Flickering lights cast shadows on EDF sale

Texas Heat Pump Electrification replaces natural gas furnaces with electric heating across ERCOT, cutting carbon emissions, lowering utility bills, shifting summer peaks to winter, and aligning higher loads with strong seasonal wind power generation.

Key Points

Statewide shift from gas furnaces to heat pumps in Texas, reducing emissions and bills while moving grid peak to winter.

✅ Up to $452 annual utility savings per household

✅ CO2 cuts up to 13.8 million metric tons in scenarios

✅ Winter peak rises, summer peak falls; wind aligns with load

What would happen if you converted all the single-family homes in Texas from natural gas to electric heating?

According to a paper from Pecan Street, an Austin-based energy research organization, the transition would reduce climate-warming pollution, save Texas households up to $452 annually on their utility bills, and flip the state from a summer-peaking to a winter-peaking system. And that winter peak would be “nothing the grid couldn’t evolve to handle,” according to co-author Joshua Rhodes, a view echoed by analyses outlining Texas grid reliability improvements statewide today.

The report stems from the reality that buildings must be part of any comprehensive climate action plan.

“If we do want to decarbonize, eventually we do have to move into that space. It may not be the lowest-hanging fruit, but eventually we will have to get there,” said Rhodes.

Rhodes is a founding partner of the consultancy IdeaSmiths and an analyst at Vibrant Clean Energy. Pecan Street commissioned the study, which is distilled from a larger original analysis by IdeaSmiths, at the request of the nonprofit Environmental Defense Fund.

In an interview, Rhodes said, “The goal and motivation were to put bounding on some of the claims that have been made about electrification: that if we electrify a lot of different end uses or sectors of the economy...power demand of the grid would double.”

Rhodes and co-author Philip R. White used an analysis tool from the National Renewable Energy Laboratory called ResStock to determine the impact of replacing natural-gas furnaces with electric heat pumps in homes across the ERCOT service territory, which encompasses 90 percent of Texas’ electricity load.

Rhodes and White ran 80,000 simulations in order to determine how heat pumps would perform in Texas homes and how the pumps would impact the ERCOT grid.

The researchers modeled the use of “standard efficiency” (ducted, SEER 14, 8.2 HSPF air-source heat pump) and “superior efficiency” (ductless, SEER 29.3, 14 HSPF mini-split heat pump) heat pump models against two weather data sets — a typical meteorological year, and 2011, which had extreme weather in both the winter and summer and highlighted blackout risks during severe heat for many regions.

Emissions were calculated using Texas’ power sector data from 2017. For energy cost calculations, IdeaSmiths used 10.93 cents per kilowatt-hour for electricity and 8.4 cents per therm for natural gas.

Nothing the grid can't handle
Rhodes and White modeled six scenarios. All the scenarios resulted in annual household utility bill savings — including the two in which annual electricity demand increased — ranging from $57.82 for the standard efficiency heat pump and typical meteorological year to $451.90 for the high-efficiency heat pump and 2011 extreme weather year.

“For the average home, it was cheaper to switch. It made economic sense today to switch to a relatively high-efficiency heat pump,” said Rhodes. “Electricity bills would go up, but gas bills can go down.”

All the scenarios found carbon savings too, with CO2 reductions ranging from 2.6 million metric tons with a standard efficiency heat pump and typical meteorological year to 13.8 million metric tons with the high-efficiency heat pump in 2011-year weather.

Peak electricity demand in Texas would shift from summer to winter. Because heat pumps provide both high-efficiency space heating and cooling, in the scenario with “superior efficiency” heat pumps, the summer peak drops by nearly 24 percent to 54 gigawatts compared to ERCOT’s 71-gigawatt 2016 summer peak, even as recurring strains on the Texas power grid during extreme conditions persist.

The winter peak would increase compared to ERCOT’s 66-gigawatt 2018 winter peak, up by 22.73 percent to 81 gigawatts with standard efficiency heat pumps and up by 10.6 percent to 73 gigawatts with high-efficiency heat pumps.

“The grid could evolve to handle this. This is not a wholesale rethinking of how the grid would have to operate,” said Rhodes.

