Canadian Hydro powers up second largest wind facility in Canada

Coinmint Plattsburgh Dispute spotlights cryptocurrency mining, hydropower electricity rates, a $1M security deposit, Public Service Commission rulings, municipal utility policies, and seasonal migration to Massena data centers as Bitcoin price volatility pressures operations.

Key Points

Legal and energy-cost dispute over crypto mining, a $1,019,503 deposit, and operations in Plattsburgh and Massena.

✅ PSC allows higher rates and requires large security deposits.

✅ Winter electricity spikes drove a $1M deposit calculation.

✅ Coinmint shifted capacity to Massena data centers.

A few years ago, there was a lot of buzz about the North Country becoming the next Silicon Valley of cryptocurrency, even as Maine debated a 145-mile line that could reshape regional power flows. One of the companies to flock here was Coinmint. The cryptomining company set up shop in Plattsburgh in 2017 and declared its intentions to be a good citizen.

Today, Coinmint is fighting a legal battle to avoid paying the city’s electric utility more than $1 million owed for a security deposit. In addition to that dispute, a local property manager says the firm was evicted from one of its Plattsburgh locations.

Companies like Coinmint chose to come to the North Country because of the relatively low electricity prices here, thanks in large part to the hydropower dam on the St. Lawrence River in Massena, and regionally, projects such as the disputed electricity corridor have drawn attention to transmission costs and access. Coinmint operates its North Country Data Center facilities in Plattsburgh and Massena. In both locations, racks of computer servers perform complex calculations to generate cryptocurrency, such as bitcoin.

When cryptomining began to take off in Plattsburgh, the cost of one bitcoin was skyrocketing. That brought hype around the possibility of big business and job creation in the North Country. But cryptomininers like Coinmint were using massive amounts of energy in the winter of 2017-2018, and that season, electric bills of everyday Plattsburgh residents spiked.

Many cryptomining firms operate in a state of flux, beholden to the price of Bitcoin and other cryptocurrencies, even as the end to the 'war on coal' declaration did little to change utilities' choices. When the price of one bitcoin hit $20,000 in 2017, it fell by 30% just days later. That’s one reason why the price of electricity is so critical for companies like Coinmint to turn a profit. 

Plattsburgh puts the brakes on “cryptocurrency mining”
In early 2018, Plattsburgh passed a moratorium on cryptocurrency mining operations, after residents complained of higher-than-usual electric bills.

“Your electric bill’s $100, then it’s at $130. Why? It’s because these guys that are mining the bitcoins are riding into town, taking advantage of a situation,” said resident Andrew Golt during a 2018 public hearing.

Coinmint aimed to assuage the worries of residents and other businesses. “At the end of the day we want to be a good citizen in whatever communities we’re in,” Coinmint spokesman Kyle Carlton told NCPR at that 2018 meeting.

“We’re open to working with those communities to figure out whatever solutions are going to work.”

The ban was lifted in Feb. 2019. However, since it didn’t apply to companies that were already mining cryptocurrency in Plattsburgh, Coinmint has operated in the city all along.

Coinmint challenges attempt to protect ratepayers
New rules passed by the New York Public Service Commission in March 2018 allow municipal power authorities including Plattsburgh’s to charge big energy users such as Coinmint higher electricity rates, amid customer backlash in other utility deals. The new rules also require them to put down a security deposit to ensure their bills get paid.

But Coinmint disputes that deposit charge. The company has been embroiled in a legal fight for nearly a year against Plattsburgh Municipal Lighting Department (PMLD) in an attempt to avoid paying the electric utility’s security deposit bill of $1,019,503. That bill is based on an estimate of what would cover two months of electricity use if a company were to leave town without paying its electric bills.

Coinmint would not discuss the dispute on the record with NCPR. Legal documents show the firm argues the deposit charge is inflated, based on a flawed calculation resulting in a charge hundreds of thousands of dollars higher than what it should be.

“Essentially they’re arguing that they should only have to put up some average of their monthly bills without accounting for the fact that winter bills are significantly higher than the average,” said Ken Podolny, an attorney representing the Plattsburgh utility.

The company took legal action in February 2019 against PMLD in the hopes New York’s energy regulator, the Public Service Commission, would agree with Coinmint that the deposit charge was too high. An informal commission hearing officer disagreed, and ruled in October the charge was calculated correctly.

