Italy considering solar capacity cap

TotalEnergies VSB Acquisition accelerates renewable energy growth, expanding wind and solar portfolios across Germany and Europe, advancing decarbonization, net-zero targets, and the energy transition through a US$1.65 billion strategic clean power investment.

Key Points

A US$1.65B deal: TotalEnergies acquires VSB to scale wind and solar in Europe and advance net-zero goals.

✅ US$1.65B purchase expands wind and solar pipeline

✅ Strengthens presence in Germany and wider Europe

✅ Advances net-zero, energy transition objectives

In a major move to expand its renewable energy portfolio, French energy giant TotalEnergies has announced its decision to acquire German renewable energy developer VSB for US$1.65 billion. This acquisition represents a significant step in TotalEnergies' strategy to accelerate its transition from fossil fuels to greener energy sources, aligning with the global push towards sustainability and carbon reduction, as reflected in Europe's green surge across key markets.

Strengthening TotalEnergies’ Renewable Energy Portfolio

TotalEnergies has long been one of the largest players in the global energy market, historically known for its oil and gas operations. However, in recent years, the company has made a concerted effort to diversify its portfolio and shift its focus toward renewable energy. The purchase of VSB, a leading developer of wind and solar energy projects, occurs amid rising European wind investment trends and is a clear reflection of TotalEnergies' commitment to this green energy transition.

VSB, based in Dresden, Germany, specializes in the development, construction, and operation of renewable energy projects, particularly wind and solar power. The company has a significant presence in Europe, with a growing portfolio of projects in countries like Germany, where clean energy accounts for 50% of electricity today, Poland, and the Czech Republic. The acquisition will allow TotalEnergies to bolster its renewable energy capacity, particularly in the wind and solar sectors, which are key components of its long-term sustainability goals.

By acquiring VSB, TotalEnergies is not only increasing its renewable energy output but also gaining access to a highly experienced team with a proven track record in energy project development. This move is expected to expedite TotalEnergies’ renewable energy ambitions, enabling the company to build on VSB’s strong market presence and established partnerships across Europe.

VSB’s Strategic Role in the Energy Transition

VSB’s expertise in the renewable energy sector makes it a valuable addition to TotalEnergies' green energy strategy. The company has been at the forefront of the energy transition in Europe, particularly in wind energy development, as offshore wind is set to become a $1 trillion business over the coming decades. Over the years, VSB has completed numerous large-scale wind projects, including both onshore and offshore installations.

The acquisition also positions TotalEnergies to better compete in the rapidly growing European renewable energy market, including the UK, where offshore wind is powering up alongside strong demand due to increased governmental focus on achieving net-zero emissions by 2050. Germany, in particular, has set ambitious renewable energy targets as part of its Energiewende initiative, which aims to reduce the country’s carbon emissions and increase the share of renewables in its energy mix. By acquiring VSB, TotalEnergies is not only enhancing its capabilities in Germany but also gaining a foothold in other European markets where VSB has operations.

With Europe increasingly shifting toward wind and solar power as part of its decarbonization efforts, including emerging solutions like offshore green hydrogen that complement wind buildouts, VSB’s track record of developing large-scale, sustainable energy projects provides TotalEnergies with a strong competitive edge. The acquisition will further TotalEnergies' position as a leader in the renewable energy space, especially in wind and solar power generation.

Financial and Market Implications

The US$1.65 billion deal marks TotalEnergies' largest renewable energy acquisition in recent years and underscores the growing importance of green energy investments within the company’s broader business strategy. TotalEnergies plans to use this acquisition to scale up its renewable energy assets and move closer to its target of achieving net-zero emissions by 2050. The deal also positions TotalEnergies to capitalize on the expected growth of renewable energy across Europe, particularly in countries with aggressive renewable energy targets and incentives.

The transaction is also expected to boost TotalEnergies’ presence in the global renewable energy market. As the world increasingly turns to wind, solar, and other sustainable energy sources, TotalEnergies is positioning itself to be a major player in the global energy transition. The acquisition of VSB complements TotalEnergies' previous investments in renewable energy and further aligns its portfolio with international sustainability trends.

From a financial standpoint, TotalEnergies’ purchase of VSB reflects the growing trend of large energy companies investing heavily in renewable energy. With wind and solar power becoming more economically competitive with fossil fuels, this investment is seen as a prudent long-term strategy, one that is likely to yield strong returns as demand for clean energy continues to rise.

