TVA faces federal scrutiny over climate goals, electricity rates


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TVA Rates and Renewable Energy Scrutiny spotlights electricity rates, distributed energy resources, solar and wind deployment, natural gas plans, grid access charges, energy efficiency cuts, and House oversight of lobbying, FERC inquiries, and least-cost planning.

 

Key Points

A congressional probe into TVA pricing and practices affecting renewables, energy efficiency, and climate goals.

✅ House panel probes TVA rates, DER and solar policies.

✅ Efficiency programs cut; least-cost planning questioned.

✅ Inquiry on lobbying, hidden fees; FERC scrutiny.

 

The Tennessee Valley Authority is facing federal scrutiny about its electricity rates and climate action, amid ongoing debates over network profits in other markets.

Members of the House Committee on Energy and Commerce are “requesting information” from TVA about its ratepayer bills and “out of concern” that TVA is interfering with the deployment of renewable and distributed energy resources, even as companies such as Tesla explore electricity retail to expand customer options.

“The Committee is concerned that TVA’s business practices are inconsistent with these statutory requirements to the disadvantage of TVA’s ratepayers and the environment,” the committee said in a letter to TVA CEO Jeffrey Lyash.

The four committee members — U.S. Reps. Frank Pallone, Jr. (D-NJ), Bobby L. Rush (D-IL), Diana DeGette (D-CO), and Paul Tonko (D-NY) — suggested that Tennessee Valley residents pay too much for electricity despite TVA’s relatively low rates, even as regulators have, in other cases, scrutinized mergers like the Hydro One-Avista deal to safeguard ratepayers, underscoring similar concerns. In 2020, Tennessee residents had electric bills higher than the national average, while low-income residents in Memphis have historically faced one of the highest energy burdens in the U.S.

In 2018, TVA reduced its wholesale rate while adding a grid access charge on local power companies—and interfered with the adoption of solar energy. Internal TVA documents obtained through a Freedom of Information Act request by the Energy and Policy Institute revealed that TVA permitted local power companies to impose new fees on distributed solar generation to “lessen the potential decrease in TVA load that may occur through the adoption of [behind the meter] generation.”

Additionally, the committee said TVA is not prioritizing energy conservation and efficiency or “least-cost planning” that includes renewables, as seen in oversight such as the OEB's Hydro One rates decision emphasizing cost allocation. TVA reduced its energy efficiency programs by nearly two-thirds between 2014 and 2018 and cut its energy efficiency customer incentive programs.

At this time, TVA has not aligned its long-term planning with the Biden administration’s goal to achieve a carbon-free electricity sector by 2035. TVA’s generation mix, which is roughly 60% carbon-free, comprises 39% nuclear, 19% coal, 26% natural gas, 11% hydro, 3% wind and solar, and 1% energy efficiency programs, according to TVA.

The committee is “greatly concerned that TVA has invested comparatively little to date in deploying solar and wind energy, while at the same time considering investments in new natural gas generation.”

TVA has announced plans to shutter the Kingston and Cumberland coal plants and is evaluating whether to replace this generation with natural gas, which is a fossil fuel, while debates over grid privatization raise questions about consumer benefits. TVA’s coal and natural gas plants represent most of the largest sources of greenhouses emissions in Tennessee.

TVA responded with a statement without directly addressing the committee’s concerns. TVA said its “developing and implementing emerging technologies to drive toward net-zero emissions by 2050.”

The final question that the House committee posed is whether TVA is funding any political activity. In 2019, the committee questioned TVA about its membership to the now-disbanded Utility Air Regulatory Group, a coalition that was involved in over 200 lawsuits that primarily fought Clear Air Act regulations.

TVA revealed that it had contributed $7.3 million to the industry lobbying group since 2001. Since TVA doesn’t have shareholders, customers paid for UARG membership fees, echoing findings that deferred utility costs burden customers in other jurisdictions. An Office of the Inspector General investigation couldn’t prove whether TVA’s contributions directly funded litigation because UARG didn’t have a line-by-line accounting of what they did with TVA’s dollars.

