Greenpeace crashes coal meeting using phony front

Offshore wind power accelerates low-carbon electrification, leveraging floating turbines, high capacity factors, HVDC transmission, and hydrogen production to decarbonize grids, cut CO2, and deliver competitive, reliable renewable energy near demand centers.

Key Points

Offshore wind power uses offshore turbines to deliver low-carbon electricity with high capacity factors and falling costs.

✅ Sea-based wind farms with 40-50% capacity factors

✅ Floating turbines unlock deep-water, far-shore resources

✅ Enables hydrogen production and strengthens grid reliability

The need for affordable low-carbon technologies is greater than ever

Global energy-related CO2 emissions reached a historic high in 2018, driven by an increase in coal use in the power sector. Despite impressive gains for renewables, fossil fuels still account for nearly two-thirds of electricity generation, the same share as 20 years ago. There are signs of a shift, with increasing pledges to decarbonise economies and tackle air pollution, and with World Bank support helping developing countries scale wind, but action needs to accelerate to meet sustainable energy goals. As electrification of the global energy system continues, the need for clean and affordable low-carbon technologies to produce this electricity is more pressing than ever. This World Energy Outlook special report offers a deep dive on a technology that today has a total capacity of 23 GW (80% of it in Europe) and accounts for only 0.3% of global electricity generation, but has the potential to become a mainstay of the world's power supply. The report provides the most comprehensive analysis to date of the global outlook for offshore wind, its contributions to electricity systems and its role in clean energy transitions.

The offshore wind market has been gaining momentum

The global offshore wind market grew nearly 30% per year between 2010 and 2018, benefitting from rapid technology improvements. Over the next five years, about 150 new offshore wind projects are scheduled to be completed around the world, pointing to an increasing role for offshore wind in power supplies. Europe has fostered the technology's development, led by the UK offshore wind sector alongside Germany and Denmark. The United Kingdom and Germany currently have the largest offshore wind capacity in operation, while Denmark produced 15% of its electricity from offshore wind in 2018. China added more capacity than any other country in 2018.

The untapped potential of offshore wind is vast

The best offshore wind sites could supply more than the total amount of electricity consumed worldwide today. And that would involve tapping only the sites close to shores. The IEA initiated a new geospatial analysis for this report to assess offshore wind technical potential country by country. The analysis was based on the latest global weather data on wind speed and quality while factoring in the newest turbine designs. Offshore wind's technical potential is 36 000 TWh per year for installations in water less than 60 metres deep and within 60 km from shore. Global electricity demand is currently 23 000 TWh. Moving further from shore and into deeper waters, floating turbines could unlock enough potential to meet the world's total electricity demand 11 times over in 2040. Our new geospatial analysis indicates that offshore wind alone could meet several times electricity demand in a number of countries, including in Europe, the United States and Japan. The industry is adapting various floating foundation technologies that have already been proven in the oil and gas sector. The first projects are under development and look to prove the feasibility and cost-effectiveness of floating offshore wind technologies.

Offshore wind's attributes are very promising for power systems

New offshore wind projects have capacity factors of 40-50%, as larger turbines and other technology improvements are helping to make the most of available wind resources. At these levels, offshore wind matches the capacity factors of gas- and coal-fired power plants in some regions – though offshore wind is not available at all times. Its capacity factors exceed those of onshore wind and are about double those of solar PV. Offshore wind output varies according to the strength of the wind, but its hourly variability is lower than that of solar PV. Offshore wind typically fluctuates within a narrower band, up to 20% from hour to hour, than solar PV, which varies up to 40%.

Offshore wind's high capacity factors and lower variability make its system value comparable to baseload technologies, placing it in a category of its own – a variable baseload technology. Offshore wind can generate electricity during all hours of the day and tends to produce more electricity in winter months in Europe, the United States and China, as well as during the monsoon season in India. These characteristics mean that offshore wind's system value is generally higher than that of its onshore counterpart and more stable over time than that of solar PV. Offshore wind also contributes to electricity security, with its high availability and seasonality patterns it is able to make a stronger contribution to system needs than other variable renewables. In doing so, offshore wind contributes to reducing CO2 and air pollutant emissions while also lowering the need for investment in dispatchable power plants. Offshore wind also has the advantage of avoiding many land use and social acceptance issues that other variable renewables are facing.

