Improvements necessary in Wisconsin to maintain system stability

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Upper Midwest utilities have identified improvements needed in the regionÂ’s high-voltage electricity transmission system to ensure they can deliver the renewable energy necessary to meet MinnesotaÂ’s renewable energy milestones beginning in 2016.

MinnesotaÂ’s 2007 Next Generation Energy Act requires that utilities increase renewables on their systems in increments and by 2025 deliver 25 percent of their energy from renewable sources (Xcel Energy is required to deliver 30 percent by 2020). ItÂ’s estimated that 4,000 to 6,000 megawatts of renewable energy will be needed to meet MinnesotaÂ’s Renewable Energy Standard. North Dakota, South Dakota and Wisconsin have 10 percent by 2015 renewable energy targets.

The utilities identified transmission needs in studies published just recently.

The studies confirmed that replacing a 60-year-old 230-kilovolt line that runs between Granite Falls and Shakopee with a double-circuit 345-kilovolt line would unlock up to 2,000 megawatts of transmission capacity from wind-rich areas in southern and western Minnesota, North Dakota and South Dakota.

“Upgrading the 230-kilovolt line is the most cost-effective way to meet the 2016 renewable energy standard milestone,” said Kent Larson, transmission vice president at Xcel Energy. “The upgrade will optimize capacity from the CapX2020 Group 1 lines, which are moving through the permitting processes, and serve as the next phase of our regional transmission build out to efficiently deliver wind power to our customers.”

The 125-mile line would cost an estimated $350 million, with an additional $110 million for underlying system improvements.

The studies also found that further upgrades in Minnesota and the Dakotas (beyond the 230-kilovolt line upgrade) will not provide significant benefit prior to installation of a high-voltage transmission line between the La Crosse, Wis., area and the Madison, Wis., area. Without a line to the east of Minnesota, the transmission system will reach a “tipping point” where reliability is compromised, according to the studies.

The studies found that the combination of the new 345-kilovolt double circuit line between Granite Falls and Shakopee and a new Wisconsin line would increase the transmission system transfer capability by 1,600 megawatts for a total increase — with the 2,000 megawatts from the new 345-kilovolt line in Minnesota — of approximately 3,600 megawatts.

A joint transmission planning study now under way by several utilities aims to determine the need for a new transmission line between La Crosse and Madison. The study is expected to be completed by 2010.

“The renewable energy requirements of states in the Upper Midwest will be efficiently met with further 345-kilovolt transmission line expansion,” said Will Kaul, transmission vice president at Great River Energy. “Policy changes, such as the passage of a national renewable energy standard, may lead to the consideration of a 765-kilovolt overlay. However, the 345-kilovolt projects identified in the studies conducted by the Upper Midwest transmission-owning utilities are still required as a foundational component of a 765-kilovolt overlay.”

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Tunisia moves ahead with smart electricity grid

Tunisia Smart Grid Project advances with an AFD loan as STEG deploys smart meters in Sfax, upgrades grid infrastructure, boosts energy efficiency, curbs losses, and integrates renewable energy through digitalization and advanced communication systems.

 

Key Points

A national program funded by an AFD $131.7M loan to modernize STEG, deploy smart meters, and integrate renewable energy.

✅ 430,000 smart meters in Sfax during phase one

✅ 20-year AFD loan with 7-year grace period

✅ Cuts losses, improves efficiency, enables renewables

 

The Tunisian parliament has approved taking a $131.7 million loan from the French Development Agency for the implementation of a smart grid project.

Parliament passed legislation regarding the 400 million dinar ($131.7 million) loan plus a grant of $1.1 million.

The loan, to be repaid over 20 years with a grace period of up to 7 years, is part of the Tunisian government’s efforts to establish a strategy of energy switching aimed at reducing costs and enhancing operational efficiency.

The move to the smart grid had been postponed after the Tunisian Company of Electricity and Gas (STEG) announced in March 2017 that implementation of the first phase of the project would begin in early 2018 and cover the entire country by 2023.