The congressional committee questioned whether TVA is still paying for lobbying or litigation that opposes “public health and welfare regulations.”

This last question follows a recent trend of questioning utilities about “hidden fees.” In December, the Federal Energy Regulatory Commission issued a Notice of Inquiry to examine how bills from investor-owned utilities might contain fees that fund political activity, and regulators have penalized firms like NT Power over customer notice practices, highlighting consumer protection. The Center for Biological Diversity filed a petition to protect electric and gas customers of investor-owned utilities from paying these fees, which may be used for lobbying, campaign-related donations and litigation.

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IEC reaches settlement on Palestinian electricity debt

IEC-PETL Electricity Agreement streamlines grid management, debt settlement, and bank guarantees, shifting power supply, transmission, and distribution to PETL via IEC-built sub-stations, bolstering energy cooperation, utility billing, and payment assurance in PA areas.

 

Key Points

A 15-year deal transferring PA grid operations to PETL, settling legacy debt, and securing payments with bank guarantees.

✅ NIS 915 million repaid in 48 installments.

✅ PETL assumes distribution, O&M, and sub-station ownership.

✅ 15-year, NIS 2.8b per year supply and services contract.

 

The Palestinian Authority will pay Israel Electric NIS 915 million and take over management of its grid through Palestinian electricity supplier PETL.

The Israel Electric Corporation (IEC) (TASE: ELEC.B22) and Palestinian electricity supplier PETL have signed a draft commercial agreement under which the Palestinian Authority's (PA) debt of almost NIS 1 billion will be repaid. The agreement also transfers actual management of the supply of electricity to Palestinian customers from IEC to the Palestinian electricity authority, enabling consideration of distributed solutions such as a virtual power plant program in future planning.

Up until now, the IEC was unable to actually collect debts for electricity from Palestinian customers, because the connection with them was through the PA. Responsibility for collection will now be exclusively in Palestinian hands, with the PA providing hundreds of millions of shekels in bank guarantees for future debts. The agreement, which is valid for 15 years, amounts to an estimated NIS 2.8 billion a year, as of now.

IEC will sell electricity and related services to PETL through four high-tension sub-stations built by IEC for PETL and through high and low-tension connection points, similar to large interconnector projects like the Lake Erie Connector, for the purpose of distribution and supply of the electricity by PETL or an entity on its behalf to consumers in PA territory. PETL will have sole operational and maintenance responsibility for distribution and supply and ownership of the four sub-stations.

 

NIS 915 million in 48 payments

According to the IEC announcement, the settlement was reached following negotiations following the signing of an agreement in principle in September 2016 by the minister of finance, the government coordinator of activities in the territories, and the Palestinian minister for civilian affairs. The parties reached commercial understandings yesterday that made possible today's signing of the first commercial document of its kind regulating commercial relations - the sales of electricity - between the parties. The agreement will go into effect after it is approved by the IEC board of directors, the Public Utilities Authority (electricity), reflecting regulatory oversight akin to Ontario industrial electricity pricing consultations, and the IDF Chief Electrical Staff Officer. Representatives of IEC, the Ministry of Finance, the Public Utilities Authority (electricity), the government coordinator of activities in the territories, the civilian authority, the PA government, and PETL took part in the negotiations.

The agreement also settles the PA's historical debt to IEC. The PA will begin payment of NIS 915 million in debt for consumption of electricity before September 2016 to IEC Jerusalem District Ltd. in 48 equal installments after the final signing, as stipulated in the agreement in principle signed by the Israeli government and the PA on September 13, 2016.

The PA's debt for electricity amounted to almost NIS 2 billion in 2016. The initial spadework for the current debt settlement was accomplished in that year, after the parties reached understandings on writing off NIS 500 million of the Palestinian debt. The PA paid NIS 600 million in October 2016, and the remainder will be paid now.

