Natural gas-fired generation still needed: utility CEOs

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Natural gas-fired generation will play an important role in a carbon-constrained world because it is cleaner and more reliable than other fossil fuels, Sempra Energy Chairman and CEO Don Felsinger and other utility executives said.

California is moving aggressively to curb climate change, in part by ramping up renewable resources, but gas-fired plants will be needed to hedge green resources, Felsinger said at the Goldman Sachs 8th Annual Power & Utility Conference in New York.

Wisconsin Energy Chairman, President and CEO Gale Klappa echoed Felsinger's views. Given mounting legal challenges to coal-fired generation and the intermittent nature of renewable resources, Wisconsin Energy's "default" position is natural gas, Klappa said. At the same time, Klappa expressed concern about the rising cost of natural gas.

Klappa said he believes there is a "pretty significant move right now" to repeal his state's ban on new nuclear facilities. While Wisconsin is investing heavily in renewables, Klappa said he believes new nuclear power needs to be considered. He noted that 20% of the state's energy comes from nuclear plants.

Asked whether the nation's infrastructure is ready to support a boost in gas-fired generation, Felsinger said the US is "probably not ready as a country," but it has the most sophisticated natural gas infrastructure as any country in the world. It's "not enough but it's a start," he said.

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Only one in 10 utility firms prioritise renewable electricity – global study

Utility Renewable Investment Gap highlights Oxford study in Nature Energy: most electric utilities favor fossil fuels over clean energy transition, expanding coal and gas, risking stranded assets and missing climate targets despite global decarbonization commitments.

 

Key Points

Most utilities grow fossil capacity over renewables, slowing decarbonization and jeopardizing climate goals.

✅ Only 10% expand renewables faster than coal and gas growth

✅ 60% still add fossil plants; 15% actively cut coal and gas

✅ Risks: stranded assets, missed climate targets, policy backlash

 

Only one in 10 of the world’s electric utility companies are prioritising clean energy investment over growing their capacity of fossil fuel power plants, according to research from the University of Oxford.

The study of more than 3,000 utilities found most remain heavily invested in fossil fuels despite international efforts to reduce greenhouse gas emissions and barriers to 100% renewables in the US that persist, and some are actively expanding their portfolio of polluting power plants.

The majority of the utility companies, many of which are state owned, have made little change to their generation portfolio in recent years.

Only 10% of the companies in the study, published in the research journal Nature Energy, are expanding their renewable energy capacity, mirroring global wind and solar growth patterns, at a faster rate than their gas- or coal-fired capacity.

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Of the companies prioritising renewable energy growth, 60% have not stopped concurrently expanding their fossil fuel portfolio and only 15% of these companies are actively reducing their gas and coal capacity.

Galina Alova, the author of the report, said the research highlighted “a worrying gap between what is needed” to tackle the climate crisis, with calls for a fossil fuel lockdown gaining attention, and “what actions are being taken by the utility sector”.

The report found 10% of utilities were favouring growth in gas-fired power plants. This cluster is dominated by US utilities, even as renewables surpass coal in US generation in the broader market, eager to take advantage of the country’s shale gas reserves, followed by Russia and Germany.

Only 2% of utilities are actively growing their coal-fired power capacity ahead of renewables or gas. This cluster is dominated by Chinese utilities – which alone contributed more than 60% of coal-focused companies – followed by India and Vietnam.

The report found the majority of companies prioritising renewable energy were clustered in Europe. Many of the industry’s biggest players are investing in low-carbon energy and green technologies, even as clean energy's dirty secret prompts debate, to replace their ageing fossil fuel power plants.


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In the UK, amid UK renewables backlog that has stalled billions, coal plants are shutting at pace ahead of the government’s 2025 ban on coal-fired power in part because the UK’s domestic carbon tax on power plants make them uneconomic to run.

“Although there have been a few high-profile examples of individual electric utilities investing in renewables, this study shows that overall, the sector is making the transition to clean energy slowly or not at all,” Alova said.

“Utilities’ continued investment in fossil fuels leaves them at risk of stranded assets – where power plants will need to be retired early – and undermines global efforts to tackle climate change.”
 

 

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Ireland announces package of measures to secure electricity supplies

Ireland electricity support measures include PSO levy rebates, RESS 2 renewables, CRU-directed EirGrid backup capacity, and grid investment for the Celtic Interconnector, cutting bills, boosting security of supply, and reducing reliance on imported fossil fuels.

 

Key Points

Government steps to cut bills and secure supply via PSO rebates, RESS 2 renewables, backup power, and grid upgrades.

✅ PSO levy rebates lower domestic electricity bills.