He added, “There would be some operational changes if we went to a winter-peaking grid. There would be implications for when power plants and transmission lines schedule their downtime for maintenance. But this is not beyond the realm of reality.”

And because Texas’ wind power generation is higher in winter, a winter peak would better match the expected higher load from all-electric heating to the availability of zero-carbon electricity.

A conservative estimate
The study presented what are likely conservative estimates of the potential for heat pumps to reduce carbon pollution and lower peak electricity demand, especially when paired with efficiency and demand response strategies that can flatten demand.

Electric heat pumps will become cleaner as more zero-carbon wind and solar power are added to the ERCOT grid, as utilities such as Tucson Electric Power phase out coal. By the end of 2018, 30 percent of the energy used on the ERCOT grid was from carbon-free sources.

According to the U.S. Energy Information Administration, three in five Texas households already use electricity as their primary source of heat, much of it electric-resistance heating. Rhodes and White did not model the energy use and peak demand impacts of replacing that electric-resistance heating with much more energy efficient heat pumps.

“Most of the electric-resistance heating in Texas is located in the very far south, where they don’t have much heating at all,” Rhodes said. “You would see savings in terms of the bills there because these heat pumps definitely operate more efficiently than electric-resistance heating for most of the time.”

Rhodes and White also highlighted areas for future research. For one, their study did not factor in the upfront cost to homeowners of installing heat pumps.

“More study is needed,” they write in the Pecan Street paper, “to determine the feasibility of various ‘replacement’ scenarios and how and to what degree the upgrade costs would be shared by others.”

Research from the Rocky Mountain Institute has found that electrification of both space and water heating is cheaper for homeowners over the life of the appliances in most new construction, when transitioning from propane or heating oil, when a gas furnace and air conditioner are replaced at the same time, and when rooftop solar is coupled with electrification, aligning with broader utility trends toward electrification.

More work is also needed to assess the best way to jump-start the market for high-efficiency all-electric heating. Rhodes believes getting installers on board is key.

“Whenever a homeowner’s making a decision, if their system goes out, they lean heavily on what the HVAC company suggests or tells them because the average homeowner doesn’t know much about their systems,” he said.

More work is also needed to assess the best way to jump-start the market for high-efficiency all-electric heating, and how utility strategies such as smart home network programs affect adoption too. Rhodes believes getting installers on board is key.

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Bitcoin Energy Debate examines electricity usage, mining costs, environmental impact, and blockchain efficiency, weighing renewable power, carbon footprint, scalability, and transaction throughput to clarify stakeholder claims from Tesla, Square, academics, and policymakers.

Key Points

Debate on Bitcoin mining's power use, environmental impact, efficiency, and scalability versus alternative blockchains.

✅ Compares energy intensity with transaction throughput and system outputs.

✅ Weighs renewables, stranded power, and carbon footprint in mining.

✅ Assesses PoS blockchains, stablecoins, and scalability tradeoffs.

There is a great debate underway about the electricity required to process Bitcoin transactions. The debate is significant, the stakes are high, the views are diverse, and there are smart people on both sides. Bitcoin generates a lot of emotion, thereby producing too much heat and not enough light. In this post, I explain the importance of identifying the key issues in the debate, and of understanding the nature and extent of disagreement about how much electrical energy Bitcoin consumes.

Consider the background against which the debate is taking place. Because of its unstable price, Bitcoin cannot serve as a global mainstream medium of exchange. The instability is apparent. On January 1, 2021, Bitcoin’s dollar price was just over $29,000. Its price rose above $63,000 in mid-April, and then fell below $35,000, where it has traded recently. Now the financial media is asking whether we are about to experience another “cyber winter” as the prices of cryptocurrencies continue their dramatic declines.

Central banks warns of bubble on bitcoins as it skyrockets
As bitcoins skyrocket to more than $12 000 for one BTC, many central banks as ECB or US Federal ... [+] NURPHOTO VIA GETTY IMAGES
Bitcoin is a high sentiment beta asset, and unless that changes, Bitcoin cannot serve as a global mainstream medium of exchange. Being a high sentiment beta asset means that Bitcoin’s market price is driven much more by investor psychology than by underlying fundamentals.

