Ameren pilot project explores converting hog manure gas to electricity

China Solar Grid Parity signals unsubsidized industrial and commercial PV, rooftop solar, and feed-in tariff guarantees competing with grid electricity and coal power prices, driven by cost declines, policy reform, and technology advances.

Key Points

Point where PV in China meets or beats grid electricity, enabling unsubsidized industrial and commercial solar.

✅ City-level analysis shows cheaper PV than grid in 344 cities.

✅ 22% can beat coal power prices without subsidies.

✅ Soft-cost, permitting, and finance reforms speed uptake.

Solar power has become cheaper than grid electricity across China, a development that could boost the prospects of industrial and commercial solar, according to a new study.

Projects in every city analysed by the researchers could be built today without subsidy, at lower prices than those supplied by the grid, and around a fifth could also compete with the nation’s coal electricity prices.

They say grid parity – the “tipping point” at which solar generation costs the same as electricity from the grid – represents a key stage in the expansion of renewable energy sources.

While previous studies of nations such as Germany, where solar-plus-storage costs are already undercutting conventional power, and the US have concluded that solar could achieve grid parity by 2020 in most developed countries, some have suggested China would have to wait decades.

However, the new paper published in Nature Energy concludes a combination of technological advances, cost declines and government support has helped make grid parity a reality in Chinese today.

Despite these results, grid parity may not drive a surge in the uptake of solar, a leading analyst tells Carbon Brief.

Competitive pricing

China’s solar industry has rapidly expanded from a small, rural program in the 1990s to the largest in the world, with record 2016 solar growth underscoring the trend. It is both the biggest generator of solar power and the biggest installer of solar panels.

The installed capacity of solar panels in China in 2018 amounted to more than a third of the global total, with the country accounting for half the world’s solar additions that year.

Since 2000, the Chinese government has unveiled over 100 policies supporting the PV industry, and technological progress has helped make solar power less expensive. This has led to the cost of electricity from solar power dropping, as demonstrated in the chart below.

In their paper, Prof Jinyue Yan of Sweden’s Royal Institute of Technology and his colleagues explain that this “stunning” performance has been accelerated by government subsidies, but has also seen China overinvesting in what some describe as a clean energy's dirty secret of “redundant construction and overcapacity”. The authors write:

“Recently, the Chinese government has been trying to lead the PV industry onto a more sustainable and efficient development track by tightening incentive policies with China’s 531 New Policy.”

The researchers say the subsidy cuts under this policy in 2018 were a signal that the government wanted to make the industry less dependent on state support and shift its focus from scale to quality.

This, they say, has “brought the industry to a crossroads”, with discussions taking place in China about when solar electricity generation could achieve grid parity.

In their analysis, Yan and his team examined the prospects for building industrial and commercial solar projects without state support in 344 cities across China, attempting to gauge where or whether grid parity could be achieved.

The team estimated the total lifetime price of solar energy systems in all of these cities, taking into account net costs and profits, including project investments, electricity output and trading prices.

Besides establishing that installations in every city tested could supply cheaper electricity than the grid, they also compared solar to the price of coal-generated power. They found that 22% of the cities could build solar systems capable of producing electricity at cheaper prices than coal.

Embracing solar

Declining costs of solar technology, particularly crystalline silicon modules, mean the trend in China is also playing out around the world, with offshore wind cost declines reinforcing the shift. In May, the International Renewable Energy Agency (IRENA) said that by the beginning of next year, grid parity could become the global norm for the solar industry, and shifting price dynamics in Northern Europe illustrate the market impact.

Kingsmill Bond, an energy strategist at Carbon Tracker, says this is the first in-depth study he has seen looking at city-level solar costs in China, and is encouraged by this indication of solar becoming ever-more competitive, as seen in Germany's recent solar boost during the energy crisis. He tells Carbon Brief:

“The conclusion that industrial and commercial solar is cheaper than grid electricity means that the workshop of the world can embrace solar. Without subsidy and its distorting impacts, and driven by commercial gain.”

On the other hand, Jenny Chase, head of solar analysis at BloombergNEF, says the findings revealed by Yan and his team are “fairly old news” as the competitive price of rooftop solar in China has been known about for at least a year.

She notes that this does not mean there has been a huge accompanying rollout of industrial and commercial solar, and says this is partly because of the long-term thinking required for investment to be seen as worthwhile.

