Go-ahead for 1,000 job plant given

Work From Home Energy Consumption is driving higher electricity bills as residential usage rises. Smart meter data, ISO-New-England trends, and COVID-19 telecommuting show stronger power demand and sensitivity to utility rates across regions.

Key Points

Higher household electricity use from telecommuting, shifting load to residences and raising utility bills.

✅ Smart meters show 5-22 percent residential usage increases.

✅ Commercial demand fell as home cooling and IT loads rose.

✅ Utility rates and AC use drive bill spikes during summer.

Don't be surprised if your electric bills are looking higher than usual, with a sizable increase in the amount of power that you have used.

Summer traditionally is a peak period for electricity usage because of folks' need to run fans and air-conditioners to cool their homes or run that pool pump. But the arrival of the coronavirus and people working from home is adding to amount of power people are using.

Under normal conditions, those who work in their employer's offices might not be cooling their homes as much during the middle of the day or using as much electricity for lights and running computers.

For many, that's changed.

Estimates on how much of an increase residential electric customers are seeing as result of working from home vary widely.

ISO-New England, the regional electric grid operator, has seen a 3 percent to 5 percent decrease in commercial and industrial power demand, even as the grid overseer issued pandemic warnings nationally. The expectation is that much of that decrease translates into a corresponding increase in residential electricity usage.

But other estimates put the increase in residential electricity usage much higher. A Washington state company that makes smart electric meters, Itron, estimates that American households are using 5 percent to 10 percent more electricity per month since March, when many people began working from home as part of an effort to prevent the spread of the coronavirus.

Another smart metering company, Cambridge, Mass.-based Sense, found that average home electricity usage increased 22 percent in April compared to the same period in 2019, a reflection of people using more electricity while they stayed home. Based on its analysis of data from 5,000 homes across 30 states, Sense officials said a typical customer's monthly electric bill increased by between $22 and $25, with a larger increase for consumers in states with higher electricity rates.

Connecticut-specfic data is harder to come by.

Officials with Orange-based United Illuminating declined to provide any customer usage data, though, like others in the power industry, they did acknowledge that residential customers are using more electricity. And the state's other large electric distribution utility, Eversource, was unable to provide any recent data on residential electric usage. The company did tell Connecticut utility regulators there was a 3 percent increase in residential power usage for the week of March 21 compared to the week before.

Over the same time period, Eversource officials saw a 3 percent decrease in power usage by commercial and industrial customers.

Separately, nuclear plant workers raised concerns about pandemic precautions at some facilities, reflecting operational strains.

Alan Behm of Cheshire said he normally uses 597 kilowatt hours of electricity during an average month. But in April of this year, the amount of electricity he used rose by nearly 51 percent.

With many offices closed, the expense of heating, cooking and lighting is being shifted from employer to employee, and some utilities such as Manitoba Hydro have pursued unpaid days off to trim costs during the pandemic. And one remote work expert believes some companies are recognizing the burden those added costs are placing on workers -- and are trying to do something about it.

Technology giant Google announced in late May that it was giving employees who work from home $1,000 allowances to cover equipment costs and other expenses associated with establishing a home office.

Moe Vela, chief transparency officer for the New York City-based computer software company TransparentBusiness, said the move by Google executives is a savvy one.

"Google is very smart to have figured this out," Vela said. "This is what employees want, especially millenials. People are so much happier to be working remotely, getting those two to three hours back per day that some people spend getting to and from work is so much more important than a stipend."

Vela predicted that even after a vaccine is found for the corona virus, one of the key worklife changes is likely to be a broader acceptance of telework and working from home.

Beyond the immediate shifts, more young Canadians would work in electricity if awareness improved, pointing to future talent pipelines.

"I think that's where we're headed," he said. "I think it will make an employer more attractive as they try to attract talent from around the world."

Vela said employers save an average of $11,000 per year for each employee they have working from home.

"It would be a brilliant move if a company were to share some of that amount with employees," he said. "I wouldn't do it if it's going to cause a company to not be there (in business) though."

