Politicians, utilities line up to laud wind energy

EU Electricity Market Reform Opposition highlights nine states resisting an overhaul of the wholesale power market amid gas price spikes, urging energy efficiency, interconnection targets, and EU caution rather than redesigns affecting renewables.

Key Points

Nine EU states reject overhauling wholesale power pricing, favoring efficiency and prudent policy over redesigns.

✅ Nine states oppose redesign of wholesale power market.

✅ Call for efficiency and 15% interconnection by 2030.

✅ Ministers to debate responses amid gas-driven price spikes.

Germany, Denmark, Ireland and six other European countries said on Monday they would not support a reform of the EU electricity market, ahead of an emergency meeting of energy ministers to discuss emergency measures and the recent price spike.

European gas and power prices soared to record high levels in autumn and have remained high, prompting countries including Spain and France to urge Brussels to redesign its electricity market rules.

Nine countries on Monday poured cold water on those proposals, in a joint statement that said they "cannot support any measure that conflicts with the internal gas and electricity market" such as an overhaul of the wholesale power market altogether.

"As the price spikes have global drivers, we should be very careful before interfering in the design of internal energy markets," the statement said.

"This will not be a remedy to mitigate the current rising energy prices linked to fossil fuels markets across Europe."

Austria, Germany, Denmark, Estonia, Finland, Ireland, Luxembourg, Latvia and the Netherlands signed the statement, which called instead for more measures to save energy and a target for a 15% interconnection of the EU electricity market by 2030.

European energy ministers meet tomorrow to discuss their response to the price spike, including gas price cap strategies under consideration. Most countries are using tax cuts, subsidies and other national measures to shield consumers against the impact higher gas prices are having on energy bills, but EU governments are struggling to agree on a longer term response.

Spain has led calls for a revamp of the wholesale power market in response to the price spike, amid tensions between France and Germany over reform, arguing that the system is not supporting the EU's green transition.

Under the current system, the wholesale electricity price is set by the last power plant needed to meet overall demand for power. Gas plants often set the price in this system, which Spain said was unfair as it results in cheap renewable energy being sold for the same price as costlier fossil fuel-based power.

The European Commission has said it will investigate whether the EU power market is functioning well, but that there is no evidence to suggest a different system would have better protected countries against the surge in energy costs, and that rolling back electricity prices is tougher than it appears during such spikes.

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Commercial Electric Tariffs explain utility rate structures, peak demand charges, kWh vs kW pricing, time-of-use periods, voltage, delivery, capacity ratchets, and riders, guiding facility managers in tariff analysis for accurate energy savings.

Key Points

Commercial electric tariffs define utility pricing for energy, demand, delivery, time-of-use periods, riders, and ratchet charges.

✅ Separate kWh charges from kW peak demand fees.

✅ Verify time-of-use windows and demand interval length.

✅ Review riders, capacity ratchets, and minimum demand clauses.

Especially during these tough economic times, as major changes to electric bills are debated in some states, facility executives who don’t understand how their power is priced have been disappointed when their energy projects failed to produce expected dollar savings. Here’s how not to be one of them.

Your electric rate is spelled out in a document called a “tariff” that can be downloaded from your utility’s web page. A tariff should clearly spell out the costs for each component that is part of your rate, reflecting cost allocation practices in your region. Don’t be surprised to learn that it contains a bunch of them. Unlike residential electric rates, commercial electric bills are not based solely on the quantity of kilowatt-hours (kWh) consumed in a billing period (in the United States, that’s a month). Instead, different rates may apply to how your power is supplied, how it is delivered via electricity delivery charges, when it was consumed, its voltage, how fast it was used (in kW), and other factors.

If a tariff’s lingo and word structure are too opaque, spend some time with a utility account rep to translate it. Many state utility commissions also have customer advocates that may assist as they explore new utility rate designs that affect customers. Alternatively, for a fee, facility managers can privately chat with an energy consultant.

