Will electricity supplant natural gas?

By Toronto Star


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Natural gas is a cleaner fuel when compared to coal, but in the context of climate change, it's far from being our saviour. Once all of Ontario's coal plants are shut down – we're told by 2014 – then the next greenhouse gas emitter on the global warming hit list is, by default, natural gas.

"About 36 per cent of Toronto's carbon dioxide emissions come from natural gas," says Philip Jessup, executive director of the Toronto Atmospheric Fund.

It calls attention to our strategy of doubling natural gas plant capacity as part of the province's 20-year power system plan. It also puts the spotlight on "fuel-switching" – that is, ditching your electric stove in favour of natural gas, or getting rid of that electric resistance heating in favour of a natural gas-fired furnace.

Compared to electric heating, there's no disputing that natural gas is currently cheaper. But is it cleaner than electricity?

Not in Ontario. Not in Toronto. In fact, once all coal plants are shut down, a lion's share of the electricity in the province will come from nuclear, hydroelectric and wind power. That means using electricity to heat your home will result in far less greenhouse gas emissions than using a natural gas appliance.

So the question is, how do we make using electricity cheaper?

Duane Hallowell, 34, a former cryogenic engineer with the U.S. navy, is focused on this mission. He founded a company in Maine three years ago, called Hallowell International, aimed at getting households in northern U.S. and Canadian climates off of fossil fuels.

What he invented was a new kind of heat pump, which as a technology has existed for decades. The difference is that Hallowell's heat pump, called Acadia, was designed to work efficiently in temperatures as low as minus 30 degrees Celsius – that is, in Canadian winters.

"For the same amount of energy to heat a house with resistance heating, you could heat three homes with an Acadia," he says. "And that's a worst-case scenario."

There are typically two kinds of electrical heat pump systems – air-source and ground-source.

The latter is what we commonly know as low-temperature geothermal, which cools a building by extracting heat from inside and dumping it in the ground; or in reverse, heats a building by pulling heat out of the ground and releasing it inside.

Geothermal systems can run $25,000 to $35,000 for a residential retrofit, which is a tough bite to swallow even though the payback is much quicker than, say, solar power or small-wind systems. A big part of that cost is the need to drill holes in the ground and line it with tubing. Glycol or food-grade ethanol in the tubing acts as the energy carrier, exchanging heat between the ground and the building.

A ground-source system is more efficient than an air-source one. The temperature in the ground is more constant than the ambient air, so ground-source heat pumps don't have to work as hard.

But hurdles to their deployment remain. If the drilling or tube laying isn't done properly, or if the system isn't sized accurately for a home's cooling and heating needs, fixing it can be a nightmare.

These risks are falling, which is encouraging, and generous government incentives – $7,000 from Ottawa and the province combined – do help ease financial pain. But nagging "what if" worries of ground-source systems remain.

In urban areas, geothermal also poses problems. When you live in the Annex or Beaches and have little backyard space to spare, then the logistics of drilling holes and laying tubing become tricky. Tricky equals higher cost.

Air-source heat pumps work in much the same way as geothermal systems, but instead of the ground, they use outside air to extract and release heat. Home refrigerators work in a similar way. They extract heat from the food in your fridge and release it from coils behind it.

Air conditioners are a one-way heat pump – in summer it extracts heat from inside air and dumps it outside. Air-source heat pumps are popular in the U.S. south because they work like air conditioners, plus they can provide limited heating if temperatures drop.

"Unfortunately, they're still just being developed primarily as air conditioners with a major deficiency in heating," says Hallowell.

It's why they've never taken off in Canada. Once temperatures drop below freezing, a conventional air-source heat pump is useless.

Hallowell saw the neglect, so he went ahead and engineered a better air-source heat pump – one that operates during the summer like an Energy Star central air conditioner but in the winter handles all of a home's heating needs. "Are we as efficient as geothermal?" asks Hallowell. "Well, we're close."

Natural Resources Canada is now testing the Acadia system. I consulted an energy consultant who is also testing it for the Manitoba energy ministry. He didn't want to be named, but had good things to say.