The idea of a company sharing whatever savings it achieves by having employees work from home wasn't well received by many Connecticut residents who responded to questions posed via social media by Hearst Connecticut Media. More than 100 people responded and an overwhelming number of people spoke out against the idea.

"You are saving on gas and other travel related expenses, so the small increase in your electric bill shouldn't really be a concern," said Kathleen Bennett Charest of Wallingford.

Jim Krupp, also of Wallingford, said, "to suggest that the employers compensate the employees makes as much sense as suggesting that the employees should take a pay cut due to their reduced expenses for travel, day care, and eating lunch at work."

"Employers must still maintain their offices and incur all of the fixed expenses involved, including basic utilities, taxes and insurance," Krupp said. "The cost savings (for employers) that are realized are also offset by increased costs of creating and maintaining IT networks that allow employees to access their work sites from home and the costs of monitoring and managing the work force."

Kiki Nichols Nugent of Cheshire said she was against the idea of an employee trying to get their employer to pay for the increased electricity costs associated with working from home.

"I would not nickle and dime," Nugent said. "If companies are saving on electricity now, maybe employers will give better raises next year."

New Haven resident Chris Smith said he is "just happy to have a job where I am able to telecommute."

"When teleworking becomes more the norm, either now or in the future, we may see increased wages for teleworkers either for the lower cost to the employer or for the increase in productivity it brings," Smith said.

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Solar Plus Storage is accelerating across utilities and microgrids, pairing rooftop solar with lithium-ion batteries to enhance grid resilience, reduce peak costs, prevent blackouts, and leverage tax credits amid falling prices and decarbonization goals.

Key Points

Solar Plus Storage combines solar generation with batteries to shift load, boost reliability, and cut energy costs.

✅ Cuts peak demand charges and enhances blackout resilience

✅ Falling battery and solar costs drive nationwide utility adoption

✅ Enables microgrids and grid services like frequency regulation

Todd Karin was prepared when California’s largest utility shut off power to millions of people to avoid the risk of wildfires last month. He’s got rooftop solar panels connected to a single Tesla Powerwall in his rural home near Fairfield, California. “We had backup power the whole time,” Karin says. “We ran the fridge and watched movies.”

Californians worried about an insecure energy future are increasingly looking to this kind of solution. Karin, a 31-year-old postdoctoral fellow at Lawrence Berkeley National Laboratory, spent just under $4,000 for his battery by taking advantage of tax credits. He's also saving money by discharging the battery on weekday evenings, when energy is more expensive during peak demand periods. He expects to save around $1,500 over the 10 years the battery is under warranty.

The economics don’t yet work for every household, but the green-power combo of solar panels plus batteries is popping up on a much bigger scale in some unexpected places. Owners of a rice processing plant in Arkansas are building a system to generate 26 megawatts of solar power and store another 40 MW. The plant will cut its power bill by a third, and owners say they will pass the savings to local rice growers. New York’s JFK Airport is installing solar plus storage to reduce its power load by 10 percent, while Pittsburgh International Airport is building a 20-MW solar and natural gas microgrid to keep it independent from the local utility. Officials at both airports are worried about recent power shutdowns due to weather and overload-related blackouts.

And residents of the tiny northern Missouri town of Green City (pop. 608) are getting 2.5 MW of solar plus four hours of battery storage from the state’s public utility next year. The solar power won’t go directly to townspeople, but instead will back up the town’s substation, reducing the risk of a potential shutdown. It’s part of a $68 million project to improve the reliability of remote substations far from electric generating stations.

“It’s a pretty big deal for us,” says Chad Raley, who manages technology and renewables at Ameren, a Missouri utility that is building three rural solar-plus-storage projects to better manage the flow of electricity across the local grid. “It gives us so much flexibility with renewable generation. We can’t control the sun or clouds or wind, but we can have battery storage.”