Common mistakes

Many facility managers try to estimate savings based on an averaged electric rate, i.e., annual electric spend divided by annual kWh. However, in markets where electricity demand is flat, such a number may obscure the fastest rising cost component: monthly peak demand charges, measured in dollars per kW (or kilo-volt-amperes, kVA).

This charge is like a monthly speeding ticket, based solely on the highest speed you drove during that time. In some areas, peak demand charges now account for 30 to 60 percent of a facility’s annual electric spend. When projecting energy cost savings, failing to separately account for kW peak demand and kWh consumption may result in erroneous results, and a lot of questions from the C-suite.

How peak demand charges are calculated varies among utilities. Some base it on the highest average speed of use across one hour in a month, while others may use the highest average speed during a 15- or 30-minute period. Others may average several of the highest speeds within a defined time period (for example, 8 a.m. to 6 p.m. on weekdays). It is whatever your tariff says it is.

Because some power-consuming (or producing) devices, including those tied to smart home electricity networks, vary in their operation or abilities, they may save money on a few — but not all — of those rate components. If an equipment vendor calculates savings from its product by using an average electric rate, take pause. Tell the vendor to return after the proposal has been redone using tariff-based numbers.

When a vendor is the only person calculating potential savings from using a product, there’s also a built-in conflict of interest: The person profiting from an equipment sale should not also be the one calculating its expected financial return. Before signing any energy project contracts, it’s essential that someone independent of the deal reviews projected savings. That person (typically an energy or engineering consultant) should be quite familiar with your facility’s electric tariff, including any special provisions, riders, discounts, etc., that may pertain. When this doesn’t happen, savings often don’t occur as planned. 

For example, some utilities add another form of demand charge, based on the highest kW in a year. It has various names: capacity, contract demand, or the generic term “ratchet charge.” Some utilities also have a minimum ratchet charge which may be based on a percent of a facility’s annual kW peak. It ensures collection of sufficient utility revenue to cover the cost of installed transmission and distribution even when a customer significantly cuts its peak demand.

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Offshore wind power accelerates low-carbon electrification, leveraging floating turbines, high capacity factors, HVDC transmission, and hydrogen production to decarbonize grids, cut CO2, and deliver competitive, reliable renewable energy near demand centers.

Key Points

Offshore wind power uses offshore turbines to deliver low-carbon electricity with high capacity factors and falling costs.

✅ Sea-based wind farms with 40-50% capacity factors

✅ Floating turbines unlock deep-water, far-shore resources

✅ Enables hydrogen production and strengthens grid reliability

The need for affordable low-carbon technologies is greater than ever

Global energy-related CO2 emissions reached a historic high in 2018, driven by an increase in coal use in the power sector. Despite impressive gains for renewables, fossil fuels still account for nearly two-thirds of electricity generation, the same share as 20 years ago. There are signs of a shift, with increasing pledges to decarbonise economies and tackle air pollution, and with World Bank support helping developing countries scale wind, but action needs to accelerate to meet sustainable energy goals. As electrification of the global energy system continues, the need for clean and affordable low-carbon technologies to produce this electricity is more pressing than ever. This World Energy Outlook special report offers a deep dive on a technology that today has a total capacity of 23 GW (80% of it in Europe) and accounts for only 0.3% of global electricity generation, but has the potential to become a mainstay of the world's power supply. The report provides the most comprehensive analysis to date of the global outlook for offshore wind, its contributions to electricity systems and its role in clean energy transitions.

The offshore wind market has been gaining momentum

The global offshore wind market grew nearly 30% per year between 2010 and 2018, benefitting from rapid technology improvements. Over the next five years, about 150 new offshore wind projects are scheduled to be completed around the world, pointing to an increasing role for offshore wind in power supplies. Europe has fostered the technology's development, led by the UK offshore wind sector alongside Germany and Denmark. The United Kingdom and Germany currently have the largest offshore wind capacity in operation, while Denmark produced 15% of its electricity from offshore wind in 2018. China added more capacity than any other country in 2018.

