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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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Hertel-New York Interconnection delivers Hydro-Quebec renewable energy via a cross-border transmission line to New York City by 2025, supplying 1,250 MW through underground and underwater routes under a 25-year contract.

Key Points

A cross-border line delivering 1,250 MW of Hydro-Quebec hydropower to New York City via underground routes.

✅ 1,250 MW clean power to NYC by 2025

✅ 56.1 km underground, 1.6 km underwater in Quebec

✅ 25-year contract; Mohawk partnership revenue

Hydro-Quebec announced Thursday it has chosen the route for the Hertel-New York interconnection line, which will begin construction in the spring of 2023 in Quebec.

The project will deliver 1,250 megawatts of Quebec hydroelectricity to New York City starting in 2025, even as a recent electricity shortage report warns about rising demand at home.

It's a 25-year contract for Hydro-Quebec, the largest export contract for the province-owned company, and comes as hydrogen production investments gain traction in Eastern Canada.

The Crown corporation has not disclosed potential revenues from the project, but Premier François Legault mentioned on social media last September that a deal in principle worth more than $20 billion over 25 years was in the works.

The route includes a 56.1-kilometre underground and a 1.6-kilometre underwater section, similar to the Lake Erie Connector project planned under Lake Erie.

Eight municipalities in the Montérégie region will be affected: La Prairie, Saint-Philippe, Saint-Jacques-le-Mineur, Saint-Édouard, Saint-Patrice-de-Sherrington, Saint-Cyprien-de-Napierville, Saint-Bernard-de-Lacolle and Lacolle.

Across the country, new renewables such as wind projects in Yukon are receiving federal support, reflecting broader grid decarbonization.

The last part of the route will run along Fairbanks Creek to the Richelieu River, where it will connect with the American network.

Further south, there will be a 545-kilometre link between the Canada-U.S. border and New York City, while a separate Maine transmission approval advances a New England pathway for Quebec power.

Hydro-Quebec is holding two consultations on the project, on Dec. 8 in Lacolle and Dec. 9 in Saint-Jacques-le-Mineur.

Elsewhere in Atlantic Canada, EV-to-grid integration pilots are underway to test how vehicles can support the power system.

Once the route is in service, the Quebec line will be subject to a partnership between Hydro-Quebec and the Mohawk Council of Kahnawake, which will benefit from economic remunerations for 40 years.

To enhance reliability, grid-scale battery storage projects are also expanding in Ontario.

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BC Hydro COVID-19 Site C updates detail monitoring, self-isolation at the work camp, Northern Health coordination, social distancing, reduced staffing, progress on diversion tunnels, Highway 29 realignment, and public reports to Peace River Regional District.

Key Points

Regular reports on COVID-19 monitoring, isolation protocols, staffing, and Site C work with Northern Health.

✅ Daily updates to Peace River Regional District

✅ Isolation rooms reserved in camp dorms

✅ Construction continues with social distancing

BC Hydro says it will begin giving regular updates to the public and the Peace River Regional District about its monitoring of the coronavirus COVID-19 at Site C, reflecting broader industry alerts such as a U.S. grid warning on pandemic risks.

BC Hydro met with the Peace River Regional District Sunday via phone call to discuss the forthcoming measures.

"We did a make a commitment to provide regular updates to Peace River Regional District member communities on an ongoing basis," said spokesman Dave Conway.

"(It's) certainly one of the things that we heard that they want and we heard that strongly and repeatedly."

Conway said updates could be posted as early as Monday on BC Hydro's website for the project.

As of March 23, there were sixteen people in self-isolation at the work camp just outside Fort St. John. Conway did not know how many of the workers have been tested for the virus, but said there are no confirmed cases on site. Provincial guidelines are being followed, he said.

"If they show any of the following symptoms, so sneezing, sore throat, muscle aches, headaches, coughs, or difficulty breathing, they're isolated for 14 days," Conway said.

"We're being very cautious of our application of the guidelines. We're asking anybody to self isolate if they have any slight symptoms."

BC Hydro has set aside one 30-room dorm at the camp for workers who need to isolate themselves, similar to measures in other jurisdictions where the power industry may house staff on-site to maintain operations, and has another four dorms with another 120 rooms that can be used as necessary. Conway could not immediately say whether additional rooms at hotels or at its apartment block have also been reserved.

There have been  700 workers home since a scale-back in construction was announced on March 18, and more workers are expected to be sent home this week. There were 940 people in camp on March 23, Conway said.

"To put that into perspective, the number of people staying in camp at this time of year, based on previous years, usually averages around 1,700," Conway said.

Brad Sperling, board chair for the Peace River Regional District, said BC Hydro has committed to formulating a strategy over the next few days to keep local government and public informed.

