Energy expert urges efficiency over adding capacity

Sulphur Hexafluoride (SF6) Emissions drive rising greenhouse gas impacts in electrical switchgear, power grids, and renewables, with extreme global warming potential, long atmospheric lifetime, and leakage risks challenging climate targets and grid decarbonization.

Key Points

SF6 emissions are leaks from electrical switchgear and grids, a high-GWP gas with ~1,000-year lifetime.

✅ 23,500x CO2 global warming potential (GWP)

✅ Leaks from switchgear, breakers, gas-insulated substations

✅ Clean air and vacuum alternatives emerging for MV/HV

Sulphur hexafluoride, or SF6, is widely used in the electrical industry to prevent short circuits and accidents.

But leaks of the little-known gas in the UK and the rest of the EU in 2017 were the equivalent of putting an extra 1.3 million cars on the road.

Levels are rising as an unintended consequence of the green energy boom and the broader global energy transition worldwide.

Cheap and non-flammable, SF6 is a colourless, odourless, synthetic gas. It makes a hugely effective insulating material for medium and high-voltage electrical installations.

It is widely used across the industry, from large power stations to wind turbines to electrical sub-stations in towns and cities.

It prevents electrical accidents and fires.

However, the significant downside to using the gas is that it has the highest global warming potential of any known substance. It is 23,500 times more warming than carbon dioxide (CO2).

Just one kilogram of SF6 warms the Earth to the same extent as 24 people flying London to New York return.

It also persists in the atmosphere for a long time, warming the Earth for at least 1,000 years.

So why are we using more of this powerful warming gas?

The way we make electricity around the world is changing rapidly, with New Zealand's push to electrify in its energy system.

Where once large coal-fired power stations brought energy to millions, the drive to combat climate change and to move away from coal means they are now being replaced by mixed sources of power including wind, solar and gas.

This has resulted in many more connections to the electricity grid, and with EU electricity use could double by 2050, a rise in the number of electrical switches and circuit breakers that are needed to prevent serious accidents.

Collectively, these safety devices are called switchgear. The vast majority use SF6 gas to quench arcs and stop short circuits.

"As renewable projects are getting bigger and bigger, we have had to use it within wind turbines specifically," said Costa Pirgousis, an engineer with Scottish Power Renewables on its new East Anglia wind farm, which doesn't use SF6 in turbines.

"As we are putting in more and more turbines, we need more and more switchgear and, as a result, more SF6 is being introduced into big turbines off shore.

"It's been proven for years and we know how it works, and as a result it is very reliable and very low maintenance for us offshore."

How do we know that SF6 is increasing?

Across the entire UK network of power lines and substations, there are around one million kilograms of SF6 installed.

A study from the University of Cardiff found that across all transmission and distribution networks, the amount used was increasing by 30-40 tonnes per year.

This rise was also reflected across Europe with total emissions from the 28 member states in 2017 equivalent to 6.73 million tonnes of CO2. That's the same as the emissions from 1.3 million extra cars on the road for a year.

Researchers at the University of Bristol who monitor concentrations of warming gases in the atmosphere say they have seen significant rises in the last 20 years.

"We make measurements of SF6 in the background atmosphere," said Dr Matt Rigby, reader in atmospheric chemistry at Bristol.

"What we've seen is that the levels have increased substantially, and we've seen almost a doubling of the atmospheric concentration in the last two decades."

How does SF6 get into the atmosphere?

The most important means by which SF6 gets into the atmosphere is from leaks in the electricity industry.

Electrical company Eaton, which manufactures switchgear without SF6, says its research indicates that for the full life-cycle of the product, leaks could be as high as 15% - much higher than many other estimates.

Louis Schaeffer, electrical business manager at Eaton, said: "The newer gear has very low leak rates but the key question is do you have newer gear?

"We looked at all equipment and looked at the average of all those leak rates, and we didn't see people taking into account the filling of the gas. Plus, we looked at how you recycle it and return it and also included the catastrophic leaks."

How damaging to the climate is this gas?

Concentrations in the atmosphere are very small right now, just a fraction of the amount of CO2 in the air.

However, the global installed base of SF6 is expected to grow by 75% by 2030, as data-driven electricity demand surges worldwide.

Another concern is that SF6 is a synthetic gas and isn't absorbed or destroyed naturally. It will all have to be replaced and destroyed to limit the impact on the climate.

Developed countries are expected to report every year to the UN on how much SF6 they use, but developing countries do not face any restrictions on use.