✅ RESS 2 adds wind, solar, and hydro to the grid.

✅ EirGrid to procure temporary backup capacity for winter peaks.

 

Ireland's Cabinet has approved a package of measures to help mitigate the rising cost of rising electricity bills, as Irish provider price increases continue to pressure consumers, and to ensure secure supplies to electricity for households and business across Ireland over the coming years.

The package of measures includes changes to the Public Service Obligation (PSO) levy (beyond those announced earlier in the year), which align with emerging EU plans for more fixed-price electricity contracts to improve price stability. The changes will result in rebates, and thus savings, for domestic electricity bills over the course of the next PSO year beginning in October. This further reduction in the PSO levy occurs because of a fall in the relative cost of renewable energy, compared to fossil fuel generation.

The Government has also approved the final results of the second onshore Renewable Electricity Support Scheme (RESS 2) auction, echoing how Ontario's electricity auctions have aimed to lower costs for consumers. This will bring significantly more indigenous wind, solar and hydro-electric energy onto the National Grid. This, in turn, will reduce our reliance on increasingly expensive imported fossil fuels, as the UK explores ending the gas-electricity price link to curb bills.

The package also includes Government approval for the provision of funding for back-up generation capacity, to address risks to security of electricity supply over the coming winters, similar to the UK's forthcoming energy security law approach in this area. The Commission for the Regulation of Utilities (CRU), which has statutory responsibility for security of supply, has directed EirGrid to procure additional temporary emergency generation capacity (for the winters of 2023/2024 to 2025/2026). This will ultimately provide flexible and temporary back-up capacity, to safeguard secure supplies of electricity for households and businesses as we deploy longer-term generation capacity.

Today’s measures also see an increased borrowing limit (€3 billion) for EirGrid – to strengthen our National Grid as part of 'Shaping Our Electricity Future' and to deliver the Celtic (Ireland-France) Interconnector, amid wider European moves to revamp the electricity market that could enhance cross-border resilience. An increased borrowing limit (€650 million) for Bord na Móna will drive greater deployment of indigenous renewable energy across the Midlands and beyond – as part of its 'Brown to Green' strategy, while measures like the UK's household energy price cap illustrate the scale of consumer support elsewhere.

 

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The Haves and Have-Nots of Electricity in California

California Public Safety Power Shutoffs highlight wildfire prevention as PG&E outages disrupt schools, businesses, and rural communities, driving generator use, economic hardship, and emergency preparedness across Northern California during high-wind events.

 

Key Points

Utility outages to reduce wildfire risk during extreme winds, impacting homes and businesses in high-risk California.

✅ PG&E cuts power during high winds to prevent wildfires

✅ Costs rise for generators, fuel, batteries, and spoiled food

✅ Rural, low-income communities face greater economic losses

 

The intentional blackout by California’s largest utility this week put Forest Jones out of work and his son out of school. On Friday morning Mr. Jones, a handyman and single father, sat in his apartment above a tattoo parlor waiting for the power to come back on and for school to reopen.

“I’ll probably lose $400 or $500 dollars because of this,” said Mr. Jones, who lives in the town of Paradise, which was razed by fire last year and is slowly rebuilding. “Things have been really tough up here.”

Millions of people were affected by the blackout, which spanned the outskirts of Silicon Valley to the forests of Humboldt County near the Oregon border. But the outage, which the power company said was necessary to reduce wildfire risk across the region, also drew a line between those who were merely inconvenienced and those who faced a major financial hardship.

To have the lights on, the television running and kitchen appliances humming is often taken for granted in America, even as U.S. grid during coronavirus questions persisted. During California’s blackout it became an economic privilege.

The economic impacts of the shut-off were especially acute in rural, northern towns like Paradise, where incomes are a fraction of those in the San Francisco Bay Area.

Both wealthy and poorer areas were affected by the blackout but interviews across the state suggested that being forced off the grid disproportionately hurt the less affluent. One family in Humboldt County said they had spent $150 on batteries and water alone during the shutdown.

“To be prepared costs money,” Sue Warhaftig, a massage therapist who lives in Mill Valley, a wealthy suburb across the Golden Gate Bridge from San Francisco. Ms. Warhaftig spent around two days without electricity but said she had been spared from significant sacrifices during the blackout.

She invested in a generator to keep the refrigerator running and to provide some light. She cooked in the family’s Volkswagen camper van in her driveway. At night she watched Netflix on her phone, which she was able to charge with the generator. Her husband, a businessman, is in London on a work trip. Her two sons, both grown, live in Southern California and Seattle.