As a general matter, high sentiment beta assets are difficult to value and difficult to arbitrage. Bitcoin qualifies in this regard. As a general matter, there is great disagreement among investors about the fair values of high sentiment beta assets. Bitcoin qualifies in this regard.

One major disagreement about Bitcoin involves the very high demand for electrical power associated with Bitcoin transaction processing, an issue that came to light several years ago. In recent months, the issue has surfaced again, in a drama featuring disagreement between two prominent industry leaders, Elon Musk (from Tesla and SpaceX) and Jack Dorsey (from Square).

On one side of the argument, Musk contends that Bitcoin’s great need for electrical power is detrimental to the environment, especially amid disruptions in U.S. coal and nuclear power that increase supply strain.  On the other side, Dorsey argues that Bitcoin’s electricity profile is a benefit to the environment, in part because it provides a reliable customer base for clean electric power. This might make sense, in the absence of other motives for generating clean power; however, it seems to me that there has been a surge in investment in alternative technologies for producing electricity that has nothing to do with cryptocurrency. So I am not sure that the argument is especially strong, but will leave it there. In any event, this is a demand side argument.

A supply side argument favoring Bitcoin is that the processing of Bitcoin transactions, known as “Bitcoin mining,” already uses clean electrical power, power which has already been produced, as in hydroelectric plants at night, but not otherwise consumed in an era of flat electricity demand across mature markets.

Both Musk and Dorsey are serious Bitcoin investors. Earlier this year, Tesla purchased $1.5 billion of Bitcoin, agreed to accept Bitcoin as payment for automobile sales, and then reversed itself. This reversal appears to have pricked an expanding Bitcoin bubble. Square is a digital transaction processing firm, and Bitcoin is part of its long-term strategy.

Consider two big questions at the heart of the digital revolution in finance. First, to what degree will blockchain replace conventional transaction technologies? Second, to what degree will competing blockchain based digital assets, which are more efficient than Bitcoin, overcome Bitcoin’s first mover advantage as the first cryptocurrency?

To gain some insight about possible answers to these questions, and the nature of the issues related to the disagreement between Dorsey and Musk, I emailed a series of academics and/or authors who have expertise in blockchain technology.

David Yermack, a financial economist at New York University, has written and lectured extensively on blockchains. In 2019, Yermack wrote the following: “While Bitcoin and successor cryptocurrencies have grown remarkably, data indicates that many of their users have not tried to participate in the mainstream financial system. Instead they have deliberately avoided it in order to transact in black markets for drugs and other contraband … or evade capital controls in countries such as China.” In this regard, cyber-criminals demanding ransom for locking up their targets information systems often require payment in Bitcoin. Recent examples of cyber-criminal activity are not difficult to find, such as incidents involving Kaseya and Colonial Pipeline.

David Yermack continues: “However, the potential benefits of blockchain for improving data security and solving moral hazard problems throughout the financial system have become widely apparent as cryptocurrencies have grown.” In his recent correspondence with me, he argues that the electrical power issue associated with Bitcoin “mining,” is relatively minor because Bitcoin miners are incentivized to seek out cheap electric power, and patterns shifted as COVID-19 changed U.S. electricity consumption across sectors.

Thomas Philippon, also a financial economist at NYU, has done important work characterizing the impact of technology on the resource requirements of the financial sector. He has argued that historically, the financial sector has comprised about 6-to-7% of the economy on average, with variability over time. Unit costs, as a percentage of assets, have consistently been about 2%, even with technological advances. In respect to Bitcoin, he writes in his correspondence with me that Bitcoin is too energy inefficient to generate net positive social benefits, and that energy crisis pressures on U.S. electricity and fuels complicate the picture, but acknowledges that over time positive benefits might be possible.

Emin Gün Sirer is a computer scientist at Cornell University, whose venture AVA Labs has been developing alternative blockchain technology for the financial sector. In his correspondence with me, he writes that he rejects the argument that Bitcoin will spur investment in renewable energy relative to other stimuli. He also questions the social value of maintaining a fairly centralized ledger largely created by miners that had been in China and are now migrating to other locations such as El Salvador.