"They're the real deal. Technically, there's no massive, innovative, wizardry here. Just compressors and booster coils and good control systems. Very well done."

His only concern was that Hallowell is still new to the market so it doesn't yet have a track record for service and maintenance. "So if you're getting one of these early units, see if they'd provide guarantees of servicing and back-up."

Hallowell's Canadian distributor, MITS Air Conditioning Inc. of Mississauga, says it costs $14,000 to $16,000 to purchase and install an Acadia system, compared to about $11,000 for a high-end air conditioner and gas furnace.

Unlike geothermal, there's no ripping up of grass. No drilling. "If it does break it's easy to fix because there's nothing underground," says Jim Chaters at MITS.

Currently, the federal government offers a $400 incentive to purchase an air-source heat pump. The province matches that. Hallowell is trying to get that incentive increased so it's at least half of what geothermal systems get.

Chaters, who sells all kinds of conventional heating and cooling equipment, says four years ago he'd never given much thought to heat-pump technology. Then his eco-minded daughter began pushing him to look for better options.

"Air-source heat pumps are the future, because they're getting more and more efficient."

Jessup at the Toronto Atmospheric Fund adds: "We are going to have to move to these technologies in a big way if we are to meet the ambitious (emissions) targets that Toronto council has set."

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Will Iraq have enough electricity for coming hot summer days?

Iraq Electricity Crisis intensifies as summer heat drives demand; households face power outages, reliance on private generators, distorted tariffs, and strained grid capacity despite government reforms, Siemens upgrades, and IEA warnings.

 

Key Points

A supply-demand gap causing outages, generator reliance, and grid inefficiencies across Iraq, worsened by summer peaks.

✅ Siemens deal to upgrade generation and grid

✅ Progressive tariffs to curb demand and waste

✅ Private generators fill gaps but raise costs

 

At a demonstration in June 2018, protesters in Basra loaded a black box resembling a coffin with the inscription “Electricity” onto the roof of a car. This was one demonstration of how much of a political issue electricity is in Iraq.

With what is likely to be another hot summer ahead, there is increasing pressure on the Baghdad government to improve access to electricity and water.

Many Iraqis blame the government for not providing adequate services despite the country’s oil wealth. Protests in southern Iraq last year turned violent, with demonstrators attacking governmental and political parties’ buildings; in neighboring Iran, blackouts also sparked protests over outages.

“It is very hard” to deal with the electricity issues, said Iraqi journalist Methaq al-Fayyadh, adding that the lack of reliable electricity was not a new problem and affects most parts of the country.

Dozens of people protested June 1 in Karbala against prices for new generators and demanded an improvement to the electricity situation.

In anticipation of high temperatures during Eid al-Fitr, the Electricity Ministry called on governorates to adhere to allocated quotas and told the public to ration electricity.

“Outages remain a daily occurrence for most households because increasing generating capacity has been outrun by increasing demand for electricity, as surging demand worldwide demonstrates,” noted the International Energy Agency (IAE) in April.

This is particularly the case, the authors said, as the hot summer months, when temperatures can top 50 degrees Celsius, drive up the use of air conditioning.

The Iraqi government has made improving the electricity supply one of its priorities, including nuclear power plans under consideration. The Electricity Ministry, headed by Luay al-Khatteeb, announced in May that national electricity production had reached 17 gigawatts.

Khatteeb presented comparative electricity data for May from 2018 and 2019, indicating production increases on every day of the month. IEA data indicate that available electricity supply has increased over the past five years and the gap between supply and demand has widened.

The government signed an agreement with German company Siemens this year to upgrade Iraq’s electricity grid, and in parallel deals with Iran to rehabilitate and develop the grid were finalized, according to Iranian officials. The agreement “includes the addition of new and highly efficient power generation capacity, rehabilitation and upgrade of existing plants and the expansion of transmission and distribution networks,” Siemens said.

