LifeVillage demonstration project planned in Cote dÂ’Ivoire

U.S. Offshore Wind Capacity is set to exceed 1 GW by 2024, driven by BOEM approvals, federal leases, and resilient supply chains, with eastern states scaling renewable energy, turbines, and content despite COVID-19 disruptions.

Key Points

Projected gigawatt-scale offshore wind growth enabled by BOEM approvals, federal leases, and East Coast state demand.

✅ 17+ GW leased; only 1,870 MW in announced first phases.

✅ BOEM approvals are critical to reach >1 GW by 2024.

✅ Local supply chains mitigate COVID-19 impacts and lower costs.

Offshore wind in the U.S. will exceed 1 GW of capacity by 2024 and add more than 1 GW annually by 2027, a trajectory consistent with U.S. offshore wind power trends, according to a report released last week by Navigant Research.

The report calculated over 17 GW of offshore state and federal leases for wind production, reflecting forecasts that $1 trillion offshore wind market growth is possible. However, the owners of those leases have only announced first phase plans for 1,870 MW of capacity, leaving much of the projects in early stages with significant room to grow, according to senior research analyst Jesse Broehl.

The Business Network for Offshore Wind (BNOW) believes it is possible to hit 1 GW by 2023-24, according to CEO Liz Burdock. While the economy has taken a hit from the coronavirus pandemic, she said the offshore wind industry can continue growing as "the supply chain from Asia and Europe regains speed this summer, and the administration starts clearing" plans of construction.

BNOW is concerned with the economic hardship imposed on secondary and tertiary U.S. suppliers due to the global spread of COVID-19.

Offshore wind has been touted by many eastern states and governors as an opportunity to create jobs, with U.S. wind employment expected to expand, according to industry forecasts. Analysts see the growing momentum of projects as a way to further lower costs by creating a local supply chain, which could be jeopardized by a long-term shutdown and recession.

"The federal government must act now — today, not in December — and approve project construction and operation plans," a recent BNOW report said. Approving any of the seven projects before BOEM, which has recently received new lease requests, currently would allow small businesses to get to work "following the containment of the coronavirus," but approval of the projects next year "may be too late to keep them solvent."

The prospects for maintaining momentum in the industry falls largely to the Department of the Interior's Bureau of Ocean Energy Management (BOEM). The industry cannot hit the 1 GW milestone without project approvals by BOEM, which is revising processes to analyze federal permit applications in the context of "greater build out of offshore wind capacity," according to its website.

"It is heavily dependent on the project approval success," Burdock told Utility Dive.

Currently, seven projects are awaiting determinations from BOEM on their construction operation plans in Massachusetts, New York, where a major offshore wind farm was recently approved, New Jersey and Maryland, with more to be added soon, a BNOW spokesperson told Utility Dive.

To date, only one project has received BOEM approval for development in federal waters, a 12 MW pilot by Dominion Energy and Ørsted in Virginia. The two-turbine project is a stepping stone to a commercial-scale 2.6 GW project the companies say could begin installation as soon as 2024, and gave the developers experience with the permitting process.

In the U.S., developers have the capacity to develop 16.9 GW of offshore wind in federal U.S. lease areas, even as wind power's share of the electricity mix surges nationwide, Broehl told Utility Dive, but much of that is in early stages. The Navigant report did not address any impacts of coronavirus on offshore wind, he said.

Although Massachusetts has legislation in place to require utilities to purchase 1.6 GW of wind power by 2026, and several other projects are in early development stages, Navigant expects the first large offshore wind projects in the U.S. (exceeding 200 MW) will come online in 2022 or later, and the first projects with 400 MW or more capacity are likely to be built by 2024-2025, and lessons from the U.K.'s experience could help accelerate timelines. The U.S. would add about 1.2 GW in 2027, Broehl said.

The federal leasing activities along with the involvement from Eastern states and utilities "virtually guarantees that a large offshore wind market is going to take off in the U.S.," Broehl said.

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Alberta Electricity Rate Cap stays despite carbon tax repeal, keeping the Regulated Rate Option at 6.8 cents/kWh. Levy funds cover market gaps as the UCP reviews NDP policies to maintain affordable utility bills.