Right now, scientists are detecting concentrations in the atmosphere that are 10 times the amount declared by countries in their reports. Scientists say this is not all coming from countries like India, China and South Korea.

One study found that the methods used to calculate emissions in richer countries "severely under-reported" emissions over the past two decades.

Why hasn't this been banned?

SF6 comes under a group of human-produced substances known as F-gases. The European Commission tried to prohibit a number of these environmentally harmful substances, including gases in refrigeration and air conditioning, back in 2014.

But they faced strong opposition from industries across Europe.

"In the end, the electrical industry lobby was too strong and we had to give in to them," said Dutch Green MEP Bas Eickhout, who was responsible for the attempt to regulate F-gases.

"The electric sector was very strong in arguing that if you want an energy transition, and you have to shift more to electricity, you will need more electric devices. And then you also will need more SF6.

"They used the argument that otherwise the energy transition would be slowed down."

What do regulator and electrical companies say about the gas?

Everyone is trying to reduce their dependence on the gas, and US control efforts suggest targeted policies can drive declines, as it is universally recognised as harmful to the climate.

In the UK, energy regulator Ofgem says it is working with utilities to try to limit leaks of the gas.

"We are using a range of tools to make sure that companies limit their use of SF6, a potent greenhouse gas, where this is in the interest of energy consumers," an Ofgem spokesperson told BBC News.

"This includes funding innovation trials and rewarding companies to research and find alternatives, setting emissions targets, rewarding companies that beat those targets, and penalising those that miss them."

Are there alternatives - and are they very expensive?

The question of alternatives to SF6 has been contentious over recent years.

For high-voltage applications, experts say there are very few solutions that have been rigorously tested.

"There is no real alternative that is proven," said Prof Manu Haddad from the school of engineering at Cardiff University.

"There are some that are being proposed now but to prove their operation over a long period of time is a risk that many companies don't want to take."

Medium voltage operations there are several tried-and-tested materials. Some in the industry say that the conservative nature of the electrical industry is the key reason that few want to change to a less harmful alternative.

"I will tell you, everyone in this industry knows you can do this; there is not a technical reason not to do it," said Louis Schaffer from Eaton.

"It's not really economic; it's more a question that change takes effort and if you don't have to, you won't do it."

Some companies are feeling the winds of change

Sitting in the North Sea some 43km from the Suffolk coast, Scottish Power Renewables has installed one of world's biggest wind farms, in line with a sustainable electric planet vision, where the turbines will be free of SF6 gas.

East Anglia One will see 102 of these towering generators erected, with the capacity to produce up to 714MW (megawatts) of power by 2020, enough to supply half a million homes.

Previously, an installation like this would have used switchgear supplied with SF6, to prevent the electrical accidents that can lead to fires.

Each turbine would normally have contained around 5kg of SF6, which, if it leaked into the atmosphere, would add the equivalent of around 117 tonnes of carbon dioxide. This is roughly the same as the annual emissions from 25 cars.

"In this case we are using a combination of clean air and vacuum technology within the turbine. It allows us to still have a very efficient, reliable, high-voltage network but to also be environmentally friendly," said Costa Pirgousis from Scottish Power Renewables.

"Once there are viable alternatives on the market, there is no reason not to use them. In this case, we've got a viable alternative and that's why we are using it."

But even for companies that are trying to limit the use of SF6, there are still limitations. At the heart of East Anglia One sits a giant offshore substation to which all 102 turbines will connect. It still uses significant quantities of the highly warming gas.

What happens next ?

The EU will review the use of SF6 next year and will examine whether alternatives are available. However, even the most optimistic experts don't think that any ban is likely to be put in place before 2025.

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Carbon Nanotube Solvent Electricity enables wire-free electrochemistry as organic solvents like acetonitrile pull electrons, powering alcohol oxidation and packed bed reactors, energy harvesting, and micro- and nanoscale robots via redox-driven current.

Key Points

Solvent-driven electron extraction from carbon nanotube particles generates current for electrochemistry.

✅ 0.7 V per particle via solvent-induced electron flow

✅ Packed bed reactors drive alcohol oxidation without wires

✅ Scalable for micro- and nanoscale robots; energy harvesting

MIT engineers have discovered a new way of generating electricity, alongside advances in renewable power at night that broaden what's possible, using tiny carbon particles that can create a current simply by interacting with liquid surrounding them.