The Iraqi prime minister’s office said the 4-year plan would be worth $15.7 billion. The first phase includes the installation of 13 transformer stations, cooling systems for power stations and building a 500-megawatt, gas-fired power plant south of Baghdad.

In an interview with Al-Monitor, Khatteeb said radical changes would happen in 2020, stating that the current situation was not “ideal” but “better” because of steps taken to create more energy, amid discussions on energy cooperation with Iran that could shape implementation.

Robert Tollast, of the Iraq Energy Institute, said the economics of the electricity system is distorted. Subsidies ensured that electricity provided by the national grid is almost free, he said. However, while the subsidies were designed to help the poor, the tariff system disadvantages them and does not create incentives to consume electricity more efficiently, he said.

A large part of families’ electricity expenditures goes to operators of privately owned generators, which run on fuel. These neighbourhood generators are used to close gaps in the electricity supply but are expensive, and regional fuel arrangements such as ENOC’s swap of Iraqi fuel have highlighted supply constraints. Generator operators have sometimes worked with armed groups to prevent upgrades to the grid that could hurt their business.

Until 1990, the Iraq electricity sector was considered among the best in the region. That legacy was destroyed by successive wars and international sanctions. With Iraq’s population growing at a rate of 1 million per year, peak demand is projected to double by 2030 if left unchecked, the IEA estimated.

Tollast said efforts to improve the distribution system and increase capacity are key but it is important “to tackle the problem from the demand side.” This entails implementing a progressive tariff scheme so users pay more if they consume more, he said. There is a “tremendous use of energy per capita in Iraq,” Tollast said.

In the current tariff structure, consumers pay a fixed price if they use more than 4,000-kilowatt hours per year, a relatively low amount, meaning the price per unit drops the more one consumes.

Any change to the tariff system must be accompanied by a “political campaign” to explain the changes, said Tollast, adding that more investment in the electricity sector and a “change in culture” of using electricity was needed. “The current system is unsustainable, even with high oil prices,” he said.

Fayyadh said people don’t expect the government will be able to fix the electricity issue before summer, having failed to do so in the past.

Tollast struck a more optimistic tone, saying it was unlikely that Iran, which supplies about 40% of Iraq’s power, would cut its export of electricity to Iraq this year as it did in 2018. He added that the water situation was better than last year when the country experienced drought. Iraq has also been processing more flare gas, which can be used to generate electricity.

“There is an expectation that this year might not be as bad as last year,” he concluded.

 

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Europe's Worst Energy Nightmare Is Becoming Reality

European Energy Crisis shocks markets as Russia slashes gas via Nord Stream, spiking prices and triggering rationing, LNG imports, storage shortfalls, and emergency measures to secure energy security before a harsh winter.

 

Key Points

Europe-wide gas shock from reduced Russian flows drives price spikes, rationing risk, LNG reliance, and emergency action.

✅ Nord Stream cuts deepen supply insecurity and storage gaps

✅ LNG imports rise but terminal capacity and shipping are tight

✅ Policy tools: rationing, subsidies, demand response, coal restarts

 

As Russian gas cutoffs upend European energy security, the continent is struggling to cope with what experts say is one of its worst-ever energy crises—and it could still get much worse. 

For months, European leaders have been haunted by the prospect of losing Russia’s natural gas supply, which accounts for some 40 percent of European imports and has been a crucial energy lifeline for the continent. That nightmare is now becoming a painful reality as Moscow slashes its flows in retaliation for Europe’s support for Ukraine, dramatically increasing energy prices and forcing many countries to resort to emergency plans, including emergency measures to limit electricity prices in some cases, and as backup energy suppliers such as Norway and North Africa are failing to step up.

“This is the most extreme energy crisis that has ever occurred in Europe,” said Alex Munton, an expert on global gas markets at Rapidan Energy Group, a consultancy. “Europe [is] looking at the very real prospect of not having sufficient gas when it’s most needed, which is during the coldest part of the year.”

“Prices have shot through the roof,” added Munton, who noted that European natural gas prices—nearly $50 per MMBTu—have eclipsed U.S. price rises by nearly tenfold, and that rolling back electricity prices is tougher than it appears in the current market. “That is an extraordinarily high price to be paying for natural gas, and really there is no immediate way out from here.” 