Coinmint appealed the ruling in November and a hearing on the appeal could come as soon as February.

Less than a week after Coinmint lost its initial challenge of the deposit charge, the company made a splashy announcement trumpeting its plans to “migrate its Plattsburgh, New York infrastructure to its Massena, New York location for the 2019-2020 winter season.”

The announcement made no mention of the appeal or the recent ruling against Coinmint. The company attributed its new plan to “exceptionally-high” electricity rates in Plattsburgh, as hydropower transmission projects elsewhere in New England faced their own controversies. 

"We recognize some in the Plattsburgh community have blamed our operation for pushing rates higher for everyone so, while we disagree with that assessment, we hope this seasonal migration will have a positive impact on rates for all our neighbors,” said Coinmint cofounder Prieur Leary in the press statement.

“In the event that doesn't happen, we trust the community will look for the real answers for these high costs." Prieur Leary has since been removed from the corporate team page on the company’s website.

The company still operates in Plattsburgh at one of its locations in the city. As for staff, while at least two Coinmint employees have moved from Plattsburgh to Massena, where the company operates a data center inside a former Alcoa aluminum plant, it is unclear how many people in total have made the move.

Coinmint left its second Plattsburgh location in 2019. The company would not discuss that move on the record, yet the circumstances of the departure are murky.

The local property manager of the industrial park site told NCPR, “I have no comment on our evicted tenant Coinmint.” The property owner, California’s Karex Property Management Services, also would not comment regarding the situation, noting that “all staff have been told to not discuss anything regarding our past tenant Coinmint.”

Today, Bitcoin and other cryptocurrencies are worth a fraction of what they were back in 2017 when Coinmint came to the North Country, and now, amid a debate over Bitcoin's electricity use shaping market sentiment, the future of the entire industry here remains uncertain.

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Nova Scotia Power solar charge proposes an $8/kW monthly system access fee on net metering customers, citing grid costs. UARB review, carbon credits, rate hikes, and solar industry impacts fuel political and consumer backlash.

Key Points

A proposed $8/kW monthly grid access fee on net metered solar customers, delayed to Feb 1, 2023, pending UARB review.

✅ $8/kW monthly system access fee on net metering

✅ Delay to Feb 1, 2023 after industry and political pushback

✅ UARB review; debate over grid costs and carbon credits

Nova Scotia Power has pushed back by a year the start date of a proposed new charge for customers who generate electricity and sell it back to the grid, following days of concern from the solar industry and politicians worried that it will damage the sector.

The company applied to the Nova Scotia Utility and Review Board (UARB) last week for various changes, including a "system access charge" of $8 per kilowatt monthly on net metered installations, and the province cannot order the utility to lower rates under current law. The vast majority of the province's 4,100 net metering customers are residential customers with solar power, according to the application. 

The proposed charge would have come into effect Tuesday if approved, but Nova Scotia Power said in a news release Tuesday it will change the date in its filing from Feb. 1, 2022, to Feb. 1, 2023.

"We understand that the solar industry was taken off guard," utility CEO Peter Gregg said in an interview.

"There could have been an opportunity to have more conversations in advance."

Gregg said the utility will meet with members of the solar industry over the next year to work on finding solutions that support the sector's growth, while addressing what NSP sees as an inequity in the net metering system.

NSP recognized that customers who choose solar invest a significant amount and pay for the electricity they use, but they don't pay for costs associated with accessing the electrical grid when they need energy, such as on cold winter evenings when the sun is not shining.

"I know that's hit a nerve, but it doesn't take away the fact that it is an issue," Gregg said.

He said this is an issue utilities are navigating around North America, where seasonal rate designs have sparked consumer backlash in New Brunswick, and NSP is open to hearing ideas for other models of charges or fees.

The utility's suggested system access charge closely resembles one proposed in California, which has also raised major concerns from the solar industry and been criticized by the likes of Elon Musk, and has parallels to Massachusetts solar demand charges as well.

Although the "solar profile" of Nova Scotia and California is very different, with far more solar customers in that state, and in other provinces such as Saskatchewan, NDP criticism of 8% hikes has intensified affordability debates, Gregg said the fundamental issues are the same.