The lifetime of a PV system tends to be around two decades, whereas the average lifespan of a Chinese company is only around eight years, according to Chase. Furthermore, there is an even simpler explanation, as she explains to Carbon Brief:

“There’s also the fact that companies just can’t be bothered a lot of the time – there are roofs all over Europe where solar could probably save money, but people are not jumping to do it.”

According to Chase, a “much more exciting” development came earlier this year, when the Chinese government developed a policy for “subsidy-free solar”.

This involved guaranteeing the current coal-fired power price to solar plants for 20 years, creating what is essentially a low feed-in tariff and leading to what she describes as “a lot of nice, low-risk projects”.

As for the beneficial effects of grid parity, based on how things have played out in countries where it has already been achieved, Chase says it does not necessarily mean a significant uptake of solar power will follow:

“Grid parity solar is never as popular as subsidised solar, and ironically you don’t generally have a rush to build grid parity solar because you may as well wait until next year and get cheaper solar.”

Policy proposals

In their paper, Yan and his team lay out policy changes they think would help provide an economic incentive, in combination with grid parity, to encourage the uptake of solar power systems.

Technology costs may have fallen for smaller solar projects of the type being deployed on the rooftops of businesses, but they note that the so-called “soft costs” – including installation and maintenance – tend to be “very impactful”.

Specifically, they say aspects such as financing, land acquisition and grid accommodation, which make up over half the total cost, could be cut down:

“Labour costs are not significant [in China] because of the relatively low wages of direct labour and related installation overhead. Customer acquisition has largely been achieved in China by the mature market, with customers’ familiarity with PV systems, and with the perception that PV systems are a reliable technology. However, policymakers should consider strengthening the targeted policies on the following soft costs.”

Among the measures they suggest are new financing schemes, an effort to “streamline” the complicated procedures and taxes involved, and more geographically targeted government policies, alongside innovations like peer-to-peer energy sharing that can improve utilization.

As their analysis showed the price of solar electricity had fallen further in some cities than others, the researchers recommend targeting future subsidies at the cities that are performing less well – keeping costs to a minimum while still providing support when it is most needed.

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U.S. Power Grid D+ Rating underscores aging infrastructure, rising outages, cyber threats, EMP and solar flare risks, strained transmission lines, vulnerable transformers, and slow permitting, amplifying reliability concerns and resilience needs across national energy systems.

Key Points

ASCE's D+ grade flags aging infrastructure, rising outages, and cyber, EMP, and weather risks needing investment.

✅ Major outages rising; weather remains top disruption driver.

✅ Aging transformers, transmission lines, limited maintenance.

✅ Cybersecurity gaps via smart grid, EV charging, SCADA.

The U.S. power grid just received its “grade card” from the American Society of Civil Engineers (ASCE) and it barely passed.

The overall rating of our antiquated electrical system was a D+. Major power outages in the United States, including widespread blackouts, have grown from 76 in 2007 to 307 in 2011, according to the latest available statistics. The major outage figures do not take into account all of the smaller outages which routinely occur due to seasonal storms.

The American Society of Civil Engineers power grid grade card rating means the energy infrastructure is in “poor to fair condition and mostly below standard, with many elements approaching the end of their service life.” It further means a “large portion of the system exhibits significant deterioration” with a “strong risk of failure.”

Such a designation is not reassuring and validates those who purchased solar generators over the past several years.

#google#

The vulnerable state of the power grid gets very little play by mainstream media outlets. Concerns about a solar flare or an electromagnetic pulse (EMP) attack instantly sending us back to an 1800s existence are legitimate, but it may not take such an extreme act to render the power grid a useless tangle of wires. The majority of the United States’ infrastructure and public systems evaluated by the ASCE earned a “D” rating. A “C” ranking (public parks, rail and bridges) was the highest grade earned. It would take a total of $3.6 trillion in investments by 2020 to fix everything, the report card stated. To put that number in perspective, the federal government’s budget for all of 2012 was slightly more, $3.7 trillion.

“America relies on an aging electrical grid and pipeline distribution systems, some of which originated in the 1880s,” the report read. “Investment in power transmission has increased since 2005, but ongoing permitting issues, weather events, including summer blackouts that strain local systems, and limited maintenance have contributed to an increasing number of failures and power interruptions. While demand for electricity has remained level, the availability of energy in the form of electricity, natural gas, and oil will become a greater challenge after 2020 as the population increases. Although about 17,000 miles of additional high-voltage transmission lines and significant oil and gas pipelines are planned over the next five years, permitting and siting issues threaten their completion. The electric grid in the United States consists of a system of interconnected power generation, transmission facilities, and distribution facilities.”