Bob Seeman is an engineer, lawyer, and businessman, who has written a book entitled Bitcoin: The Mother of All Scams. In his correspondence with me, he writes that his professional experience with Bitcoin led him to conclude that Bitcoin is nothing more than unlicensed gambling, a point he makes in his book.

David Gautschi is an academic at Fordham University with expertise in global energy. I asked him about studies that compare Bitcoin’s use of energy with that of the U.S. financial sector. In correspondence with me, he cautioned that the issues are complex, and noted that online technology generally consumes a lot of power, with electricity demand during COVID-19 highlighting shifting load profiles.

My question to David Gautschi was prompted by a study undertaken by the cryptocurrency firm Galaxy Digital. This study found that the financial sector together with the gold industry consumes twice as much electrical power as Bitcoin transaction processing. The claim by Galaxy is that Bitcoin’s electrical power needs are “at least two times lower than the total energy consumed by the banking system as well as the gold industry on an annual basis.”

Galaxy’s analysis is detailed and bottom up based. In order to assess the plausibility of its claims, I did a rough top down analysis whose results were roughly consistent with the claims in the Galaxy study. For sake of disclosure, I placed the heuristic calculations I ran in a footnote.1 If we accept the Galaxy numbers, there remains the question of understanding the outputs produced by the electrical consumption associated with both Bitcoin mining and U.S. banks’ production of financial services. I did not see that the Galaxy study addresses the output issue, and it is important.

Consider some quick statistics which relate to the issue of outputs. The total market for global financial services was about $20 trillion in 2020. The number of Bitcoin transactions processed per day was about 330,000 in December 2020, and about 400,000 in January 2021. The corresponding number for Bitcoin’s digital rival Ethereum during this time was about 1.1 million transactions per day. In contrast, the global number of credit card transactions per day in 2018 was about 1 billion.2

Bitcoin Value Falls
LONDON, ENGLAND - NOVEMBER 20: A visual representation of the cryptocurrencies Bitcoin and Ethereum ... [+] GETTY IMAGES
These numbers tell us that Bitcoin transactions comprise a small share, on the order of 0.04%, of global transactions, but use something like a third of the electricity needed for these transactions. That said, the associated costs of processing Bitcoin transactions relate to tying blocks of transactions together in a blockchain, not to the number of transactions. Nevertheless, even if the financial sector does indeed consume twice as much electrical power as Bitcoin, the disparity between Bitcoin and traditional financial technology is striking, and the experience of Texas grid reliability underscores system constraints when it comes to output relative to input.  This, I suggest, weakens the argument that Bitcoin’s electricity demand profile is inconsequential because Bitcoin mining uses slack electricity.

A big question is how much electrical power Bitcoin mining would require, if Bitcoin were to capture a major share of the transactions involved in world commerce. Certainly much more than it does today; but how much more?

Given that Bitcoin is a high sentiment beta asset, there will be a lot of disagreement about the answers to these two questions. Eventually we might get answers.

At the same time, a high sentiment beta asset is ill suited to being a medium of exchange and a store of value. This is why stablecoins have emerged, such as Diem, Tether, USD Coin, and Dai. Increased use of these stable alternatives might prevent Bitcoin from ever achieving a major share of the transactions involved in world commerce.

We shall see what the future brings. Certainly El Salvador’s recent decision to make Bitcoin its legal tender, and to become a leader in Bitcoin mining, is something to watch carefully. Just keep in mind that there is significant downside to experiencing foreign exchange rate volatility. This is why global financial institutions such as the World Bank and IMF do not support El Salvador’s decision; and as I keep saying, Bitcoin is a very high sentiment beta asset.

In the past I suggested that Bitcoin bubble would burst when Bitcoin investors conclude that its associated processing is too energy inefficient. Of course, many Bitcoin investors are passionate devotees, who are vulnerable to the psychological bias known as motivated reasoning. Motivated reasoning-based sentiment, featuring denial,3 can keep a bubble from bursting, or generate a series of bubbles, a pattern we can see from Bitcoin’s history.