Many officials and energy experts worry that the crisis will only deepen after Nord Stream 1, the largest gas pipeline from Russia to Europe, is taken down for scheduled maintenance this week. Although the pipeline is supposed to be under repair for only 10 days, the Kremlin’s history of energy blackmail and weaponization has stoked fears that Moscow won’t turn it back on—leaving heavily reliant European countries in the lurch. (Russia’s second pipeline to Germany, Nord Stream 2, was killed in February as Russian President Vladimir Putin prepared to invade Ukraine, leaving Nord Stream 1 as the biggest direct gas link between Russia and Europe’s biggest economy.)

“Everything is possible. Everything can happen,” German economy minister Robert Habeck told Deutschlandfunk on Saturday. “It could be that the gas flows again, maybe more than before. It can also be the case that nothing comes.”

That would spell trouble for the upcoming winter, when demand for energy surges and having sufficient natural gas is necessary for heating. European countries typically rely on the summer months to refill their gas storage facilities. And at a time of war, when the continent’s future gas supply is uncertain, having that energy cushion is especially crucial.

If Russia’s prolonged disruptions continue, experts warn of a difficult winter: one of potential rationing, industrial shutdowns, and even massive economic dislocation. British officials, who just a few months ago warned of soaring power bills for consumers, are now warning of even worse, despite a brief fall to pre-Ukraine war levels in gas prices earlier in the year.

Europe could face a “winter of discontent,” said Helima Croft, a managing director at RBC Capital Markets. “Rationing, industrial shut-ins—all of that is looming.”

Unrest has already been brewing, with strikes erupting across the continent as households struggle under the pressures of spiraling costs of living and inflationary pressures. Some of this discontent has also had knock-on effects in the energy market. In Norway, the European Union’s biggest supplier of natural gas after Russia, mass strikes in the oil and gas industries last week forced companies to shutter production, sending further shockwaves throughout Europe.

European countries are at risk of descending into “very, very strong conflict and strife because there is no energy,” Frans Timmermans, the vice president of the European Commission, told the Guardian. “Putin is using all the means he has to create strife in our societies, so we have to brace ourselves for a very difficult period.”

The pain of the crisis, however, is perhaps being felt most clearly in Germany, which has been forced to turn to a number of energy-saving measures, including rationing heated water and closing swimming pools. To cope with the crunch, Berlin has already entered the second phase of its three-stage emergency gas plan; last week, it also moved to bail out its energy giants amid German utility troubles that have been financially slammed by Russian cutoffs. 

But it’s not just Germany. “This is happening all across Europe,” said Olga Khakova, an expert on European energy security at the Atlantic Council, who noted that France has also announced plans to nationalize the EDF power company as it buckles under mounting economic losses, and the EU outlines gas price cap strategies to temper volatility. “The challenging part is how much can these governments provide in support to their energy consumers, to these companies? And what is that breaking point?”

The situation has also complicated many countries’ climate goals, even as some call it a wake-up call to ditch fossil fuels for Europe. In late June, Germany, Italy, Austria, and the Netherlands announced they would restart old coal power plants as they grapple with shrinking supplies. 

The potential outcomes that European nations are grappling with reveal how this crisis is occurring on a scale that has only been seen in times of war, Munton said. In the worst-case scenario, “we’re talking about rationing gas supplies, and this is not something that Europe has had to contend with in any other time than the wartime,” he said. “That’s essentially where things have got to now. This is an energy war.”

They also underscore the long and painful battle that Europe will continue to face in weaning itself off Russian gas. Despite the continent’s eagerness to leave Moscow’s supply behind, experts say Europe will likely remain trapped in this spiraling crisis until it can develop the infrastructure for greater energy independence—and that could take years. U.S. gas, shipped by tanker, is one option, but that requires new terminals to receive the gas and U.S. energy impacts remain a factor for policymakers. New pipelines take even longer to build—and there isn’t a surfeit of eligible suppliers.