Electoral director Karen Goodings said she was pleased by that, and that it's important to everyone that BC Hydro works with Northern Health and adheres to provincial guidelines.

"The senior governments are critical to what measures will be undertaken not only on the project, including the camp, but also on the rules around transportation of workers and on addressing workplace conduct investigations at other utilities," Goodings wrote in an email.

On Sunday, the Site C leisure bus was seen at Totem Mall with two passengers on board.

Conway said the ongoing use of the shuttle is being monitored and evaluated, and is operating under social distancing and extra cleaning guidelines aligned with public transportation changes that have come under BC Transit.

The bus makes 10 trips per day from the camp, with an average of two passengers per trip, Conway said.

"We still have, of course, people in camp, and it's an opportunity for guests to get out and go for a walk and re-provision themselves for essentials for personal needs," Conway said.

Construction of the river diversion tunnels continues to meet a fall deadline, while work also carries on to realign Highway 29, build the transmission line, and clear the valley and future reservoir. Other site security and environmental monitoring work also continues, as utilities confront a dangerous dam-climbing trend driven by social media.

BC Hydro has said measures have been put into place, amid concerns similar to those voiced by nuclear plant workers about precautions at industrial sites, to minimize the potential spread of the COVID-19 on site, such as closing the camp gym and theatre, eliminating self serve dining stations, as well as non-essential travel, tours, and meetings.

Some workers, however, have raised worries about the tight working conditions on site, noting field safety incidents that highlight risks in the sector.

The province announced Monday 48 new cases in B.C., including one more in the Northern Health region, bringing the region's total to five, while Saskatchewan's numbers show how the crisis has reshaped that province. Their precise whereabouts are not being reported by B.C. public health officials.

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Electric Buses reduce urban emissions and noise, but require charging infrastructure, grid upgrades, and depot redesigns; they offer lower operating costs and simpler maintenance, with range limits influencing routes, schedules, and on-route fast charging.

Key Points

Battery-electric buses cut emissions and noise while lowering operating and maintenance costs for transit agencies.

✅ Lower emissions, noise; improved rider experience

✅ Requires charging, grid upgrades, depot redesigns

✅ Range limits affect routes; on-route fast charging helps

In lots of ways, the electric bus feels like a technology whose time has come. Transportation is responsible for about a quarter of global emissions, and those emissions are growing faster than in any other sector. While buses are just a small slice of the worldwide vehicle fleet, they have an outsize effect on the environment. That’s partly because they’re so dirty—one Bogotá bus fleet made up just 5 percent of the city’s total vehicles, but a quarter of its CO2, 40 percent of nitrogen oxide, and more than half of all its particulate matter vehicle emissions. And because buses operate exactly where the people are concentrated, we feel the effects that much more acutely.

Enter the electric bus. Depending on the “cleanliness” of the electric grid into which they’re plugged, e-buses are much better for the environment. They’re also just straight up nicer to be around: less vibration, less noise, zero exhaust. Plus, in the long term, e-buses have lower operating costs, and related efforts like US school bus electrification are gathering pace too.

So it makes sense that global e-bus sales increased by 32 percent last year, according to a report from Bloomberg New Energy Finance, as the age of electric cars accelerates across markets worldwide. “You look across the electrification of cars, trucks—it’s buses that are leading this revolution,” says David Warren, the director of sustainable transportation at bus manufacturer New Flyer.

Today, about 17 percent of the world’s buses are electric—425,000 in total. But 99 percent of them are in China, where a national mandate promotes all sorts of electric vehicles. In North America, a few cities have bought a few electric buses, or at least run limited pilots, to test the concept out, and early deployments like Edmonton's first e-bus offer useful lessons as systems ramp up. California has even mandated that by 2029 all buses purchased by its mass transit agencies be zero-emission.

But given all the benefits of e-buses, why aren’t there more? And why aren’t they everywhere?

“We want to be responsive, we want to be innovative, we want to pilot new technologies and we’re committed to doing so as an agency,” says Becky Collins, the manager of corporate initiative at the Southeastern Pennsylvania Transportation Authority, which is currently on its second e-bus pilot program. “But if the diesel bus was a first-generation car phone, we’re verging on smartphone territory right now. It’s not as simple as just flipping a switch.”

One reason is trepidation about the actual electric vehicle. Some of the major bus manufacturers are still getting over their skis, production-wise. During early tests in places like Belo Horizonte, Brazil, e-buses had trouble getting over steep hills with full passenger loads. Albuquerque, New Mexico, canceled a 15-bus deal with the Chinese manufacturer BYD after finding equipment problems during testing. (The city also sued). Today’s buses get around 225 miles per charge, depending on topography and weather conditions, which means they have to re-up about once a day on a shorter route in a dense city. That’s an issue in a lot of places.