For those with a typical 10-kilowatt solar system, which generates around $1,800 of electricity a year, the new charge would mean those customers would be required to pay $960 back to NSP. That would roughly double the length of time it takes for those customers to pay off their investment for the panels.

David Brushett, chair of Solar Nova Scotia, said he relayed concerns from solar installers and others in the industry to Gregg on Monday. 

Brushett said the year delay is a positive first step, but he is still calling on the province to take a strong stance against the application, which has led to customers cancelling their panel installations and companies considering layoffs.

"There's still an urgency to this situation that hasn't been addressed, and we need to kind of protect the industry," he said Tuesday.

NSP's original application proposed exempting net metering customers who enrolled before Feb. 1, 2022, from the charge for 25 years after they sign up. But any benefit would be lost if those customers sold their home, and the exemption wouldn't extend to the new buyers, said Brushett.

Carbon offsets missing from equation: industry
Brushett said NSP "completely ignored" the fact that it's getting free carbon offset credits from homeowners who use solar energy under the provincial cap and trade program.

If the net metering system continues as is, NSP has said non-solar customers would pay about $55 million between now and 2030. That number assumes about 2,000 people sign up for net metering each year over the next nine years.

When asked whether those carbon emission credits were factored into the calculations for the proposed charge, Gregg said, "I don't believe in the current structure it is, but it's something that certainly we'd be open to hearing about."

Brushett said his group is finalizing a legal response to NSP's proposal and has already filed an official complaint against the company with the UARB.

Base charge on actual electrical output: customer
At least one shareholder in NSP parent company Emera is considering selling his shares in response to the application.

Joe Hood, a shareholder from Middle Sackville, said the proposed charge won't apply to his existing 11.16-kilowatt solar system, but if it did, it would cost him $1,071 a year.

"I am offended that a company I would invest in would do this to the solar industry in Nova Scotia," he said.

According to his meter, Hood said he pushed 9,600 kilowatt hours of solar electricity to the grid last year— some only for a brief period, and all of which was used by his home by the end of the year.

Under the proposed charge, someone with one solar panel who goes away on vacation in the summer would push all their electricity to the grid, and be charged far less than someone with 10 panels who has used all their own power and hasn't pushed anything.

"Nova Scotia Power's argument is that it's an issue with the grid. Well, then it should be based on what touches the grid," Hood said.

Far from actually making the system fair for everyone, Hood said this charge places solar only in the hands of the super-rich or NSP, with projects like its community solar gardens in Amherst, N.S.

Green Party suggests legislation update
Nova Scotia's Green Party also said Tuesday that Gregg's arguments of fairness are misleading, echoing earlier premier opposition to a 14% hike on rates.

The party is calling for an update to the Electricity Act that would "prevent penalizing any activity that helps Nova Scotia reach its emissions target," aligning with calls to make the electricity system more accountable to residents.

In its application, NSP has also asked to increase electricity rates for residential customers by at least 10 per cent over the next three years, amid debate that culminated in a 14% rate hike approval by regulators. 

The company wants to maintain its nine per cent rate of return.

NSP expects to earn $153 million this year, $192 million in 2023, and $213 million in 2024 from its rate of return. 

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Goreway Power Station Overbilling exposed by Ontario Energy Board shows IESO oversight failures, GCG gaming, and $100M in inappropriate payments at the Brampton natural gas plant, penalized with fines and repayments impacting Ontario ratepayers.

Key Points

Goreway exploited IESO GCG flaws, causing about $100M in improper payouts and fines.

✅ OEB probe flagged $89M in ineligible start-up O&M charges

✅ IESO fined Goreway $10M; majority of excess costs recovered

✅ Audit found $200M in overbilling across nine generators

Hydro customers shelled out about $100 million in "inappropriate" payments to a natural gas plant that exploited flaws in how Ontario manages its private electricity generators, according to the Ontario Energy Board.

The company operating the Goreway Power Station in Brampton "gamed" the system for at least three years, according to an investigation by the provincial energy regulator. 

The investigation also delivers stinging criticism of the provincial government's Independent Electricity System Operator (IESO), slamming it for a lack of oversight. The probe by the Ontario Energy Board's market surveillance panel was completed nearly a year ago, but was only made public in November because it was buried on its website without a news release. CBC News is the first media outlet to report on the investigation.  

