University researchers focus on solar power

California Managed Decline of Fossil Fuels aligns oil phaseout with carbon neutrality, leveraging ZEV adoption, solar and wind growth, severance taxes, drilling setbacks, fracking oversight, CARB rules, and CalGEM regulation to deliver a just transition.

Key Points

California's strategy to phase out oil and gas while meeting carbon-neutral goals through policy, regulation, and equity.

✅ Severance taxes fund clean energy and workforce transition.

✅ Setbacks restrict drilling near schools, homes, and hospitals.

✅ CARB and CalGEM tighten fracking oversight and ZEV targets.

California’s energy past is on a collision course with its future. Think of major oil-producing U.S. states, and Texas, Alaska or North Dakota probably come to mind. Although its position relative to other states has been falling for 20 years, California remains the seventh-largest oil-producing state, with 162 million barrels of crude coming up in 2018, translating to tax revenue and jobs.

At the same time, California leads the nation in solar rooftops and electric vehicles on the road by a wide margin and ranking fifth in installed wind capacity. Clean energy is the state’s future, and the state is increasingly exporting its energy policies across the West, influencing regional markets. By law, California must have 100 percent carbon-free electricity by 2045, and an executive order signed by former Governor Jerry Brown calls for economywide carbon-neutrality by the same year.

So how can the state reconcile its divergent energy path? How should clean-energy-minded lawmakers wind down California’s oil and gas sector in a way that aligns with the state’s long-term climate targets while providing a just transition for the industry’s workforce?

Any efforts to reduce fossil fuel supply must run parallel to aggressive demand-reduction measures such as California’s push to have 5 million zero-emission vehicles on the road by 2030, said Ethan Elkind, director of Berkeley Law's climate program, especially amid debates over keeping the lights on without fossil fuels in the near term. After all, if oil demand in California remains strong, crude from outside the state will simply fill the void.

“If we don’t stop using it, then that supply is going to get here, even if it’s not produced in-state,” Elkind said in an interview.

Lawmakers have a number of options for policies that would draw down and eventually phase out fossil fuel production in California, according to a new report from the Center for Law, Energy and the Environment at the UC Berkeley School of Law, co-authored by Elkind and Ted Lamm.

They could impose a higher price on California's oil production through a "severance" tax or carbon-based fee, with the revenue directed to measures that wean the state from fossil fuels. (California, alone among major oil-producing states, does not have an oil severance tax.)

Lawmakers could establish a minimum drilling setback from schools, playgrounds, homes and other sensitive sites. They could push the state's oil and gas regulator, the California Geologic Energy Management Division, to prioritize environmental and climate concerns.

A major factor holding lawmakers back is, of course, politics, including debates over blackouts and climate policy that shape public perception. Given the state’s clean-energy ambitions, it might surprise non-Californians that the oil and gas industry is one of the Golden State’s most powerful special interest groups.

Overcoming a "third-rail issue" in California politics
The Western States Petroleum Association, the sector’s trade group in California's capital of Sacramento, spent $8.8 million lobbying state policymakers in 2019, more than any other interest group. Over the last five years, the group, which cultivates both Democratic and Republican lawmakers, has spent $43.3 million on lobbying, nearly double the total of the second-largest lobbying spender.

Despite former Governor Brown’s reputation as a climate champion, critics say he was unwilling to forcefully take on the oil and gas industry. However, things may take a different turn under Brown's successor, Governor Gavin Newsom.

In May 2019, when Newsom released California's midyear budget revision (PDF), the governor's office noted the need for "careful study and planning to decrease demand and supply of fossil fuels, while managing the decline in a way that is economically responsible and sustainable.”

Related reliability concerns surfaced as blackouts revealed lapses in power supply across the state.

Writing for the advocacy organization Oil Change International, David Turnbull observed, “This may mark the first time that a sitting governor in California has recognized the need to embark upon a managed decline of fossil fuel supply in the state.”