It was also reported that an arrangement of securities and guarantees to ensure payment to IEC under the agreement had been settled, including the past debt. IEC will obtain a bank guarantee and a PA guarantee, in addition to the existing collection mechanisms at the company's disposal.

Minister of Finance Moshe Kahlon said, "Signing the commercial agreement is a historic step completing the agreement signed by the governments in September 2016. Strengthening economic cooperation between Israel and the PA is above all an Israeli security interest. The agreement will ensure future payments to the IEC and reinforce its financial position. I congratulate the negotiating teams for the completion of their task."

Minister of National Infrastructure, Energy, and Water Resources Dr. Yuval Steinitz said, "In my meeting last year with Palestinian Prime Minister Rami Hamdallah in Jenin, we agreed that it was necessary to settle the debt and formalize relations between IEC and the PA. The settlement signed today is a breakthrough, both in the measures for payment of the Palestinian debt to IEC and Israel and in arranging future relations to prevent more debts from emerging in the future. With the signing of the agreement, we will be able to make progress with the Palestinians in developing a modern electrical grid, aligning with regional initiatives like the Cyprus electricity highway, according to the model of the sub-station we inaugurated in Jenin."

IEC chairperson Yiftah Ron Tal said, "This is a historic event. In this agreement, IEC is correcting for the first time a historical distortion of accumulated debt without guarantees, ability to collect it, or control over the amount of debt. This anchor agreement not only constitutes an unprecedented financial achievement; it also constitutes an important milestone in regulating electricity commercial relations between the Israeli and Palestinian electric companies, comparable to cross-border efforts such as the Ireland-France interconnector in Europe."

 

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BloombergNEF: World offshore wind costs 'drop 32% per cent'

Global Renewable LCOE Trends reveal offshore wind costs down 32%, with 10MW turbines, lower CAPEX and OPEX, and parity for solar PV and onshore wind in Europe, China, and California, per BloombergNEF analysis.

 

Key Points

Benchmarks showing falling LCOE for offshore wind, onshore wind, and solar PV, driven by larger turbines and lower CAPEX

✅ Offshore wind LCOE $78/MWh; $53-64/MWh in DK/NL excl. transmission

✅ Onshore wind $47/MWh; solar PV $51/MWh, best $26-36/MWh

✅ Cost drivers: 10MW turbines, lower CAPEX/OPEX, weak China demand

 

World offshore wind costs have fallen 32% from just a year ago and 12% compared with the first half of 2019, according to a BNEF long-term outlook from BloombergNEF.

In its latest Levelized Cost of Electricity (LCOE) Update, BloombergNEF said its current global benchmark LCOE estimate for offshore wind is $78 a megawatt-hour.

“New offshore wind projects throughout Europe, including the UK's build-out, now deploy turbines with power ratings up to 10MW, unlocking CAPEX and OPEX savings,” BloombergNEF said.

In Denmark and the Netherlands, it expects the most recent projects financed to achieve $53-64/MWh excluding transmission.

New solar and onshore wind projects have reached parity with average wholesale power prices in California and parts of Europe, while in China levelised costs are below the benchmark average regulated coal price, according to BloombergNEF.

The company's global benchmark levelized cost figures for onshore wind and PV projects financed in the last six months are at $47 and $51 a megawatt-hours, underscoring that renewables are now the cheapest new electricity option in many regions, down 6% and 11% respectively compared with the first half of 2019.

BloombergNEF said for wind this is mainly down to a fall in the price of turbines – 7% lower on average globally compared with the end of 2018.

In China, the world’s largest solar market, the CAPEX of utility-scale PV plants has dropped 11% in the last six months, reaching $0.57m per MW.

“Weak demand for new plants in China has left developers and engineering, procurement and construction firms eager for business, and this has put pressure on CAPEX,” BloombergNEF said.

It added that estimates of the cheapest PV projects financed recently – in India, Chile and Australia – will be able to achieve an LCOE of $27-36/MWh, assuming competitive returns for their equity investors.