Offshore wind is on track to be a competitive source of electricity

Offshore wind is set to be competitive with fossil fuels within the next decade, as well as with other renewables including solar PV. The cost of offshore wind is declining and is set to fall further. Financing costs account for 35% to 50% of overall generation cost, and supportive policy frameworks are now enabling projects to secure low cost financing in Europe, with zero-subsidy tenders being awarded. Technology costs are also falling. The levelised cost of electricity produced by offshore wind is projected to decline by nearly 60% by 2040. Combined with its relatively high value to the system, this will make offshore wind one of the most competitive sources of electricity. In Europe, recent auctions indicate that offshore wind will soon beat new natural gas-fired capacity on cost and be on a par with solar PV and onshore wind. In China, offshore wind is set to become competitive with new coal-fired capacity around 2030 and be on par with solar PV and onshore wind. In the United States, recent project proposals indicate that offshore wind will soon be an affordable option, even as the 1 GW timeline continues to evolve, with potential to serve demand centres along the country's east coast.

Innovation is delivering deep cost reductions in offshore wind, and transmission costs will become increasingly important. The average upfront cost to build a 1 gigawatt offshore wind project, including transmission, was over $4 billion in 2018, but the cost is set to drop by more than 40% over the next decade. This overall decline is driven by a 60% reduction in the costs of turbines, foundations and their installation. Transmission accounts for around one-quarter of total offshore wind costs today, but its share in total costs is set to increase to about one-half as new projects move further from shore. Innovation in transmission, for example through work to expand the limits of direct current technologies, will be essential to support new projects without raising their overall costs.

Offshore wind is set to become a $1 trillion business

Offshore wind power capacity is set to increase by at least 15-fold worldwide by 2040, becoming a $1 trillion business. Under current investment plans and policies, the global offshore wind market is set to expand by 13% per year, reflecting its growth despite Covid-19 in recent years, passing 20 GW of additions per year by 2030. This will require capital spending of $840 billion over the next two decades, almost matching that for natural gas-fired or coal-fired capacity. Achieving global climate and sustainability goals would require faster growth: capacity additions would need to approach 40 GW per year in the 2030s, pushing cumulative investment to over $1.2 trillion. 

The promising outlook for offshore wind is underpinned by policy support in an increasing number of regions. Several European North Seas countries – including the United Kingdom, Germany, the Netherlands and Denmark – have policy targets supporting offshore wind. Although a relative newcomer to the technology, China is quickly building up its offshore wind industry, aiming to develop a project pipeline of 10 GW by 2020. In the United States, state-level targets and federal incentives are set to kick-start the U.S. offshore wind surge in the coming years. Additionally, policy targets are in place and projects under development in Korea, Japan, Chinese Taipei and Viet Nam.

 The synergies between offshore wind and offshore oil and gas activities provide new market opportunities. Since offshore energy operations share technologies and elements of their supply chains, oil and gas companies started investing in offshore wind projects many years ago. We estimate that about 40% of the full lifetime costs of an offshore wind project, including construction and maintenance, have significant synergies with the offshore oil and gas sector. That translates into a market opportunity of $400 billion or more in Europe and China over the next two decades. The construction of foundations and subsea structures offers potential crossover business, as do practices related to the maintenance and inspection of platforms. In addition to these opportunities, offshore oil and gas platforms require electricity that is often supplied by gas turbines or diesel engines, but that could be provided by nearby wind farms, thereby reducing CO2 emissions, air pollutants and costs.