“We were inconvenienced but life wasn’t interrupted,” Ms. Warhaftig said. “But so many people’s lives were.

Pacific Gas & Electric restored power to large sections of Northern California on Friday, including Paradise, where the electricity came back on in the afternoon. But hundreds of thousands of people in other areas remained in the dark. The carcasses of burned cars still littered the landscape around Paradise, where 86 people died in the Camp Fire last year, some of them while trying to escape.

Officials at power company said that by Saturday they hoped to have restored power to 98 percent of the customers who were affected.

The same dangerous winds that spurred the shut-off in Northern California have put firefighters to work in the south. The authorities in Los Angeles County ordered the evacuation of nearly 100,000 people on Friday as the Saddleridge Fire burned nearly 5,000 acres and destroyed 25 structures. The Sandalwood Fire, which ignited Thursday in Riverside County, had spread to more than 800 acres and destroyed 74 structures by Friday afternoon.

While this week’s outage was the first time many customers in Northern California experienced a deliberate power shut-off, residents in and around Paradise have had their power cut four times in recent months, residents say.

Many use a generator, but running one has become increasingly expensive with gasoline now at more than $4 a gallon in California.

On Friday, Dennis and Viola Timmer drove up the hill to their home in Magalia, a town adjacent to Paradise, loaded with $102 dollars of gasoline for their generators. It was their second gasoline run since the power went out Tuesday night.

The couple, retired and on a fixed income after Mr. Timmer’s time in the Navy and in construction, said the power outage had severely limited their ability to do essential tasks like cooking, or to leave the house.

“You know what it feels like? You’re in jail,” said Ms. Timmer, 72. “You can’t go anywhere with the generators running.”

Since the generators are not powerful enough to run heat or air conditioning, the couple slept in their den with an electric space heater.

“It’s really difficult because you don’t have a normal life,” Ms. Timmer said. “You’re trying to survive.”

To be sure, the shutdown has affected many people regardless of economic status, and similar disruptions abroad, like a London power outage that disrupted routines, show how widespread such challenges can be. The areas without power were as diverse as the wealthy suburbs of Silicon Valley, the old Gold Rush towns of the Sierra Nevada, the East Bay of San Francisco and the seaside city of Arcata.

Ms. Cahn’s cellphone ran out of power during the blackout and even when she managed to recharge it in her car cell service was spotty, as it was in many areas hit by the blackout.

Accustomed to staying warm at night with an electric blanket, Ms. Cahn slept under a stack of four blankets.

“I’m doing what I have to do which is not doing very much,” she said.

Further south in Marin City, Chanay Jackson stood surrounded by fumes from generators still powering parts of the city.

She said that food stamps were issued on the first of the month and that many residents who had to throw away food were out of luck.

“They’re not going to issue more food stamps just because the power went out,” Ms. Jackson said. “So they’re just screwed until next month.”

Strong winds have many times in the past caused power lines to come in contact with vegetation, igniting fires that are then propelled by the gusts, and hurricanes elsewhere have crippled infrastructure with Louisiana grid rebuild after Laura according to state officials. This was the case with the Camp Fire.

Since higher elevations had more extreme winds many of the neighborhoods where power was turned off this week were in hills and canyons, including in the Sierra Nevada.

The shut-off, which by one estimate affected a total of 2.5 million people, has come under strong criticism by residents and politicians, and warnings from Cal ISO about rolling blackouts as the power grid strained. The company’s website crashed just as customers sought information about the outage. Gov. Gavin Newsom called it unacceptable. But his comments were nuanced, criticizing the way the shut-off was handled, not the rationale for it. Mr. Newsom and others said the ravages of the Camp Fire demanded preventive action to prevent a reoccurrence.

Yet the calculus of trying to avoid deadly fires by shutting off power will continue to be debated as California enters its peak wildfire season, even as electricity reliability during COVID-19 was generally maintained for most consumers.

In the city of Grass Valley, Matthew Gottschalk said he and his wife realized that a generator was essential when they calculated that they had around $500 worth of food in their fridge.

“I don’t know what we would have done,” said Mr. Gottschalk, whose power went out Tuesday night.

His neighbors are filling coolers with ice. Everyone is hoping the power will come back on soon.

“Ice is going to run out and gas is going to run out,” he said.

 

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Minister approves 30-megawatt wind farm expansion in Eastern Kings

Eastern Kings Wind Farm Expansion advances P.E.I. renewable energy with seven new wind turbines, environmental assessment, wildlife monitoring of birds and bats, and community consultation to double output to 30 MW for domestic consumption.

 

Key Points

A P.E.I. project adding seven turbines for 30 MW, under 17 conditions, with wildlife monitoring and community oversight.