The first solar-plus-storage installations started about a decade ago on a small scale in sunny states like California, Hawaii, and Arizona. Now they’re spreading across the country, driven by falling prices of both solar panels and lithium-ion batteries the size of a shipping container imported from both China and South Korea, with wind, solar, and batteries making up most of the utility-scale pipeline nationwide. These countries have ramped up production efficiencies and lowered labor costs, leaving many US manufacturers in the dust. In fact, the price of building a comparable solar-plus-storage generating facility is now cheaper than operating a coal-fired power plant, industry officials say. In certain circumstances, the cost is equal to some natural gas plants.

“This is not just a California, New York, Massachusetts thing,” says Kelly Speakes-Backman, CEO of the Energy Storage Association, an industry group in Washington. She says more than 30 states have renewable storage on the grid. Utilities have proposed and states have approved 7 gigawatts to be installed by 2030, and most new storage will be paired with solar across the US.

Speakes-Backman estimates the unit cost of electricity produced from a solar-plus-storage system will drop 10 to 15 percent each year through 2024, supporting record growth in solar and storage investments. “If you have the option of putting out a polluting or non-polluting generating source at the same price, what are you going to pick?” says Speakes-Backman.

She notes that PJM, a large Mid-Atlantic wholesale grid operator, announced it will deploy battery storage to help smooth out fluctuating power from two wind farms it operates. “When the grid fluctuates, storage can react to it quickly and can level out the supply,” she says. In the Midwest, grid-level battery storage is also being used to absorb extra wind power. Batteries hold onto the wind and put it back onto the grid when people need it.

While the solar-plus-storage trend isn’t yet putting a huge dent in our fossil fuel use, according to Paul Denholm, an energy analyst at the National Renewable Energy Laboratory in Golden, Colorado, it is a good beginning and has the side effect of cutting air pollution. By 2021, solar and other renewable energy sources will overtake coal as a source of energy, and the US is moving toward 30% electricity from wind and solar, according to a new report by the Institute for Energy Economics and Financial Analysis, a nonprofit think tank based in Cleveland.

That’s a glimmer of hope in a somewhat dreary week of news on carbon emissions. A new United Nations report released this week finds that the planet is on track to warm by 3.9 degrees Celsius (7 Fahrenheit) by 2100 unless drastic cuts are made by phasing out gas-powered cars, eliminating new coal-fired power plants, and changing how we grow and manage land, and scientists are working to improve solar and wind power to limit climate change as well.

Energy-related greenhouse gas emissions in the US rose 2.7 percent in 2018 after several years of decline. The Trump administration has rolled back climate policies from the Obama years, including withdrawing from the Paris climate accords.

There may be hope from green power initiatives outside the Beltway, though, and from federal proposals like a tenfold increase in US solar that could remake the electricity system. Arizona plans to boost solar-plus-storage from today’s 6 MW to a whopping 850 MW by 2025, more than the entire capacity of large-scale batteries in the US today. And some folks might be cheering the closing of the West’s biggest coal-fired power plant, the 2.25-gigawatt Navajo Generating Station, in Arizona, which had spewed soot and carbon dioxide over the region for 45 years until last week. The closure might help the planet and clear the hazy smog over the Grand Canyon.

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Power plant staff sequestration isolates essential operators on-site at plants and control centers, safeguarding critical infrastructure and grid reliability during the COVID-19 pandemic under DHS CISA guidance, with social distancing, offset shifts, and stockpiled supplies.

Key Points

A protocol isolating essential grid workers on-site to maintain operations at plants and control centers.

✅ Ensures grid reliability and continuity of critical infrastructure

✅ Implements social distancing, offset shifts, and isolation protocols

✅ Stockpiles food, beds, PPE, and sanitation for essential crews

The U.S. electric industry may ask essential staff to live on site at power plants and control centers to keep operations running if the coronavirus outbreak worsens, after a U.S. grid warning from the overseer, and has been stockpiling beds, blankets, and food for them, according to industry trade groups and electric cooperatives.

The contingency plans, if enacted, would mark an unprecedented step by power providers to keep their highly-skilled workers healthy as both private industry and governments scramble to minimize the impact of the global pandemic that has infected more than 227,000 people worldwide, with some utilities such as BC Hydro at Site C reporting COVID-19 updates as the situation evolves.

