattle City Light and others are looking at various ways to promote charging during ideal times. One method is time-of-day rates. For the Seattle chargers unveiled last month, users will pay 31 cents per kilowatt hour during peak daytime hours and 17 cents during off-peak hours. The utility will monitor use at its charging stations to see how effective the rates are at shifting charging to more favorable times.

The utility also is working on a pilot program to study charging behavior at home. And it is partnering with customers such as King County Metro that are electrifying large vehicle fleets, including growing electric truck fleets that will demand significant power, to make sure they have both the infrastructure and charging patterns to integrate smoothly.

“Traditionally, our utility approach is to meet the load demand,” said Emeka Anyanwu, energy innovation and resources officer for Seattle City Light.

Instead, he said, the utility is working with customers to see whether they can use existing assets without the need for additional investment.

Numerous analysts say that approach is crucial.

“Even if there’s an overall increase in consumption, it really matters when that occurs,” said Sally Talberg, head of the Michigan Public Service Commission, which oversees the state’s utilities. “The encouragement of off-peak charging and other technology solutions that could come to bear could offset any negative impact.”

One of those solutions is smart charging, a system in which vehicles are plugged in but don’t charge until they receive a signal from the grid that demand has tapered off a sufficient amount. This is often paired with a lower rate for drivers who use it. Several smart-charging pilot programs are being conducted by utilities, although they have not yet been phased in widely, amid ongoing debates over charging control among manufacturers and utilities.

In many places, the increased electricity demand from electric vehicles is seen as a benefit to utilities and rate payers. In the Northwest, electricity consumption has remained relatively stagnant since 2000, despite robust population growth and development. That’s because increasing urbanization and building efficiency have driven down electricity needs.

Electric vehicles could help push electricity consumption closer to utilities’ capacity for production. That would bring in revenue for the providers, which would help defray the costs for maintaining that capacity, lowering rates for all customers.

“Having EV loads is welcome, because it’s environmentally cleaner and helps sustain revenues for utilities,” said Massoud Jourabchi, manager of economic analysis for the Northwest Power and Conservation Council, which develops power plans for the region.

Colorado also is working to promote electric cars, with the aim of putting 940,000 on the road by 2030. The state has adopted California’s zero-emission vehicles mandate, which requires automakers to reach certain market goals for their sales of cars that don’t burn fossil fuels, while extending tax credits for the purchase of such cars, investing in charging stations and electrifying state fleets.

Auto dealers have opposed the mandate, saying it infringes on consumer freedom.

“We think it should be a customer choice, a consumer choice and not a government mandate,” said Tim Jackson, president and chief executive of the Colorado Automobile Dealers Association.

Jackson also said that there’s not yet a strong consumer appetite for electric vehicles, meaning that manufacturers that fail to sell the mandated number of emission-free vehicles would be required to purchase credits, which he thinks would drive up the price of their other models.

Republicans in the state have registered similar concerns, saying electric vehicle adoption should take place based on market forces, not state intervention.

Many in the utility community are excited about the potential for electric cars to serve as mobile energy storage for the grid. Vehicle-to-grid technology, known as V2G, would allow cars charging during the day to take on surplus power from renewable energy sources.

Then, during peak demand times, electric vehicles would return some of that stored energy to the grid. As demand tapers off in the evening, the cars would be able to recharge.

In practice, V2G technology could be especially beneficial if used by heavy-duty fleets, such as school buses or utility vehicles. Those fleets would have substantial battery storage and long periods where they are idle, such as evenings and weekends — and even longer periods such as summer and the holiday season when school is out. The batteries on a bus, Jourabchi said, could store as much as 10 times the electricity needed to power a home for a day.

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Canadian Power Crews Aid Florida after Hurricane Irma, supporting power restoration for Tampa Electric and Florida Power & Light. Hydro One and Nova Scotia Power teams provide mutual aid to speed outage repairs across communities.

Key Points

Mutual aid effort sending Canadian utility crews to restore power and repair outages in Florida after Hurricane Irma.

✅ Hydro One and Nova Scotia Power deploy line technicians

✅ Support for Tampa Electric and Florida Power & Light

✅ Goal: rapid power restoration and outage repairs statewide

Hundreds of Canadian power crews are heading to Florida to help restore power to millions of people affected by Hurricane Irma.

Two dozen Nova Scotia Power employees were en route Tampa on Tuesday morning. An additional 175 Hydro One employees from across Ontario are also heading south. Tuesday to assist after receiving a request for assistance from Tampa Electric.

Nearly 7½ million customers across five states were without power Tuesday morning as Irma — now a tropical storm — continued inland, while a power outage update from the Carolinas underscored the regional strain.

In an update On Tuesday, Florida Power & Light said its "army" of crews had already restored power to 40 per cent of the five million customers affected by Irma in the first 24 hours.

FPL said it expects to have power restored in nearly all of the eastern half of the state by the end of this coming weekend. Almost everyone should have power restored by the end of day on Sept. 22, except for areas still under water.Jason Cochrane took a flight from Halifax Stanfield International Airport along with 19 other NSP power line technicians, two supervisors and a restoration team lead, drawing on lessons from the Maritime Link first power project between Newfoundland and Nova Scotia. "It's different infrastructure than what we have to a certain extent, so there'll be a bit of a learning curve there as well," Cochrane said. "But we'll be integrated into their workforce, so we'll be assisting them to get everything put back together."

