Tampa Electric offers tips for storm readiness

Medicine Hat Bitcoin Mining Facility drives massive electricity demand and energy use, leveraging natural gas and nearby wind power; Hut 8 touts economic growth, while critics cite carbon emissions, renewables integration, and climate impact.

Key Points

A Hut 8 project in Alberta that mines bitcoin at scale, consuming up to 60 MW and impacting energy and emissions.

✅ Consumes more than 60 MW, rivaling citywide electricity use

✅ Sited by natural gas plant; wind turbines nearby

✅ Economic gains vs. carbon emissions and climate risks

On the day of the grand opening of the largest bitcoin mining project in the country, the weather was partly cloudy and 15 C. On a Friday afternoon like this one, the new facility uses as much electricity as all of Medicine Hat, Alta., a city of more than 60,000 people and home to several large industrial plants.

The vast amount of electricity needed for bitcoin mining is why the city of Medicine Hat has championed the economic benefits of the project, while environmentalists say they are wary of the significant energy use.

Toronto-based Hut 8 has spent more than $100 million to develop the 4½-hectare site on the northern edge of the city. It has 56 shipping containers, each filled with 180 computer servers that digitally mine for bitcoin around the clock.

The company said it has already mined more than 3,300 bitcoins in Alberta, including at its much smaller site in Drumheller. On average, the Medicine Hat facility mines about 20 bitcoins per day. The value of bitcoin can fluctuate daily, but has sold recently for around $9,000.

The bitcoin mining facility is located right beside the city of Medicine Hat's new natural gas-fired power plant and four wind turbines are a short distance away. The bitcoin plant can consume more than 60 megawatts of power, more than 10 times more electricity used by any other facility in the city, according to the mayor.

That's why, in the event of a summer heat wave, the city has provisions in place to pull the plug on the electricity it provides to Hut 8, mirroring utility pauses on crypto loads seen elsewhere, so there won't be any blackouts for residents, according to the mayor.

Still, some say the bitcoin mining industry wastes far too much energy

"It's a huge magnitude when you talk about the carbon emissions," said Saeed Kaddoura, an analyst with the Pembina Institute, an environmental think-tank. "Moving forward, there needs to be some consideration on what the environmental impact of this is."

Medicine Hat owns its own natural gas and electricity generation and distribution businesses. The city leases the land to Hut 8 and the facility employs 40 full-time workers. Add up the economic benefits and the city of Medicine Hat will receive a significant financial boost from the new project, says Ted Clugston, the city's mayor.

Financial details of the city's deal with Hut 8 are not disclosed.

For more than a century, the city has attracted business by offering low-cost energy, and the mayor said this project is no different.

"They could have gone anywhere in the world and they chose Medicine Hat," said Clugston. "[Hut 8] is not here for renewable energy because it is not reliable. They need gas-fired generation and we have it in spades."

Environmental groups are concerned by the sheer amount of energy consumed by bitcoin mining, with some utilities warning they can't serve new energy-intensive customers right now, especially in places like Medicine Hat where most of the electricity is produced by fossil fuels.

The bitcoin system is designed, so only a limited number of the cryptocurrency can be mined everyday. Over time, as more miners compete for a decreasing number of available bitcoins, facilities will have to use more electricity compared to the amount of the cryptocurrency they collect.

"The way the bitcoin algorithm works is that it's designed to waste as much electricity as possible. And the more popular bitcoin becomes, the more electricity it wastes," said Keith Stewart, a spokesperson for Greenpeace.

Stewart questions whether natural gas should be used to produce a digital product.

"If you live in Alberta, you want to have heat and light, those types of things. I don't think bitcoin is a necessity of life for anyone," he said.

The CEO of Hut 8 completely disagrees, arguing the cryptocurrency is essential.  

"Bitcoin was created during the financial crisis. It has really served a purpose in terms of providing the opportunity for people who don't necessarily trust their government or their central banks," said Andrew Kiguel.

Related News

• Electricity Forum News

• Power Generation News

NB Power Pulp and Paper Subsidies lower electricity rates for six New Brunswick mills using firm power benchmarks and interruptible discounts, while government mandates, utility debt, ratepayer impacts, and competitiveness pressures shape provincial energy policy.

Key Points

Provincial mandates that buy down firm electricity rates for six mills to a national average, despite NB Power's debt.

✅ Mandated buy-down to match national firm electricity rates

✅ Ignores large non-firm interruptible power discounts

✅ Raises equity concerns amid NB Power debt and rate pressure

An effort to fix NB Power's struggling finances that is supposed to involve a look at "all options" will not include a review of the policy that requires the utility to subsidize electricity prices for six New Brunswick pulp and paper mills, according to the Department of Natural Resources and Energy Development.