“It is significant because typically this is one of those third-rail issues, kind of a hot potato that governors don’t even want to touch at all — including Jerry Brown, to a large extent, who really focused much more on the demand side of fuel consumption in the state,” said Berkeley Law’s Elkind.

California's revised budget included $1.5 million for a Transition to a Carbon-Neutral Economy report, which is being prepared by University of California researchers for the California Environmental Protection Agency. In an email, a CalEPA spokesperson said the report is due by the end of this year.

Winding down oil and gas production
Since the release of the revised budget last May, Newsom has taken initial steps to increase oversight of the oil and gas industry. In July 2019, he fired the state’s top oil and gas regulator for issuing too many permits to hydraulically fracture, or frack, wells.

Later in the year, he appointed new leadership to oversee oil and gas regulation in the state, and he signed a package of bills that placed constraints on fossil fuel production. The next month, Newsom halted the approval of new fracking operations until pending permits could be reviewed by a panel of scientists at Lawrence Livermore National Laboratory. The California Geologic Energy Management Division (CalGEM) did not resume issuing fracking permit approvals until April of this year.

Not all steps have been in the same direction. This month Newsom dropped a proposal to add dozens of analysts, engineers and geologists at CalGEM, citing COVID-related economic pressure. The move would have increased regulatory oversight on fossil fuel producers and was opposed by the state's oil industry.

Ultimately, more durable measures to wind down fossil fuel supply and demand will require new legislation, even as regulators weigh whether the state needs more power plants to maintain reliability.

A 2019 bill by Assemblymember Al Muratsuchi (D-Torrance), AB 345, would have codified the minimum 2,500-foot setback for new oil and gas wells. However, before the final vote in the Assembly, the bill’s buffer requirement was dropped and replaced with a requirement for CalGEM “to consider a setback distance of 2,500 feet.” The bill passed the Assembly in January over "no" votes from several moderate Democrats; it now awaits action in the Senate.

A bill previously introduced by Assemblymember Phil Ting (D-San Francisco), AB 1745, didn’t even make it that far. Ting’s bill would have required that all new passenger cars registered in the state after January 1, 2040, be zero-emission vehicles (ZEV). The bill died in committee without a vote in April 2018.

But the backing of the California Air Resources Board (CARB), one of the world's most powerful air-quality regulators, could change the political conversation. In March, CARB chair Mary Nichols said she now supports consideration of California establishing a 100 percent zero-emission vehicle sales target by 2030, as policymakers also consider a revamp of electricity rates to clean the grid.

“In the past, I’ve been skeptical about whether that would do more harm than good in terms of the backlash by dealers and others against something that sounded so un-California like,” Nichols said during an online event. “But as time has gone on, I’ve become more convinced that we need to send the longer-term signal about where we’re headed.”

Another complicating factor for California’s political leaders is the lack of a willing federal partner — at least in the short term — in winding down oil and gas production, amid warnings about a looming electricity shortage that could pressure the grid.

Under the Trump administration, the Bureau of Land Management, which oversees 15 million acres of federal land in California, has pushed to open more than 1 million acres of public and private land across eight counties in Central California to fracking. In January 2020, California filed a federal lawsuit to block the move.

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Texas Utility COVID-19 Relief suspends disconnections, waives late fees, extends payment plans, and supports broadband access as electric, gas, and internet providers help customers during the statewide emergency with speed upgrades and student WiFi initiatives.

Key Points

Texas utilities pause disconnections, waive fees, expand access, and offer flexible payment plans during COVID-19.

✅ Disconnections and late fees suspended by gas, power, internet.

✅ Payment plans and deferred balances after emergency.

✅ Bandwidth caps lifted; student WiFi access for remote learning.

In response to the COVID-19 pandemic, Texas utility companies have taken unprecedented steps to keep customers' lights on, gas flowing, and online connections stable -- even if they can't pay, amid concerns over pandemic electricity shutoffs nationwide.

