Power plant idea counts on big break

Switch-On Project Electric Trucks accelerate California freight decarbonization, deploying Volvo VNR Electric rigs with high-capacity charging infrastructure, zero-emissions operations, and connected safety features to cut greenhouse gases and improve urban air quality.

Key Points

A California program deploying Volvo VNR Electric trucks and charging to decarbonize freight and improve air quality.

✅ 70 Volvo VNR Electric trucks for regional logistics

✅ Strategic high-capacity charging for heavy-duty fleets

✅ Lower TCO via fuel savings and reduced maintenance

In a significant step toward sustainable transportation, the Switch-On project is bringing 70 Volvo VNR Electric trucks to California. This initiative aims to bolster the state's efforts to reduce emissions and transition to greener logistics solutions. The arrival of these electric vehicles marks an important milestone in California's commitment to combating climate change and improving air quality.

The Switch-On Project: Overview and Goals

The Switch-On project is a collaborative effort designed to enhance electric truck adoption in California. It focuses on developing the necessary infrastructure and technology to support electric vehicles (EVs) in the freight and logistics sectors, building on recent nonprofit investments at California ports. The project not only seeks to increase the availability of electric trucks but also aims to demonstrate their effectiveness in real-world applications.

California has set ambitious goals for reducing greenhouse gas emissions, particularly from the transportation sector, which is one of the largest contributors to air pollution. By introducing electric trucks into freight operations, the state aims to significantly cut emissions, improve public health, and pave the way for a more sustainable future.

The Volvo VNR Electric Trucks

The Volvo VNR Electric trucks are specifically designed for regional distribution and urban transport, aligning with Volvo's broader electric lineup as the company expands offerings, making them ideal for the needs of California’s freight industry. With a range of approximately 250 miles on a single charge, these trucks can efficiently handle most regional routes. Equipped with advanced technology, including regenerative braking and connectivity features, the VNR Electric models enhance operational efficiency and safety.

These trucks not only provide a cleaner alternative to traditional diesel vehicles but also promise lower operational costs over time. With reduced fuel expenses and lower maintenance needs, and emerging vehicle-to-grid pilots that can create new value streams, businesses can benefit from significant savings while contributing to environmental sustainability.

Infrastructure Development

A crucial aspect of the Switch-On project is the development of charging infrastructure to support the new fleet of electric trucks. The project partners are working on installing high-capacity charging stations strategically located throughout California while addressing utility planning challenges that large fleets will pose to the power system. This infrastructure is essential to ensure that electric trucks can be charged efficiently, minimizing downtime and maximizing productivity.

The charging stations are designed to accommodate the specific needs of heavy-duty vehicles, and corridor models like BC's Electric Highway provide useful precedents for network design, allowing for rapid charging that aligns with operational schedules. This development not only supports the new fleet but also encourages other logistics companies to consider electric trucks as a viable option for their operations.

Benefits to California

The introduction of 70 Volvo VNR Electric trucks will have several positive impacts on California. Firstly, it will significantly reduce greenhouse gas emissions from the freight sector, contributing to the state’s ambitious climate goals even as grid expansion will be needed to support widespread electrification across sectors. The transition to electric trucks is expected to improve air quality, particularly in urban areas that struggle with high pollution levels.

Moreover, the project serves as a model for other regions considering similar initiatives. By showcasing the practicality and benefits of electric trucks, California hopes to inspire widespread adoption across the nation. As the market for electric vehicles continues to grow, this project can play a pivotal role in accelerating the transition to sustainable transportation solutions.

Industry and Community Reactions

The arrival of the Volvo VNR Electric trucks has been met with enthusiasm from both industry stakeholders and community members. Logistics companies are excited about the opportunity to reduce their carbon footprints and operational costs. Meanwhile, environmental advocates applaud the project as a crucial step toward cleaner air and healthier communities.

California’s commitment to sustainable transportation has positioned it as a leader in the shift to electric vehicles amid an ongoing biofuels vs. EVs debate over the best path forward, setting an example for other states and countries.