Key Points

Program capping RRO power at 6.8 cents/kWh, using levy funds to offset market prices while the UCP reviews policy.

✅ RRO cap fixed at 6.8 cents/kWh for eligible customers

✅ Levy funds pay generators when market prices exceed the cap

✅ UCP reviewing NDP policies to ensure affordable rates

Alberta's carbon tax has been cancelled, but a consumer price cap on electricity — which the levy pays for — is staying in place for now.

June electricity rates are due out on Monday, about four days after the new UCP government did away with the carbon charge on natural gas and vehicle fuel.

Part of the levy's revenue was earmarked by the previous NDP government to keep power prices at or below 6.8 cents per kilowatt hour under new electricity rules set by the province.

"The Regulated Rate Option cap of 6.8 cents/kWh was implemented by the previous government and currently remains in effect. We are reviewing all policies put in place by the former government and will make decisions that ensure more affordable electricity rates for job-creators and Albertans," said a spokesperson for Alberta's energy ministry in an emailed statement.

Albertans with regulated rate contracts and all City of Medicine Hat utility customers only pay that amount or less, though some Alberta ratepayers have faced deferral-related arrears.

If the actual market price rises above that, the difference is paid to generators directly from levy funds, a buffer that matters as experts warn prices are set to soar later this year.

The government has paid more than $55 million to utilities over the past year ending in March 2019, due to that electricity price cap being in place.

Alberta Energy says the price gap program will continue, at least for the time being, amid electricity policy changes being considered.

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Coal-to-Clean Energy Hubs leverage Bipartisan Infrastructure Law and Inflation Reduction Act funding to repurpose mine lands with microgrids, advanced nuclear, carbon capture, and rare earth processing, boosting energy security, jobs, and grid modernization.

Key Points

They are federal projects converting coal communities and mine lands into clean energy hubs, repurposing infrastructure.

✅ DOE demos on mine lands: microgrids, nuclear, carbon capture.

✅ Funding from BIL, CHIPS and IRA targets energy communities.

✅ Rare earths from coal waste bolster EV supply chains.

The Biden administration is channeling hundreds of millions of dollars in clean energy funding from recent legislation into its efforts to turn coal communities into clean energy hubs, the White House said.

The administration gave an update on its push across agencies to kick-start projects nationwide with funding Congress approved during Biden’s first two years in office. The effort includes $450 million from the Bipartisan Infrastructure Law that the Department of Energy will allocate to an array of new clean energy demonstration projects on former mine lands.

“These projects could focus on a range of technologies from microgrids to advanced nuclear to power plans with carbon capture,” Energy Secretary Jennifer Granholm said on a call with reporters Monday. “They’ll prove out the potential to reactivate or repurpose existing infrastructure like transmission lines and substations across an aging U.S. power grid, and these projects could spur new economic development in these communities.”

Among the projects the White House highlighted, it said $16 million from the infrastructure law will go to the University of North Dakota and West Virginia University to create design studies for the first-ever full-scale refinery facility in the U.S. that could extract and separate rare earth elements and minerals from coal mine waste streams. The materials are critical for electric vehicle-battery components that are currently heavily sourced from outside the U.S.

“Those efforts will pave the way toward building a first of its kind facility that produces essential materials for solar panels, wind turbines, EVs and more while cleaning up polluted land and water and creating good-paying jobs for local workers,” Granholm said.

Biden created an interagency working group focused on revitalizing coal-power communities through federal investments when he took office. In 2021, the group selected 25 priority areas ranging from West Virginia to Wyoming to focus on development, as high natural gas prices strengthened the case for clean electricity. There are nearly 18,000 identified mine sites across 1.5 million acres in the United States, according to the White House.

The massive effort fits into a broader Biden administration push to both fight climate change and support communities that have lost economic activity during a transition away from fossil fuel sources such as coal. While Biden’s most ambitious clean energy plans fell flat in Congress in the face of opposition from Republicans and some Democrats after the previous administration’s power plant overhaul, three major laws still unlocked funding for his administration to deploy.

Many of the initiatives are made possible through the Bipartisan Infrastructure Law, Chips and Science Act and the Inflation Reduction Act, even without a clean electricity standard on the books. The task force aims to make sure communities most affected by the changing energy landscape are taking maximum advantage of the federal benefits.