The liquid, an organic solvent, draws electrons out of the particles, generating a current, unlike devices based on a cheap thermoelectric material that rely on heat, that could be used to drive chemical reactions or to power micro- or nanoscale robots, the researchers say.

"This mechanism is new, and this way of generating energy is completely new," says Michael Strano, the Carbon P. Dubbs Professor of Chemical Engineering at MIT. "This technology is intriguing because all you have to do is flow a solvent through a bed of these particles. This allows you to do electrochemistry, but with no wires."

In a new study describing this phenomenon, the researchers showed that they could use this electric current to drive a reaction known as alcohol oxidation—an organic chemical reaction that is important in the chemical industry.

Strano is the senior author of the paper, which appears today in Nature Communications. The lead authors of the study are MIT graduate student Albert Tianxiang Liu and former MIT researcher Yuichiro Kunai. Other authors include former graduate student Anton Cottrill, postdocs Amir Kaplan and Hyunah Kim, graduate student Ge Zhang, and recent MIT graduates Rafid Mollah and Yannick Eatmon.

Unique properties
The new discovery grew out of Strano's research on carbon nanotubes—hollow tubes made of a lattice of carbon atoms, which have unique electrical properties. In 2010, Strano demonstrated, for the first time, that carbon nanotubes can generate "thermopower waves." When a carbon nanotube is coated with layer of fuel, moving pulses of heat, or thermopower waves, travel along the tube, creating an electrical current that exemplifies turning thermal energy into electricity in nanoscale systems.

That work led Strano and his students to uncover a related feature of carbon nanotubes. They found that when part of a nanotube is coated with a Teflon-like polymer, it creates an asymmetry, distinct from conventional thermoelectric materials approaches, that makes it possible for electrons to flow from the coated to the uncoated part of the tube, generating an electrical current. Those electrons can be drawn out by submerging the particles in a solvent that is hungry for electrons.

To harness this special capability, the researchers created electricity-generating particles by grinding up carbon nanotubes and forming them into a sheet of paper-like material. One side of each sheet was coated with a Teflon-like polymer, and the researchers then cut out small particles, which can be any shape or size. For this study, they made particles that were 250 microns by 250 microns.

When these particles are submerged in an organic solvent such as acetonitrile, the solvent adheres to the uncoated surface of the particles and begins pulling electrons out of them.

"The solvent takes electrons away, and the system tries to equilibrate by moving electrons," Strano says. "There's no sophisticated battery chemistry inside. It's just a particle and you put it into solvent and it starts generating an electric field."

Particle power
The current version of the particles can generate about 0.7 volts of electricity per particle. In this study, the researchers also showed that they can form arrays of hundreds of particles in a small test tube. This "packed bed" reactor, unlike thin-film waste-heat harvesters for electronics, generates enough energy to power a chemical reaction called an alcohol oxidation, in which an alcohol is converted to an aldehyde or a ketone. Usually, this reaction is not performed using electrochemistry because it would require too much external current.

"Because the packed bed reactor is compact, it has more flexibility in terms of applications than a large electrochemical reactor," Zhang says. "The particles can be made very small, and they don't require any external wires in order to drive the electrochemical reaction."

In future work, Strano hopes to use this kind of energy generation to build polymers using only carbon dioxide as a starting material. In a related project, he has already created polymers that can regenerate themselves using carbon dioxide as a building material, in a process powered by solar energy and informed by devices that generate electricity at night as a complement. This work is inspired by carbon fixation, the set of chemical reactions that plants use to build sugars from carbon dioxide, using energy from the sun.

In the longer term, this approach could also be used to power micro- or nanoscale robots. Strano's lab has already begun building robots at that scale, which could one day be used as diagnostic or environmental sensors. The idea of being able to scavenge energy from the environment, including approaches that produce electricity 'out of thin air' in ambient conditions, to power these kinds of robots is appealing, he says.

"It means you don't have to put the energy storage on board," he says. "What we like about this mechanism is that you can take the energy, at least in part, from the environment."

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UK power grid bottleneck is stalling renewable energy, with connection queues, planning delays, and transmission infrastructure gaps raising costs, slowing decarbonization, and deterring investment as government considers reforms led by a new chief adviser.

Key Points

Delays and capacity gaps that hinder connecting new generation and demand, raising costs and slowing decarbonization.

✅ Connection queues delay projects for years

✅ Planning and NIMBY barriers stall transmission builds

✅ Investment costs on bills risk political pushback

During his three decades at investment bank Morgan Stanley, Franck Petitgas developed a reputation for solving problems that vexed others. Fixing the UK’s creaking power grid could be his most challenging task yet.