Looking Ahead: TotalEnergies' Green Transition

TotalEnergies' acquisition of VSB is part of the company’s broader strategy to diversify its energy offerings and shift away from its traditional reliance on oil and gas. The company has already made significant strides in renewable energy, with investments in solar, wind, and battery storage projects across the globe, as developments like France's largest battery storage platform underline this momentum. The VSB acquisition will only accelerate these efforts, positioning TotalEnergies as one of the foremost leaders in the clean energy revolution.

By 2030, TotalEnergies plans to allocate more than 25% of its total capital expenditure to renewable energies and electricity. The company has already set ambitious goals to reduce its carbon footprint and shift its business model to align with the global drive toward sustainability. The integration of VSB into TotalEnergies’ portfolio signals a firm commitment to these goals, ensuring the company remains at the forefront of the energy transition.

In conclusion, TotalEnergies’ purchase of VSB for US$1.65 billion marks a significant milestone in the company’s renewable energy journey. By acquiring a company with deep expertise in wind and solar power development, TotalEnergies is taking decisive steps to strengthen its position in the renewable energy market and further its ambitions of achieving net-zero emissions by 2050. This acquisition will not only enhance the company’s growth prospects but also contribute to the ongoing global shift toward clean, sustainable energy sources.

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Wave Energy Converters can deliver marine power to the grid, with DOE-backed PacWave enabling offshore testing, robust designs, and renewable electricity from oscillating waves to decarbonize coastal communities and replace diesel in remote regions.

Key Points

Wave energy converters are devices that transform waves' oscillatory motion into electricity for the grid or loads.

✅ DOE's PacWave enables full-scale, grid-connected offshore testing.

✅ Multiple designs convert oscillating motion into torque and power.

✅ Ideal for islands, microgrids, and replacing diesel generation.

Waves off the coast of the U.S. could generate 2.64 trillion kilowatt hours of electricity per year — that’s about 64% of last year’s total utility-scale electricity generation in the U.S. We won’t need that much, but one day experts do hope that wave energy will comprise about 10-20% of our electricity mix, alongside other marine energy technologies under development today.

“Wave power is really the last missing piece to help us to transition to 100% renewables, ” said Marcus Lehmann, co-founder and CEO of CalWave Power Technologies, one of a number of promising startups focused on building wave energy converters.

But while scientists have long understood the power of waves, it’s proven difficult to build machines that can harness that energy, due to the violent movement and corrosive nature of the ocean, combined with the complex motion of waves themselves, even as a recent wave and tidal market analysis highlights steady advances.

″Winds and currents, they go in one direction. It’s very easy to spin a turbine or a windmill when you’ve got linear movement. The waves really aren’t linear. They’re oscillating. And so we have to be able to turn this oscillatory energy into some sort of catchable form,” said Burke Hales, professor of cceanography at Oregon State University and chief scientist at PacWave, a Department of Energy-funded wave energy test site off the Oregon Coast. Currently under construction, PacWave is set to become the nation’s first full-scale, grid-connected test facility for these technologies, a milestone that parallels U.K. wind power lessons on scaling new industries, when it comes online in the next few years.

“PacWave really represents for us an opportunity to address one of the most critical barriers to enabling wave energy, and that’s getting devices into the open ocean,” said Jennifer Garson, Director of the Water Power Technologies Office at the U.S. Department of Energy.

At the beginning of the year, the DOE announced $25 million in funding for eight wave energy projects to test their technology at PacWave, as offshore wind forecasts underscore the growing investor interest in ocean-based energy. We spoke with a number of these companies, which all have different approaches to turning the oscillatory motion of the waves into electrical power.

Different approaches
Of the eight projects, Bay Area-based CalWave received the largest amount, $7.5 million. 

″The device we’re testing at PacWave will be a larger version of this,” said Lehmann. The x800, our megawatt-class system, produces enough power to power about 3,000 households.”

CalWave’s device operates completely below the surface of the water, and as waves rise and fall, surge forward and backward, and the water moves in a circular motion, the device moves too. Dampers inside the device slow down that motion and convert it into torque, which drives a generator to produce electricity, a principle mirrored in some wind energy kite systems as they harvest aerodynamic forces.

“And so the waves move the system up and down. And every time it moves down, we can generate power, and then the waves bring it back up. And so that oscillating motion, we can turn into electricity just like a wind turbine,” said Lehmann.

Another approach is being piloted by Seattle-based Oscilla Power, which was awarded $1.8 million from the DOE, and is getting ready to deploy its wave energy converter off the coast of Hawaii, at the U.S. Navy Wave Energy Test site.