Best-in-class onshore wind farms in Brazil, India, Mexico and Texas can reach levelized costs as low as $26-31/MWh already, the research said.

Programs such as the World Bank wind program are helping developing countries accelerate wind deployment as costs continue to drop.

BloombergNEF associate in the energy economics team Tifenn Brandily said: “This is a three- stage process. In phase one, new solar and wind get cheaper than new gas and coal plants on a cost-of- energy basis.

“In phase two, renewables reach parity with power prices. In phase three, they become even cheaper than running existing thermal plants.

“Our analysis shows that phase one has now been reached for two-thirds of the global population.

“Phase two started with California, China and parts of Europe. We expect phase three to be reached on a global scale by 2030.

“As this all plays out, thermal power plants will increasingly be relegated to a balancing role, looking for opportunities to generate when the sun doesn’t shine or the wind doesn’t blow.”

 

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Oil crash only a foretaste of what awaits energy industry

Oil and Gas Profitability Decline reflects shale-driven oversupply, OPEC-Russia dynamics, LNG exports, renewables growth, and weak demand, signaling compressed margins for producers, stressed petrodollar budgets, and shifting energy markets post-Covid.

 

Key Points

A sustained squeeze on hydrocarbon margins from agile shale supply, weaker OPEC leverage, and expanding renewables.

✅ Shale responsiveness caps prices and erodes industry rents

✅ OPEC-Russia cuts face limited impact versus US supply

✅ Renewables and EVs slow long-term oil and gas demand

 

The oil-price crash of March 2020 will probably not last long. As in 2014, when the oil price dropped below $50 from $110 in a few weeks, this one will trigger a temporary collapse of the US shale industry. Unless the coronavirus outbreak causes Armageddon, cheap oil will also support policymakers’ efforts to help the global economy.

But there will be at least one important and lasting difference this time round — and it has major market and geopolitical implications.

The oil price crash is a foretaste of where the whole energy sector was going anyway — and that is down.

It may not look that way at first. Saudi Arabia will soon realise, as it did in 2015, that its lethal decision to pump more oil is not only killing US shale but its public finances as well. Riyadh will soon knock on Moscow’s door again. Once American shale supplies collapse, Russia will resume co-operation with Saudi Arabia.

With the world economy recovering from the Covid-19 crisis by then, and with electricity demand during COVID-19 shifting, moderate supply cuts by both countries will accelerate oil market recovery. In time, US shale producers will return too.

Yet this inevitable bounceback should not distract from two fundamental factors that were already remaking oil and gas markets. First, the shale revolution has fundamentally eroded industry profitability. Second, the renewables’ revolution will continue to depress growth in demand.

The combined result has put the profitability of the entire global hydrocarbon industry under pressure. That means fewer petrodollars to support oil-producing countries’ national budgets, including Canada's oil sector exposures. It also means less profitable oil companies, which traditionally make up a large segment of stock markets, an important component of so many western pension funds.

Start with the first factor to see why this is so. Historically, the geological advantages that made oil from countries such as Saudi Arabia so cheap to produce were unique. Because oil and gas were produced at costs far below the market price, the excess profits, or “rent”, enjoyed by the industry were very large.

Furthermore, collusion among low-cost producers has been a winning strategy. The loss of market share through output cuts was more than compensated by immediately higher prices. It was the raison d’être of Opec.

The US shale revolution changed all this, exposing the limits of U.S. energy dominance narratives. A large oil-producing region emerged with a remarkable ability to respond quickly to price changes and shrink its costs over time. Cutting back cheap Opec oil now only increases US supplies, with little effect on world prices.

That is why Russia refused to cut production this month. Even if its cuts did boost world prices — doubtful given the coronavirus outbreak’s huge shock to demand — that would slow the shrinkage of US shale that Moscow wants.

Shale has affected the natural gas industry even more. Exports of US liquefied natural gas now put an effective ceiling on global prices, and debates over a clean electricity push have intensified when gas prices spike.