The untapped potential of offshore wind is vast

The best offshore wind sites could supply more than the total amount of electricity consumed worldwide today. And that would involve tapping only the sites close to shores. The IEA initiated a new geospatial analysis for this report to assess offshore wind technical potential country by country. The analysis was based on the latest global weather data on wind speed and quality while factoring in the newest turbine designs. Offshore wind's technical potential is 36 000 TWh per year for installations in water less than 60 metres deep and within 60 km from shore. Global electricity demand is currently 23 000 TWh. Moving further from shore and into deeper waters, floating turbines could unlock enough potential to meet the world's total electricity demand 11 times over in 2040. Our new geospatial analysis indicates that offshore wind alone could meet several times electricity demand in a number of countries, including in Europe, the United States and Japan. The industry is adapting various floating foundation technologies that have already been proven in the oil and gas sector. The first projects are under development and look to prove the feasibility and cost-effectiveness of floating offshore wind technologies.

Offshore wind's attributes are very promising for power systems

New offshore wind projects have capacity factors of 40-50%, as larger turbines and other technology improvements are helping to make the most of available wind resources. At these levels, offshore wind matches the capacity factors of gas- and coal-fired power plants in some regions – though offshore wind is not available at all times. Its capacity factors exceed those of onshore wind and are about double those of solar PV. Offshore wind output varies according to the strength of the wind, but its hourly variability is lower than that of solar PV. Offshore wind typically fluctuates within a narrower band, up to 20% from hour to hour, than solar PV, which varies up to 40%.

Offshore wind's high capacity factors and lower variability make its system value comparable to baseload technologies, placing it in a category of its own – a variable baseload technology. Offshore wind can generate electricity during all hours of the day and tends to produce more electricity in winter months in Europe, the United States and China, as well as during the monsoon season in India. These characteristics mean that offshore wind's system value is generally higher than that of its onshore counterpart and more stable over time than that of solar PV. Offshore wind also contributes to electricity security, with its high availability and seasonality patterns it is able to make a stronger contribution to system needs than other variable renewables. In doing so, offshore wind contributes to reducing CO2 and air pollutant emissions while also lowering the need for investment in dispatchable power plants. Offshore wind also has the advantage of avoiding many land use and social acceptance issues that other variable renewables are facing.

Offshore wind is on track to be a competitive source of electricity

Offshore wind is set to be competitive with fossil fuels within the next decade, as well as with other renewables including solar PV. The cost of offshore wind is declining and is set to fall further. Financing costs account for 35% to 50% of overall generation cost, and supportive policy frameworks are now enabling projects to secure low cost financing in Europe, with zero-subsidy tenders being awarded. Technology costs are also falling. The levelised cost of electricity produced by offshore wind is projected to decline by nearly 60% by 2040. Combined with its relatively high value to the system, this will make offshore wind one of the most competitive sources of electricity. In Europe, recent auctions indicate that offshore wind will soon beat new natural gas-fired capacity on cost and be on a par with solar PV and onshore wind. In China, offshore wind is set to become competitive with new coal-fired capacity around 2030 and be on par with solar PV and onshore wind. In the United States, recent project proposals indicate that offshore wind will soon be an affordable option, even as the 1 GW timeline continues to evolve, with potential to serve demand centres along the country's east coast.

Innovation is delivering deep cost reductions in offshore wind, and transmission costs will become increasingly important. The average upfront cost to build a 1 gigawatt offshore wind project, including transmission, was over $4 billion in 2018, but the cost is set to drop by more than 40% over the next decade. This overall decline is driven by a 60% reduction in the costs of turbines, foundations and their installation. Transmission accounts for around one-quarter of total offshore wind costs today, but its share in total costs is set to increase to about one-half as new projects move further from shore. Innovation in transmission, for example through work to expand the limits of direct current technologies, will be essential to support new projects without raising their overall costs.