Earlier this year, Prime Minister Rishi Sunak appointed Petitgas as his chief business adviser, and the former financier has been pushing to tackle the gridlock that’s left projects waiting endlessly for a connection, an issue he sees as one of the biggest problems for industry.

But there are no easy solutions to tackle the years-long queue to get on the grid or the drawn-out planning process for building clean power generation, with the energy transition stalled by supply delays compounding the problem. And sluggish progress in expanding and improving the electricity network is preventing the construction of new housing developments and offices, as well as slowing the transition to greener power.

That transition has already taken a knock after Sunak last week controversially watered down some of the UK’s climate ambitions, citing in part the cost to consumers. He also acknowledged the issues surrounding the grid and promised the “most transformative plans” in response, drawing on lessons from Europe’s power crisis where applicable. Those are due to be unveiled within weeks. 

Shortly after his appointment, Petitgas offered reassurances to business leaders at a meeting in Downing Street that solutions were being worked on, according to people familiar with the matter. But there’s a lack of confidence across business that enough will be done.

Cost is a big factor in the expansion of the electricity grid, and some argue a state-owned generation model could ease bills over time. Improving the onshore network alone could require investment of between £100 billion and £240 billion ($122-$293 billion) by 2050, according to a government analysis last year. 

With network expansion funded through power bills, that’s a big ask, particularly with Sunak trailing in polls ahead of an election expected next year.

“It’s very difficult for politicians to say more money should be on bills,” said Emma Pinchbeck, chief executive of Energy UK, a trade body. “So you get to a situation where no one wants to pay for the infrastructure investment until it’s really sticky, and that’s where we’ve got to with the grid.”

There are huge competitive and economic implications if the UK falls further behind. With US President Joe Biden spending an estimated $370 billion on climate measures through his Inflation Reduction Act, and China already a world leader in electric vehicles, Britain’s grid inaction is holding it back in the global race to decarbonize, said Jess Ralston, an analyst at the Energy and Climate Intelligence Unit think tank.

“The UK is dithering and delaying, and not making any strategic decisions,” she said. “You can see companies just saying ‘I’m going to the US, or I’m going to China’.” 

In a statement, the government said it’s a “priority to speed up the time taken to connect new power generators and power consumers to the grid.” It added that it’s taking “significant steps to accelerate grid infrastructure,” including support for new Channel interconnectors announced this year.

The government expects demand for electricity to double by 2035 and that will mean more generation that needs to be linked up to the network by cables and pylons. Local grids will also have to expand to accommodate more connection points for electric vehicles and homes, and invest in large-scale energy storage capacity to balance supply.

But so far, the rapid rise in renewable energy investment has not been accompanied by matching spend on the power network, according to BloombergNEF, a pattern seen in Germany’s grid expansion woes as well.

“The pace and scale of what we now have to deliver is significantly different from the last few decades,” said Carl Trowell, president of UK strategic infrastructure at National Grid. “It’s a national endeavor.”

In June, Electricity Networks Commissioner Nick Winser sent the government recommendations for how to accelerate construction of more transmission infrastructure. He said efforts to decarbonize the power sector will be “wasted if we cannot get the power to homes and businesses.”

“We need a seriously stronger sense of urgency,” said Kevin O’Donovan, country manager for Statkraft UK, which is holding off investment in four wind farms and two solar projects due to grid connection delays.

In addition to cost, the other major stumbling block is planning. Politicians in the governing Conservative Party are wary of angering voters with new infrastructure in rural areas that typically vote Tory. Across the country, “Not In My Back Yard” campaigners – NIMBYs — pose a major challenge to projects.

Petitgas, 62, retired from Morgan Stanley last year after nearly 30 years at the bank, where he led its international division from London. The issues over connections and planning have been repeatedly pointed out to Petitgas by investors and trade groups over a series of meetings this year, according to people familiar with the matter, requesting anonymity discussing private talks.

Yet with a general election looming and the issue plagued by political headaches, many are skeptical that Sunak can find the solutions needed.

One business chief said Downing Street considers the issue too tricky and expensive to tackle in the short-term. Others are concerned that while Petitgas has license from Sunak, he doesn’t have influence across the relevant departments to get grids to the top of the agenda.