STEG was to have received funding some time ago. Last year at the Africa Smart Grid Summit in Tunis, the company said it would initiate an international tender during the first quarter of 2019 to start the project.

The French funding is to be allocated to implementation of the first phase only, which will involve development of control and communication stations and the improvement of infrastructure, where regulatory outcomes such as the Hydro One T&D rates decision can influence investment planning in comparable markets.

It includes installation of 430,000 “intelligent” metres over three years in Sfax governorate in southern Tunisia. The second phase of the project is planned to extend the programme to the rest of the country.

Smart metres to be installed in homes and businesses in Sfax account for about 10% of the total number of metres to be deployed in Tunisia.

At the beginning of 2017, the Industrial Company of Metallic Articles (SIAM), a Tunisian industrial electrical equipment and machinery company, signed an agreement with Huawei for the Chinese company to supply smart electricity metres. The value of the deal was not disclosed.

The smart grid is designed to reduce power waste, reduce the number of unpaid bills, prevent consumer fraud such as power theft in India across distribution networks, improve the ecosystem and increase competitiveness in the electricity sector.

Experts said the main difference between the traditional and smart grids is the adoption of advanced infrastructure for measuring electricity consumption and for communication between the power plant and consumers. The data exchange allows power plants to coordinate electricity production with actual demand.

STEG previously indicated that it had implemented measures to ensure the transition to the smart grid, especially since digitalisation is playing an important role in the energy sector.

The project, which translates Tunisia’s energy plans in the form of a partnership between the public and private sectors, aims at reaching 30% of the country’s electricity need from renewable sources by 2025, even as entities like the TVA face climate goals scrutiny that can affect electricity rates in other markets.

The development of the smart grid will allow STEG to monitor consumption patterns, detect abuses and remotely monitor the grid’s power supply, at a time when regulators have questioned UK network profits to spur efficiency, underscoring the value of transparency.

“The smart grid will change the face of the energy system towards the use of renewable energies,” said Tunisian Industry Minister Slim Feriani. At the forum on alternative energies, he pointed out that energy sector digitisation requires investments in technology and a change in the consumption mentality, as new entrants consider roles like Tesla electricity retailer plans in advanced markets.

Official data indicate that Tunisia’s energy deficit accounts for one-third of the country’s annual trade deficit, which reached record levels of more than $6 billion last year.

STEG, whose debts have reached $329 million over the past eight years, a situation resembling Manitoba Hydro debt pressures in Canada, has not disclosed when and how funding would be secured for the completion of the second phase. The company insists it is working to prevent further losses and to collect its unpaid bills.

STEG CEO Moncef Harrabi, earlier this year, said: “The current situation of the company has forced us to take immediate action to reduce the worsening of the crisis and stop the financial bleeding caused by losses.”

He said the company had repeatedly asked the government to pay subsidy instalments due to the company and to enact binding decisions to force government institutions and departments to pay electricity bills, while elsewhere measures like Thailand power bill cuts have been used to support consumers.

The Tunisian government has yet to disburse the subsidy instalments due STEG for 2018 and 2019, which amount to $658 million. STEG also imports natural gas from Algeria for its power plants at a cost of $1.1 billion a year.

 

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7 steps to make electricity systems more resilient to climate risks

Electricity System Climate Resilience underpins grid reliability amid heatwaves and drought, integrating solar, wind, hydropower, nuclear, storage, and demand response with efficient transmission, flexibility, and planning to secure power for homes, industry, and services.

 

Key Points

Power systems capacity to endure extreme weather and integrate clean energy, maintaining reliability and flexibility.

✅ Grid hardening, transmission upgrades, and digital forecasting.

✅ Flexible low-carbon supply: hydropower, nuclear, storage.

✅ Demand response, efficient cooling, and regional integration.

 

Summer is just half done in the northern hemisphere and yet we are already seeing electricity systems around the world struggling to cope with the severe strain of heatwaves and low rainfall.