The program is meant "to enable New Brunswick's pulp and paper companies have access to competitive priced electricity,"  said the department's communications officer Nick Brown in an email Monday 

"Keeping our large industries competitive with other Canadian jurisdictions, amid Nova Scotia rate hike opposition debates elsewhere, is important," he wrote, knocking down the idea the subsidy program might be scrutinized for shortcomings like other NB Power expenses.

Figures released last week show NB Power paid out $9.7 million in rate subsidies to the mills under the program in the fiscal year ended in March 2021, even though the utility was losing $4 million for the year and falling deeper into debt, amid separate concerns about old meter issues affecting households.

Subsidies went to three mills owned by J.D. Irving Ltd. including two in Saint John and one in Lake Utopia, two owned by the AV group in Nackawic and Atholville and the Twin Rivers pulp mill in Edmundston.

The New Brunswick government has made NB Power subsidize pulp and paper mills like Twin Rivers Paper Company since 2012, and is requiring the program to continue despite financial problems at the utility. (CBC)
It was NB Power's second year in a row of financial losses, while it is supposed to pay down $500 million of its $4.9 billion debt load in the next five years to prepare for the refurbishment of the Mactaquac dam, a burden comparable to customers in Newfoundland paying for Muskrat Falls elsewhere under separate policies, under a directive issued by the province

NB Power president Keith Cronkhite said he was "very disappointed" with debt increasing last year instead of  falling and senior vice president and chief financial officer Darren Murphy said everything would be under the microscope this year to turn the utility's finances around.  

"We need to do better," said Murphy on Thursday

"We need to step back and make sure we're considering all options, including approaches like Newfoundland's ratepayer shield agreement on megaproject overruns, to achieve that objective because the objective is quickly closing in on us."

However, reviewing the subsidy program for the six pulp and paper mills is apparently off limits.

The subsidy program requires NB Power to buy down the cost of "firm" electricity bought by pulp and paper mills to a national average that is calculated by the Department of Natural Resources and Energy Development.

Last year the province declared the price mills in New Brunswick pay to be an average of  7.536 cents per kilowatt hour (kwh).  It is higher than rates in five other provinces that have mills, which the province points to as justification for the subsidies, even as Nova Scotia's 14% rate hike approval highlights broader upward pressure, although the true significance of that difference is not entirely clear.

In British Columbia, the large forest products company Paper Excellence operates five pulp and paper mills which are charged 17.2 per cent less for firm electricity than the six mills in New Brunswick.

The Paper Excellence Paper Mill in Port Alberni, B.C. pays lower electricity prices than mills in New Brunswick, a benefit largely offset by higher property taxes. It's a factor New Brunswick does not count in calculating subsidies NB Power must pay. (Paper Excellence)
However, local property taxes on the five BC mills are a combined $7.8 million higher than the six New Brunswick plants, negating much of that difference.

The province's subsidy formula does not account for differences like that or for the fact New Brunswick mills buy a high percentage of their electricity at cheap non-firm prices.

Not counting the subsidies, NB Power already sells high volumes of what it calls interruptible and surplus power to industry at deep discounts on the understanding it can be cut off and redeployed elsewhere on short notice when needed.

Actual interruptions in service are rare.  Last year there were none, but NB Power sold 837 million kilowatt hours of the discounted power to industry at an average price of 4.9 cents per kwh.   

NB Power does not disclose how much of the $22 million or more in savings went to the six mills, but the price was 35 per cent below NB Power's posted rate for the plants and rivaled firm prices big mills receive anywhere in Canada, including Quebec.

Asked why the subsidy program ignores large amounts of discounted interruptible power used by New Brunswick mills in making comparisons between provinces, Brown said regulations governing the program require a comparison of firm prices only.

"The New Brunswick average rate is based on NB Power's published large industrial rate for firm energy, as required by the Electricity from Renewable Resources regulation," he wrote.

The subsidy program itself was imposed on NB Power by the province in 2012 to aid companies suffering after years of poor markets for forest products following the 2008 financial collapse and recession.  

Providing subsidies has cost NB Power $100 million so far and has continued even as markets for pulp products improved significantly and NB Power's own finances worsened.

Report warned against subsidies
NB Power has never directly criticized the program, but in a matter currently in front the of the New Brunswick Energy and Utilities Board looking at how NB Power might restructure its rates, including proposals such as seasonal rates that could prompt backlash, an independent consultant hired by the utility suggested rate subsidies to large export oriented manufacturing facilities, like pulp and paper mills, is generally a poor idea.