Conclusion

The Switch-On project represents a major advancement in California's efforts to transition to electric transportation. With the deployment of 70 Volvo VNR Electric trucks, the state is not only taking a significant step toward reducing emissions but also demonstrating the feasibility of electric logistics solutions.

As infrastructure develops and more electric trucks hit the roads, California is paving the way for a greener, more sustainable future in transportation. The success of this project could have far-reaching implications, influencing policies and practices in the broader freight industry and beyond.

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Germany 2025 Energy Costs forecast electricity and heating price trends amid gas volatility, renewables expansion, grid upgrades, and policy subsidies, highlighting impacts on households, industries, efficiency measures, and the Energiewende transition dynamics.

Key Points

Electricity stabilizes, gas-driven heating stays high; renewables, subsidies, and efficiency measures moderate costs.

✅ Power prices stabilize above pre-crisis levels

✅ Gas volatility keeps heating bills elevated

✅ Subsidies and efficiency upgrades offset some costs

As Germany moves into 2025, the country is facing significant shifts in heating and electricity costs. With a variety of factors influencing energy prices, including geopolitical tensions, government policies, and the ongoing transition to renewable energy sources, consumers and businesses alike are bracing for potential changes in their energy bills. In this article, we will explore how heating and electricity costs are expected to evolve in Germany in the coming year and what that means for households and industries.

Energy Price Trends in Germany

In recent years, energy prices in Germany have experienced notable fluctuations, particularly due to the aftermath of the global energy crisis, which was exacerbated by the Russian invasion of Ukraine. This geopolitical shift disrupted gas supplies, which in turn affected electricity prices and strained local utilities across the country. Although the German government introduced measures to mitigate some of the price increases, many households have still felt the strain of higher energy costs.

For 2024, experts predict that electricity prices will likely stabilize but remain higher than pre-crisis levels. While electricity prices nearly doubled in 2022, they have gradually started to decline, and the market has adjusted to the new realities of energy supply and demand. Despite this, the cost of electricity is expected to stay elevated as Germany continues to phase out coal and nuclear energy while ramping up the use of renewable sources, which often require significant infrastructure investments.

Heating Costs: A Mixed Outlook

Heating costs in Germany are heavily influenced by natural gas prices, which have been volatile since the onset of the energy crisis. Gas prices, although lower than the peak levels seen in 2022, are still considerably higher than in the years before. This means that households relying on gas heating can expect to pay more for warmth in 2024 compared to previous years.

The government has implemented measures to cushion the impact of these increased costs, such as subsidies for vulnerable households and efforts to support energy efficiency upgrades. Despite these efforts, consumers will still feel the pinch, particularly in homes that use older, less efficient heating systems. The transition to more sustainable heating solutions, such as heat pumps, remains a key goal for the German government. However, the upfront cost of such systems can be a barrier for many households.

The Role of Renewable Energy and the Green Transition

Germany has set ambitious goals for its energy transition, known as the "Energiewende," which aims to reduce reliance on fossil fuels and increase the share of renewable energy sources in the national grid. In 2024, Germany is expected to see further increases in renewable energy generation, particularly from wind and solar power. While this transition is essential for reducing carbon emissions and improving long-term energy security, the shift comes with its own challenges already documented in EU electricity market trends reports.

One of the main factors influencing electricity costs in the short term is the intermittency of renewable energy sources. Wind and solar power are not always available when demand peaks, requiring backup power generation from fossil fuels or stored energy. Additionally, the infrastructure needed to accommodate a higher share of renewables, including grid upgrades and energy storage solutions, is costly and will likely contribute to rising electricity prices in the near term.

On a positive note, Germany's growing investment in renewable energy is expected to make the country less reliant on imported fossil fuels, particularly natural gas, which has been a major source of price volatility. Over time, as the share of renewables in the energy mix grows, the energy system should become more stable and less susceptible to geopolitical shocks, which could lead to more predictable and potentially lower energy costs in the long run.

Government Interventions and Subsidies

To help ease the burden on consumers, the German government has continued to implement various measures to support households and businesses. One of the key programs is the reduction in VAT (Value Added Tax) on electricity, which has been extended in some regions. This measure is designed to make electricity more affordable for all households, particularly those on fixed incomes facing EU energy inflation pressures that have hit the poorest hardest.