I find the argument that Bitcoin is necessary to provide the right incentives for the development of clean alternatives for generating electricity to be interesting, but less than compelling. Are there no other incentives, such as evolving utility trends, or more efficient blockchain technologies? Bitcoin does have a first mover advantage relative to other cryptocurrencies. I just think we need to be concerned about getting locked into an technologically inferior solution because of switching costs.

There is an argument to made that decisions, such as how to use electric power, are made in markets with self-interested agents properly evaluating the tradeoffs. That said, think about why most of the world adopted the Windows operating system in the 1980s over the superior Mac operating system offered by Apple. Yes, we left it to markets to determine the outcome. People did make choices; and it took years for Windows to catch up with the Mac’s operating system.

My experience as a behavioral economist has taught me that the world is far from perfect, to expect to be surprised, and to expect people to make mistakes. We shall see what happens with Bitcoin going forward.

As things stand now, Bitcoin is well suited as an asset for fulfilling some people’s urge to engage in high stakes gambling. Indeed, many people have a strong need to engage in gambling. Last year, per capita expenditure on lottery tickets in Massachusetts was the highest in the U.S. at over $930.

High sentiment beta assets offer lottery-like payoffs. While Bitcoin certainly does a good job of that, it cannot simultaneously serve as an effective medium of exchange and reliable store of value, even setting aside the issue at the heart of the electricity debate.

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Ontario Electricity Demand Drop During COVID-19 reflects a 1,000-2,000 MW decline as IESO balances the grid, shifts peak demand later, throttles generators and baseload nuclear, and manages exports amid changing load curves.

Key Points

An about 10% reduction in Ontario's load, shifting peaks and requiring IESO grid balancing measures.

✅ Demand down 1,000-2,000 MW; roughly 10% below normal.

✅ Peak shifts later in morning as home use rises.

✅ IESO throttles generators; baseload nuclear stays online.

It’s as if the COVID-19 epidemic had tripped a circuit breaker, shutting off all power to a city the size of Ottawa.

Virus-induced restrictions that have shut down large swaths of normal commercial life across Canada has led to a noticeable drop in demand for power in Ontario and reflect a global demand dip according to reports, insiders said on Friday.

Terry Young, vice-president with the Independent Electricity System Operator, said planning was underway for further declines in usage and for whether Ontario will embrace more clean power in the long term, given the delicate balance that needs to be maintained between supply and demand.

“We’re now seeing demand that is running about 1,000 to 2,000 megawatts less than we would normally see,” Young said. “You’re essentially seeing a city the size of Ottawa drop off demand during the day.”

At the high end, a 2,000 megawatt reduction would be close to the equivalent peak demand of Ottawa and London, Ont., combined.

The decline, in the order of 10 per cent from the 17,000 to 18,000 megawatts of usage that might normally be expected and similar to the UK’s 10% drop reported during lockdowns, began last week, Young said. The downward trend became more noticeable as governments and health authorities ordered non-essential businesses to close and people to stay home. However, residential and hospital usage has climbed.

Experts say frequent hand-washing and staying away from others is the most effective way to curb the spread of the highly contagious coronavirus, which poses a special risk to older people and those with underlying health conditions. As a result, factories and other big users have reduced production or closed entirely.

Because electricity cannot be stored, generators need to throttle back their output as domestic demand shrinks and exports to places such as the United States, including New York City, which is also being hit hard by the coronavirus, fall.

“We’re watching this carefully,” Young said. “We’re able to manage this drop, but it’s something we obviously have to keep watching…and making sure we’re not over-generating electricity.”

Turning off generation, especially for nuclear plants, is an intensive process, as are restarts and would likely happen only if the downward demand trend intensifies significantly, amid concerns over Ontario’s electricity getting dirtier if baseload is displaced. However, one of North America’s largest generators, Bruce Power near Kincardine, Ont., said it had a large degree of flexibility to scale down or up.

“We have the ability to provide one-third of our output as a dynamic response, which is unique to our facility,” said James Scongack, an executive vice-president with Bruce Power. “We developed this coming out of the 2008 downturn and it’s been a critical system asset for the last decade.”