If you want to buy an electric bus, you need to buy into an entire electric bus system. The vehicle is just the start.

The number one thing people seem to forget about electric buses is that they need to get charged, and emerging projects such as a bus depot charging hub illustrate how infrastructure can scale. “We talk to many different organizations that get so fixated on the vehicles,” says Camron Gorguinpour, the global senior manager for the electric vehicles at the World Resources Institute, a research organization, which last month released twin reports on electric bus adoption. “The actual charging stations get lost in the mix.”

But charging stations are expensive—about $50,000 for your standard depot-based one. On-route charging stations, an appealing option for longer bus routes, can be two or three times that. And that’s not even counting construction costs. Or the cost of new land: In densely packed urban centers, movements inside bus depots can be tightly orchestrated to accommodate parking and fueling. New electric bus infrastructure means rethinking limited space, and operators can look to Toronto's TTC e-bus fleet for practical lessons on depot design. And it’s a particular pain when agencies are transitioning between diesel and electric buses. “The big issue is just maintaining two sets of fueling infrastructure,” says Hanjiro Ambrose, a doctoral student at UC Davis who studies transportation technology and policy.

“We talk to many different organizations that get so fixated on the vehicles. The actual charging stations get lost in the mix as the American EV boom gathers pace across sectors.”

Then agencies also have to get the actual electricity to their charging stations. This involves lengthy conversations with utilities about grid upgrades, rethinking how systems are wired, occasionally building new substations, and, sometimes, cutting deals on electric output, since electric truck fleets will also strain power systems in parallel. Because an entirely electrified bus fleet? It’s a lot to charge. Warren, the New Flyer executive, estimates it could take 150 megawatt-hours of electricity to keep a 300-bus depot charged up throughout the day. Your typical American household, by contrast, consumes 7 percent of that—per year. “That’s a lot of work by the utility company,” says Warren.

For cities outside of China—many of them still testing out electric buses and figuring out how they fit into their larger fleets—learning about what it takes to run one is part of the process. This, of course, takes money. It also takes time. Optimists say e-buses are more of a question of when than if. Bloomberg New Energy Finance projects that just under 60 percent of all fleet buses will be electric by 2040, compared to under 40 percent of commercial vans and 30 percent of passenger vehicles.

Which means, of course, that the work has just started. “With new technology, it always feels great when it shows up,” says Ambrose. “You really hope that first mile is beautiful, because the shine will come off. That’s always true.”

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Champlain Hudson Power Express Converter Station brings Canadian hydropower via HVDC to Queens, converting 1,250 MW to AC for New York City's grid, replacing a retired fossil site with a zero-emission, grid-scale clean energy hub.

Key Points

A Queens converter turning 1,250 MW HVDC hydropower into AC for NYC's grid, repurposing an Astoria fossil site.

✅ 340-mile underwater/underground HVDC link from Quebec to Queens

✅ 1,250 MW DC-AC conversion feeding directly into NY grid by 2026

✅ Replaces Astoria oil site; supports NY's 70% renewables by 2030

New York Governor Kathy Hochul has announced the start of construction on the converter station of the Champlain Hudson Power Express transmission line, a project to bring electricity generated from Canadian hydropower to New York City.

The 340 mile (547 km) transmission line is a proposed underwater and underground high-voltage direct current power transmission line to deliver the power from Quebec, Canada, to Queens, New York City. The project is being developed by Montreal-based public utility Hydro-Quebec (QBEC.UL) and its U.S. partner Transmission Developers, while neighboring New Brunswick has signed NB Power deals to bring more Quebec electricity into the province.

The converter station for the line will be the first-ever transformation of a fossil fuel site into a grid-scale zero-emission facility in New York City, its backers say.

Workers have already removed six tanks that previously stored 12 million gallons (45.4 million liters) of heavy oil for burning in power plants and nearly four miles (6.44 km) of piping from the site in the Astoria, Queens neighborhood, echoing Hydro-Quebec's push to wean the province off fossil fuels as regional power systems decarbonize.

The facility is expected to begin operating in 2026, even as the Ontario-Quebec power deal was not renewed elsewhere in the region. Once the construction is completed, it will convert 1,250 megawatts of energy from direct current to alternating current power that will be fed directly into the state's power grid, helping address transmission constraints that have impeded incremental Quebec-to-U.S. power deliveries.

“Renewable energy plays a critical role in the transformation of our power grid while creating a cleaner environment for our future generations,” Hochul said. The converter station is a step towards New York’s target for 70% of the state’s electricity to come from renewable sources by 2030, as neighboring Quebec has closed the door on nuclear power and continues to lean on hydropower.

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El Salvador Geothermal Expansion boosts renewable energy with a 7 MW Berlin binary ORC plant, upgrades at Ahuachapan, and pipeline projects, strengthening clean power capacity, grid reliability, and sustainable growth in Central America.