Moreover, the government has been providing financial incentives for households and businesses to invest in energy-efficient technologies, such as insulation and energy-saving heating systems, complementing the earlier 200 billion euro energy shield announced to buffer surging prices. These incentives are intended to reduce overall energy consumption, which could offset some of the rising costs.

The outlook for heating and electricity costs in Germany for 2024 is mixed, even as energy demand hit a historic low amid economic stagnation. While some relief from the extreme price spikes of 2022 may be felt, energy costs will still be higher than they were in previous years. Households relying on gas heating will likely see continued elevated costs, although those who invest in energy-efficient solutions or renewable heating technologies may be able to offset some of the increases. Similarly, electricity prices are expected to stabilize but remain high due to the country’s ongoing transition to renewable energy sources.

While the green transition is crucial for long-term sustainability, consumers must be prepared for potentially higher energy costs in the short term. Government subsidies and incentives will help alleviate some of the financial pressure, but households should consider strategies to reduce energy consumption, such as investing in more efficient heating systems or adopting renewable energy solutions like solar panels.

As Germany navigates these changes, the country’s energy future will undoubtedly be shaped by a delicate balance between environmental goals and the economic realities of transitioning to a greener energy system.

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TVA Rates and Renewable Energy Scrutiny spotlights electricity rates, distributed energy resources, solar and wind deployment, natural gas plans, grid access charges, energy efficiency cuts, and House oversight of lobbying, FERC inquiries, and least-cost planning.

Key Points

A congressional probe into TVA pricing and practices affecting renewables, energy efficiency, and climate goals.

✅ House panel probes TVA rates, DER and solar policies.

✅ Efficiency programs cut; least-cost planning questioned.

✅ Inquiry on lobbying, hidden fees; FERC scrutiny.

The Tennessee Valley Authority is facing federal scrutiny about its electricity rates and climate action, amid ongoing debates over network profits in other markets.

Members of the House Committee on Energy and Commerce are “requesting information” from TVA about its ratepayer bills and “out of concern” that TVA is interfering with the deployment of renewable and distributed energy resources, even as companies such as Tesla explore electricity retail to expand customer options.

“The Committee is concerned that TVA’s business practices are inconsistent with these statutory requirements to the disadvantage of TVA’s ratepayers and the environment,” the committee said in a letter to TVA CEO Jeffrey Lyash.

The four committee members — U.S. Reps. Frank Pallone, Jr. (D-NJ), Bobby L. Rush (D-IL), Diana DeGette (D-CO), and Paul Tonko (D-NY) — suggested that Tennessee Valley residents pay too much for electricity despite TVA’s relatively low rates, even as regulators have, in other cases, scrutinized mergers like the Hydro One-Avista deal to safeguard ratepayers, underscoring similar concerns. In 2020, Tennessee residents had electric bills higher than the national average, while low-income residents in Memphis have historically faced one of the highest energy burdens in the U.S.

In 2018, TVA reduced its wholesale rate while adding a grid access charge on local power companies—and interfered with the adoption of solar energy. Internal TVA documents obtained through a Freedom of Information Act request by the Energy and Policy Institute revealed that TVA permitted local power companies to impose new fees on distributed solar generation to “lessen the potential decrease in TVA load that may occur through the adoption of [behind the meter] generation.”

Additionally, the committee said TVA is not prioritizing energy conservation and efficiency or “least-cost planning” that includes renewables, as seen in oversight such as the OEB's Hydro One rates decision emphasizing cost allocation. TVA reduced its energy efficiency programs by nearly two-thirds between 2014 and 2018 and cut its energy efficiency customer incentive programs.

At this time, TVA has not aligned its long-term planning with the Biden administration’s goal to achieve a carbon-free electricity sector by 2035. TVA’s generation mix, which is roughly 60% carbon-free, comprises 39% nuclear, 19% coal, 26% natural gas, 11% hydro, 3% wind and solar, and 1% energy efficiency programs, according to TVA.

The committee is “greatly concerned that TVA has invested comparatively little to date in deploying solar and wind energy, while at the same time considering investments in new natural gas generation.”