“We don’t see there being a scenario where our baseload will not be needed,” he said, even as some warn Ontario may be short of electricity in the coming years.

The province’s publicly owned Ontario Power Generation said it was also in conversations with the system operator, which provides direction to generators, and is often cited in the Ontario election discussion.

One clear shift in normal work-day usage with so many people staying at home has been the change in demand patterns. Typically, Young said, there’s a peak from about 7 a.m. to 8 a.m. as people wake and get ready to go to work or school. The peak is now occurring later in the morning, Young said.

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US Summer Energy Bills Crisis is driven by record heatwaves, soaring electricity prices, AC cooling demand, energy poverty risks, and LIHEAP relief, straining low-income households, vulnerable seniors, and budgets amid volatile utilities and peak demand.

Key Points

Rising household energy costs from extreme heat, higher electricity prices, and AC demand, straining vulnerable families.

✅ Record heatwaves drive peak electricity and cooling loads

✅ Tiered rates and volatile markets inflate utility bills

✅ LIHEAP aid and cooling centers offer short-term relief

As the sweltering heat of summer continues to grip much of the United States, American households are grappling with a staggering rise in energy bills. The combination of record-breaking temperatures and rising electricity prices is placing an unprecedented financial strain on families, raising concerns about the long-term impact on household budgets and overall well-being.

Record Heat and Energy Consumption

This summer has witnessed some of the hottest temperatures on record across the country. With many regions experiencing prolonged heatwaves, the demand for air conditioning and cooling systems has surged amid unprecedented electricity demand across parts of the U.S. The increased use of these energy-intensive appliances has led to a sharp rise in electricity consumption, which, combined with elevated energy prices, has pushed household energy bills to new heights.

The situation is particularly dire for households that are already struggling financially. Many families are facing energy bills that are not only higher than usual but are reaching levels that are unsustainable, underscoring electricity struggles for thousands of families across the country. This has prompted concerns about the potential for energy poverty, where individuals are forced to make difficult choices between paying for essential services and covering other necessary expenses.

Impact on Low-Income and Vulnerable Households

Low-income households and vulnerable populations are disproportionately affected by these soaring energy costs. For many, the financial burden of high energy bills is compounded by energy insecurity during the pandemic and other economic pressures, such as rising food prices and stagnant wages. The strain of paying for electricity during extreme heat can lead to tough decisions, including cutting back on other essential needs like healthcare or education.

Moreover, the heat itself poses a serious health risk, particularly for the elderly, children, and individuals with pre-existing health conditions. High temperatures can exacerbate conditions such as cardiovascular and respiratory illnesses, making the need for reliable cooling even more critical. For those struggling to afford adequate cooling, the risk of heat-related illnesses and fatalities increases significantly.

Utilities and Energy Pricing

The sharp rise in energy bills can be attributed to several factors, including higher costs of electricity production and distribution. The ongoing transition to cleaner energy sources, while necessary for long-term environmental sustainability, has introduced short-term volatility in energy markets. Additionally, power-company supply chain crises and increased demand during peak summer months have contributed to higher prices.

Utilities are often criticized for their pricing structures, which can be complex and opaque. Some regions, including areas where California electricity bills soar under scrutiny, use tiered pricing models that charge higher rates as energy consumption increases. This can disproportionately impact households that need to use more energy during extreme heat, further exacerbating financial strain.

Government and Community Response

In response to the crisis, various government and community initiatives are being rolled out to provide relief. Federal and state programs aimed at assisting low-income households with energy costs are being expanded. These programs, such as the Low-Income Home Energy Assistance Program (LIHEAP), offer financial assistance to help with utility bills, but demand often outstrips available resources.

Local community organizations are also stepping in to offer support. Initiatives include distributing fans and portable air conditioners, providing temporary cooling centers, and offering financial assistance to help cover energy costs. These efforts are crucial in helping to mitigate the immediate impact of high energy bills on vulnerable households.