Offshore wind can accelerate clean energy transitions

Offshore wind can help drive energy transitions by decarbonising electricity and by producing low-carbon fuels. Over the next two decades, its expansion could avoid between 5 billion and 7 billion tonnes of CO2 emissions from the power sector globally, while also reducing air pollution and enhancing energy security by reducing reliance on imported fuels. The European Union is poised to continue leading the wind energy at sea in Europe industry in support of its climate goals: its offshore wind capacity is set to increase by at least fourfold by 2030. This growth puts offshore wind on track to become the European Union's largest source of electricity in the 2040s. Beyond electricity, offshore wind's high capacity factors and falling costs makes it a good match to produce low-carbon hydrogen, a versatile product that could help decarbonise the buildings sector and some of the hardest to abate activities in industry and transport. For example, a 1 gigawatt offshore wind project could produce enough low-carbon hydrogen to heat about 250 000 homes. Rising demand for low-carbon hydrogen could also dramatically increase the market potential for offshore wind. Europe is looking to develop offshore "hubs" for producing electricity and clean hydrogen from offshore wind.

It's not all smooth sailing

Offshore wind faces several challenges that could slow its growth in established and emerging markets, but policy makers and regulators can clear the path ahead. Developing efficient supply chains is crucial for the offshore wind industry to deliver low-cost projects. Doing so is likely to call for multibillion-dollar investments in ever-larger support vessels and construction equipment. Such investment is especially difficult in the face of uncertainty. Governments can facilitate investment of this kind by establishing a long-term vision for offshore wind and by drawing on U.K. policy lessons to define the measures to be taken to help make that vision a reality. Long-term clarity would also enable effective system integration of offshore wind, including system planning to ensure reliability during periods of low wind availability.

The success of offshore wind depends on developing onshore grid infrastructure. Whether the responsibility for developing offshore transmission lies with project developers or transmission system operators, regulations should encourage efficient planning and design practices that support the long-term vision for offshore wind. Those regulations should recognise that the development of onshore grid infrastructure is essential to the efficient integration of power production from offshore wind. Without appropriate grid reinforcements and expansion, there is a risk of large amounts of offshore wind power going unused, and opportunities for further expansion could be stifled. Development could also be slowed by marine planning practices, regulations for awarding development rights and public acceptance issues.

The future of offshore wind looks bright but hinges on the right policies

The outlook for offshore wind is very positive as efforts to decarbonise and reduce local pollution accelerate. While offshore wind provides just 0.3% of global electricity supply today, it has vast potential around the world and an important role to play in the broader energy system. Offshore wind can drive down CO2 emissions and air pollutants from electricity generation. It can also do so in other sectors through the production of clean hydrogen and related fuels. The high system value of offshore wind offers advantages that make a strong case for its role alongside other renewables and low-carbon technologies. Government policies will continue to play a critical role in the future of offshore wind and  the overall pace of clean energy transitions around the world.

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Ontario SMR BWRX-300 leads Canada in next-gen nuclear energy at Darlington, with GE Vernova and Hitachi, delivering clean, reliable power via modular design, passive safety, scalability, and lower costs for grid integration.

Key Points

Ontario SMR BWRX-300 is a 300 MW modular boiling water reactor at Darlington with passive safety and clean power.

✅ 300 MW BWR supplies power for about 300,000 homes

✅ Passive safety enables safe shutdown without external power

✅ Modular design reduces costs and speeds grid integration

Ontario has initiated the construction of Canada's first small modular nuclear reactor (SMR), supported by OPG's SMR commitment to deployment, marking a significant milestone in the province's energy strategy. This development positions Ontario at the forefront of next-generation nuclear technology within the G7 nations.

The project, known as the Darlington New Nuclear Project, is being led by Ontario Power Generation (OPG) in collaboration with GE Vernova and Hitachi Nuclear Energy, and through its OPG-TVA partnership on new nuclear technology development. The chosen design is the BWRX-300, a 300-megawatt boiling water reactor that is approximately one-tenth the size and complexity of traditional nuclear reactors. The first unit is expected to be operational by 2029, with plans for additional units to follow.

Each BWRX-300 reactor is projected to supply electricity to about 300,000 homes, contributing to Ontario's efforts, which include the decision to refurbish Pickering B for additional baseload capacity, to meet the anticipated 75% increase in electricity demand by 2050. The compact design of the SMR allows for easier integration into existing infrastructure, reducing the need for extensive new transmission lines.