“Those new and expanded operations are coming to energy communities and creating good paying jobs,” Biden’s senior advisor for clean energy innovation and implementation John Podesta said on the call. “These laws can provide substantial federal support to energy communities like capping abandoned oil and gas wells, extracting critical minerals, building battery factories and launching demonstration projects in carbon capture or green hydrogen.”

The administration touted the potential benefits of the Inflation Reduction Act, a bill passed by Democrats to spur clean energy investments last year, even as early assessments show mixed results to date. At the time, U.S. consumers were dealing with decades-high inflation fueled in part by an energy crisis and high gas prices that drove debate — a point Republicans emphasized as the plan moved through Congress.

Deputy Treasury Secretary Wally Adeyemo said the Inflation Reduction Act aims to both “lower the deficit, as well as promote our energy security, lowering energy costs for consumers and combatting climate change.”

“As the Treasury works to implement the law, we’re focused on ensuring that all Americans benefit from the growth of the clean energy economy, particularly those who live in communities that have been dependent on the energy sector for job for a long time,” Adeyemo told reporters. “Economic growth and productivity are higher when all communities are able to reach their full potential.”

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UK low-carbon electricity 2019 saw stalled growth as renewables rose slightly, wind expanded, nuclear output fell, coal hit record lows, and net-zero targets demand faster deployment to cut CO2 intensity below 100gCO2/kWh.

Key Points

Low-carbon sources supplied 54% of UK power in 2019, up just 1TWh; wind grew, nuclear fell, and coal dropped to 2%.

✅ Wind up 8TWh; nuclear down 9TWh amid outages

✅ Fossil fuels 43% of generation; coal at 2%

✅ Net-zero needs 15TWh per year added to 2030

The amount of electricity generated by low-carbon sources in the UK stalled in 2019, Carbon Brief analysis shows.

Low-carbon electricity output from wind, solar, nuclear, hydro and biomass rose by just 1 terawatt hour (TWh, less than 1%) in 2019. It represents the smallest annual increase in a decade, where annual growth averaged 9TWh. This growth will need to double in the 2020s to meet UK climate targets while replacing old nuclear plants as they retire.

Some 54% of UK electricity generation in 2019 came from low-carbon sources, including 37% from renewables and 20% from wind alone, underscoring wind's leading role in the power mix during key periods. A record-low 43% was from fossil fuels, with 41% from gas and just 2% from coal, also a record low. In 2010, fossil fuels generated 75% of the total.

Carbon Brief’s analysis of UK electricity generation in 2019 is based on figures from BM Reports and the Department for Business, Energy and Industrial Strategy (BEIS). See the methodology at the end for more on how the analysis was conducted.

The numbers differ from those published earlier in January by National Grid, which were for electricity supplied in Great Britain only (England, Wales and Scotland, but excluding Northern Ireland), including via imports from other countries.

Low-carbon low
In 2019, the UK became the first major economy to target net-zero greenhouse gas emissions by 2050, increasing the ambition of its legally binding Climate Change Act.

To date, the country has cut its emissions by around two-fifths since 1990, with almost all of its recent progress coming from the electricity sector.

Emissions from electricity generation have fallen rapidly in the decade since 2010 as coal power has been almost phased out and even gas output has declined. Fossil fuels have been displaced by falling demand and by renewables, such as wind, solar and biomass.

But Carbon Brief’s annual analysis of UK electricity generation shows progress stalled in 2019, with the output from low-carbon sources barely increasing compared to a year earlier.

The chart below shows low-carbon generation in each year since 2010 (grey bars) and the estimated level in 2019 (red). The pale grey bars show the estimated future output of existing low-carbon sources after old nuclear plants retire and the pale red bars show the amount of new generation needed to keep electricity sector emissions to less than 100 grammes of CO2 per kilowatt hour (gCO2/kWh), the UK’s nominal target for the sector.

 Annual electricity generation in the UK by fuel, terawatt hours, 2010-2019. Top panel: fuel by fuel. Bottom panel: cumulative total generation from all sources. Source: BEIS energy trends, BM Reports and Carbon Brief analysis. Chart by Carbon Brief using Highcharts.
As the chart shows, the UK will require significantly more low-carbon electricity over the next decade as part of meeting its legally binding climate goals.