✅ Seven new turbines, larger than existing units

✅ 17 conditions, monthly compliance reporting

✅ Two-year wildlife study for birds and bats

 

A proposal to expand an existing wind farm in eastern P.E.I. has been given the go-ahead, according to P.E.I.’s Department of Environment, Water and Climate Change, as related grid work like a new transmission line progresses in the region.

Minister Natalie Jameson approved the P.E.I. Energy Corporation’s Eastern Kings Wind Farm expansion project, the province announced in a release Wednesday afternoon, as Atlantic Canada advances other renewable initiatives like tidal power to diversify supply.

The project will be subject to 17 conditions, which were drawn from a review of the 80 responses the province received from the public on the proposed Eastern Kings Wind Farm expansion.

The corporation must provide a summary on the status of each condition to the department on a monthly basis.

“This decision balances the needs of people, communities, wellness and the environment,” Jameson said in the release.

“It allows this renewable energy project to proceed and reduce greenhouse [gas] emissions that cause climate change while mitigating the project’s impact to the Island’s ecosystem.”

The P.E.I. Energy Corporation wants to double the output of its Eastern Kings Wind Farm with the installation of seven wind turbines between the communities of Elmira and East Point to develop 30 megawatts of wind power for domestic consumption, according to the minister’s impact assessment, aligning with regional moves to expand wind and solar projects across Atlantic Canada.

The new turbines are expected to be larger than the existing 10 at the site, even as regional utilities study major grid changes to integrate more renewables.

Project must comply with conditions

In February, the province said it would identify any specific questions or concerns it felt needed to be addressed in the submissions, according to Greg Wilson, manager of environmental land management for the province, while some advocate for independent electricity planning to guide such decisions.

Public feedback closed in January, after an earlier extension to wait for a supplemental report on birds and bats.

The corporation needs to comply with all conditions – such as monitoring environmental impact, setting up an environmental management plan and creating a committee to address concerns – listed in the release on Wednesday, amid calls from environmental advocates to reduce biomass use in electricity generation.

A condition in the release suggests representatives from L’nuey, the Souris and Area Wildlife Branch, the Rural Municipality of Eastern Kings and local residents to make up the committee.

The corporation will also need to conduct a study over two years after construction to look at the impact on bats and birds, and implement a protocol to report deaths of birds to federal and provincial authorities.

According to Canada Energy Regulator, roughly 98 per cent of power generated on P.E.I. comes from wind farms. It also said there were 203 megawatts installed on P.E.I. as of 2018, and the majority of energy consumed on the Island comes from New Brunswick from a mix of nuclear, fossil fuels and hydroelectricity, while in Nova Scotia, the utility has increased biomass generation as part of its supply mix.

 

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Purdue: As Ransomware Attacks Increase, New Algorithm May Help Prevent Power Blackouts

Infrastructure Security Algorithm prioritizes cyber defense for power grids and critical infrastructure, mitigating ransomware, blackout risks, and cascading failures by guiding utilities, regulators, and cyber insurers on optimal security investment allocation.

 

Key Points

An algorithm that optimizes security spending to cut ransomware and blackout risks across critical infrastructure.

✅ Guides utilities on optimal security allocation

✅ Uses incentives to correct human risk biases

✅ Prioritizes assets to prevent cascading outages

 

Millions of people could suddenly lose electricity if a ransomware attack just slightly tweaked energy flow onto the U.S. power grid, as past US utility intrusions have shown.

No single power utility company has enough resources to protect the entire grid, but maybe all 3,000 of the grid's utilities could fill in the most crucial security gaps if there were a map showing where to prioritize their security investments.

Purdue University researchers have developed an algorithm to create that map. Using this tool, regulatory authorities or cyber insurance companies could establish a framework for protecting the U.S. power grid that guides the security investments of power utility companies to parts of the grid at greatest risk of causing a blackout if hacked.

Power grids are a type of critical infrastructure, which is any network - whether physical like water systems or virtual like health care record keeping - considered essential to a country's function and safety. The biggest ransomware attacks in history have happened in the past year, affecting most sectors of critical infrastructure in the U.S. such as grain distribution systems in the food and agriculture sector and the Colonial Pipeline, which carries fuel throughout the East Coast, prompting increased military preparation for grid hacks in the U.S.

With this trend in mind, Purdue researchers evaluated the algorithm in the context of various types of critical infrastructure in addition to the power sector, including electricity-sector IoT devices that interface with grid operations. The goal is that the algorithm would help secure any large and complex infrastructure system against cyberattacks.