Offshore wind is set to become a $1 trillion business

Offshore wind power capacity is set to increase by at least 15-fold worldwide by 2040, becoming a $1 trillion business. Under current investment plans and policies, the global offshore wind market is set to expand by 13% per year, reflecting its growth despite Covid-19 in recent years, passing 20 GW of additions per year by 2030. This will require capital spending of $840 billion over the next two decades, almost matching that for natural gas-fired or coal-fired capacity. Achieving global climate and sustainability goals would require faster growth: capacity additions would need to approach 40 GW per year in the 2030s, pushing cumulative investment to over $1.2 trillion. 

The promising outlook for offshore wind is underpinned by policy support in an increasing number of regions. Several European North Seas countries – including the United Kingdom, Germany, the Netherlands and Denmark – have policy targets supporting offshore wind. Although a relative newcomer to the technology, China is quickly building up its offshore wind industry, aiming to develop a project pipeline of 10 GW by 2020. In the United States, state-level targets and federal incentives are set to kick-start the U.S. offshore wind surge in the coming years. Additionally, policy targets are in place and projects under development in Korea, Japan, Chinese Taipei and Viet Nam.

 The synergies between offshore wind and offshore oil and gas activities provide new market opportunities. Since offshore energy operations share technologies and elements of their supply chains, oil and gas companies started investing in offshore wind projects many years ago. We estimate that about 40% of the full lifetime costs of an offshore wind project, including construction and maintenance, have significant synergies with the offshore oil and gas sector. That translates into a market opportunity of $400 billion or more in Europe and China over the next two decades. The construction of foundations and subsea structures offers potential crossover business, as do practices related to the maintenance and inspection of platforms. In addition to these opportunities, offshore oil and gas platforms require electricity that is often supplied by gas turbines or diesel engines, but that could be provided by nearby wind farms, thereby reducing CO2 emissions, air pollutants and costs.

Offshore wind can accelerate clean energy transitions

Offshore wind can help drive energy transitions by decarbonising electricity and by producing low-carbon fuels. Over the next two decades, its expansion could avoid between 5 billion and 7 billion tonnes of CO2 emissions from the power sector globally, while also reducing air pollution and enhancing energy security by reducing reliance on imported fuels. The European Union is poised to continue leading the wind energy at sea in Europe industry in support of its climate goals: its offshore wind capacity is set to increase by at least fourfold by 2030. This growth puts offshore wind on track to become the European Union's largest source of electricity in the 2040s. Beyond electricity, offshore wind's high capacity factors and falling costs makes it a good match to produce low-carbon hydrogen, a versatile product that could help decarbonise the buildings sector and some of the hardest to abate activities in industry and transport. For example, a 1 gigawatt offshore wind project could produce enough low-carbon hydrogen to heat about 250 000 homes. Rising demand for low-carbon hydrogen could also dramatically increase the market potential for offshore wind. Europe is looking to develop offshore "hubs" for producing electricity and clean hydrogen from offshore wind.

It's not all smooth sailing

Offshore wind faces several challenges that could slow its growth in established and emerging markets, but policy makers and regulators can clear the path ahead. Developing efficient supply chains is crucial for the offshore wind industry to deliver low-cost projects. Doing so is likely to call for multibillion-dollar investments in ever-larger support vessels and construction equipment. Such investment is especially difficult in the face of uncertainty. Governments can facilitate investment of this kind by establishing a long-term vision for offshore wind and by drawing on U.K. policy lessons to define the measures to be taken to help make that vision a reality. Long-term clarity would also enable effective system integration of offshore wind, including system planning to ensure reliability during periods of low wind availability.

The success of offshore wind depends on developing onshore grid infrastructure. Whether the responsibility for developing offshore transmission lies with project developers or transmission system operators, regulations should encourage efficient planning and design practices that support the long-term vision for offshore wind. Those regulations should recognise that the development of onshore grid infrastructure is essential to the efficient integration of power production from offshore wind. Without appropriate grid reinforcements and expansion, there is a risk of large amounts of offshore wind power going unused, and opportunities for further expansion could be stifled. Development could also be slowed by marine planning practices, regulations for awarding development rights and public acceptance issues.