Wind Farms

Multiple parts of the UK’s climate plans are under pressure. Earlier this month, an auction for contracts to build new wind farms received zero bids from developers, even as wind leads the power mix in many regions, marking yet another green setback. 

The UK is already behind on its target of having 50 gigawatts of offshore wind built by 2030, up from 14 GW today. The challenge is accelerating development without railroading local communities.

Within Sunak’s Conservative Party, some lawmakers are pushing back on new infrastructure in their local areas. A group including Environment Secretary Therese Coffey and former Home Secretary Priti Patel is campaigning against building new pylons across a stretch of eastern England.

According to Adam Bell, director of policy at consultancy Stonehaven, backbench pressure means Sunak is unlikely to take major action on the grid in the near term. He doesn’t see the prime minister accepting Winser’s recommendations, least of all accelerating planning decisions.

“Over the last year, Sunak has favored party management over things that will benefit the country,” Bell said. 

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Assault on Kyiv's Power Grid intensifies as missiles and drones strike critical energy infrastructure. Ukraine's air defenses intercept threats, yet blackouts, heating risks, and civilian systems damage mount amid escalating winter conditions.

Key Points

Missile and drone strikes on Kyiv's power grid to cripple infrastructure, cause blackouts, and pressure civilians.

✅ Targets power plants, substations, and transmission lines

✅ Air defenses intercept many missiles and drones

✅ Blackouts jeopardize heating, safety, and communications

In a troubling escalation of hostilities, Russian forces launched a relentless five-hour assault on Kyiv, employing missiles and drones to target critical infrastructure, particularly Ukraine's power grid. This attack not only highlights the ongoing conflict between Russia and Ukraine but also underscores the vulnerability of essential services, as seen in power outages in western Ukraine in recent weeks, in the face of military aggression.

The Nature of the Attack

The assault began early in the morning and continued for several hours, with air raid sirens ringing out across the capital as residents were urged to seek shelter. Eyewitnesses reported a barrage of missile strikes, along with the ominous whir of drones overhead. The Ukrainian military responded with its air defense systems, successfully intercepting a number of the incoming threats, but several strikes still managed to penetrate the defenses.

One of the most alarming aspects of this attack was its focus on Ukraine's energy infrastructure. Critical power facilities were hit, resulting in significant disruptions to electricity supply across Kyiv and surrounding regions. The attacks not only caused immediate outages but also threatened to complicate efforts to keep the lights on in the aftermath.

Impacts on Civilians and Infrastructure

The consequences of the missile and drone strikes were felt immediately by residents. Many found themselves without power, leading to disruptions in heating, lighting, and communications. With winter approaching, the implications of such outages become even more serious, as keeping the lights on this winter becomes harder while temperatures drop and the demand for heating increases.

Emergency services were quickly mobilized to assess the damage and begin repairs, but the scale of the attack posed significant challenges. In addition to the direct damage to power facilities, the strikes created a climate of fear and uncertainty among civilians, even as many explore new energy solutions to endure blackouts.

Strategic Objectives Behind the Assault

Military analysts suggest that targeting Ukraine's energy infrastructure is a calculated strategy by Russian forces. By crippling the power grid, the intention may be to sow chaos and undermine public morale, forcing the government to divert resources to emergency responses rather than frontline defenses. This tactic has been employed previously, with significant ramifications for civilian life and national stability.

Moreover, as winter approaches, the vulnerability of Ukraine’s energy systems becomes even more pronounced, with analysts warning that winter looms over the battlefront for civilians and troops alike. With many civilians relying on electric heating and other essential services, an attack on the power grid can have devastating effects on public health and safety. The psychological impact of such assaults can also contribute to a sense of hopelessness among the population, potentially influencing public sentiment regarding the war.

International Response and Solidarity

The international community has responded with concern to the recent escalation in attacks. Ukrainian officials have called for increased military support and defensive measures to protect critical infrastructure from future assaults, amid policy shifts such as the U.S. ending support for grid restoration that complicate planning. Many countries have expressed solidarity with Ukraine, reiterating their commitment to support the nation as it navigates the complexities of this ongoing conflict.

In addition to military assistance, humanitarian aid is also critical, and instances of solidarity such as Ukraine helping Spain amid blackouts demonstrate shared resilience. As the situation continues to evolve, many organizations are working to provide relief to those affected by the attacks, offering resources such as food, shelter, and medical assistance. The focus remains not only on immediate recovery efforts but also on long-term strategies to bolster Ukraine’s resilience against future attacks.

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

Key Points

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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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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