Key Points

A national push adding binary-cycle capacity at Berlin and Ahuachapan, boosting geothermal supply and advancing sites.

✅ 7 MW Berlin binary ORC plant entering service.

✅ Ahuachapan upgrade adds 2 MW, total geothermal 204 MW.

✅ Next: Chinameca, San Miguel, San Vicente, World Bank backed.

El Salvador is set to expand its renewable energy capacity with the inauguration of the 7-MW Berlin binary geothermal power plant, slated to go online later this year. This new addition marks a significant milestone in the country’s geothermal energy development, highlighting its commitment to sustainable energy solutions. The plant, which has already been installed and is currently undergoing testing, is expected to boost the nation’s geothermal capacity, contributing to its growing renewable energy portfolio.

The Role of Geothermal Energy in El Salvador’s Energy Mix

Geothermal energy plays a pivotal role in El Salvador's energy landscape. With the combined output from the Ahuachapan and Berlin geothermal plants, geothermal energy now accounts for about 21% of the country's net electricity supply. This makes geothermal the second-largest source of energy generation in El Salvador, underscoring its importance as a reliable and sustainable energy resource alongside emerging options like advanced nuclear microreactor technologies in the broader low-carbon mix.

In addition to the Berlin plant, El Salvador has made significant improvements to its Ahuachapan geothermal power plant. Recent upgrades have increased its generation capacity by 2 MW, further enhancing the country’s geothermal energy output. Together, the Ahuachapan and Berlin plants bring the total installed geothermal capacity to 204 MW, positioning El Salvador as a regional leader in geothermal energy development.

The Berlin Binary Geothermal Plant: A Technological Milestone

The Berlin binary geothermal power plant is especially noteworthy for several reasons. It is the first geothermal power plant to be constructed in El Salvador since 2007, marking a significant step in the country's ongoing efforts to expand its renewable energy infrastructure while reinforcing attention to risk management in light of Hawaii geothermal safety concerns reported elsewhere. The plant utilizes a binary cycle geothermal system, which is known for its efficiency in extracting energy from lower temperature geothermal resources, making it an ideal solution for regions like Berlin, where geothermal resources are abundant but at lower temperatures.

The plant was built by Turboden, an Italian company specializing in organic Rankine cycle (ORC) technology. The binary cycle system operates by transferring heat from the geothermal fluid to a secondary fluid, which then drives a turbine to generate electricity. This system allows for the efficient use of geothermal resources that might otherwise be too low in temperature for traditional geothermal plants, enabling pairing with thermal storage demonstration solutions to optimize output.

Future Geothermal Developments in El Salvador

El Salvador is not stopping with the Berlin geothermal plant. The country is actively working on other geothermal projects, including those in Chinameca, San Miguel, and San Vicente. These developments are expected to add 50 MW of additional capacity in their first phase, reflecting a broader shift as countries pursue hydrogen-ready power plants to reduce emissions, with a second phase, supported by the World Bank, planned to add another 100 MW.

The Chinameca, San Miguel, and San Vicente projects represent the next wave of geothermal development in El Salvador. When completed, these plants will significantly increase the country’s geothermal capacity, further diversifying its energy mix and reducing reliance on fossil fuels, and will require ongoing grid upgrades, a task complicated elsewhere by Germany grid expansion challenges highlighted in Europe.

International Support and Collaboration

El Salvador’s geothermal development efforts are supported by various international partners, including the World Bank, which has been instrumental in financing the expansion of geothermal projects, as utilities such as SaskPower geothermal plans in Canada explore comparable pathways. This collaboration highlights the global recognition of El Salvador’s potential in geothermal energy and its efforts to position itself as a hub for geothermal energy development in Central America.

Additionally, the country’s expertise in geothermal energy, especially in binary cycle technology, has attracted international attention. El Salvador’s progress in the geothermal sector could serve as a model for other countries in the region that are looking to harness their geothermal resources to reduce energy costs and promote sustainable energy development.

The upcoming launch of the Berlin binary geothermal power plant is a testament to El Salvador’s commitment to sustainable energy. As the country continues to expand its geothermal capacity, it is positioning itself as a leader in renewable energy in the region. The binary cycle technology employed at the Berlin plant not only enhances energy efficiency but also demonstrates El Salvador’s ability to adapt and innovate within the renewable energy sector.

With the continued development of projects in Chinameca, San Miguel, and San Vicente, and ongoing international collaboration, El Salvador’s geothermal energy sector is set to play a crucial role in the country’s energy future. As global demand for clean energy grows, exemplified by U.S. solar capacity additions this year, El Salvador’s investments in geothermal energy are helping to build a more sustainable, resilient, and energy-independent future.

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