The excess payments to Goreway Power Station included:

• $89 million in ineligible expenses billed as the costs of firing up power production. 
• $5.6 million paid in three months from a flaw in how IESO calculated top-ups for the company committing to generate power a day in advance.   
• Of $11.2 million paid to compensate the company for IESO ordering it to start or stop generating power, the investigation concluded "a substantial portion ... was the result of gaming."  

Most privately-owned natural gas-fired plants in the province do not generate electricity constantly, but start and stop production in response to fluctuating market demand, even as the energy minister has requested an halt to natural gas generation across the grid.  IESO pays them a premium for the costs of firing up production, through what it calls "generation cost guarantee" programs. 

But the investigation found IESO did little checking into the details of Goreway Power Station's billings. 

Goreway Power Station, located near Highway 407 in Brampton, Ont., is an 875 megawatt natural gas power plant. (Goreway)

"Conservatively, at least $89 million of Goreway's submissions were clearly ineligible by any reasonable measure," concludes the report.

"Goreway routinely submitted what were obviously inappropriate expenses to be reimbursed by the IESO, and ultimately borne by Ontario ratepayers,"

The investigation panel found an "extraordinary pattern" to these billings by Goreway Power Station, suggesting the IESO should have caught on sooner. The company submitted more than $100 million in start-up operating and maintenance costs during the three-year period investigated — more than all other gas-fired generators in the province combined. The company's costs per start-up were more than double the next most expensive power generator. 

"Goreway repeatedly exploited defects in the GCG (generation cost guarantee) program, and in doing so received at least $89 million in gamed GCG payments." 

Company fined $10M

The investigation covered a three-year period from when Goreway Power Station began generating power in June 2009. Investigators said that delays in releasing documents slowed down their probe, and they only obtained all the records they needed in April 2016.

The investigating panel does not have the power to impose penalties on companies it found broke the rules. 

The IESO fined Goreway Power Station $10 million. The company has also repaid IESO "a substantial portion" of the excess payments it received during its first six years of operating, but the exact figure is blacked out in the investigation report that was made public. 

The control room from which the provincial government's Independent Electricity System Operator manages Ontario's power supply. The agency is also responsible for managing contracts with private power producers.(IESO)

"Goreway does not agree with many of the draft report's findings and conclusions, including any suggestion that Goreway engaged in gaming or that it deliberately misled the IESO," writes lawyer George Vegh on behalf of the company in a response to the investigation report, dated Aug. 1.

"Goreway has implemented initiatives designed to ensure that compliance is a chief operating principle."     

The power station, located near Highway 407 in Brampton, is a joint venture between Toyota Tsusho Corp. and JERA Co. Inc. During the period under scrutiny, the project was run by Toyota Tsusho and Chubu Electric Power Inc., both headquartered in Japan. 

Investigators fear 'same situation' exists today

The report blames the provincially-controlled IESO for creating a system with defects that allowed the over-billing. 

"Goreway was able to — and repeatedly did — exploit these defects," says the investigation report. It goes on to explain the flaws "have created opportunities for exploitation, to the serious financial disadvantage of Ontario's ratepayers," even as greening Ontario's grid could entail massive costs.

The investigation suggests IESO hasn't made adequate changes to ensure it won't happen again, at a time when an analysis of a dirtier grid is raising concerns.   

"Goreway stands as a clear example of how generators are able to exploit the generation costs guarantee regime," says the report.

"The Panel is concerned that the same situation remains in place today." 

PC energy critic Todd Smith raised CBC News' report on the Goreway Power Station in Tuesday's question period. (Ontario Legislature)

After CBC News broke the story Tuesday, the provincial government was forced to respond in question period, amid a broader push for new gas plants to boost electricity production. 

"Here we have yet another gas plant scandal in Peel region that's costing electricity customers over $100 million," said PC energy critic Todd Smith. He slammed "the incompetence of a government that once again failed to look out for electricity customers." 

Economic Development Minister Brad Duguid said: "There is no excuse for any company in this province to ever game the system."

Nine companies overbilled $200M: audit 

The IESO found out about the overbilling "some time ago," said Duguid.

"They fully investigated, they've recovered most of the cost, they delivered a $10 million fine — the biggest fine on record."