Long-Term Solutions and Sustainability

The current crisis highlights the need for long-term solutions to address both the causes and consequences of high energy costs. Investing in energy efficiency and renewable energy technologies can help reduce the overall demand for electricity and lower long-term costs. Improvements in building insulation, the adoption of energy-efficient appliances, and advancements in smart grid technologies to prevent summer power outages are all essential components of a sustainable energy future.

Furthermore, addressing income inequality and supporting economic stability are critical to ensuring that all households can manage their energy needs without facing financial hardship. Policymakers will need to consider a range of strategies, including financial support programs, regulatory reforms, and infrastructure investments, to create a more equitable and resilient energy system.

Conclusion

As American households endure the double burden of extreme summer heat and skyrocketing energy bills, the need for immediate relief and long-term solutions has never been clearer. The current crisis serves as a reminder of the broader challenges facing the nation’s energy system and the importance of addressing both short-term needs and long-term sustainability. By investing in efficient technologies, supporting vulnerable populations, and developing resilient infrastructure, the U.S. can work towards a future where energy costs are manageable, and everyone has access to the resources they need to stay safe and comfortable.

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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.

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Texas power grid highlights ERCOT reliability strains from extreme heat, climate change, and low wind, as natural gas and renewables balance tight capacity amid EV charging growth, heat pumps, and blackout risk across the U.S.

Key Points

Texas power grid is ERCOT-run and isolated, balancing natural gas and wind amid extreme weather and electrification.

✅ Isolated from other U.S. grids, limited import support

✅ Vulnerable to extreme heat, winter storms, low wind

✅ Demand growth from EVs and heat pumps stresses capacity

Texas has a unique state-run power grid facing a Texas grid crisis that has raised concerns, but its issues with extreme weather, and balancing natural gas and wind, hold lessons for an entire U.S. at risk for power outages from climate change.

Grid operator the Electric Reliability Council of Texas, or ERCOT, which has drawn criticism from Elon Musk recently, called on consumers to voluntarily reduce power use on Monday when dangerous heat gripped America’s second-most populous state.

The action paid off as the Texas grid avoided blackouts — and a repeat of its winter crisis — despite record or near-record temperatures that depleted electric supplies amid a broader supply-chain crisis affecting utilities this summer, and risked lost power to more than 26 million customers. ERCOT later on Monday lifted the call for conservation.

For sure, it’s a unique situation, as the state-run power grid system runs outside the main U.S. grids. Still, all Americans can learn from Texas about the fragility of a national power grid that is expected to be challenged more frequently by hot and cold weather extremes brought on by climate change, including potential reliability improvements policymakers are weighing.

The grid will also be tested by increased demand to power electric vehicles (EVs) and conversions to electric heat pumps — all as part of a transition to a “greener” future.

Why is Texas different?
ERCOT, the main, but not only, Texas grid, is unique in its state-run, and not regional, format used by the rest of the country. Because it’s an energy-rich state, Texas has been able to set power prices below those seen in other parts of the country, and its independence gives it more pricing authority, while lawmakers consider market reforms to avoid blackouts. But during unusual strain on the system, such as more people blasting their air conditioners longer to combat a record heat wave, it also has no where else to turn.

A lethal winter power shortage in February 2021, during a Texas winter storm that left many without power and water, notoriously put the state and its independent utility in the spotlight when ERCOT failed to keep residents warm and pipes from bursting. Texas’s 2021 outage left more than 200 people dead and rang up $20 billion in damage. Fossil-fuel CL00, 0.80% backers pointed to the rising use of intermittent wind power, which generates 23% of Texas’s electricity. Others said natural-gas equipment was frozen under the extreme conditions.

This week, ERCOT is asking for voluntary conservation between 2 p.m. and 8 p.m. local time daily due to record high electricity demand from the projected heat wave, and also because of low wind. ERCOT said current projections show wind generation coming in at less than 10% of capacity. ERCOT stressed that no systemwide outages are expected, and Gov. Greg Abbott has touted grid readiness heading into fall, but it was acting preemptively.

A report late last year from the North American Electric Reliability Corp. (NERC) said the Texas system without upgrades could see a power shortfall of 37% in extreme winter conditions. NERC’s outlook suggested the state and ERCOT isn’t prepared for a repeat of weather extremes.

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