These challenges highlight the urgent need for strong and well-planned policies and investments to improve the security of our electricity systems, which supply power to homes, offices, factories, hospitals, schools and other fundamental parts of our economies and societies. This means making our electricity systems more resilient to the effects of global warming – and more efficient and flexible as they incorporate rising levels of solar and wind power, as solar is now the cheapest electricity in history according to the IEA, which will be critical for reaching net-zero emissions in time to prevent even worse impacts from climate change.

A range of different countries, including the US, Canada and Iraq, have been hard hit by extreme weather recently in the form of unusually high temperatures. In North America, the heat soared to record levels in the Pacific Northwest. An electricity watchdog says that five US regions face elevated risks to the security of their electricity supplies this summer, underscoring US grid climate risks that could worsen, and that California’s risk level is even higher.

Heatwaves put pressure on electricity systems in multiple ways. They increase demand as people turn up air conditioning, driving higher US electricity bills for many households, and as some appliances work harder to maintain cool temperatures. At the same time, higher temperatures can also squeeze electricity supplies by reducing the efficiency and capacity of traditional thermal power plants, such as coal, natural gas and nuclear. Extreme heat can reduce the availability of water for cooling plants or transporting fuel, forcing operators to reduce their output. In some cases, it can result in power plants having to shut down, increasing the risk of outages. If the heat wave is spread over a wide geographic area, it also reduces the scope for one region to draw on spare capacity from its neighbours, since they have to devote their available resources to meeting local demand.

A recent heatwave in Texas forced the grid operator to call for customers to raise their thermostats’ temperatures to conserve energy. Power generating companies suffered outages at much higher rates than expected, providing an unwelcome reminder of February’s brutal cold snap when outages – primarily from natural gas power plants – left up to 5 million customers across the US without power over a period of four days.

At the same time, lower than average rainfall and prolonged dry weather conditions are raising concerns about hydropower’s electricity output in various parts of the world, including Brazil, China, India and North America. The risks that climate change brings in the form of droughts adds to the challenges faced by hydropower, the world’s largest source of clean electricity, highlighting the importance of developing hydropower resources sustainably and ensuring projects are climate resilient.

The recent spate of heatwaves and unusually long dry spells are fresh warnings of what lies ahead as our climate continues to heat up: an increase in the scale and frequency of extreme weather events, which will cause greater impacts and strains on our energy infrastructure.

Heatwaves will increase the challenge of meeting electricity demand while also decarbonizing the electricity supply. Today, the amount of energy used for cooling spaces – such as homes, shops, offices and factories – is responsible for around 1 billion tonnes of global CO2 emissions. In particular, energy for cooling can have a major impact on peak periods of electricity demand, intensifying the stress on the system. Since the energy demand used for air conditioners worldwide could triple by 2050, these strains are set to grow unless governments introduce stronger policy measures to improve the energy efficiency of air conditioning units.

Electricity security is crucial for smooth energy transitions
Many countries around the world have announced ambitious targets for reaching net-zero emissions by the middle of this century and are seeking to step up their clean energy transitions. The IEA’s recent Global Roadmap to Net Zero by 2050 makes it clear that achieving this formidable goal will require much more electricity, much cleaner electricity and for that electricity to be used in far more parts of our economies than it is today. This means electricity reaching much deeper into sectors such as transport (e.g. EVs), buildings (e.g. heat-pumps) and industry (e.g. electric-arc steel furnaces), and in countries like New Zealand's electrification plans it is accelerating broader efforts. As clean electricity’s role in the economy expands and that of fossil fuels declines, secure supplies of electricity become ever-more important. This is why the climate resilience of the electricity sector must be a top priority in governments’ policy agendas.

Changing climate patterns and more frequent extreme weather events can hit all types of power generation sources. Hydropower resources typically suffer in hot and dry conditions, but so do nuclear and fossil fuel power plants. These sources currently help ensure electricity systems have the flexibility and capacity to integrate rising shares of solar and wind power, whose output can vary depending on the weather and the time of day or year.