Meantime, Palestine City Council members plan to discuss hardship measures Monday, as some states such as New Jersey and New York implement moratoriums on shut-offs, but have no plans yet to ease the burden of paying two other essential services during the statewide emergency -- trash collection and water. Those services are billed through the city.

For many residents, money will be tight after the statewide emergency declaration. Businesses are cutting back or closing. Workers are staying home to avoid the coronavirus.

"We are putting our customers first," Larry Ball, spokesman for Atmos Energy, a Dallas-based natural gas company, told the Herald-Press Friday. "The safety of all of our customers has always been our first priority."

While the declared emergency remains in effect, Atmos has suspended all late fees and customer disconnections, a step similar to PG&E's shutoff moratorium in California.

"Atmos Energy's commitment to safety, paired with our culture, have led us during unique times," Kevin Akers, Atmos President and CEO said. "This will be no different."

Internet Service Providers SuddenLink and Centurylink have similarly suspended all disconnections and late fees. Additionally, Centurylink, a global company serving 36 states, has promised to scrap bandwidth limits, while ensuring the highest speeds possible.

SuddenLink, a division of Altice Business, is also partnering with school districts in their service area to offer its Student WiFi product free for 60 days. That will allow students who have school-issued devices, but no dedicated home Internet access, the ability to use the Optimum WiFi Hot Spot Network to access their school's network and resources.

Electric companies such as TXU and Houston-based Gexa Energy also are working to keep customers safe and connected, and Entergy's relief fund highlights additional support for customers.

During the declared emergency, Gexa is waiving all disconnection and reconnection fees, as well as late fees, a policy focus that later intersected with debates over a proposed electricity market bailout in Texas. Payment plans will be set up for customers, after the crisis ends, Gexa Energy officials said.

"Everyone needs their power on," a Gexa spokesman said. "That is our number one priority."

TXU, based in Irving, is waiving late fees, extending payment due dates with no down-payment required, and deferring customer balances over multiple installments, while some retailers like Griddy underscored the risks of variable-rate plans.

If customers still can't pay, TXU officials said, the company will keep their lights on, a commitment underscored after the Texas winter storm outages exposed vulnerabilities. Customers in need should call 800-242-9113.

"The coronavirus is causing uncertainty and many hardships," Scott Hudson, president of TXU energy, said. "We are committed to serving our communities."

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Africa Energy Access Funding faces disbursement bottlenecks as SDG 7 goals demand investment in decentralized solar, minigrids, and rural electrification; COVID-19 pressures donors, requiring faster approvals, standardized documentation, and stronger project preparation and due diligence.

Key Points

Financing to expand Africa's electrification, advancing SDG 7 via disbursement to decentralized solar and minigrids.

✅ Accelerates investment for SDG 7 and rural electrification

✅ Prioritizes decentralized solar, minigrids, and utilities

✅ Speeds approvals, standard docs, and project preparation

The time frame from final funding approval to disbursement can be the most painful part of any financing process, and the access-to-electricity sector is not spared.

Amid the global spread of the coronavirus over the last few weeks, there have been several funding pledges to promote access to electricity in Africa. In March, the African Development Bank and other partners committed $160 million for the Facility for Energy Inclusion to boost electricity connectivity in Africa through small-scale solar systems and minigrids. Similarly, the Export-Import Bank of the United States allocated $91.5 million for rural electrification in Senegal.

Rockefeller chief wants to redefine 'energy poverty'

Rajiv Shah, president of The Rockefeller Foundation, believes that SDG 7 on energy access lacks ambition. He hopes to drive an effort to redefine it.

Currently, funding is not being adequately deployed to help achieve universal access to energy. The International Energy Agency’s “Africa Energy Outlook 2019” report estimated that an almost fourfold increase in current annual access-to-electricity investments — approximately $120 billion a year over the next 20 years — is required to provide universal access to electricity for the 530 million people in Africa that still lack it.