The nominal 100gCO2/kWh target for 2030 was set in the context of the UK’s less ambitious goal of cutting emissions to 80% below 1990 levels by 2050. Now that the country is aiming to cut emissions to net-zero by 2050, that 100gCO2/kWh indicator is likely to be the bare minimum.

Even so, it would require a rapid step up in the pace of low-carbon expansion, compared to the increases seen over the past decade. On average, low-carbon generation has risen by 9TWh each year in the decade since 2010 – including a rise of just 1TWh in 2019.

Given scheduled nuclear retirements and rising demand expected by the Committee on Climate Change (CCC) – with some electrification of transport and heating – low-carbon generation would need to increase by 15TWh each year until 2030, just to meet the benchmark of 100gCO2/kWh.

For context, the 3.2 gigawatt (GW) Hinkley C new nuclear plant being built in Somerset will generate around 25TWh once completed around 2026. The world’s largest offshore windfarm, the 1.2GW Hornsea One scheme off the Yorkshire coast, will generate around 5TWh each year.

The new Conservative government is targeting 40GW of offshore wind by 2030, up from today’s figure of around 8GW. If policies are put in place to meet this goal, then it could keep power sector emissions below 100gCO2/kWh, depending on the actual performance of the windfarms built.

However, new onshore wind and solar, further new nuclear or other low-carbon generation, such as gas with carbon capture and storage (CCS), is likely to be needed if demand is higher than expected, or if the 100gCO2/kWh benchmark is too weak in the context of net-zero by 2050.

The CCC says it is “likely” to “reflect the need for more rapid deployment” of low-carbon towards net-zero emissions in its advice on the sixth UK carbon budget for 2033-2037, due in September.

Trading places
Looking more closely at UK electricity generation in 2019, Carbon Brief’s analysis shows why there was so little growth for low-carbon sources compared to the previous year.

There was another increase for wind power in 2019 (up 8TWh, 14%), with record wind generation as several large new windfarms were completed including the 1.2GW Hornsea One project in October and the 0.6GW Beatrice offshore windfarm in Q2 of 2019. But this was offset by a decline for nuclear (down 9TWh, 14%), due to ongoing outages for reactors at Hunterston in Scotland and Dungeness in Kent.

(Analysis of data held by trade organisation RenewableUK suggests some 0.6GW of onshore wind capacity also started operating in 2019, including the 0.2GW Dorenell scheme in Moray, Scotland.)

As a result of these movements, the UK’s windfarms overtook nuclear for the first time ever in 2019, becoming the country’s second-largest source of electricity generation, and earlier, wind and solar together surpassed nuclear in the UK as momentum built. This is shown in the figure below, with wind (green line, top panel) trading places with nuclear (purple) and gas (dark blue) down around 25% since 2010 but remaining the single-largest source.

 Annual electricity generation in the UK by fuel, terawatt hours, 2010-2019. Top panel: fuel by fuel. Bottom panel: cumulative total generation from all sources. Source: BEIS energy trends, BM Reports and Carbon Brief analysis. Chart by Carbon Brief using Highcharts.
The UK’s currently suspended nuclear plants are due to return to service in January and March, according to operator EDF, the French state-backed utility firm. However, as noted above, most of the UK’s nuclear fleet is set to retire during the 2020s, with only Sizewell B in Suffolk due to still be operating by 2030. Hunterston is scheduled to retire by 2023 and Dungeness by 2028.

Set against these losses, the UK has a pipeline of offshore windfarms, secured via “contracts for difference” with the government, at a series of auctions. The most recent auction, in September 2019, saw prices below £40 per megawatt hour – similar to current wholesale electricity prices.

However, the capacity contracted so far is not sufficient to meet the government’s target of 40GW by 2030, meaning further auctions – or some other policy mechanism – will be required.

Coal zero
As well as the switch between wind and nuclear, 2019 also saw coal fall below solar for the first time across a full year, echoing the 2016 moment when wind outgenerated coal across the UK, after it suffered another 60% reduction in electricity output. Just six coal plants remain in the UK, with Aberthaw B in Wales and Fiddlers Ferry in Cheshire closing in March.