As governments and utilities pursue the decarbonization of electricity systems, mainly through growing levels of solar and wind, and carbon-free electricity options, they need to ensure they have sufficiently robust and diverse sources of flexibility to ensure secure supplies, including in the event of extreme weather events. This means that the possible decommissioning of existing power generation assets requires careful assessments that take into account the importance of climate resilience.

Ensuring electricity security requires long-term planning and stronger policy action and investment
The IEA is committed to helping governments make well-informed decisions as they seek to build a clean and secure energy future. With this in mind, here are seven areas for action for ensuring electricity systems are as resilient as possible to climate risks:

1. Invest in electricity grids to make them more resilient to extreme weather. Spending today is far below the levels needed to double the investment for cleaner, more electrified energy systems, particularly in emerging and developing economies. Economic recovery plans from the COVID-19 crisis offer clear opportunities for economies that have the resources to invest in enhancing grid infrastructure, but much greater international efforts are required to mobilize and channel the necessary spending in emerging and developing economies.

2. Improve the efficiency of cooling equipment. Cost-effective technology already exists in most markets to double or triple the efficiency of cooling equipment. Investing in higher efficiency could halve future energy demand and reduce investment and operating costs by $3 trillion between now and 2050. In advance of COP26, the Super-Efficient Equipment and Appliance Deployment (SEAD) initiative is encouraging countries to sign up to double the energy efficiency of equipment sold in their countries by 2030.

3. Enable the growth of flexible low-carbon power sources to support more solar and wind. These electricity generation sources include hydropower and nuclear, for countries who see a role for one or both of them in their energy transitions. Guaranteeing hydropower resilience in a warming climate will require sophisticated methods and tools – such as the ones implemented in Brazil – to calculate the necessary level of reserves and optimize management of reservoirs and hydropower output even in exceptional conditions. Batteries and other forms of storage, combined with solar or wind, can also provide important amounts of flexibility by storing power and releasing it when needed.

4. Increase other sources of electricity system flexibility. Demand-response and digital technologies can play an important role. The IEA estimates that only a small fraction of the huge potential for demand response in the buildings sector is actually tapped at the moment. New policies, which associate digitalization and financial behavioural incentives, could unlock more flexibility. Regional integration of electricity systems across national borders can also increase access to flexible resources.

5. Expedite the development and deployment of new technologies for managing extreme weather threats. The capabilities of electricity utilities in forecasting and situation awareness should be enhanced with the support of the latest information and communication technologies.

6. Make climate resilience a central part of policy-making and system planning. The interconnected nature of recent extreme weather events reminds us that we need to account for many contingencies when planning resilient power systems. Climate resilience should be integral to policy-making by governments and power system planning by utilities and relevant industries, and debates over Canadian climate policy underscore how grid implications must be considered. According to the recent IEA report on climate resilience, only nine out of 38 IEA member and association countries include concrete actions on climate adaptation and resilience for every segment of electricity systems.

7. Strengthen international cooperation on electricity security. Electricity underpins vital services and basic needs, such as health systems, water supplies and other energy industries. Maintaining a secure electricity supply is thus of critical importance. The costs of doing nothing in the face of growing climate threats are becoming abundantly clear. The IEA is working with all countries in the IEA family, as well as others around the world, by providing unrivalled data, analysis and policy advice on electricity security issues. It is also bringing governments together at various levels to share experiences and best practices, and identify how to hasten the shift to cleaner and more resilient energy systems.


 

 

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India to Ration Coal Supplies as Electricity Demand Surges

India Coal Supply Rationing redirects shipments from high-inventory power plants to stations facing shortages as electricity demand surges, inventories fall, and outages persist; Coal India, NTPC imports, and smaller mines bolster domestic supply.

 

Key Points

A temporary policy redirecting coal from high-stock plants to shortage-hit plants amid rising demand

✅ Shipments halted 1 week to plants with >14 days coal stock

✅ Smaller mines asked to raise output; NTPC to import 270,000 tons

✅ Outages at Adani and Tata Mundra units pressure domestic supply

 

India will ration coal supplies to power plants with high inventories to direct more shipments to stations battling shortages, even as shortages ease in some regions, as surging demand outstrips production.