The program that Goreway exploited became the subject of an audit that the IESO launched in 2011. The agency uncovered $200 million in ineligible billings by nine power producers, wrote the IESO vice president for policy Terry Young in an email to CBC News.

The IESO has recovered up to 85 per cent of those ineligible costs, Young noted.

Reforms to the design of the the program have removed the potential for overpayments and made it more efficient, he said, even as Ontario weighs embracing clean power more broadly. Last year, its total annual costs dropped to $23 million, down from $61 million in 2014.

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Germany Energiewende Lessons highlight climate policy tradeoffs, as renewables, wind and solar face grid constraints, coal phase-out delays, rising electricity prices, and public opposition, informing Canada on diversification, hydro, oil and gas, and balanced transition.

Key Points

Insights from Germany's renewable shift on costs, grid limits, and emissions to guide Canada's balanced energy policy.

✅ Evidence: high power prices, delayed coal exit, limited grid buildout

✅ Land, materials, and wildlife impacts challenge wind and solar scale-up

✅ Diversification: hydro, nuclear, gas, and storage balance reliability

News that Greta Thunberg is visiting Alberta should be welcomed by all Canadians.

The teenaged Swedish environmentalist has focused global attention on the climate change debate like never before. So as she tours our province, where selling renewable energy could be Alberta's next big thing, what better time for a reality check than to look at a country that is furthest ahead in already adapting steps that Greta is advocating.

That country is Germany. And it’s not a pretty sight.

Germany embraced the shift toward renewable energy before anyone else, and did so with gusto. The result?

Germany’s largest newsmagazine Der Spiegel published an article on May 3 of this year entitled “A Botched Job in Germany.” The cover showed broken wind turbines and half-finished transition towers against a dark silhouette of Berlin.

Germany’s renewable energy transition, Energiewende, is a bust. After spending and committing a total of US$580 billion to it from 2000 to 2025.

Why is that? Because it’s been a nightmare of foolish dreams based on hope rather than fact, resulting in stalled projects and dreadfully poor returns.

Last year Germany admitted it had to delay its phase-out of coal and would not meet its 2020 greenhouse gas emissions reduction commitment. Only eight per cent of the transmission lines needed to support this new approach to powering Germany have been built.

Opposition to renewables is growing due to electricity prices rising to the point they are now among the highest in the world. Wind energy projects in Germany are now facing the same opposition that pipelines are here in Canada. 

Opposition to renewables in Germany, reports Forbes, is coming from people who live in rural or suburban areas, in opposition to the “urbane, cosmopolitan elites who fetishize their solar roofs and Teslas as a sign of virtue.” Sound familiar?

So, if renewables cannot successfully power Germany, one of the richest and most technologically advanced countries in the world, who can do it better?

The biggest problem with using wind and solar power on a large scale is that the physics just don’t work. They need too much land and equipment to produce sufficient amounts of electricity.

Solar farms take 450 times more land than nuclear power plants to produce the same amount of electricity. Wind farms take 700 times more land than natural gas wells.

The amount of metal required to build these sites is enormous, requiring new mines. Wind farms are killing hundreds of endangered birds.

No amount of marketing or spin can change the poor physics of resource-intensive and land-intensive renewables.

But, wait. Isn’t Norway, Greta’s neighbour, dumping its energy investments and moving into alternative energy like wind farms in a big way?

No, not really. Fact is only 0.8 per cent of Norway’s power comes from wind turbines. The country is blessed with a lot of hydroelectric power, but that’s a historical strength owing to the country’s geography, nothing new.

And yet we’re being told the US$1-trillion Oslo-based Government Pension Fund Global is moving out of the energy sector to instead invest in wind, solar and other alternative energy technologies. According to 350.org activist Nicolo Wojewoda this is “yet another nail in the coffin of the coal, oil, and gas industry.”

Well, no.

Norway’s pension fund is indeed investing in new energy forms, but not while pulling out of traditional investments in oil and gas. Rather, as any prudent fund manager will, they are diversifying by making modest investments in emerging industries such as Alberta's renewable energy surge that will likely pay off down the road while maintaining existing investments, spreading their investments around to reduce risk. Unfortunately for climate alarmists, the reality is far more nuanced and not nearly as explosive as they’d like us to think.