Oscilla Power’s device is composed of two parts. One part floats on the surface and moves with the waves in all directions — up and down, side to side and rotationally. This float is connected to a large, ring-shaped structure which hangs below the surface, and is designed to stay relatively steady, much like how underwater kites leverage a stable reference to generate power. The difference in motion between the float and the ring generates force on the connecting lines, which is used to rotate a gearbox to drive a generator.

″The system that we’re deploying in Hawaii is what we call the Triton-C. This is a community-scale system,” said Balky Nair, CEO of Oscilla Power. “It’s about a third of the size of our flagship product. It’s designed to be 100 kilowatt rated, and it’s designed for islands and small communities.”

Nair is excited by wave energy’s potential to generate electricity in remote regions, which currently rely on expensive and polluting diesel imports to meet their energy needs when other renewables aren’t available, and similar tidal energy for remote communities efforts in Canada point to viable models. Before wave energy is adopted at-scale, many believe we’ll see wave energy replacing diesel generators in off-the-grid communities.

A third company, C-Power, based in Charlottesville, Virginia, was awarded more than $4 million to test its grid-scale wave energy converter at PacWave. But first, the company wants to commercialize its smaller scale system, the SeaRAY, which is designed for lower-power applications. 

″Think about sensors in the ocean, research, metocean data gathering, maybe it’s monitoring or inspection,” said C-Power CEO Reenst Lesemann on the initial applications of his device.

The SeaRAY consists of two floats and a central body, the nacelle, which contains the drivetrain. As waves pass by, the floats bob up and down, rotating about the nacelle and turning their own respective gearboxes which power the electric generators.

Eventually, C-Power plans to scale up its SeaRAY so that it’s capable of satellite communications and deep water deployments, before building a larger system, called the StingRAY, for terrestrial electricity generation.

Meanwhile, one Swedish company, Eco Wave Power, is taking another approach completely, eschewing offshore technologies in favor of simpler wave power devices that can be installed on breakwaters, piers, and jetties.

“All the expensive conversion machinery, instead of being inside the floaters like in the competing technologies, is on land just like a regular power station. So basically this enables a very low installation, operation, and maintenance cost,” explained CEO Inna Braverman.

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High-Temperature Superconducting Cables enable lossless, high-voltage, underground transmission for grid modernization, linking renewable energy to cities with liquid nitrogen cooling, boosting efficiency, cutting emissions, reducing land use, and improving resilience against disasters and extreme weather.

Key Points

Liquid-nitrogen-cooled power cables delivering electricity with near-zero losses, lower voltage, and greater resilience.

✅ Near-lossless transmission links renewables to cities efficiently

✅ Operate at lower voltage, reducing substation size and cost

✅ Underground, compact, and resilient to extreme weather events

For most of us, transmitting power is an invisible part of modern life. You flick the switch and the light goes on.

But the way we transport electricity is vital. For us to quit fossil fuels, we will need a better grid, with macrogrid planning connecting renewable energy in the regions with cities.

Electricity grids are big, complex systems. Building new high-voltage transmission lines often spurs backlash from communities, as seen in Hydro-Que9bec power line opposition over aesthetics and land use, worried about the visual impact of the towers. And our 20th century grid loses around 10% of the power generated as heat.

One solution? Use superconducting cables for key sections of the grid. A single 17-centimeter cable can carry the entire output of several nuclear plants. Cities and regions around the world have done this to cut emissions, increase efficiency, protect key infrastructure against disasters and run powerlines underground. As Australia prepares to modernize its grid, it should follow suit with smarter electricity infrastructure initiatives seen elsewhere. It's a once-in-a-generation opportunity.

What's wrong with our tried-and-true technology?
Plenty.

The main advantage of high voltage transmission lines is they're relatively cheap.

But cheap to build comes with hidden costs later. A survey of 140 countries found the electricity currently wasted in transmission accounts for a staggering half-billion tons of carbon dioxide—each year.

These unnecessary emissions are higher than the exhaust from all the world's trucks, or from all the methane burned off at oil rigs.

Inefficient power transmission also means countries have to build extra power plants to compensate for losses on the grid.

Labor has pledged A$20 billion to make the grid ready for clean energy, and international moves such as US-Canada cross-border approvals show the scale of ambition needed. This includes an extra 10,000 kilometers of transmission lines. But what type of lines? At present, the plans are for the conventional high voltage overhead cables you see dotting the countryside.

System planning by Australia's energy market operator shows many grid-modernizing projects will use last century's technologies, the conventional high voltage overhead cables, even as Europe's HVDC expansion gathers pace across its network. If these plans proceed without considering superconductors, it will be a huge missed opportunity.