Supplies to plants with more than two weeks’ coal inventory will be halted for a week, a team headed by federal Coal Secretary Alok Kumar decided on Saturday, the Power Ministry said in a statement. The government has also requested smaller mines to raise output to supplement shipments from state miner Coal India Ltd., and is taking steps to get nuclear back on track to diversify the energy mix.

A jump in electricity consumption spurred by a reviving economy and an extended summer, after an earlier steep demand decline in India, is driving demand for coal, which helps produce about 70% of the nation’s electricity. The surge in demand complicates India’s clean-energy transition efforts amid solar supply headwinds that cloud near-term alternatives, and may bolster arguments favoring the country’s dependence on coal to fuel economic growth.

“There’s no doubt India will continue to need coal for stable power for years,” said Rupesh Sankhe, vice president at Elara Capital India Pvt. in Mumbai. “Plants that meet environmental standards and are able to produce power efficiently will see utilization rising, but I doubt we’re going to have many new coal plants.”  

Coal stockpiles at the country’s power plants had fallen to 14.7 million tons as of Aug. 24, tumbling 62% from a year earlier, according to the latest data from the Central Electricity Authority. More than 88 gigawatts of generation plants, about half the capacity monitored by the power ministry, had inventories of six days or less as of that date, the data show. Power demand jumped 10.5% in July from a year earlier, even as global electricity use dipped 15% during the pandemic, according to the government.
Outages at some large plants that run on imported coal have increased the burden on those that burn domestic supplies, aiding shortfalls.

Adani Power Ltd. had almost 2 gigawatts of capacity in outage at its Mundra plant in Gujarat at the start of the week, while Tata Power Co. Ltd. had shut 80% of its 4-gigawatt plant in the same town for maintenance, power ministry data show.

NTPC Ltd., the largest power generator, will import the 270,000 tons of coal it left out from contracts placed earlier to mitigate the fuel shortage, reflecting higher imported coal volumes this fiscal, the power ministry said in a separate statement.

 

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California's solar energy gains go up in wildfire smoke

California Wildfire Smoke Impact on Solar reduces photovoltaic output, as particulate pollution, soot, and haze dim sunlight and foul panels, cutting utility-scale generation and grid reliability across CAISO during peak demand and heatwaves.

 

Key Points

How smoke and soot cut solar irradiance and foul panels, slashing PV generation and straining CAISO grid operations.

✅ Smoke blocks sunlight; soot deposition reduces panel efficiency.

✅ CAISO reported ~30% drop versus July during peak smoke.

✅ Longer fire seasons threaten solar reliability and capacity planning.

 

Smoke from California’s unprecedented wildfires was so bad that it cut a significant chunk of solar power production in the state, even as U.S. solar generation rose in 2022 nationwide. Solar power generation dropped off by nearly a third in early September as wildfires darkened the skies with smoke, according to the US Energy Information Administration.

Those fires create thick smoke, laden with particles that block sunlight both when they’re in the air and when they settle onto solar panels. In the first two weeks of September, soot and smoke caused solar-powered electricity generation to fall 30 percent compared to the July average, according to the California Independent System Operator (CAISO), which oversees nearly all utility-scale solar energy in California, where wind and solar curtailments have been rising amid grid constraints. It was a 13.4 percent decrease from the same period last year, even though solar capacity in the state has grown about 5 percent since September 2019.

California depends on solar installations for nearly 20 percent of its electricity generation, and has more solar capacity than the next five US states trailing it combined as it works to manage its solar boom sustainably. It will need even more renewable power to meet its goal of 100 percent clean electricity generation by 2045, building on a recent near-100% renewable milestone that underscored the transition. The state’s emphasis on solar power is part of its long-term efforts to avoid more devastating effects of climate change. But in the short term, California’s renewables are already grappling with rising temperatures.