The NSP team will join 86 other Nova Scotians from their parent company, Emera, who are also heading to Tampa. Halifax-based Emera, whose regional projects include the Maritime Link, owns a subsidiary in Tampa.

"We're going to be doing anything that we can to help Tampa Electric get their customers back online," said NSP spokesperson Tiffany Chase. "We know there's been significant damage to their system as a result of that severe storm and so anything that our team can do to assist them, we want to do down in Tampa."

Crews have been told to expect to be on the ground in the U.S. for two weeks, but that could change as they get a better idea of what they're dealing with.

'It's neat to have an opportunity like this to go to another country and to help out.'- Jason Cochrane, power line technician

"It's neat to have an opportunity like this to go to another country and to help out and to get the power back on safely," said Cochrane.

Chase said she doesn't know how much the effort will cost but it will be covered by Tampa Electric. She also said Nova Scotia Power will pull its crews back if severe weather heads toward Atlantic Canada, as utilities nationwide work to adapt to climate change in their planning.

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Polycrystalline Tin Selenide Thermoelectrics enable waste heat recovery with ZT 3.1, matching single crystals while cutting costs, powering greener car engines, industrial furnaces, and thermoelectric generators via p-type and emerging n-type designs.

Key Points

Low-cost tin selenide devices that turn waste heat into power, achieving ZT 3.1 and enabling p-type and n-type modules.

✅ Oxygen removal prevents heat-leaking tin oxide grain skins.

✅ Polycrystalline ingots match single-crystal ZT 3.1 at lower cost.

✅ N-type tin selenide in development to pair with p-type.

So-called thermoelectric generators turn waste heat into electricity without producing greenhouse gas emissions, providing what seems like a free lunch. But despite helping power the Mars rovers, the high cost of these devices has prevented their widespread use. Now, researchers have found a way to make cheap thermoelectrics that work just as well as the pricey kind. The work could pave the way for a new generation of greener car engines, industrial furnaces, and other energy-generating devices.

“This looks like a very smart way to realize high performance,” says Li-Dong Zhao, a materials scientist at Beihang University who was not involved with the work. He notes there are still a few more steps to take before these materials can become high-performing thermoelectric generators. However, he says, “I think this will be used in the not too far future.”

Thermoelectrics are semiconductor devices placed on a hot surface, like a gas-powered car engine or on heat-generating electronics using thin-film converters to capture waste heat. That gives them a hot side and a cool side, away from the hot surface. They work by using the heat to push electrical charges from one to the other, a process of turning thermal energy into electricity that depends on the temperature gradient. If a device allows the hot side to warm up the cool side, the electricity stops flowing. A device’s success at preventing this, as well as its ability to conduct electrons, feeds into a score known as the figure of merit, or ZT.

 Over the past 2 decades, researchers have produced thermoelectric materials with increasing ZTs, while related advances such as nighttime solar cells have broadened thermal-to-electric concepts. The record came in 2014 when Mercouri Kanatzidis, a materials scientist at Northwestern University, and his colleagues came up with a single crystal of tin selenide with a ZT of 3.1. Yet the material was difficult to make and too fragile to work with. “For practical applications, it’s a non-starter,” Kanatzidis says.

So, his team decided to make its thermoelectrics from readily available tin and selenium powders, an approach that, once processed, makes grains of polycrystalline tin selenide instead of the single crystals. The polycrystalline grains are cheap and can be heated and compressed into ingots that are 3 to 5 centimeters long, which can be made into devices. The polycrystalline ingots are also more robust, and Kanatzidis expected the boundaries between the individual grains to slow the passage of heat. But when his team tested the polycrystalline materials, the thermal conductivity shot up, dropping their ZT scores as low as 1.2.

In 2016, the Northwestern team discovered the source of the problem: an ultrathin skin of tin oxide was forming around individual grains of polycrystalline tin selenide before they were pressed into ingots. And that skin acted as an express lane for the heat to travel from grain to grain through the material. So, in their current study, Kanatzidis and his colleagues came up with a way to use heat to drive any oxygen away from the powdery precursors, leaving pristine polycrystalline tin selenide, whereas other devices can generate electricity from thin air using ambient moisture.

The result, which they report today in Nature Materials, was not only a thermal conductivity below that of single-crystal tin selenide but also a ZT of 3.1, a development that echoes nighttime renewable devices showing electricity from cold conditions. “This opens the door for new devices to be built from polycrystalline tin selenide pellets and their applications to be explored,” Kanatzidis says.

Getting through that door will still take some time. The polycrystalline tin selenide the team makes is spiked with sodium atoms, creating what is known as a “p-type” material that conducts positive charges. To make working devices, researchers also need an “n-type” version to conduct negative charges.

Zhao’s team recently reported making an n-type single-crystal tin selenide by spiking it with bromine atoms. And Kanatzidis says his team is now working on making an n-type polycrystalline version. Once n-type and p-type tin selenide devices are paired, researchers should have a clear path to making a new generation of ultra-efficient thermoelectric generators. Those could be installed everywhere from automobile exhaust pipes to water heaters and industrial furnaces to scavenge energy from some of the 65% of fossil fuel energy that winds up as waste heat. 

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