How could superconducting cables help?
Superconduction is where electrons can flow without resistance or loss. Built into power cables, it holds out the promise of lossless electricity transfer, over both long and short distances. That's important, given Australia's remarkable wind and solar resources are often located far from energy users in the cities.

High voltage superconducting cables would allow us to deliver power with minimal losses from heat or electrical resistance and with footprints at least 100 times smaller than a conventional copper cable for the same power output.

And they are far more resilient to disasters and extreme weather, as they are located underground.

Even more important, a typical superconducting cable can deliver the same or greater power at a much lower voltage than a conventional transmission cable. That means the space needed for transformers and grid connections falls from the size of a large gym to only a double garage.

Bringing these technologies into our power grid offers social, environmental, commercial and efficiency dividends.

Unfortunately, while superconductors are commonplace in Australia's medical community (where they are routinely used in MRI machines and diagnostic instruments) they have not yet found their home in our power sector.

One reason is that superconductors must be cooled to work. But rapid progress in cryogenics means you no longer have to lower their temperature almost to absolute zero (-273℃). Modern "high temperature" superconductors only need to be cooled to -200℃, which can be done with liquid nitrogen—a cheap, readily available substance.

Overseas, however, they are proving themselves daily. Perhaps the most well-known example to date is in Germany's city of Essen. In 2014, engineers installed a 10 kilovolt (kV) superconducting cable in the dense city center. Even though it was only one kilometer long, it avoided the higher cost of building a third substation in an area where there was very limited space for infrastructure. Essen's cable is unobtrusive in a meter-wide easement and only 70cm below ground.

Superconducting cables can be laid underground with a minimal footprint and cost-effectively. They need vastly less land.

A conventional high voltage overhead cable requires an easement of about 130 meters wide, with pylons up to 80 meters high to allow for safety. By contrast, an underground superconducting cable would take up an easement of six meters wide, and up to 2 meters deep.

This has another benefit: overcoming community skepticism. At present, many locals are concerned about the vulnerability of high voltage overhead cables in bushfire-prone and environmentally sensitive regions, as well as the visual impact of the large towers and lines. Communities and farmers in some regions are vocally against plans for new 85-meter high towers and power lines running through or near their land.

Climate extremes, unprecedented windstorms, excessive rainfall and lightning strikes can disrupt power supply networks, as the Victorian town of Moorabool discovered in 2021.

What about cost? This is hard to pin down, as it depends on the scale, nature and complexity of the task. But consider this—the Essen cable cost around $20m in 2014. Replacing the six 500kV towers destroyed by windstorms near Moorabool in January 2020 cost $26 million.

While superconducting cables will cost more up front, you save by avoiding large easements, requiring fewer substations (as the power is at a lower voltage), and streamlining approvals.

Where would superconductors have most effect?
Queensland. The sunshine state is planning four new high-voltage transmission projects, to be built by the mid-2030s. The goal is to link clean energy production in the north of the state with the population centers of the south, similar to sending Canadian hydropower to New York to meet demand.

Right now, there are major congestion issues between southern and central Queensland, and subsea links like Scotland-England renewable corridors highlight how to move power at scale. Strategically locating superconducting cables here would be the best location, serving to future-proof infrastructure, reduce emissions and avoid power loss.

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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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Solar Plus Storage is accelerating across utilities and microgrids, pairing rooftop solar with lithium-ion batteries to enhance grid resilience, reduce peak costs, prevent blackouts, and leverage tax credits amid falling prices and decarbonization goals.

Key Points

Solar Plus Storage combines solar generation with batteries to shift load, boost reliability, and cut energy costs.

✅ Cuts peak demand charges and enhances blackout resilience

✅ Falling battery and solar costs drive nationwide utility adoption

✅ Enables microgrids and grid services like frequency regulation

Todd Karin was prepared when California’s largest utility shut off power to millions of people to avoid the risk of wildfires last month. He’s got rooftop solar panels connected to a single Tesla Powerwall in his rural home near Fairfield, California. “We had backup power the whole time,” Karin says. “We ran the fridge and watched movies.”

Californians worried about an insecure energy future are increasingly looking to this kind of solution. Karin, a 31-year-old postdoctoral fellow at Lawrence Berkeley National Laboratory, spent just under $4,000 for his battery by taking advantage of tax credits. He's also saving money by discharging the battery on weekday evenings, when energy is more expensive during peak demand periods. He expects to save around $1,500 over the 10 years the battery is under warranty.