While decentralized renewable energy across communities, particularly solar, has been instrumental in serving the hardest-to-reach populations, tracking done by Sustainable Energy for All — in the 20 countries with about 80% of those living without access to sustainable energy — suggests that decentralized solar received only 1.2% of the total electricity funding.

The spread of COVID-19 is contributing significantly to Africa’s electricity challenges across the region, creating a surge in the demand for energy from the very important health facilities, an exponential increase in daytime demand as a result of most people staying and working indoors, and a rise from some food processing companies that have scaled up their business operations to help safeguard food security, among others. Thankfully — and rightly so — access-to-electricity providers are increasingly being recognized as “essential service” providers amid the lockdowns across cities.

To start tackling Africa’s electricity challenges more effectively, “funding-ready” energy providers must be able to access and fulfill the required conditions to draw down on the already pledged funding. What qualifies as “funding readiness” is open to argument, but having a clear, commercially viable business and revenue model that is suitable for the target market is imperative.

Developing the skills required to navigate the due-diligence process and put together relevant project documents is critical and sometimes challenging for companies without prior experience. Typically, the final form of all project-related agreements is a prerequisite for the final funding approval.

In addition, having the right internal structures in place — for example, controls to prevent revenue leakage, an experienced management team, a credible board of directors, and meeting relevant regulatory requirements such as obtaining permits and licenses — are also important indicators of funding readiness.

1. Support for project preparation. Programs — such as the Private Financing Advisory Network and GET.invest’s COVID-19 window — that provide business coaching to energy project developers are key to helping surmount these hurdles and to increasing the chances of these projects securing funding or investment. Donor funding and technical-assistance facilities should target such programs.

2. Project development funds. Equity for project development is crucial but difficult to attract. Special funds to meet this need are essential, such as the $760,000 for the development of small-scale renewable energy projects across sub-Saharan Africa recently approved by the African Development Bank-managed Sustainable Energy Fund for Africa.

3. Standardized investment documentation. Even when funding-ready energy project developers have secured investors, delays in fulfilling the typical preconditions to draw down funds have been a major concern. This is a good time for investors to strengthen their technical assistance by supporting the standardization of approval documents and funding agreements across the energy sector to fast-track the disbursement of funds.

4. Bundled investment approvals and more frequent approval sessions. While we implement mechanisms to hasten the drawdown of already pledged funding, there is no better time to accelerate decision-making for new access-to-electricity funding to ensure we are better prepared to weather the next storm. Donors and investors should review their processes to be more flexible and allow for more frequent meetings of investment committees and boards to approve transactions. Transaction reviews and approvals can also be conducted for bundled projects to reduce transaction costs.

5. Strengthened local capacity. African countries must also commit to strengthening the local manufacturing and technical capacity for access-to-electricity components through fiscal incentives such as extended tax holidays, value-added-tax exemptions, accelerated capital allowances, and increased investment allowances.

The ongoing pandemic and resulting impacts due to lack of electricity have further shown the need to increase the pace of implementation of access-to-electricity projects. We know that some of the required capital exists, and much more is needed to achieve Sustainable Development Goal 7 — about access to affordable and clean energy for all — by 2030.

It is time to accelerate our support for access-to-electricity companies and equip them to draw down on pledged funding, while calling on donors and investors to speed up their funding processes to ensure the electricity gets to those most in need.

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Toronto Electricity Demand Growth underscores IESO projections of rising peak load by 2050, driven by population growth, electrification, new housing density, and tech economy, requiring grid modernization, transmission upgrades, demand response, and local renewable energy.

Key Points

It refers to the projected near-doubling of Toronto's peak load by 2050, driven by electrification and urban growth.