“The focus needs to be on things that keep the lights on and the gas flowing,” said Scott Aaronson, vice president of security and preparedness at the Edison Electric Institute (EEI), the nation’s biggest power industry association. He said that some “companies are already either sequestering a healthy group of their essential employees or are considering doing that and are identifying appropriate protocols to do that.”

Maria Korsnick, president of the Nuclear Energy Institute, said that some of the nation’s nearly 60 nuclear power plants are also “considering measures to isolate a core group to run the plant, stockpiling ready-to-eat meals and disposable tableware, laundry supplies and personal care items.”

Neither group identified specific companies, though nuclear worker concerns have been raised in some cases.

Electric power plants, oil and gas infrastructure and nuclear reactors are considered “critical infrastructure” by the federal government, and utilities continue to emphasize safety near downed lines even during emergencies. The U.S. Department of Homeland Security is charged with coordinating plans to keep them operational during an emergency.

A DHS spokesperson said that its Cybersecurity and Infrastructure Security Agency had issued guidance to local governments and businesses on Thursday asking them to implement policies to protect their critical staff from the virus, even as an EPA telework policy emerged during the pandemic.

“When continuous remote work is not possible, businesses should enlist strategies to reduce the likelihood of spreading the disease,” the guidance stated. “This includes, but is not necessarily limited to, separating staff by off-setting shift hours or days and/or social distancing.”

Public health officials have urged the public to practice social distancing as a preventative measure to slow the spread of the virus, and as more people work from home, rising residential electricity use is being observed alongside daily routines. If workers who are deemed essential still leave, go to work and return to their homes, it puts the people they live with at risk of exposure. 

California has imposed a statewide shutdown, asking all citizens who do not work in those critical infrastructure industries not to leave their homes, a shift that may raise household electricity bills for consumers. Similar actions have been put in place in cities across America.

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Rolls-Royce and Exelon UKSMR Partnership accelerates factory-built small modular reactors, nuclear power, clean energy, 440MW units, advanced manufacturing, fleet deployment, net zero goals, and resilient, low-cost baseload generation in the UK and globally.

Key Points

A partnership to deploy factory-built SMR stations, providing 440MW low-carbon baseload for the UK and export markets.

✅ 440MW factory-built SMR units with rapid modular assembly

✅ Exelon to operate and enhance high capacity factors

✅ Supports UK net zero, jobs, and export-led manufacturing

Rolls-Royce and Exelon Generation have signed a Memorandum of Understanding to pursue the potential for Exelon Generation to operate compact nuclear power stations both in the UK and internationally, including markets such as Canada where New Brunswick SMR questions are prompting public debate today.

Exelon Generation will be using their operational experience to assist Rolls Royce in the development and deployment of the UKSMR.

Rolls-Royce is leading a consortium that is designing a low-cost factory built nuclear power station, known as a small modular reactor (SMR), with UK mini-reactor approval anticipated as development progresses. Its standardised, factory-made components and advanced manufacturing processes push costs down, while the rapid assembly of the modules and components inside a weatherproof canopy on the power station site itself avoid costly schedule disruptions.

The consortium is working with its partners and UK Government to secure a commitment for a fleet of factory built nuclear power stations, each providing 440MW of electricity, to be operational within a decade, helping the UK meet its net zero obligations in line with the green industrial revolution policy set out by government. A fleet deployment in the UK will lead to the creation of new factories that will make the components and modules which will help the economy recover from the Covid-19 pandemic and pave the way for significant export opportunities as well.

The consortium members feature the best of nuclear engineering, construction and infrastructure expertise in Assystem, Atkins, BAM Nuttall, Jacobs, Laing O'Rourke, National Nuclear Laboratory, Nuclear Advanced Manufacturing Research Centre, Rolls-Royce and TWI. Exelon will add valuable operational experience to the team.