The economics don’t yet work for every household, but the green-power combo of solar panels plus batteries is popping up on a much bigger scale in some unexpected places. Owners of a rice processing plant in Arkansas are building a system to generate 26 megawatts of solar power and store another 40 MW. The plant will cut its power bill by a third, and owners say they will pass the savings to local rice growers. New York’s JFK Airport is installing solar plus storage to reduce its power load by 10 percent, while Pittsburgh International Airport is building a 20-MW solar and natural gas microgrid to keep it independent from the local utility. Officials at both airports are worried about recent power shutdowns due to weather and overload-related blackouts.

And residents of the tiny northern Missouri town of Green City (pop. 608) are getting 2.5 MW of solar plus four hours of battery storage from the state’s public utility next year. The solar power won’t go directly to townspeople, but instead will back up the town’s substation, reducing the risk of a potential shutdown. It’s part of a $68 million project to improve the reliability of remote substations far from electric generating stations.

“It’s a pretty big deal for us,” says Chad Raley, who manages technology and renewables at Ameren, a Missouri utility that is building three rural solar-plus-storage projects to better manage the flow of electricity across the local grid. “It gives us so much flexibility with renewable generation. We can’t control the sun or clouds or wind, but we can have battery storage.”

The first solar-plus-storage installations started about a decade ago on a small scale in sunny states like California, Hawaii, and Arizona. Now they’re spreading across the country, driven by falling prices of both solar panels and lithium-ion batteries the size of a shipping container imported from both China and South Korea, with wind, solar, and batteries making up most of the utility-scale pipeline nationwide. These countries have ramped up production efficiencies and lowered labor costs, leaving many US manufacturers in the dust. In fact, the price of building a comparable solar-plus-storage generating facility is now cheaper than operating a coal-fired power plant, industry officials say. In certain circumstances, the cost is equal to some natural gas plants.

“This is not just a California, New York, Massachusetts thing,” says Kelly Speakes-Backman, CEO of the Energy Storage Association, an industry group in Washington. She says more than 30 states have renewable storage on the grid. Utilities have proposed and states have approved 7 gigawatts to be installed by 2030, and most new storage will be paired with solar across the US.

Speakes-Backman estimates the unit cost of electricity produced from a solar-plus-storage system will drop 10 to 15 percent each year through 2024, supporting record growth in solar and storage investments. “If you have the option of putting out a polluting or non-polluting generating source at the same price, what are you going to pick?” says Speakes-Backman.

She notes that PJM, a large Mid-Atlantic wholesale grid operator, announced it will deploy battery storage to help smooth out fluctuating power from two wind farms it operates. “When the grid fluctuates, storage can react to it quickly and can level out the supply,” she says. In the Midwest, grid-level battery storage is also being used to absorb extra wind power. Batteries hold onto the wind and put it back onto the grid when people need it.

While the solar-plus-storage trend isn’t yet putting a huge dent in our fossil fuel use, according to Paul Denholm, an energy analyst at the National Renewable Energy Laboratory in Golden, Colorado, it is a good beginning and has the side effect of cutting air pollution. By 2021, solar and other renewable energy sources will overtake coal as a source of energy, and the US is moving toward 30% electricity from wind and solar, according to a new report by the Institute for Energy Economics and Financial Analysis, a nonprofit think tank based in Cleveland.

That’s a glimmer of hope in a somewhat dreary week of news on carbon emissions. A new United Nations report released this week finds that the planet is on track to warm by 3.9 degrees Celsius (7 Fahrenheit) by 2100 unless drastic cuts are made by phasing out gas-powered cars, eliminating new coal-fired power plants, and changing how we grow and manage land, and scientists are working to improve solar and wind power to limit climate change as well.

Energy-related greenhouse gas emissions in the US rose 2.7 percent in 2018 after several years of decline. The Trump administration has rolled back climate policies from the Obama years, including withdrawing from the Paris climate accords.

There may be hope from green power initiatives outside the Beltway, though, and from federal proposals like a tenfold increase in US solar that could remake the electricity system. Arizona plans to boost solar-plus-storage from today’s 6 MW to a whopping 850 MW by 2025, more than the entire capacity of large-scale batteries in the US today. And some folks might be cheering the closing of the West’s biggest coal-fired power plant, the 2.25-gigawatt Navajo Generating Station, in Arizona, which had spewed soot and carbon dioxide over the region for 45 years until last week. The closure might help the planet and clear the hazy smog over the Grand Canyon.

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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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