✅ IESO projects peak demand nearly doubling by 2050

✅ Drivers: population, densification, EVs, heat pumps

✅ Solutions: efficiency, transmission, storage, demand response

Toronto faces a significant challenge in meeting the growing electricity needs of its expanding population and ambitious development plans. According to a new report from Ontario's Independent Electricity System Operator (IESO), Toronto's peak electricity demand is expected to nearly double by 2050. This highlights the need for proactive steps to secure adequate electricity supply amidst the city's ongoing economic and population growth.

Key Factors Driving Demand

Several factors are contributing to the projected increase in electricity demand:

Population Growth: Toronto is one of the fastest-growing cities in North America, and this trend is expected to continue. More residents mean more need for housing, businesses, and other electricity-consuming infrastructure.

• New Homes and Density: The city's housing strategy calls for 285,000 new homes within the next decade, including significant densification in existing neighbourhoods. High-rise buildings in urban centers are generally more energy-intensive than low-rise residential developments.
• Economic Development: Toronto's robust economy, a hub for tech and innovation, attracts new businesses, including energy-intensive AI data centers that fuel further demand for electricity.
• Electrification: The push to reduce carbon emissions is driving the electrification of transportation and home heating, further increasing pressure on Toronto's electricity grid.

Planning for the Future

Ontario and the City of Toronto recognize the urgency to secure stable and reliable electricity supplies to support continued growth and prosperity without sacrificing affordability, drawing lessons from British Columbia's clean energy shift to inform local approaches. Officials are collaborating to develop a long-term plan that focuses on:

• Energy Efficiency: Efforts aim to reduce wasteful electricity usage through upgrades to existing buildings, promoting energy-efficient appliances, and implementing smart grid technologies. These will play a crucial role in curbing overall demand.
• New Infrastructure: Significant investments in building new electricity generation, transmission lines, and substations, as well as regional macrogrids to enhance reliability, will be necessary to meet the projected demands of Toronto's future.
• Demand Management: Programs incentivizing energy conservation during peak hours will help to avoid strain on the grid and reduce the need to build expensive power plants only used at peak demand times.

Challenges Ahead

The path ahead isn't without its hurdles.  Building new power infrastructure in a dense urban environment like Toronto can be time-consuming, expensive, and sometimes disruptive, especially as grids face harsh weather risks that complicate construction and operations. Residents and businesses might worry about potential rate increases required to fund these necessary investments.

Opportunity for Innovation

The IESO and the city view the situation as an opportunity to embrace innovative solutions. Exploring renewable energy sources within and near the city, developing local energy storage systems, and promoting distributed energy generation such as rooftop solar, where power is created near the point of use, are all vital strategies for meeting needs in a sustainable way.

Toronto's electricity future depends heavily on proactive planning and investment in modernizing its power infrastructure.  The decisions made now will determine whether the city can support economic growth, address climate goals and a net-zero grid by 2050 ambition, and ensure that lights stay on for all Torontonians as the city continues to expand.
 

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Nova Scotia Integrated Resource Plan evaluates NSPI supply options, UARB oversight, Muskrat Falls imports, coal retirements, wind and biomass expansion, transmission upgrades, storage, and least-cost pathways to decarbonize the grid for ratepayers.

Key Points

A 25-year roadmap assessing supply, imports, costs, and emissions to guide least-cost decarbonization for Nova Scotia.

✅ Compares wind, biomass, gas, imports, and storage costs

✅ Addresses coal retirements, emissions caps, and reliability

✅ Recommends transmission upgrades and Muskrat Falls utilization

Maintaining a viable electricity network requires good long-term planning and, as a recent grid operations report notes, ongoing operational improvements. The existing stock of generating assets can become obsolete through aging, changes in fuel prices or environmental considerations. Future changes in demand must be anticipated.

Periodically, an integrated resource plan is created to predict how all this will add up during the ensuing 25 years. That process is currently underway and is led by Nova Scotia Power Inc. (NSPI) and will be submitted for approval to the Utilities and Review Board (UARB).