Until then, European leaders will continue to scramble to secure enough supplies—and can only hope for mild weather. The “worst-case scenario is people having to choose between eating and heating come winter,” Croft said. 

 

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Manitoba Hydro's burgeoning debt surpasses $19 billion

Manitoba Hydro Debt Load surges past $19.2B as the Crown corporation faces shrinking net income, restructuring costs, and PUB rate decisions, driven by Bipole III, Keeyask construction, aging infrastructure, and rising interest rate risks.

 

Key Points

Manitoba Hydro Debt Load refers to the utility's escalating borrowings exceeding $19B, pressuring rates and finances.

✅ Debt rose to $19.2B; projected near $25B within five years.

✅ Major drivers: Bipole III, Keeyask, aging assets, restructuring.

✅ Rate hikes sought; PUB approved 3.6% vs 7.9% request.

 

Manitoba Hydro's debt load now exceeds $19 billion as the provincial Crown corporation grapples with a shrinking net income amid ongoing efforts to slay costs.

The utility's annual report, to be released publicly on Tuesday, also shows its total consolidated net income slumped from $71 million in 2016-2017 to $37 million in the last fiscal year, mirroring a Hydro One profit drop as electricity revenue fell.

It said efforts to restructure the utility and reduce costs are partly to blame for the $34 million drop in year-over-year income.

These earnings come nowhere close, however, to alleviating Hydro's long-term debt problem, a dynamic also seen in a BC Hydro deferred costs report about customer exposure. The figure is pegged at $19.2 billion this fiscal year, up from $16.1 billion the previous year and $14.2 billion in 2016.

The utility projects its debt will grow to about $25 billion in the next five years. Its largest expenses include finishing the Bipole III line, working on the Keeyask Generating System that is halfway done and rebuilding aging wood poles and substations, the report said.

"This level of debt increases the potential financial exposure from risks facing the corporation and is a concern for both

the corporation and our customers who may be exposed to higher rate increases in the event of rising interest rates, a prolonged drought or a major system failure," outgoing president and CEO Kelvin Shepherd wrote.

The income drop is primarily a result of the $50 million spent in the form of restructuring charges associated with the utility's efforts to streamline the organization and drive down costs, amid NDP criticism of Hydro changes related to government policy.

Those efforts included the implementation of buyouts for employees through what the utility dubbed its "voluntary departure program."

Among the changes, Manitoba Hydro reduced its workforce by 800 employees, which is expected to save the utility over $90 million per year. It also reduced its management positions by 26 per cent, a Monday news release said, while Hydro One leadership upheaval in Ontario drove its shares down during comparable governance turmoil.

To improve its financial situation, Hydro has applied for rate increases, even as the Consumers Coalition pushes to have the proposal rejected. The Public Utilities Board offered a 3.6 per cent average rate hike, instead of the 7.9 per cent jump the utility asked for.

In May, when the PUB rendered its decision, it made several recommendations as an alternative to raising rates, including receiving a share of carbon tax revenue and asking the government to help pay for Bipole III.

Hydro is projecting a net income of $70 million for 2018-2019, which includes the impact of the recent rate increase. That total reflects an approximately 20 per cent reduction in net income from 2017-18 after restructuring costs are calculated.

 

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Electric vehicles are a hot topic in southern Alberta

Canada Electric Vehicle Adoption is accelerating as EV range doubles, fast-charging networks expand along the Trans-Canada Highway, and drivers shift from internal combustion to clean transportation to cut emissions and support climate goals.

 

Key Points

Canada Electric Vehicle Adoption reflects rising EV uptake, longer range, and expanding fast-charging infrastructure.

✅ Average EV range in Canada has nearly doubled in six years.

✅ Fast chargers expanding along Trans-Canada and major corridors.

✅ Gasoline and diesel demand projected to fall sharply by 2040.

 

As green technology for vehicles continues to grow in popularity, with a recent EV event in Regina drawing strong interest, attendance at a seminar in southern Alberta Wednesday showed plenty people want to switch to electric.