Tom Samson, interim Chief Executive Officer of the UKSMR consortium, said: 'Nuclear power is central to tackling climate change and economic recovery, but it must be affordable, reliable and investable and the way we manufacture and assemble our power station brings its cost down to be comparable with offshore wind.

'It's a compelling proposition that could draw new players into the UK's power generation landscape, improving choice for consumers and providing uninterrupted low carbon energy to homes and businesses.

'The opportunity to partner with Exelon is a very exciting prospect for our program, complementing our existing Consortium partnerships with one of the world's largest nuclear operator adds an important dimension to our growth ambitions, embodies the strength of the UK and USA alliance on nuclear matters and reflects wider international moves, such as a Canadian premiers' SMR initiative to accelerate technology development, and offers our future customers the ability to achieve the highest performance standards associated with Exelon's outstanding operational track record.'

The power stations will be built by the UKSMR consortium, before being handed over to be operated by power generation companies. Exelon Generation will work closely with the consortium during the pre-operation period. Exelon Nuclear operates 21 nuclear reactors in America, and U.S. regulators recently issued a final safety evaluation for a NuScale SMR that underscores momentum in the sector. The Exelon nuclear fleet is an integral part of the U.S. clean power mix; it produces more than 158 million megawatt-hours of clean electricity every year.

Bryan Hanson, EVP and COO of Exelon Generation said: 'We believe that SMRs are a crucial part of the world's clean energy mix, as projects like Darlington SMRs advance in Ontario. With our experience both in the US and internationally, Exelon is confident that we can help Rolls Royce ensure SMRs play a key role in the UK's energy future. We've had a very strong record of performance for 20 consecutive years, with a 2019 capacity factor of 95.7 percent. We will leverage this experience to achieve sustainably high capacity factors for the UKSMRs.'

Ralph Hunter, Managing Director of Exelon Nuclear Partners, who runs Exelon's international clean energy business, said: 'We have a strong track record of success to be the operator of choice for the UKSMR. We will help develop operational capability, training and human capacity development in the UK, as utilities such as Ontario Power Generation commit to SMRs abroad, ensuring localisation of skills and a strong culture of safety, performance and efficiency.'

By 2050 a full UK programme of a fleet of factory built nuclear power stations in the UK could create:

Up to 40,000 jobs GBP52BN of value to the UK economy GBP250BN of exports

The current phase of the programme has been jointly funded by all consortium members and UK Research and Innovation.

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2040 Energy Outlook projects a shifting energy mix as renewables scale, EV adoption accelerates, and IEA forecasts plateauing oil demand alongside rising natural gas, highlighting policy, efficiency, and decarbonization trends that shape global consumption.

Key Points

A data-driven view of future energy mix, covering renewables, fossil fuels, EVs, oil demand, and policy impacts.

✅ Renewables reach 16-30% by 2040, higher with strong policy support.

✅ Fossil fuels remain dominant, with oil flat and natural gas rising.

✅ EV share surges, cutting oil use; efficiency curbs demand growth.

Which is more plausible: flying taxis, wind turbine arrays stretching miles into the ocean, and a solar roof on every house--or a scorched-earth, flooded post-Apocalyptic world? 

We have no way of peeking into the future, but we can certainly imagine it. There is plenty of information about where the world is headed and regardless of how reliable this information is—or isn’t—we never stop wondering. Will the energy world of 20 years from now be better or worse than the world we live in now? 

The answer may very well lie in the observable trends.

A Growing Population

The global population is growing, and it will continue to grow in the next two decades. This will drive a steady growth in energy demand, at about 1 percent per year, according to the International Energy Agency.

This modest rate of growth is good news for all who are concerned about the future of the planet. Parts of the world are trying to reduce their energy consumption, and this should have a positive effect on the carbon footprint of humanity. The energy thirst of most parts of the world will continue growing, however, hence the overall growth.

The world’s population is currently growing at a rate of a little over 1 percent annually. This rate of growth has been slowing since its peak in the 1960s and forecasts suggest that it will continue to slow. Growth in energy demand, on the other hand, may at some point stop moving in tune with population growth trends as affluence in some parts of the world grows. The richer people get, the more energy they need. So, to the big question: where will this energy come from?