The economic impact of the project is substantial. The construction of four such reactors is expected to create up to 18,000 jobs and contribute approximately $38.5 billion CAD to the Canadian economy, reflecting the economic benefits of nuclear projects over 65 years. The modular nature of SMRs also allows for scalability, with each additional unit potentially reducing costs through economies of scale.

Safety is a paramount consideration in the design of the BWRX-300. The reactor employs passive safety features, meaning it can safely shut down without the need for external power or operator intervention. This design enhances the reactor's resilience to potential emergencies, aligning with stringent regulatory standards.

Ontario's commitment to nuclear energy is further demonstrated by its plans for four SMRs at the Darlington site. This initiative reflects a broader strategy to diversify the province's energy mix, incorporating clean and reliable power sources to complement renewable energy efforts.

While the development of SMRs in Ontario is a significant step forward, it also aligns with the Canadian nuclear initiative positioning Canada as a leader in the global nuclear energy landscape. The successful implementation of the BWRX-300 could serve as a model for other nations exploring advanced nuclear technologies.

Ontario's groundbreaking work on small modular nuclear reactors represents a forward-thinking approach to energy generation. By embracing innovative technologies, the province is not only addressing future energy demands but also, through the Pickering NGS life extension, contributing to the global transition towards sustainable and secure energy solutions.

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EU Energy Price Crisis drives soaring electricity bills as natural gas sets pay-as-clear power prices; leaders debate price caps, common gas purchasing, market reform, renewables, and ETS changes amid Ukraine war supply shocks.

Key Points

A surge in gas-driven power costs linked to pay-as-clear pricing, supply shocks, and policy rifts across the EU market.

✅ Gas sets marginal power price via pay-as-clear mechanism

✅ Spain pushes decoupling and temporary price caps

✅ EU weighs joint gas buying, efficiency, more renewables

Nothing grabs politicians' attention faster than angry voters, and they've had plenty to be furious about as natural gas and electricity bills have soared to stomach-churning levels in recent months, as this UK natural gas analysis illustrates across markets.

That's led to a scramble to figure out ways to get those costs down, with emergency price-limiting measures under discussion — but that's turning out to be very difficult, so the likeliest result is that EU leaders meeting later this week won't come up with any solutions.

“There is no single easy answer to tackle the high electricity prices given the diversity of situations among Member States. Some options are only suitable for specific national contexts,” the European Commission said on Wednesday. “They all carry costs and drawbacks.” 

The initial problem was a surge in gas demand in Asia last year coupled with lower-than-normal Russian gas deliveries that left European gas storage at unusually low levels. Now the war in Ukraine is making matters even worse, as pressure grows for the bloc to rapidly cut its imports of Russian oil, coal and natural gas — although some national leaders reject the economic costs that would entail.

"We will end this dependence as quickly as we can, but to do that from one day to the next would mean plunging our country and all of Europe into a recession," German Chancellor Olaf Scholz warned on Wednesday.

The problem for the bloc is that its liberalized electricity market is tightly tied to the price of natural gas; power prices are set by the final input needed to balance demand — called pay-as-clear — which in most cases is set by natural gas. That's led to countries with large amounts of cheaper renewable or nuclear energy seeing sharp spikes in power prices thanks to the cost of that final bit of gas-fired electricity.

A Spanish-led coalition that includes Portugal, Belgium and Italy wants deep reforms to the EU price model, fueling a broader electricity market revamp debate in Brussels.

Others, such as the Netherlands and Germany, strongly oppose such an approach, echoing how nine countries oppose reforms at the EU level, and want to focus on cushioning the effects of the high prices on consumers and businesses, while letting the market operate. 

A third group, largely in Central Europe, wants to use the price spike to revamp or scrap the bloc's Emissions Trading System and to rethink its Fit for 55 climate legislation.

The European Commission has been holding the middle ground — arguing that the current market model makes sense, but encouraging countries to boost the amount of renewable electricity, in a wake-up call to ditch fossil fuels for Europe, to cut energy use and increase efficiency.

In draft conclusions of this week's European Council summit, seen by POLITICO, EU leaders, amid a France-Germany tussle over reform, call for things like a common approach to buying gas, aimed at preventing countries from competing against each other. But there's no big movement on electricity prices.