FreeU, a series of informal education sessions about electric power and climate change, including electricity vs hydrogen considerations, helped participants to learn more about the world-changing technology.

Also included at the talks was a special electric vehicle meet up, where people interested in the technology could learn about it, first hand, from drivers who've already gone gasless despite EV shortages and wait times in many regions.

"That's kind of a warning or a caution or whatever you want to call it. You get addicted to these things and that's a good example."

James Byrne, a professor of geography at the University of Lethbridge says people are much more willing these days to look to alternatives for their driving needs, though cost remains a key barrier for many.

"The internal combustion engine is on its way out. It served us well, but electric vehicles are much cleaner, aligning with Canada's EV goals set by policymakers today."

According to the Canada Energy Regulator, the average range of electric vehicles in Canada have almost doubled in the past six years.

The agency also predicts a massive decrease in gasoline and diesel use (359 petajoules and 92 petajoules respectively) in Canada by 2040. In that same timeframe, electricity use, even though fossil-fuel share remains, is expected to increase by 118 petajoules.

The country is also developing its network of fast charging stations, so running out of juice will be less of a worry for prospective buyers, even as 2035 EV mandate debate continues among analysts.

"They have just about Interstate in the U.S. covered," Marshall said. "In Canada, they're building out the [Trans-Canada Highway] right now."

 

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Marine Renewables Canada shifts focus towards offshore wind

Marine Renewables Canada Offshore Wind integrates marine renewables, tidal and wave energy, advancing clean electricity, low-carbon power, supply chain development, and regulatory alignment to scale offshore wind energy projects across Canada's coasts and global markets.

 

Key Points

An initiative to grow offshore wind using Canada's marine strengths, shared supply chains, and regulatory synergies.

✅ Leverages tidal and wave energy expertise for offshore wind

✅ Aligns supply chain, safety, and regulatory frameworks

✅ Supports low-carbon power and clean electricity goals

 

With a growing global effort to develop climate change solutions and increase renewable electricity production, including the UK offshore wind growth in recent years, along with Canada’s strengths in offshore and ocean sectors, Marine Renewables Canada has made a strategic decision to grow its focus by officially including offshore wind energy in its mandate.

Marine Renewables Canada plans to focus on similarities and synergies of the resources in order to advance the sector as a whole and ensure that clean electricity from waves, tides, rivers, and offshore wind plays a significant role in Canada’s low-carbon future.

“Many of our members working on tidal energy and wave energy projects also have expertise that can service offshore wind projects both domestically and internationally,” says Tim Brownlow, Chair of Marine Renewables Canada. “For us, offshore wind is a natural fit and our involvement will help ensure that Canadian companies and researchers are gaining knowledge and opportunities in the offshore wind sector as it grows.”

Canada has the longest coastlines in the world, giving it huge potential for offshore wind energy development. In addition to the resource, Canada has significant capabilities from offshore and marine industries that can contribute to offshore wind energy projects. The global offshore wind market is estimated to grow by over 650% by 2030 and presents new opportunities for Canadian business.

“The federal government’s recent inclusion of offshore renewables in legislation, including a plan for regulating offshore wind developed by the government, and support for emerging renewable energy technologies are important steps toward building this industry,” says Elisa Obermann, executive director of Marine Renewables Canada. “There are still challenges to address before we’ll see offshore wind energy development in Canada, but we see a great opportunity to get more involved now, increase our experience, and help inform future development.”

Like wave and tidal energy, offshore wind projects operate in harsh marine environments and development presents many of the same challenges and benefits as it does for other marine renewable energy resources. Marine Renewables Canada has recognized that there is significant overlap between offshore wind and wave and tidal energy when it comes to the supply chain, regulatory issues, and the operating environment. The association plans to focus on similarities and synergies of the resources in order to advance the sector as a whole, leveraging Canada’s opportunity in the global electricity market to ensure that clean electricity from waves, tides, rivers, and offshore wind plays a significant role in Canada’s low-carbon future.

 

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Turning thermal energy into electricity

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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