Coal-fired plants are still the largest single source of electricity in Nova Scotia. They need to be replaced with more environmentally friendly sources when they reach the end of their useful lives. Other sources include wind, hydroelectricity from rivers, biomass, as seen in increased biomass use by NS Power, natural gas and imports from other jurisdictions.

Imports are used sparingly today but will be an important source when the electricity from Muskrat Falls comes on stream. That project has big capacity. It can produce all the power needed in Newfoundland and Labrador (NL), where Quebec's power ambitions influence regional flows, plus the amount already committed to Nova Scotia, and still have a lot left over.

Some sources of electricity are more valuable than others. The daily amount of power from wind and solar cannot be controlled. Fuel-based sources and hydro can.

Utilities make their profits by providing the capital necessary to build infrastructure. Most of the money is borrowed but a portion, typically 30 per cent, usually comes from NSPI or a sister company. On that they receive a rate of return of nine per cent. Nova Scotia can borrow money today at less than two per cent.

The largest single investment of that type is the $1.577-billion Maritime Link connecting power from Newfoundland to Nova Scotia. It continues through to the New Brunswick border to facilitate exports to the United States. NSPI’s sister company, NSP Maritime Link Inc. (NSPML), is making nine per cent on $473 million of the cost.

There is little unexploited hydro capacity in Nova Scotia and there will not be any new coal-fired plants. Large-scale solar is not competitive in Nova Scotia’s climate. Nova Scotia’s needs would not accommodate the amount of nuclear capacity needed to be cost-effective, even as New Brunswick explores small reactors in its strategy.

So the candidates for future generating resources are wind, natural gas, biomass (though biomass criticism remains) and imports from other jurisdictions. Tidal is a promising opportunity but is still searching for a commercially viable technology. 

NSPI is commendably transparent about its process (irp.nspower.ca). At this stage there is little indication of the conclusions they are reaching but that will presumably appear in due course.

The mountains of detail might obscure the fact that NSPI is not an unbiased arbiter of choices for the future.

It is reported that they want to prematurely close the Trenton 5 coal plant in 2023-25. It is valued at $88.5 million. If it is closed early, ratepayers will still have to pay off the remaining value even though the plant will be idle. NSPI wants to plan a decommissioning of five of its other seven plants. There is a federal emissions constraint but retiring coal plants earlier than needed will cost ratepayers a lot.

Whenever those plants are closed, there will be a need for new sources of power. NSPI is proposing to plan for new investments in new transmission infrastructure to facilitate imports. Other possibilities would be additional wind farms, consistent with the shift to more wind and solar projects, thermal plants that burn natural gas or biomass, or storage for excess wind power that arrives before it can be used. The investment in storage could be anywhere from $20 million to $200 million.

These will add to the asset burden funded by ratepayers, even as industrial customers seek discounts while still paying for shuttered coal infrastructure.

External sources of new power will not provide NSPI the same opportunity: wind power by independent producers might be less expensive because they are willing to settle for less than nine per cent or because they are more efficient. Buying more power from Muskrat Falls will use transmission infrastructure we are already paying for. If a successful tidal technology is found, it will not be owned by NSPI or a sister company, which are no longer trying to perfect the technology.

This is not to suggest that NSPI would misrepresent the alternatives. But they can tilt the discussion in their favour. How tough will they be negotiating for additional Muskrat Falls power when it hurts their profits? Arguing for premature coal retirement on environmental grounds is fair game but whether the cost should be accepted is a political choice. 

NSPI is in a conflict of interest. We need a different process. An independent body should author the integrated resource plan. They should be fully informed about NSPI’s views.

They should communicate directly with Newfoundland and Labrador for Muskrat power, with independent wind producers, and with tidal power companies. The UARB cannot do any of these things.

The resulting plan should undergo the same UARB review that NSPI’s version would. This enhances the likelihood that Nova Scotians will get the least-cost alternative.

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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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