“It does not seem realistic to expect a result on the energy discussion at this European Council,” one diplomat said, stressing that the governments will need to see more analysis before committing to any more steps.

Looking for action
Spain wanted a much more robust response. Madrid has been arguing since last summer for “decoupling” gas from the electricity market; together with Portugal, it also mulled limiting the wholesale price of electricity to €180 per megawatt-hour — a proposal that Spain abandoned under fire from industry and consumer groups. 

Now Madrid is pushing to get a specific permission in the summit's final conclusions that would allow countries to voluntarily apply certain short-term solutions such as gas price cap strategies, according to a draft with track changes seen by POLITICO.

The issue with a cap is if gas prices are higher than the cap, Spain might not be able to buy any gas.

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Trump Offshore Wind Pledge signals a push for deregulation over renewable energy, challenging climate policy, green jobs, and coastal development while citing marine ecosystems, navigation, and energy independence amid state-federal permitting and legal hurdles.

Key Points

Trump's vow to cancel offshore wind projects favors deregulation and fossil fuels, impacting climate policy and jobs.

✅ Day-one plan to scrap offshore wind leases and permits

✅ Risks to renewable targets, grid mix, and coastal supply chains

✅ Likely court fights and state-federal regulatory conflicts

During his tenure as President of the United States, Donald Trump made numerous promises and policy proposals, many of which sparked controversy and debate. One such pledge was his vow to scrap offshore wind projects on "day one" of his presidency. This bold statement, while appealing to certain interests, raised concerns about its potential impact on U.S. offshore wind growth and environmental conservation efforts.

Trump's opposition to offshore wind projects stemmed from various factors, including his skepticism towards renewable energy, even as forecasts point to a $1 trillion offshore wind market in coming years, concerns about aesthetics and property values, and his focus on promoting traditional energy sources like coal and oil. Throughout his presidency, Trump prioritized deregulation and sought to roll back environmental policies introduced by previous administrations, arguing that they stifled economic growth and hindered American energy independence.

The prospect of scrapping offshore wind projects drew mixed reactions from different stakeholders. Supporters of Trump's proposal pointed to potential benefits such as preserving scenic coastal landscapes, protecting marine ecosystems, and addressing concerns about navigational safety and national security. Critics, however, raised valid concerns about the implications of such a decision on the renewable energy sector, including progress toward getting 1 GW on the grid nationwide, climate change mitigation efforts, and job creation in the burgeoning green economy.

Offshore wind energy has emerged as a promising source of clean, renewable power with the potential to reduce greenhouse gas emissions and diversify the energy mix. Countries like Denmark, the United Kingdom, and Germany have made significant investments in offshore wind in Europe, demonstrating its viability as a sustainable energy solution. In the United States, offshore wind projects have gained traction in states like Massachusetts, New York, and New Jersey, where coastal conditions are conducive to wind energy generation.

Trump's pledge to scrap offshore wind projects on "day one" of his presidency raised questions about the feasibility and legality of such a move. While the president has authority over certain aspects of energy policy and regulatory oversight, the development of offshore wind projects often involves multiple stakeholders, including state governments, local communities, private developers, and federal agencies, and actions such as Interior's move on Vineyard Wind illustrate federal leverage in permitting. Any attempt to halt or reverse ongoing projects would likely face legal challenges and regulatory hurdles, potentially delaying or derailing implementation.

Moreover, Trump's stance on offshore wind projects reflected broader debates about the future of energy policy, environmental protection, and economic development. While some argued for prioritizing fossil fuel extraction and traditional energy infrastructure, others advocated for a transition towards clean, renewable energy sources, drawing on lessons from the U.K. about wind deployment, to mitigate climate change and promote sustainable development. The Biden administration, which succeeded the Trump presidency, has signaled a shift towards a more climate-conscious agenda, including support for renewable energy initiatives and commitments to rejoin international agreements like the Paris Climate Accord.