On top of all this, there is also the renewables’ revolution, though a green revolution has not been guaranteed in the near term. Around the world, wind and solar have become ever-cheaper options to generate electricity. Storage costs have also dropped and network management improved. Even in the US, renewables are displacing coal and gas. Electrification of vehicle fleets will damp demand further, as U.S. electricity, gas, and EVs face evolving pressures.

Eliminating fossil fuel consumption completely would require sustained and costly government intervention, and reliability challenges such as coal and nuclear disruptions add to the complexity. That is far from certain. Meanwhile, though, market forces are depressing the sector’s usual profitability.

The end of oil and gas is not immediately around the corner. Still, the end of hydrocarbons as a lucrative industry is a distinct possibility. We are seeing that in dramatic form in the current oil price crash. But this collapse is merely a message from the future.

 

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Are major changes coming to your electric bill?

California Income-Based Electricity Rates propose a fixed monthly fee set by income as utilities and the CPUC weigh progressive pricing, aiming to cut low-income bills while PG&E, SCE, and SDG&E retain usage-based charges.

 

Key Points

CPUC plan adds income-tiered fixed fees to lower low-income bills while keeping per-kWh usage charges.

✅ Adds fixed monthly fees by income to complement per-kWh charges

✅ Cuts bills for low-income households; higher earners pay more

✅ Utilities say revenue neutral; conservation signals preserved

 

California’s electric bills — already some of the highest in the nation — are rising as electricity prices soar across the state, but regulators are debating a new plan to charge customers based on their income level. 

Typically what you pay for electricity depends on how much you use. But the state’s three largest electric utilities — Southern California Edison Company, Pacific Gas and Electric Company and San Diego Gas & Electric Company — have proposed a plan to charge customers not just for how much energy they use, but also based on their household income, moving toward income-based flat-fee utility bills over time. Their proposal is one of several state regulators received designed to accommodate a new law to make energy less costly for California’s lowest-income customers.

Some state Republican lawmakers are warning the changes could produce unintended results, such as weakening incentives to conserve electricity or raising costs for customers using solar energy, and some have introduced a plan to overturn the charges in the Legislature.

But the utility companies say the measure would reduce electricity bills for the lowest income customers. Those residents would save about $300 per year, utilities estimate.

California households earning more than $180,000 a year would end up paying an average of $500 more a year on their electricity bills, according to the proposal from utility companies. 

The California Public Utilities Commission’s deadline for deciding on the suggested changes is July 1, 2024, as regulators face calls for action from consumers and advocates. The proposals come at a time when many moderate and low-income families are being priced out of California by rising housing costs.  

Who wants to change the fee structure?
Lawmakers passed and Gov. Gavin Newsom signed a comprehensive energy bill last summer that mandates restructuring electricity pricing across the state. 

The Legislature passed the measure in a “trailer-bill” process that limited deliberation. Included in the 21,000-word law are a few sentences requiring the public utilities commission to establish a “fixed monthly fee” based on each customer’s household income. 

A similar idea was first proposed in 2021 by researchers at UC Berkeley and the nonprofit thinktank Next 10. Their main recommendation was to split utility costs into two buckets. Fixed charges, which everyone has to pay just to be connected to the energy grid, would be based on income levels. Variable charges would depend on how much electricity you use.

Utilities say that part of customers’ bills still will be based on usage, but the other portion will reduce costs for lower- and middle-income customers, who “pay a greater percentage of their income towards their electricity bill relative to higher income customers,” the utilities argued in a recent filing. 

They said the current billing system is unjust, regressive and fails to recognize differences in energy usage among households,

“When we were putting together the reform proposal, front and center in our mind were customers who live paycheck to paycheck, who struggle to pay for essentials such as energy, housing and food,” Caroline Winn, CEO of San Diego Gas & Electric in a statement. 

The utilities say in their proposal that the changes likely would not reduce or increase their revenues.