"We do not recommend offering subsidies to exporters," says the report by Christensen Associates Energy Consulting of Madison, Wis.

"There are two serious economic problems with subsidizing exports. The first is that the benefits may be less than the costs. The second problem is that subsidies tend to last forever, even if the circumstances that initially justified the subsidies have disappeared."

The Christensen report did not directly assess the merits of the current subsidy for pulp and paper mills but it addressed the issue because it said in the design of new rates "one NB Power business customer has raised the possibility that their electricity-intensive business ought to be granted subsidies because of the potential to generate extra benefits for the Province through increases in their exports"

That, said Christensen, rarely benefits the public.

"The direct costs of the subsidies are the subsidies themselves, a part of which ends up in the pockets of out-of-province consumers of the exported goods," said the report.  

"But there are also indirect costs due to the fact that the subsidies are financed through higher electricity prices, which means that other electricity customers have less money to spend on services provided by local businesses, thus putting a drag on the local economy."

The province does not agree.

Asked whether it has any studies or cost-benefit reviews that show the subsidy program is a net benefit to New Brunswick, the department cited none but maintained it is an important initiative, even as elsewhere governments have offered electricity bill credit relief to ratepayers.

"The program was designed to give large industrial businesses the ability to compete on a level energy field," wrote Brown.
 

Related News

• Electricity Forum News

• Energy Policy News

Ontario-Quebec Electricity Trade Agreement ends as Ontario pivots to IESO procurement, hydropower alternatives, natural gas capacity, and energy auctions, impacting grid reliability, power imports, and GHG emissions across both provincial markets.

Key Points

A seven-year power import pact; Ontario will end it, shifting to IESO procurement and gas capacity.

✅ Seasonal hydropower exchange of 2.3 TWh annually.

✅ IESO projects Quebec supply constraints by decade end.

✅ Ontario adds gas, auctions; near-term sector GHGs rise.

The Ontario government does not plan to renew the Ontario-Quebec electricity trade agreement, Radio-Canada is reporting.

The seven-year contract, which expires next year, aims to reduce Ontario's greenhouse gas (GHG) emissions by buying 2.3 Terawatt-hours of electricity from Quebec annually — that corresponds to about seven per cent of Hydro-Quebec's average annual exports.

The announcement comes as the provincially owned Quebec utility continues its legal battle over a plan to export power to Massachusetts.

The Ontario agreement has guaranteed a seasonal exchange of energy, since Quebec has a power surplus in summer, and the province's electricity needs increase in the winter. Ontario plans on exercising its last and only option in the summer of 2026, for a block of 500 megawatts.

The office of the Ontario Minister of Energy Todd Smith says the province will save money by relying "on a competitive procurement process" instead, amid debates over clean, affordable electricity policy in Ontario. And, the Independent Electricity System Operator (IESO), the equivalent of Hydro-Quebec in Ontario, added that, at any rate, Quebec is expected to "run out of electricity in the middle or at the end of the decade."

During the Quebec election campaign, Premier Francois Legault said his province needed to increase hydroelectricity production because he is expecting demand for hydroelectricity to increase by an additional 100 terawatt-hours in the coming decades — half of Hydro-Quebec's current annual output.

Coalition Avenir Quebec pitches more hydro dams to Quebec voters
The provinces will still continue to buy and sell power, reaching deals through annual energy auctions.

Eloise Edom, an associate researcher at Polytechnique Montreal's Institut de l'energie Trottier, says the announcement came as somewhat of a surprise because "we're still talking about a lot of energy."

Hydro-Quebec refused to comment on "the SIERE [Independent Electricity System Operator]'s intentions for the agreement, which ends next year," said company spokesperson Lynn St-Laurent.

No green options
Yet Ontario is running out of electricity, even as questions persist about whether it is embracing clean power to meet demand, in part because of plans to refurbish nuclear reactors at the Bruce and Darlington generator stations.

Windsor has already lost out on a $2.5-billion factory because the region is short of electricity for new industrial loads. And by 2025, Toronto will run out of power for the electrification of its transit system, according to the latest estimates from the IESO.

The Ford government recently announced that it hopes to extend the life of the Pickering nuclear station amid ongoing debate. It is also evaluating the possibility of increasing hydroelectricity production at its existing dams.

For now, Ontario is banking on its natural gas plants to meet demand, which have won most recent IESO tenders for contracts running until 2026. Last Friday, the province announced that it was going to buy an additional 1,500 megawatts by 2027.