"Multiple companies own different parts of infrastructure. When ransomware hits, it affects lots of different pieces of technology owned by different providers, so that's what makes ransomware a problem at the state, national and even global level," said Saurabh Bagchi, a professor in the Elmore Family School of Electrical and Computer Engineering and Center for Education and Research in Information Assurance and Security at Purdue. "When you are investing security money on large-scale infrastructures, bad investment decisions can mean your power grid goes out, or your telecommunications network goes out for a few days."

Protecting infrastructure from hacks by improving security investment decisions

The researchers tested the algorithm in simulations of previously reported hacks to four infrastructure systems: a smart grid, industrial control system, e-commerce platform and web-based telecommunications network. They found that use of this algorithm results in the most optimal allocation of security investments for reducing the impact of a cyberattack.

The team's findings appear in a paper presented at this year's IEEE Symposium on Security and Privacy, the premier conference in the area of computer security. The team comprises Purdue professors Shreyas Sundaram and Timothy Cason and former PhD students Mustafa Abdallah and Daniel Woods.

"No one has an infinite security budget. You must decide how much to invest in each of your assets so that you gain a bump in the security of the overall system," Bagchi said.

The power grid, for example, is so interconnected that the security decisions of one power utility company can greatly impact the operations of other electrical plants. If the computers controlling one area's generators don't have adequate security protection, as seen when Russian hackers accessed control rooms at U.S. utilities, then a hack to those computers would disrupt energy flow to another area's generators, forcing them to shut down.

Since not all of the grid's utilities have the same security budget, it can be hard to ensure that critical points of entry to the grid's controls get the most investment in security protection.

The algorithm that Purdue researchers developed would incentivize each security decision maker to allocate security investments in a way that limits the cumulative damage a ransomware attack could cause. An attack on a single generator, for instance, would have less impact than an attack on the controls for a network of generators, which sophisticated grid-disruption malware can target at scale, rather than for the protection of a single generator.

Building an algorithm that considers the effects of human behavior

Bagchi's research shows how to increase cybersecurity in ways that address the interconnected nature of critical infrastructure but don't require an overhaul of the entire infrastructure system to be implemented.

As director of Purdue's Center for Resilient Infrastructures, Systems, and Processes, Bagchi has worked with the U.S. Department of Defense, Northrop Grumman Corp., Intel Corp., Adobe Inc., Google LLC and IBM Corp. on adopting solutions from his research. Bagchi's work has revealed the advantages of establishing an automatic response to attacks, and analyses like Symantec's Dragonfly report highlight energy-sector risks, leading to key innovations against ransomware threats, such as more effective ways to make decisions about backing up data.

There's a compelling reason why incentivizing good security decisions would work, Bagchi said. He and his team designed the algorithm based on findings from the field of behavioral economics, which studies how people make decisions with money.

"Before our work, not much computer security research had been done on how behaviors and biases affect the best defense mechanisms in a system. That's partly because humans are terrible at evaluating risk and an algorithm doesn't have any human biases," Bagchi said. "But for any system of reasonable complexity, decisions about security investments are almost always made with humans in the loop. For our algorithm, we explicitly consider the fact that different participants in an infrastructure system have different biases."

To develop the algorithm, Bagchi's team started by playing a game. They ran a series of experiments analyzing how groups of students chose to protect fake assets with fake investments. As in past studies in behavioral economics, they found that most study participants guessed poorly which assets were the most valuable and should be protected from security attacks. Most study participants also tended to spread out their investments instead of allocating them to one asset even when they were told which asset is the most vulnerable to an attack.

Using these findings, the researchers designed an algorithm that could work two ways: Either security decision makers pay a tax or fine when they make decisions that are less than optimal for the overall security of the system, or security decision makers receive a payment for investing in the most optimal manner.

"Right now, fines are levied as a reactive measure if there is a security incident. Fines or taxes don't have any relationship to the security investments or data of the different operators in critical infrastructure," Bagchi said.

In the researchers' simulations of real-world infrastructure systems, the algorithm successfully minimized the likelihood of losing assets to an attack that would decrease the overall security of the infrastructure system.

Bagchi's research group is working to make the algorithm more scalable and able to adapt to an attacker who may make multiple attempts to hack into a system. The researchers' work on the algorithm is funded by the National Science Foundation, the Wabash Heartland Innovation Network and the Army Research Lab.

Cybersecurity is an area of focus through Purdue's Next Moves, a set of initiatives that works to address some of the greatest technology challenges facing the U.S. Purdue's cybersecurity experts offer insights and assistance to improve the protection of power plants, electrical grids and other critical infrastructure.

 

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Cheap material converts heat to electricity

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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