James Sallee, an associate professor at UC Berkeley, said the utilities’ prior system of billing customers mostly by measuring their electric use to pay for what are essentially fixed costs for power is inefficient and regressive. 

The proposed changes “will shift the burden, on average, to a more progressive system that recovers more from higher income households and less from lower income households,” he said.

 

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Advocates call for change after $2.9 million surplus revealed for BC Hydro fund

BC Hydro Customer Crisis Fund Surplus highlights unused grants, pilot program imbalance, and calls to reduce fees or expand eligibility. Ratepayers, regulators, and social agencies urge awareness, rebates, and aid for overdue electricity bills.

 

Key Points

A funding carryover from BC Hydro's crisis grants, sparking debate over fee reductions or more aid eligibility.

✅ $2.9M surplus from 25-cent monthly customer fee

✅ Only 2,250 grants issued; awareness and eligibility questioned

✅ Regulator may refund balance or adjust program design

 

BC Hydro is sitting on a surplus of about $2.9 million in its customer crisis fund, even as BC Hydro rates rise 3% across the province, leading to calls for the utility to reduce its take from the average customer or provide more money to those in need.

B.C. Liberal Energy Critic Greg Kyllo said if the imbalance continues in the year-old pilot program, amid a provincial rate freeze announced by the province, it’s time to cut the monthly 25 cent fee in half.

"If the grant requirement or the need in the province is going to remain where it is, they should look at rolling back the contribution level in the fund," he told CTV News Vancouver from Salmon Arm.

But social agencies who were part of the consultation around the fund in the beginning said it’s more likely that people in need don’t know about the fund and more time is necessary to get the word out.

"If they collect the money, then the program’s got to change to make sure more people are able to be helped," said Gudrun Langolf of the Council of Senior Citizens Organizations of BC.

The customer crisis fund was started in spring 2018 to give people short-term relief when they can’t pay their electricity bills, especially as a $2 monthly hike pressures household budgets. Customers can apply to get a grant of up to $500 to keep the lights on, and up to $600 if electricity heats their homes.

The public utility took in about 25 cents per customer per month which added up to a revenue of $4.5 million in the year since the program started, BC Hydro confirmed to CTV News.

But the agency only gave out 2,250 grants totalling $850,000.

Administration costs added up around $750,000 – leaving the $2.9 million remaining.

The news will come as a welcome relief to those who suddenly struggle to pay their hydro bills, particularly as Alberta ratepayers are on the hook under a utility deferral program elsewhere in Canada.

Some people who come into Disability Alliance B.C. are often anxious and emotional when they’re suddenly unable to pay their bills, said Shar Saremi, an advocate there.

"I’ve had people crying. I’ve had people who have experienced a loss in the family," she said. "A lot of the time people are stressed out, anxious, really upset. They are looking for assistance, and they aren’t sure what is available for them."

She said people are only eligible if their bills are under $1,000, which could be cutting out the people who are most in need. And because the program is in its first year, it could be undersubscribed, she said.

"A lot of people don’t know about the program, don’t know how to apply, or what kind of assistance is out there," Saremi said.

The fund was established thanks to an order from the B.C. Utilities Commission, the utilities regulator in the province.

The pilot program is going to be examined by the regulator at the end of its first year.

"Any remaining balance in the account at the end of the pilot would be returned to residential ratepayers," says a BCUC fact sheet, as BC Hydro rates are set to rise 3.75% over two years. The decision on exactly what to do with the money hasn’t yet been made.

In Manitoba, a similar program is by donation, and in Newfoundland and Labrador a lump-sum credit was offered to bill payers in a separate initiative. That program raised about $200,000 from customers and $60,000 in other income. It spent $199,000 on grants to applicants, but lost about $20,000 a year.

In Ontario, private utilities are expected to raise 0.12 per cent of their revenue, and Hydro One reconnections have highlighted the stakes for nonpayment there. Across the province, those utilities gave out about $7.3 million in grants. Any unused funds in one year are rolled over to the following year.

 

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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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