The Rise of Renewables

For all the headline space they have been claiming, it may come as a disappointing surprise to many that renewable energy, excluding hydropower, to date accounts for just 14 percent of the global primary energy mix. 

Certainly, adoption of solar and wind energy has been growing in leaps and bounds, with their global share doubling in five years in many markets, but unless governments around the world commit a lot more money and effort to renewable energy, by 2040, solar and wind’s share in the energy mix will still only rise to about 16 to 17 percent. That’s according to the only comprehensive report on the future of energy that collates data from all the leading energy authorities in the world, by non-profit Resources for the Future.

The growth in renewables adoption, however, would be a lot more impressive if governments do make serious commitments. Under that scenario, the share of renewables will double to over 30 percent by 2040, echoing milestones like over 30% of global electricity reached recently: that’s the median rate of all authoritative forecasts. Amongst them, the adoption rates of renewables vary between 15 percent and 61 percent by 2040.

Even the most bullish of the forecasts on renewables is still far below the 100-percent renewable future many would like to fantasize about, although BNEF’s 50% by 2050 outlook points to what could be possible in the power sector. 

But in 2040, most of the world’s energy will still come from fossil fuels.

EV Energy

Here, forecasters are more optimistic. Again, there is a wide variation between forecasts, but in each and every one of them the share of electric vehicles on the world’s roads in 2040 is a lot higher than the meagre 1 percent of the global car fleet EVs constitute today.
Related: Gas Prices Languish As Storage Falls To Near-Record Lows

Government policy will be the key, as U.S. progress toward 30% wind and solar shows how policy steers the power mix that EVs ultimately depend on. Bans of internal combustion engines will go a long way toward boosting EV adoption, which is why some forecasters expect electric cars to come to account for more than 50 percent of cars on the road in 2040. Others, however, are more guarded in their forecasts, seeing their share of the global fleet at between 16 percent and a little over 40 percent.

Many pin their hopes for a less emission-intensive future on electric cars. Indeed, as the number of EVs rises, they displace ICE vehicles and, respectively, the emission-causing oil that fuels for ICE cars are made from.  It should be a no brainer that the more EVs we drive, the less emissions we produce. Unfortunately, this is not necessarily the case: China is the world’s biggest EV market, and its solar PV expansion has been rapid, it has the most EVs—including passenger cars and buses—but it is also one of the biggest emitters.

Still, by 2040, if the more optimistic forecasts come true, the world will be consuming less oil than it is consuming now: anywhere from 1.2 million bpd to 20 million bpd less, the latter case envisaging an all-electric global fleet in 2040. 

This Ain’t Your Daddy’s Oil

No, it ain’t. It’s your grandchildren’s oil, for good or for bad. The vision of an oil-free world where renewable power is both abundant and cheap enough to replace all the ways in which crude oil and natural gas are used will in 2040 still be just that--a vision, with practical U.S. grid constraints underscoring the challenges. Even the most optimistic energy scenarios for two decades from now see them as the dominant source of energy, with forecasts ranging between 60 percent and 79 percent. While these extremes are both below the over-80 percent share fossil fuels have in the world’s energy mix, they are well above 50 percent, and in the U.S. renewables are projected to reach about one-fourth of electricity soon, even as fossil fuels remain foundational.

Still, there is good news. Fuel efficiency alone will reduce oil demand significantly by 2040. In fact, according to the IEA, demand will plateau at a little over 100 million bpd by the mid-2030s. Combined with the influx of EVs many expect, the world of 20 years from now may indeed be consuming a lot less oil than the world of today. It will, however, likely consume a lot more natural gas. There is simply no way around fossil fuels, not yet. Unless a miracle of politics happens (complete with a ripple effect that will cost millions of people their jobs) in 2040 we will be as dependent on oil and gas as we are but we will hopefully breathe cleaner air.

By Irina Slav for Oilprice.com

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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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