TVA has announced plans to shutter the Kingston and Cumberland coal plants and is evaluating whether to replace this generation with natural gas, which is a fossil fuel, while debates over grid privatization raise questions about consumer benefits. TVA’s coal and natural gas plants represent most of the largest sources of greenhouses emissions in Tennessee.

TVA responded with a statement without directly addressing the committee’s concerns. TVA said its “developing and implementing emerging technologies to drive toward net-zero emissions by 2050.”

The final question that the House committee posed is whether TVA is funding any political activity. In 2019, the committee questioned TVA about its membership to the now-disbanded Utility Air Regulatory Group, a coalition that was involved in over 200 lawsuits that primarily fought Clear Air Act regulations.

TVA revealed that it had contributed $7.3 million to the industry lobbying group since 2001. Since TVA doesn’t have shareholders, customers paid for UARG membership fees, echoing findings that deferred utility costs burden customers in other jurisdictions. An Office of the Inspector General investigation couldn’t prove whether TVA’s contributions directly funded litigation because UARG didn’t have a line-by-line accounting of what they did with TVA’s dollars.

The congressional committee questioned whether TVA is still paying for lobbying or litigation that opposes “public health and welfare regulations.”

This last question follows a recent trend of questioning utilities about “hidden fees.” In December, the Federal Energy Regulatory Commission issued a Notice of Inquiry to examine how bills from investor-owned utilities might contain fees that fund political activity, and regulators have penalized firms like NT Power over customer notice practices, highlighting consumer protection. The Center for Biological Diversity filed a petition to protect electric and gas customers of investor-owned utilities from paying these fees, which may be used for lobbying, campaign-related donations and litigation.

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UK Energy Price Guarantee Cost forecasts from Cornwall Insight suggest an £89bn bill, tied to wholesale gas prices, OBR projections, and fiscal policy, to shield households amid the cost of living crisis.

Key Points

It is the projected government spend to cap household bills, driven by wholesale gas prices and OBR market forecasts.

✅ Base case: £89bn over two years, per Cornwall Insight

✅ Range: £72bn to £140bn, volatile wholesale gas costs

✅ Excludes 6-month business support estimated at £22bn-£48bn

Liz Truss’s intervention to freeze energy prices for households for two years is expected to cost the government £89bn, according to the first major costing of the policy by the sector’s leading consultancy.

The analysis from Cornwall Insight, seen exclusively by the Guardian, shows the prime minister’s plan to tackle the cost of living crisis could cost as much as £140bn in a worst-case scenario.

Truss announced in early September that the average annual bill for a typical household would be capped at £2,500 to protect consumers from the intensifying cost of living crisis amid high winter energy costs and a scheduled 80% rise in the cap to £3,549.

The ultimate cost of the policy is uncertain as it is highly dependent on the wholesale cost of gas, including UK natural gas prices which have soared since Russia’s invasion of Ukraine put a squeeze on already-volatile international markets. Ballpark projections had put the cost anywhere from £100bn to £150bn.

The Office for Budget Responsibility is expected to give its forecast for the bill when it provides its independent assessment of Kwasi Kwarteng’s medium-term fiscal plan, which the chancellor said on Tuesday would still happen on 23 November despite previous reports that it would be brought forward.

Cornwall Insight analysed projections of wholesale market moves to cost the intervention. In its base case scenario, analysts expect the policy to cost £89bn. That assumes the cost of supporting each household would be just over £1,000 in the first year, and about £2,000 in the second year.

The study’s authors said the wholesale price of gas would be influenced by energy demand, the severity of weather, “geo-political uncertainty” and prices for liquified natural gas as Europe seeks to refill storage facilities, which countries have rushed to fill up this winter but which could be relatively empty by next spring.

In the best-case outcome, the policy would cost £72bn, with some projections pointing to a 16% decrease in energy bills in April for households, while the “extreme high” outlook would see the government shell out £140bn to protect 29m UK households.

Gas prices are expected to push even higher if the Kremlin decides to completely cut off Russian gas exports into Europe.

Cornwall Insight’s projection does not include a separate six-month initiative to cap costs for companies, charities and public sector organisations, which is forecast to cost £22bn to £48bn.