The future of offshore wind looks bright but hinges on the right policies

The outlook for offshore wind is very positive as efforts to decarbonise and reduce local pollution accelerate. While offshore wind provides just 0.3% of global electricity supply today, it has vast potential around the world and an important role to play in the broader energy system. Offshore wind can drive down CO2 emissions and air pollutants from electricity generation. It can also do so in other sectors through the production of clean hydrogen and related fuels. The high system value of offshore wind offers advantages that make a strong case for its role alongside other renewables and low-carbon technologies. Government policies will continue to play a critical role in the future of offshore wind and  the overall pace of clean energy transitions around the world.

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Alberta Electricity Market faces energy-only vs capacity debate as transmission, distribution, and administration fees surge; rural rates rise amid a regulated duopoly of investor-owned utilities, prompting calls for competition, innovation, and lower bills.

Key Points

Alberta's electricity market is an energy-only system with rising delivery charges and limited rural competition.

✅ Energy-only design; capacity market scrapped

✅ Delivery charges outpace energy on monthly bills

✅ Rural duopoly limits competition and raises rates

Last week, Alberta’s new Energy Minister Sonya Savage announced the government, through its new electricity rules, would be scrapping plans to shift Alberta’s electricity to a capacity market and would instead be “restoring certainty in the electricity system.”

The proposed transition from energy only to a capacity market is a contentious subject as a market reshuffle unfolds across the province that many Albertans probably don’t know much about. Our electricity market is not a particularly glamorous subject. It’s complicated and confusing and what matters most to ordinary Albertans is how it affects their monthly bills.

What they may not realize is that the cost of their actual electricity used is often just a small fraction of their bill amid rising electricity prices across the province. The majority on an average electricity bill is actually the cost of delivering that electricity from the generator to your house. Charges for transmission, distribution and franchise and administration fees are quickly pushing many Alberta households to the limit with soaring bills.

According to data from Alberta’s Utilities Consumer Advocate (UCA), and alongside policy changes, in 2004 the average monthly transmission costs for residential regulated-rate customers was below $2. In 2018 that cost was averaging nearly $27 a month. The increase is equally dramatic in distribution rates which have more than doubled across the province and range wildly, averaging from as low as $10 a month in 2004 to over $80 a month for some residential regulated-rate customers in 2018.

Where you live determines who delivers your electricity. In Alberta’s biggest cities and a handful of others the distribution systems are municipally owned and operated. Outside those select municipalities most of Alberta’s electricity is delivered by two private companies which operate as a regulated duopoly. In fact, two investor-owned utilities deliver power to over 95 per cent of rural Alberta and they continue to increase their share by purchasing the few rural electricity co-ops that remained their only competition in the market. The cost of buying out their competition is then passed on to the customers, driving rates even higher.

As the CEO of Alberta’s largest remaining electricity co-op, I know very well that as the price of materials, equipment and skilled labour increase, the cost of operating follows. If it costs more to build and maintain an electricity distribution system there will inevitably be a cost increase passed on to the consumer. The question Albertans should be asking is how much is too much and where is all that money going with these private- investor-owned utilities, as the sector faces profound change under provincial leadership?

The reforms to Alberta’s electricity system brought in by Premier Klein in the late 1900s and early 2000s contributed to a surge in investment in the sector and led to an explosion of competition in both electricity generation and retail. 

More players entered the field which put downward pressure on electricity rates, encouraged innovation and gave consumers a competitive choice, even as a Calgary electricity retailer urged the government to scrap the overhaul. But the legislation and regulations that govern rural electricity distribution in Alberta continue to facilitate and even encourage the concentration of ownership among two players which is certainly not in the interests of rural Albertans.