Two records were smashed early this September that contributed to the loss of solar power. California surpassed 2 million acres burned in a single fire season for the first time (1.7 million more acres have burned since then). And on September 15th, small particle pollution reached the highest levels recorded since 2000, according to the California Air Resources Board. Winds that stoked the flames also drove pollution from the largest fires in Northern California to Southern California, where there are more solar farms.

Smaller residential and commercial solar systems were affected, too, and solar panels during grid blackouts typically shut off for safety, although smoke was the primary issue here. “A lot of my systems were producing zero power,” Steve Pariani, founder of the solar installation company Solar Pro Energy Systems, told the San Mateo Daily Journal in September.

As the planet heats up, California’s fire seasons have grown longer, and blazes are tearing through more land than ever before, while grid operators are also seeing rising curtailments as they integrate more renewables. For both utilities and smaller solar efforts, wildfire smoke will continue to darken solar energy’s otherwise bright future, even as it becomes the No. 3 renewable source in the U.S. by generation.

 

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Germany agrees 200 bln euro package to shield against surging energy prices

Germany Energy Price Defensive Shield counters soaring gas and electricity costs with a gas price brake, VAT cut, subsidies for households and SMEs, LNG terminals, renewables, temporary nuclear extension, and targeted borrowing to curb inflation.

 

Key Points

A 200 billion euro package to cap energy costs, subsidize basics, and stabilize inflation for firms and households.

✅ Gas price brake and VAT cut reduce consumer and SME energy bills.

✅ Temporary electricity subsidies and nuclear extension aid winter supply.

✅ Funded via new borrowing; supports LNG and renewable expansion.

 

German Chancellor Olaf Scholz set out a 200 billion euro ($194 billion) "defensive shield", including a gas price brake and a cut in sales tax for the fuel, to protect companies and households from the impact of soaring energy prices in Germany.

Europe's biggest economy is trying to cope with surging gas and electricity costs, with local utilities seeking help, caused largely by a collapse in Russian gas supplies to Europe, which Moscow has blamed on Western sanctions following its invasion of Ukraine in February.

3 minute readSeptember 29, 202211:35 AM PDTLast Updated 6 days ago
Germany agrees 200 bln euro package to shield against surging energy prices
By Holger Hansen and Kirsti Knolle

"Prices have to come down, so the government will do everything it can. To this end, we are setting up a large defensive shield," said Scholz.

Under the plans, to run until spring 2024, the government will introduce an emergency price brake on gas, the details of which will be announced next month, while Europe weighs emergency measures to limit electricity prices across the bloc. It is scrapping a planned gas levy meant to help firms struggling with high spot market prices. 

A temporary electricity price brake will subsidise basic consumption for consumers and small and medium-sized companies, and complements an electricity subsidy for industries under discussion. Sales tax on gas will fall to 7% from 19%.

In its efforts to cut its dependence on Russian energy, Germany is also promoting the expansion of renewable energy and developing liquefied gas terminals, but rolling back European electricity prices remains complex.

To help households and companies weather any winter supply disruption, amid rising heating and electricity costs this winter, especially in southern Germany, two nuclear plants previously due to close by the end of this year will be able to keep running until spring 2023.

The package will be financed with new borrowing this year, as Berlin makes use of the suspension of a constitutionally enshrined limit on new debt of 0.35% of gross domestic product.

Finance Minister Christian Lindner has said he wants to comply with the limit again next year, even as the EU outlines gas price cap strategies for the market.

Lindner, of the pro-business Free Democrats (FDP) who share power with Scholz's Social Democrats and the Greens, said on Thursday the country's public finances were stable.

"We can put it no other way: we find ourselves in an energy war," said Lindner. "We want to clearly separate crisis expenditure from our regular budget management, we want to send a very clear signal to the capital markets."

He also said the steps would act as a brake on inflation, which hit its highest level in more than a quarter of century in September.

Opposition conservative Markus Soeder, premier of the southern state of Bavaria, said the steps gave the right signal.

"It gives industry and citizens confidence that we can get through the winter," he said.