Coal accounted for just 2% of UK generation in 2019, a record-low coal share since centralised electricity supplies started to operate in 1882. The fuel met 40% of UK needs as recently as 2012, but has plummeted thanks to falling demand, rising renewables, cheaper gas and higher CO2 prices.

The reduction in average coal generation hides the fact that the fuel is now often not required at all to meet the UK’s electricity needs. The chart below shows the number of days each year when coal output was zero in 2019 (red line) and the two previous years (blue).

 Cumulative number of days when UK electricity generation from renewable sources has been higher than that from fossil fuels. Source: BEIS energy trends, BM Reports and Carbon Brief analysis. Chart by Carbon Brief using Highcharts.
The 83 days in 2019 with zero coal generation amount to nearly a quarter of the year and include the record-breaking 18-day stretch without the fuel.

Great Britain has been running for a record TWO WEEKS without using coal to generate electricity – the first time this has happened since 1882.

The country’s grid has been coal-free for 45% of hours in 2019 so far.https://www.carbonbrief.org/countdown-to-2025-tracking-the-uk-coal-phase-out …

Coal generation was set for significant reductions around the world in 2019 – including a 20% reduction for the EU as a whole – according to analysis published by Carbon Brief in November.

Notably, overall UK electricity generation fell by another 9TWh in 2019 (3%), bringing the total decline to 58TWh since 2010. This is equivalent to more than twice the output from the Hinkley C scheme being built in Somerset. As Carbon Brief explained last year, falling demand has had a similar impact on electricity-sector CO2 emissions as the increase in output from renewables.

This is illustrated by the fact that the 9TWh reduction in overall generation translated into a 9TWh (6%) cut in fossil-fuel generation during 2019, with coal falling by 10TWh and gas rising marginally.

Increasingly renewable
As fossil-fuel output and overall generation have declined, the UK’s renewable sources of electricity have continued to increase. Their output has risen nearly five-fold in the past decade and their share of the UK total has increased from 7% in 2010 to 37% in 2019.

As a result, the UK’s increasingly renewable grid is seeing more minutes, hours and days during which the likes of wind, solar and biomass collectively outpace all fossil fuels put together, and on some days wind is the main source as well.

The chart below shows the number of days during each year when renewables generated more electricity than fossil fuels in 2019 (red line) and each of the previous four years (blue lines). In total, nearly two-fifths of days in 2019 crossed this threshold.

 Cumulative number of days when the UK has not generated any electricity from coal. Source: BEIS energy trends, BM Reports and Carbon Brief analysis. Chart by Carbon Brief using Highcharts.
There were also four months in 2019 when renewables generated more of the UK’s electricity than fossil fuels: March, August, September and December. The first ever such month came in September 2018 and more are certain to follow.

National Grid, which manages Great Britain’s high-voltage electricity transmission network, is aiming to be able to run the system without fossil fuels by 2025, at least for short periods. At present, it sometimes has to ask windfarm operators to switch off and gas plants to start running in order to keep the electricity grid stable.

Note that biomass accounted for 11% of UK electricity generation in 2019, nearly a third of the total from all renewables. Some two-thirds of the biomass output is from “plant biomass”, primarily wood pellets burnt at Lynemouth in Northumberland and the Drax plant in Yorkshire. The remainder was from an array of smaller sites based on landfill gas, sewage gas or anaerobic digestion.

The CCC says the UK should “move away” from large-scale biomass power plants, once existing subsidy contracts for Drax and Lynemouth expire in 2027.

Using biomass to generate electricity is not zero-carbon and in some circumstances could lead to higher emissions than from fossil fuels. Moreover, there are more valuable uses for the world’s limited supply of biomass feedstock, the CCC says, including carbon sequestration and hard-to-abate sectors with few alternatives.

Methodology
The figures in the article are from Carbon Brief analysis of data from BEIS Energy Trends chapter 5 and chapter 6, as well as from BM Reports. The figures from BM Reports are for electricity supplied to the grid in Great Britain only and are adjusted to include Northern Ireland.