The consultancy’s chief executive, Gareth Miller, said the £70bn range in its forecasts reflected “a febrile wholesale market continuing to be beset by geopolitical instability, sensitivity to demand, weather and infrastructure resilience”.

He said: “Fortune befriends the bold, but it also favours the prepared. The large uncertainties around commodity markets over the next two years means that the government could get lucky with costs coming out at the low end of the range, but the opposite could also be true.

“In each case, the government may find itself passengers to circumstances outside its control, having made policy that is a hostage to surprises, events and volatile factors. That’s a difficult position to be in.”

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The government has faced criticism, as some British MPs urge tighter limits on prices, that the policy is effectively a “blank cheque” and is not targeted at the most vulnerable in society.

Concerns over how Truss and Kwarteng intend to fund a series of measures, including the price guarantee, have spooked financial markets.

The EU, which has outlined possible gas price cap strategies in recent proposals, said last week it planned to cap the revenues of low-carbon electricity generators at €180 a megawatt hour, which is less than half current market prices. Truss has so far resisted calls to extend a levy on North Sea oil and gas operators to electricity generators, who have benefited from a link between gas and electricity prices in Britain.

Truss hopes to strike voluntary long-term deals with generators including Centrica and EDF, alongside the government’s Energy Security Bill measures, to bring down wholesale prices.

The Financial Times reported on Tuesday that the government has threatened companies with legislation to cap their revenues if voluntary deals cannot be agreed.

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Texas Power Grid Crisis strains ERCOT as extreme cold, ice storms, and heavy snow trigger rolling blackouts, load shedding, and boil-water notices, leaving millions without electricity while frozen turbines and low gas pressure hinder generation.

Key Points

A statewide emergency of outages and boil-water notices as ERCOT battles extreme cold and load shedding.

✅ Millions without power; ERCOT orders load shedding

✅ Boil-water notices in Austin, Houston, Fort Worth

✅ Frozen equipment, low gas pressure, extreme cold disrupt supply

Nearly 3 million homes and businesses in Texas remain without power, some for a third consecutive day, as severe winter weather continues to pummel the state, forcing some localities to issue boil-water notices and urge residents to reduce their electricity usage.

Heavy snowfall, ice storms and bitter temperatures continue to put an enormous strain on the state's power grid. This as the Electric Reliability Council of Texas (ERCOT), which manages roughly 75% of the Texas power grid, announced Wednesday morning that some 600,000 households had power restored overnight.

That still left another 2.7 million customers having to endure extreme cold with no indication of when the thaw would break in their homes.

"We know millions of people are suffering," ERCOT's president and CEO, Bill Magness, said in a statement Wednesday. "We have no other priority than getting them electricity. No other priority."

ERCOT also said Wednesday that it was urging local utilities to shed some 14,000 megawatts of load, which translates to roughly 2.8 million customers, to prepare for a sudden increase in demand.

"The ability to restore more power is contingent on more generation coming back online," said Dan Woodfin, the senior director of ERCOT's system operations, and utility supply-chain constraints can further complicate repair timelines for some utilities.

He said that about 185 generating units were offline, stemming from a range of factors including frozen wind turbines, low gas pressure and frozen instrumentation.

But many Texans feel abandoned by the council and power companies and they are lashing out at the local face of utilities.

The City of Austin's community-owned electric utility, Austin Energy, issued a tweet saying crews that are working to restore power are facing harassment.

"Our crews have been working 24/7 and in these elements," Austin Energy announced. "Some of our crews are reporting incidents of harassment, threatening them and even throwing things at them."

Officials pleaded with the public to remain calm. "I know people are extremely frustrated. But please, I bet of you, do not approach AE crews."

Parts of Austin are under a boil water notice, which Austin Water Director Greg Meszaros attempted to explain during a press briefing Wednesday afternoon.

"There was a large main break in that area, maybe multiple ones. We're seeing main breaks and pipes bursting by the tens of thousands. Our entire system is under stress," Meszaros said.

It's not just the Lone Star State that is being crippled by the arctic blast, with a deep freeze slamming the energy sector across the country.

At least two dozen people have died this week from weather-related incidents, according to The Associated Press.