It is also not in the spirit of the United Conservative Party platform commitment to a “market-based” system. A market-based system suggests more competition. Instead, what we have is something approaching a monopoly for many Albertans. The UCP promised a review of the transition to a capacity market that would determine which market would be best for Alberta, and through proposed electricity market changes has decided that we will remain an energy-only market.
Consumers in rural Alberta need electricity to produce the goods that power our biggest industries. Instead of regulating and approving continued rate increases from private multinational corporations, we need to drive competition and innovation that can push rates down and encourage growth and investment in rural-based industries and communities.

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Ontario electricity pricing consultations will gather business input on OEB rate design, Industrial Conservation Initiative, dynamic pricing, global adjustment, and system costs through online feedback and sector-specific in-person sessions province-wide.

Key Points

Consultations gathering business input on rates, programs, and OEB policy to improve fairness and reduce system costs.

✅ Consults on ICI, GA, dynamic pricing structures

✅ Seeks views on OEB C&I rate design changes

✅ In-person sessions across key industrial sectors

The Ontario government has announced plans to hold consultations to seek input from businesses about industrial electricity pricing and programs. This will be done through Ontario's online consultations directory and though in-person sector-specific consultation sessions across the province. The in-person sessions will be held in all areas of Ontario, and will target "key industries," including automotive and the build-out of electric vehicle charging stations infrastructure, forestry, mining, agriculture, steel, manufacturing and chemicals.

On April 1, 2019, the Ontario government published a consultation notice for this process, confirming that it is looking for input on "electricity rate design, existing tax-based incentives, reducing system costs and regulatory and delivery costs," including related proposals such as the hydrogen rate reduction proposal under discussion. The consultation process includes a list of nine questions for respondents (and presumably participants in the in-person sessions) to address. These include questions about:

The benefits of the Industrial Conservation Initiative (described below), including how it could be changed to improve fairness and industrial competitiveness, and how it could complement programs like the Hydrogen Innovation Fund that support industrial innovation.

Dynamic pricing structures that allow for lower rates in return for responding to price signals versus a flat rate structure that potentially costs more, but is more stable and predictable, as Ontario's energy storage expansion accelerates.

Interest in an all-in commodity contract with an electricity retailer, even if it involves a risk premium.

Interested parties are invited to submit their comments before May 31, 2019.

The government's consultation announcement follows recent developments in the Ontario Energy Board's (OEB) review of electricity ratemaking for commercial and industrial customers, and intertie projects such as the Lake Erie Connector that could affect market dynamics.

In December 2018, the OEB published a paper from its Market Surveillance Panel (MSP) examining the Industrial Conservation Initiative (ICI), and potential alternative approaches. The ICI is a program that allows qualifying large industrial customers to base their global adjustment (GA) payments on their consumption during five peak demand hours in a year. Customers who find ways to reduce consumption at those times, perhaps through DERs and enabling energy storage options, will reduce their electricity costs. This shifts GA costs to other customers. The MSP found that the ICI does not fairly allocate costs to those who cause them and/or benefit from them, and recommends that a better approach should be developed.

In February 2019, the OEB released its Staff Report to the Board on Rate Design for Commercial and Industrial Electricity Customers, setting out recommendations for new rate designs for electricity commercial and industrial (C&I) rate classes as Ontario increasingly turns to battery storage to meet rising demand. As described in an earlier post, the Staff Report includes recommendations to: (i) establish a fixed distribution charge for commercial customers with demands under 10 kW; (ii) implement a demand charge (rather than the current volumetric charge) for C&I customers with demands between 10kW and 50kW; and (iii) introduce a "capacity reserve charge" for customers with load displacement generation to replace stand-by charges and provide for recognition of the benefits of this generation on the system. The OEB held a stakeholder information session in mid-March on this initiative, and interested parties are now filing submissions in response to the Staff Report.

Whether and how the OEB's processes will fit together with the government's consultation process remains to be seen.

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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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