"The [Ontario energy] minister's expectations may be that the increase in natural gas prices is temporary and that it will fade," energy economist Jean-Thomas Bernard said. "With this in mind, he probably does not want to sign a long-term contract [with Hydro-Quebec] and prefers to buy electricity on a day-to-day basis and through calls for tenders."

If the Quebec deal expires, Ontario, Canada's second highest GHG emitter, would have to increase its emissions for the sector, at least in the medium term, with electricity getting dirtier as gas fills the gap.

Last year, the IESO found that it would be very difficult to set a moratorium on natural gas before 2030. The IESO must produce a final report on the subject for the energy minister by the end of November.

Related News

• Electricity Forum News

• Power Generation News

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. 

Related News

• Electricity Forum News

• Power Generation News

EU-UK Coal Power Decline 2020 underscores Covid-19's impact on power generation, with renewables rising, carbon emissions falling, and electricity demand down, revealing resilient grids and accelerating the energy transition across European markets.

Key Points

Covid-19's impact on EU-UK power: coal down, renewables up, lower emissions intensity and reduced electricity demand.

✅ Coal generation down 25.5% EU-UK; 29% in March 10-April 10 period

✅ Renewables share up to 46%; grids remained stable and flexible

✅ Electricity demand fell 10%; emissions intensity dropped 19.5%

Coal based power generation has fallen by over a quarter (25.5%) across the European Union (EU) and United Kingdom (UK) in the first three months of 2020, compared to 2019, as a result of the response to Covid-19, with renewable energy reaching a 43% share, as wind and solar outpaced gas across the EU, according to new analysis by the technology group Wärtsilä.

The impact is even more stark in the last month, with coal generation collapsing by almost one third (29%) between March 10 and April 10 compared to the same period in 2019, making up only 12% of total EU and UK generation. By contrast, renewables delivered almost half (46%) of generation – an increase of 8% compared to 2019.

In total, demand for electricity across the continent is down by one tenth (10%), mirroring global demand declines of around 15%, due to measures taken to combat Covid-19, the biggest drop in demand since the Second World War. The result is an unprecedented fall in carbon emissions from the power sector, with emission intensity falling by 19.5% compared to the same March 10-April 10 period last year. The analysis comes from the Wärtsilä Energy Transition Lab, a new free-to-use data platform developed by Wärtsilä to help the industry, policy makers and the public understand the impact of Covid-19 on European electricity markets and analyse what this means for the future design and operation of its energy systems. The goal is to help accelerate the transition to 100% renewables.

Björn Ullbro, Vice President for Europe & Africa at Wärtsilä Energy Business, said: “The impact of the Covid-19 crisis on European energy systems is extraordinary. We are seeing levels of renewable electricity that some people believed would cause systems to collapse, yet they haven’t – in fact they are coping well. The question is, what does this mean for the future?”

“What we can see today is how our energy systems cope with much more renewable power – knowledge that will be invaluable, aligning with IAEA low-carbon insights, to accelerate the energy transition. We are making this new platform freely available to support the energy industry to adapt and use the momentum this tragic crisis has created to deliver a better, cleaner energy system, faster.”

The figures mark a dramatic shift in Europe’s energy mix – one that was not anticipated to occur until the end of the decade. The impact of the Covid-19 crisis has effectively accelerated the energy transition in the short-term, even as later lockdowns saw power demand hold firm in parts of Europe, providing a unique opportunity to see how energy systems function with far higher levels of renewables.

Ullbro added: “Electricity demand across Europe has fallen due to the lockdown measures applied by governments to stop the spread of the coronavirus. However, total renewable generation has remained at pre-crisis levels with low electricity prices, combined with renewables-friendly policy measures, crowding out gas and fossil fuel power generation, especially coal. This sets the scene for the next decade of the energy transition.”

These Europe-wide impacts are mirrored at a national level, for example:

• In the UK, renewables now have a 43% share of generation, following a stall in low-carbon progress in 2019 (up 10% on the same March 10-April 10 period in 2019) with coal power down 35% and gas down 24%.
• Germany has seen the share of renewables reach 60% (up 12%) and coal generation fall 44%, resulting in a fall in the carbon intensity of its electricity of over 30%.
• Spain currently has 49% renewables with coal power down by 41%.
• Italy has seen the steepest fall in demand, down 21% so far.