The National Weather Service reports that more than 100 million Americans are being affected by extreme winter weather from the south central U.S. to the East Coast, including Arkansas, Louisiana, Mississippi, North Carolina, Virginia and West Virginia, and analysts warn of blackout risks nationwide during extreme heat as well.

The National Weather Service adds that cold temperatures over the nation's heartland will begin to "moderate in the coming days" but that many parts will remain 20 to 35 degrees below normal in the Great Plains, Mississippi Valley and lower Great Lakes region.

"Potential is increasing for significant icing across portions of the Mid-Atlantic, which will be very impactful, especially for those hardest hit from the previous ice storm," the National Weather Service tweeted Wednesday.

Texas Gov. Greg Abbott railed against ERCOT, and Elon Musk criticized the agency as unreliable, saying the utility "has been anything but reliable over the past 48 hours."

"This is unacceptable," Abbott added, as residents were facing rotating intentional power outages. The governor issued an executive order that will add reforms for how the power grid is managed, including grid reliability improvements under discussion, as an emergency legislative item for the state legislature to review.

The rolling power outages forced Fort Worth to extend a boil-water notice for roughly 212,000 residents. Officials said the outages affected the city's systems that both treat water and move it to customers.

Fort Worth officials said nine other localities that purchase water from the city are also affected, including Haslet, Keller, Lake Worth and Northlake.

Officials in Houston also issued a boil-water notice for the city's residents Wednesday.

"Do not drink the water without boiling it first," Houston Public Works said from its official Twitter account. "Bring all water to a boil for at least two minutes. Let it cool before using."

In Harris County, which includes Houston, Judge Lina Hidalgo warned residents about extended power outages.

"Let me give it to you straight, based on the visibility I have: Whether you have power or not right now, there is a possibility of power outages even beyond the length of this weather," Hidalgo said, according to Houston Public Media.

The NPR member station adds that county officials have also reported more than 300 cases of carbon monoxide poisoning since Monday as residents going without electricity search desperately for alternative sources of warmth.

"In no uncertain terms, this is a public health disaster and a public health emergency," Samuel Prater, an emergency physician at Memorial Hermann-Texas Medical Center, said at a news briefing Tuesday.

Prater warned residents that over the last 24 hours, emergency officials "have seen a striking increase in the number of cases related to improper heating sources," including indoor use of generators, charcoal grills, campfire stoves and other devices that are being used to warm homes. The result, he added, is carbon monoxide poisoning of entire families.

"If you think you or a loved one has become ill from carbon monoxide poisoning, first thing you need to do is get outside to fresh air," Prater said.

A woman and an 8-year-old girl are among those who have reportedly died from carbon monoxide poisoning after a vehicle was left running inside a garage in an attempt to generate heat, according to Houston's ABC affiliate.

As Texas endures further weather-related issues, including road and highway closures, there's a renewed focus on how the Texas power grid has failed, and why the grid is facing another crisis amid this prolonged cold.

The Texas electrical grid is "facing conditions that it was not designed for," said Emily Grubert, a professor at Georgia Tech whose expertise includes electric networks.

"These are really extreme conditions for the Texas grid. It's very cold. It's cold across the entire state, and it's cold for a long time. This does not happen very often," she said in an interview with NPR's Morning Edition.

"Demand really spiked both in the electricity and the natural gas systems at the same time as a lot of the generators were not able to operate because of those cold conditions, and not being prepared for it is really what's going on," Grubert said. "But a lot of grids are susceptible to really, really major failures when they are this far outside of design conditions."

Abbott told Fox News on Tuesday that with weather-related shutdowns in wind and solar energy, which account for more than 10% of the state's grid, renewable energy is partly to blame for the Texas power crisis, even as he later touted the grid's readiness heading into the fall.

"It just shows that fossil fuel is necessary for the state of Texas as well as other states to make sure that we'll be able to heat our homes in the wintertime and cool our homes in the summertime," Abbott said.

But Grubert said that "coal, gas and nuclear actually shut down because of the extreme cold due to things like instruments freezing, et cetera. So I think the overall point here is all of the fuels were really, really struggling."

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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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