 

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Brand New Renewable Technology Harnesses Electricity From The Cold, Dark Night

Nighttime Thermoelectric Generator converts radiative cooling into renewable energy, leveraging outer space cold; a Stanford-UCLA prototype complements solar, serving off-grid loads with low-power output during peak evening demand, using simple materials on a rooftop.

 

Key Points

A device converting nighttime radiative cooling into electricity, complementing solar for low-power evening needs.

✅ Uses thermocouples to convert temperature gradients to voltage.

✅ Exploits radiative cooling to outer space for night power.

✅ Complements solar; low-cost parts suit off-grid applications.

 

Two years ago, one freezing December night on a California rooftop, a tiny light shone weakly with a little help from the freezing night air. It wasn't a very bright glow. But it was enough to demonstrate the possibility of generating renewable power after the Sun goes down.

Working with Stanford University engineers Wei Li and Shanhui Fan, University of California Los Angeles materials scientist Aaswath Raman put together a device that produces a voltage by channelling the day's residual warmth into cooling air, effectively generating electricity from thin air with passive heat exchange.

"Our work highlights the many remaining opportunities for energy by taking advantage of the cold of outer space as a renewable energy resource," says Raman.

"We think this forms the basis of a complementary technology to solar. While the power output will always be substantially lower, it can operate at hours when solar cells cannot."

For all the merits of solar energy, it's just not a 24-7 source of power, although research into nighttime solar cells suggests new possibilities for after-dark generation. Sure, we can store it in a giant battery or use it to pump water up into a reservoir for later, but until we have more economical solutions, nighttime is going to be a quiet time for renewable solar power. 

Most of us return home from work as the Sun is setting, and that's when energy demands spike to meet our needs for heating, cooking, entertaining, and lighting.

Unfortunately, we often turn to fossil fuels to make up the shortfall. For those living off the grid, it could require limiting options and going without a few luxuries.

Shanhui Fan understands the need for a night time renewable power source well. He's worked on a number of similar devices, including carbon nanotube generators that scavenge ambient energy, and a recent piece of technology that flipped photovoltaics on its head by squeezing electricity from the glow of heat radiating out of the planet's Sun-warmed surface.

While that clever item relied on the optical qualities of a warm object, this alternative device makes use of the good old thermoelectric effect, similar to thin-film waste-heat harvesting approaches now explored.

Using a material called a thermocouple, engineers can convert a change in temperature into a difference in voltage, effectively turning thermal energy into electricity with a measurable voltage. This demands something relatively toasty on one side and a place for that heat energy to escape to on the other.

The theory is the easy part – the real challenge is in arranging the right thermoelectric materials in such a way that they'll generate a voltage from our cooling surrounds that makes it worthwhile.

To keep costs down, the team used simple, off-the-shelf items that pretty much any of us could easily get our hands on.

They put together a cheap thermoelectric generator and linked it with a black aluminium disk to shed heat in the night air as it faced the sky. The generator was placed inside a polystyrene enclosure sealed with a window transparent to infrared light, and linked to a single tiny LED.


 

For six hours one evening, the box was left to cool on a roof-top in Stanford as the temperature fell just below freezing. As the heat flowed from the ground into the sky, the small generator produced just enough current to make the light flicker to life.

At its best, the device generated around 0.8 milliwatts of power, corresponding to 25 milliwatts of power per square metre.

That might just be enough to keep a hearing aid working. String several together and you might just be able to keep your cat amused with a simple laser pointer. So we're not talking massive amounts of power.

But as far as prototypes go, it's a fantastic starting point. The team suggests that with the right tweaks and the right conditions, 500 milliwatts per square metre isn't out of the question.

"Beyond lighting, we believe this could be a broadly enabling approach to power generation suitable for remote locations, and anywhere where power generation at night is needed," says Raman.

While we search for big, bright ideas to drive the revolution for renewables, it's important to make sure we don't let the smaller, simpler solutions like these slip away quietly into the night.

This research was published in Joule.

 

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