An industry first, the Wärtsilä Energy Transition Lab has been specifically developed as an open-data platform for the energy industry to understand the impact of Covid-19 and help accelerate the energy transition. The tool provides detailed data on electricity generation, demand and pricing for all 27 EU countries and the UK, combining Entso-E data in a single, easy to use platform. It will also allow users to model how systems could operate in future with higher renewables, as global power demand surpasses pre-pandemic levels, helping pinpoint problem areas and highlight where to focus policy and investment.

Related News

• Electricity Forum News

• Power Generation News

Near-Field Thermophotovoltaics captures radiated energy across a nanoscale gap, using thin-film photovoltaic cells and indium gallium arsenide to boost power density and efficiency, enabling compact Army portable power from emitters via radiative heat transfer.

Key Points

A nanoscale TPV method capturing near-field photons for higher power density at lower emitter temperatures.

✅ Nanoscale gap boosts radiative transfer and usable photon flux

✅ Thin-film InGaAs cells recycle sub-band-gap photons via reflector

✅ Achieved ~5 kW/m2 power density with higher efficiency

With the addition of sensors and enhanced communication tools, providing lightweight, portable power has become even more challenging, with concepts such as power from falling snow illustrating how diverse new energy-harvesting approaches are. Army-funded research demonstrated a new approach to turning thermal energy into electricity that could provide compact and efficient power for Soldiers on future battlefields.

Hot objects radiate light in the form of photons into their surroundings. The emitted photons can be captured by a photovoltaic cell and converted to useful electric energy. This approach to energy conversion is called far-field thermophotovoltaics, or FF-TPVs, and has been under development for many years; however, it suffers from low power density and therefore requires high operating temperatures of the emitter.

The research, conducted at the University of Michigan and published in Nature Communications, demonstrates a new approach, where the separation between the emitter and the photovoltaic cell is reduced to the nanoscale, enabling much greater power output than what is possible with FF-TPVs for the same emitter temperature.

This approach, which enables capture of energy that is otherwise trapped in the near-field of the emitter is called near-field thermophotovoltaics or NF-TPV and uses custom-built photovoltaic cells and emitter designs ideal for near-field operating conditions, alongside emerging smart solar inverters that help manage conversion and delivery.

This technique exhibited a power density almost an order of magnitude higher than that for the best-reported near-field-TPV systems, while also operating at six-times higher efficiency, paving the way for future near-field-TPV applications, including remote microgrid deployments in extreme environments, according to Dr. Edgar Meyhofer, professor of mechanical engineering, University of Michigan.

"The Army uses large amounts of power during deployments and battlefield operations and must be carried by the Soldier or a weight constrained system," said Dr. Mike Waits, U.S. Army Combat Capabilities Development Command's Army Research Laboratory. "If successful, in the future near-field-TPVs could serve as more compact and higher efficiency power sources for Soldiers as these devices can function at lower operating temperatures than conventional TPVs."

The efficiency of a TPV device is characterized by how much of the total energy transfer between the emitter and the photovoltaic cell is used to excite the electron-hole pairs in the photovoltaic cell, where insights from near-light-speed conduction research help contextualize performance limits in semiconductors. While increasing the temperature of the emitter increases the number of photons above the band-gap of the cell, the number of sub band-gap photons that can heat up the photovoltaic cell need to be minimized.

"This was achieved by fabricating thin-film TPV cells with ultra-flat surfaces, and with a metal back reflector," said Dr. Stephen Forrest, professor of electrical and computer engineering, University of Michigan. "The photons above the band-gap of the cell are efficiently absorbed in the micron-thick semiconductor, while those below the band-gap are reflected back to the silicon emitter and recycled."

The team grew thin-film indium gallium arsenide photovoltaic cells on thick semiconductor substrates, and then peeled off the very thin semiconductor active region of the cell and transferred it to a silicon substrate, informing potential interfaces with home battery systems for distributed use.

All these innovations in device design and experimental approach resulted in a novel near-field TPV system that could complement distributed resources in virtual power plants for resilient operations.

"The team has achieved a record ~5 kW/m2 power output, which is an order of magnitude larger than systems previously reported in the literature," said Dr. Pramod Reddy, professor of mechanical engineering, University of Michigan.

Researchers also performed state-of-the-art theoretical calculations to estimate the performance of the photovoltaic cell at each temperature and gap size, informing hybrid designs with backup fuel cell solutions that extend battery life, and showed good agreement between the experiments and computational predictions.

"This current demonstration meets theoretical predictions of radiative heat transfer at the nanoscale, and directly shows the potential for developing future near-field TPV devices for Army applications in power and energy, communication and sensors," said Dr. Pani Varanasi, program manager, DEVCOM ARL that funded this work.

Related News

• Electricity Forum News

• Power Generation News