In hindsight, Trump's pledge to scrap offshore wind projects on "day one" of his presidency underscores the complexities of energy policy and the importance of balancing competing interests and priorities. While concerns about aesthetics, property values, and environmental impact are valid, addressing the urgent challenge of climate change requires bold action and innovation in the energy sector. Offshore wind energy presents an opportunity, as seen in the country's biggest offshore wind farm approved in New York, to harness the power of nature in a way that is both environmentally responsible and economically beneficial. As the United States navigates its energy future, finding common ground and forging partnerships will be essential to ensure a sustainable and prosperous tomorrow.

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UK Coal-Free Electricity Record highlights rapid growth in renewables as National Grid phases out coal; wind, solar, and offshore projects surge, green tariffs expand, and energy comparison helps consumers switch to cheaper, cleaner deals.

Key Points

Britain's longest coal-free run, enabled by renewables, lower demand, and grid shifts for cheaper, greener tariffs.

✅ Record set after two months without coal-fired generation

✅ Renewables outpace fossil fuels; wind and solar dominate

✅ Green tariffs expand; prices at three-year lows

On Wednesday 10 June, Britain hit a significant landmark: the UK went for two full months without burning coal to generate power – that's the longest period since the 1880s, following earlier milestones such as a full week without coal power in the recent past.

According to the National Grid, Britain has now run its electricity network without burning coal since midnight on the 9 April. This coal-free period has beaten the country’s previous record of 18 days, six hours and 10 minutes, which was set in June 2019, even though low-carbon generation stalled in 2019 according to analyses.

With such a shift in Britain’s drive for renewables and lower electricity demand following the coronavirus lockdown, as Britain recorded its cleanest electricity during lockdown to date, now may be the perfect time to do an online energy comparison and switch to a cheaper, greener deal.

Only a decade ago, around 40 per cent of Britain’s electricity came from coal generation, but since then the country has gradually shifted towards renewable energy, with the coal share at record lows in the system today. When Britain was forced into lockdown in response to the coronavirus pandemic, electricity demand dropped sharply, and the National Grid took the four remaining coal-fired plants off the network.

Over the past 10 years, Britain has invested heavily in renewable energy. Back in 2010, only 3 per cent of the country's electricity came from wind and solar, and many people remained sceptical. However, now, the UK has the biggest offshore wind industry in the world. Plus, last year, construction of the world’s single largest wind farm was completed off the coast of Yorkshire.

At the same time, Drax – Britain’s biggest power plant – has started to switch from burning coal to burning compressed wooden pellets instead, reflecting the UK's progress as it keeps breaking its coal-free energy record again across the grid. By this time next year, the plant hopes to have phased out coal entirely.

So far this year, renewables have generated more power than all fossil fuels put together, the BBC reports, and the energy dashboard shows the current mix in real time. Renewables have been responsible for 37 per cent of electricity supplied to the network, with wind and solar surpassing nuclear for the first time, while fossil fuels have accounted for 35 per cent. During the same period, nuclear accounted for 18 per cent and imports made up the remaining 10 per cent.

What does this mean for consumers?

As the country’s electricity supply moves more towards renewables, customers have more choice than ever before. Most of the ‘Big Six’ energy companies now have tariffs that offer 100 per cent green electricity. On top of this, specialist green energy suppliers such as Bulb, Octopus and Green Energy UK make it easier than ever to find a green energy tariff.

The good news is that our energy comparison research suggests that green energy doesn’t have to cost you more than a traditional fixed-price energy contract would. In fact, some of the cheapest energy suppliers are actually green companies.

At present, energy bills are at three-year lows, which means that now is the perfect time to switch supplier. As prices remain low and renewables begin to dominate the marketplace, more switchers will be drawn to green energy deals than ever before.

However, if you’re interested in choosing a green energy supplier, make sure that you look at the company's fuel mix. This way, you’ll be able to see whether they are guaranteeing the usage of green energy, or whether they’re just offsetting your usage. All suppliers must report how their energy is generated to Ofgem, so you’ll easily be able to compare providers.

You may find that you pay more for a supplier that generates its own energy from renewables, or pay less if the supplier simply matches your usage by buying green energy. You can decide which option is right for you after comparing the prices.

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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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