In Carbon Brief’s analysis, the BM Reports numbers are also adjusted to account for electricity used by power plants on site and for generation by plants not connected to the high-voltage national grid. This includes many onshore windfarms, as well as industrial gas combined heat and power plants and those burning landfill gas, waste or sewage gas.

By design, the Carbon Brief analysis is intended to align as closely as possible to the official government figures on electricity generated in the UK, reported in BEIS Energy Trends table 5.1.

Briefly, the raw data for each fuel is in most cases adjusted with a multiplier, derived from the ratio between the reported BEIS numbers and unadjusted figures for previous quarters.

Carbon Brief’s method of analysis has been verified against published BEIS figures using “hindcasting”. This shows the estimates for total electricity generation from fossil fuels or renewables to have been within ±3% of the BEIS number in each quarter since Q4 2017. (Data before then is not sufficient to carry out the Carbon Brief analysis.)

For example, in the second quarter of 2019, a Carbon Brief hindcast estimates gas generation at 33.1TWh, whereas the published BEIS figure was 34.0TWh. Similarly, it produces an estimate of 27.4TWh for renewables, against a BEIS figure of 27.1TWh.

National Grid recently shared its own analysis for electricity in Great Britain during 2019 via its energy dashboard, which differs from Carbon Brief’s figures.

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China Industrial Power Demand 2020 highlights COVID-19 disruption to electricity consumption as factory output stalls; IHS Markit estimates losses equal to Chile's usage, impacting thermal coal, LNG, and Hubei's industrial load.

Key Points

An analysis of COVID-19's hit to China's electricity use, cutting industry demand and fuel needs for coal and LNG.

✅ 73 billion kWh loss equals Chile's annual power use

✅ Cuts translate to 30m tonnes coal or 9m tonnes LNG

✅ Hubei peak load 21 percent below plan amid shutdowns

China’s industrial power demand in 2020 may decline by as much as 73 billion kilowatt hours (kWh), according to IHS Markit, as the outbreak of the coronavirus has curtailed factory output and prevented some workers from returning to their jobs.

FILE PHOTO: Smoke is seen from a cooling tower of a China Energy ultra-low emission coal-fired power plant during a media tour, in Sanhe, Hebei province, China July 18, 2019. REUTERS/Shivani Singh
The cut represents about 1.5% of industrial power consumption in China. But, as the country is the world’s biggest electricity consumer and analyses of China's electricity appetite routinely underscore its scale, the loss is equal to the power used in the whole of Chile and it illustrates the scope of the disruption caused by the outbreak.

The reduction is the energy equivalent of about 30 million tonnes of thermal coal, at a time when China aims to reduce coal power production, or about 9 million tonnes of liquefied natural gas (LNG), IHS said. The coal figure is more than China’s average monthly imports last year while the LNG figure is a little more than one month of imports, based on customs data.

China has tried to curtail the spread of the coronavirus that has killed more than 1,400 and infected over 60,000 by extending the Lunar New Year holiday for an extra week and encouraging people to work from home, measures that contributed to a global dip in electricity demand as well.

Last year, industrial users consumed 4.85 trillion kWh electricity, accounting for 67% of the country’s total, even as India's electricity demand showed sharp declines in the region.

Xizhou Zhou, the global head of power and Renewables at IHS Markit, said that in a severe case where the epidemic goes on past March, China’s economic growth will be only 4.2% during 2020, down from an initial forecast of 5.8%, while power consumption will climb by only 3.1%, down from 4.1% initially, even as power cuts and blackouts raise concerns.

“The main uncertainty is still how fast the virus will be brought under control,” said Zhou, adding that the impact on the power sector will be relatively modest from a full-year picture in 2020, even though China's electric power woes are already clouding solar markets.

In Hubei province, the epicenter of the virus outbreak, the peak power load at the end of January was 21% less than planned, mirroring how Japan's power demand was hit during the outbreak, data from Wood Mackenzie showed.

Industrial operating rates point to a firm reduction in power consumption in China.

Utilization rates at plastic processors are between 30% and 60% and the low levels are expected to last for another two week, according to ICIS China.

Weaving machines at textile plants are operating at below 10% of capacity, the lowest in five years, ICIS data showed. China is the world’s biggest textile and garment exporter.

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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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