Yet, that’s enough for them to spin this tale to argue Canada should exit oil and gas investment and put all of our money into wind and solar, even as Canada remains a solar power laggard according to experts.

That is not to say renewable energy projects like wind and solar don’t have a place. They do, and we must continue to innovate and research lower-polluting ways to power our societies on the path to zero-emissions electricity by 2035 in Canada.

But like it actually is in Norway, investment in renewables should supplement — not replace — fossil fuel energy systems if we aim for zero-emission electricity in Canada by 2035 without undermining reliability. We need both.

And that’s the message that Greta should hear when she arrives in Canada.

Rick Peterson is the Edmonton-based founder and Beth Bailey is a Calgary-based supporter of Suits and Boots, a national not-for-profit group of investment industry professionals that supports resource sector workers and their families.

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Calgary Winter Storm and Extreme Cold delivers heavy snowfall, ECCC warnings, blowing snow, icy roads, and dangerous wind chill across southern Alberta, as a low-pressure system and northerly inflow fuel hazardous travel and frostbite risks.

Key Points

A severe Alberta storm with heavy snow, strong winds, ECCC warnings, dangerous wind chill, and high frostbite risk.

✅ ECCC extends snowfall and winter storm warnings regionwide.

✅ Wind chill -28 to -47; frostbite possible within 5-30 minutes.

✅ AMA rescues surge; non-essential travel strongly discouraged.

Calgary and much of southern Alberta faced a significant winter storm that brought heavy snowfall, strong winds, and dangerously low temperatures. Environment and Climate Change Canada (ECCC) issued extended and expanded snowfall and winter storm warnings as persistent precipitation streamed along the southern borders. The combination of a low-pressure system off the West Coast, where a B.C. 'bomb cyclone' had left tens of thousands without power, and a northerly inflow at the surface led to significant snow accumulations in a short period.

The storm resulted in poor driving conditions across much of southern Alberta, with snow-packed and icy roads, as well as limited visibility due to blowing snow. ECCC advised postponing non-essential travel until conditions improved. As of 10 a.m. on January 17, the 511 Alberta map showed poor driving conditions throughout the region, while B.C. electricity demand hit an all-time high amid the cold.

In Calgary, the city recorded four centimeters of snow on January 16, with an additional four centimeters expected on January 17. Temperatures remained far below seasonal averages until the end of the week, and Calgary electricity use tends to surge during such cold snaps according to Enmax, with improvements starting on Sunday.

The extreme cold posed significant risks, with wind chills of -28 to -39 capable of causing frostbite in 10 to 30 minutes, as a Quebec power demand record illustrated during the deep freeze. When wind chills dropped to -40 to -47, frostbite could occur in as little as five to 10 minutes. Residents were advised to watch for signs of frostbite, including color changes on fingers and toes, pain, numbness, tingling sensations, or swelling. Those most at risk included young children, older adults, people with chronic illnesses, individuals working or exercising outdoors, and those without proper shelter.

In response to the severe weather, the Alberta Motor Association (AMA) experienced a surge in calls for roadside assistance. Between January 12 and 14, there were approximately 32,000 calls, with about 22,000 of those requiring rescues between January 12 and 14. The high volume of requests led the AMA to temporarily cease providing wait time updates on their website due to the inability to provide accurate information, while debates over Alberta electricity prices also intensified during the cold.

The storm also had broader implications across Canada. Heavy snow was expected to fall across wide swaths of southern British Columbia and parts of southern Alberta, as BC Hydro's winter payment plan offered billing relief to customers during the stretch. Northern Alberta was under extreme cold warnings, with temperatures expected to dip to -40°C through the rest of the week. Similar extreme cold was forecast for southern Ontario, with wind chill values reaching -30°C.

As the storm progressed, conditions began to improve. The wind warning for central Alberta ended by January 17, though a blowing snow advisory remained in effect for the southeast corner of the province. Northwest winds gusting up to 90 km/h combined with falling snow continued to cause poor visibility in some areas, while California power outages and landslides were reported amid concurrent severe storms along the coast. Conditions were expected to improve by mid-morning.

In the aftermath of the storm, residents were reminded of the importance of preparedness and caution during severe winter weather. Staying informed through official weather advisories, adjusting travel plans, and taking necessary precautions can help mitigate the risks associated with such extreme conditions.

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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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