Harness the power of the sun when the power goes out…

There are approximately 400,000 miles of electrical transmission lines throughout the United States, and thousands of power generating plants dot the landscape. The ASCE report card also stated that new gas-fired and renewable generation issues increase the need to add new transmission lines. Antiquated power grid equipment has reportedly prompted even more “intermittent” power outages in recent years.

The American Society of Civil Engineers accurately notes that the power grid is more vulnerable to cyber attacks than ever before, including Russian intrusions documented in recent years, and it cites the aging electrical system as the primary culprit. Although the decades-old transformers and other equipment necessary to keep power flowing around America are a major factor in the enhanced vulnerability of the power grid, moving towards a “smart grid” system is not the answer. As previously reported by Off The Grid News, smart grid systems and even electric car charging stations make the power grid more accessible to cyber hackers. During the Hack in the Box Conference in Amsterdam, HP ArcSight Product Manager Ofer Sheaf stated that electric car charging stations are in essence a computer on the street. The roadway fueling stations are linked to the power grid electrical system. If cyber hackers garner access to the power grid via the charging stations, they could stop the flow of power to a specific area or alter energy distribution levels and overload the system.

While a relatively small number of electric car charging stations exist in America now, that soon will change. Ongoing efforts by both federal and state governments to reduce our reliance on fossil fuels have resulted in grants and privately funded vehicle charging station projects. New York Governor Andrew Cuomo in April announced plans to build 360 such electrical stations in his state. A total of 3,000 car charging stations are in the works statewide and are slated for completion over the next five years.

SHIELD ActWeather-related events were the primary cause of power outages from 2007 to 2012, according to the infrastructure report card. Power grid reliability issues are emerging as the greatest threat to the electrical system, with rising attacks on substations compounding the risks. The ASCE grade card also notes that retiring and rotating in “new energy sources” is a “complex” process. Like most items we routinely purchase in our daily lives, many of the components needed to make the power grid functional are not manufactured in the United States.

The SHIELD Act is the first real piece of federal legislation in years drafted to address power grid vulnerabilities. While the single bill will not fix all of the electrical system issues, it is a big step in the right direction – if it ever makes it out of committee. Replacing aging transformers, encasing them in a high-tech version of a Faraday cage, and stockpiling extra units so instant repairs are possible would help preserve one of the nation’s most critical and life-saving pieces of infrastructure after a weather-related incident or man-made disaster.

“Geomagnetic storm environments can develop instantaneously over large geographic footprints,” solar geomagnetic researcher John Kappenman said about the fragile state of the power grid. He was quoted in an Oak Ridge National Laboratory report. “They have the ability to essentially blanket the continent with an intense threat environment and … produce significant collateral damage to critical infrastructures. In contrast to well-conceived design standards that have been successfully applied for more conventional threats, no comprehensive design criteria have ever been considered to check the impact of the geomagnetic storm environments. The design actions that have occurred over many decades have greatly escalated the dangers posed by these storm threats for this critical infrastructure.”

The power grid has morphed in size tenfold during the past 50 years. While solar flares, cyber attacks, and an EMP are perhaps the most extensive and frightening threats to the electrical system, the infrastructure could just as easily fail in large portions due to weather-related events exacerbated by climate change across regions. The power grid is basically a ticking time bomb which will spawn civil unrest, lack of food, clean water, and a multitude of fires if it does go down.

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SDG7 Energy Progress Report assesses global energy access, renewables, clean cooking, and efficiency, citing COVID-19 setbacks, financing needs, and UN-led action by IEA, IRENA, World Bank, and WHO to advance sustainable, reliable, affordable power.

Key Points

A joint study by IEA, IRENA, UN, World Bank, and WHO tracking energy access, renewables, efficiency, and financing gaps.

✅ Tracks disparities in electricity access amid COVID-19 setbacks

✅ Emphasizes renewables, clean cooking, and efficiency targets

✅ Calls for scaled public finance to unlock private investment

The seventh Sustainable Development Goal (SDG), SDG7, aims to ensure access to affordable, reliable, sustainable and modern energy for all.  

However, those nations which remain most off the grid, are set to enter 2030 without meeting this goal unless efforts are significantly scaled up, warns the new study entitled Tracking SDG 7: The Energy Progress Report, published by the International Energy Agency (IAE), International Renewable Energy Agency (IRENA), UN Department of Economic and Social Affairs (UN DESA), World Bank, and World Health Organization (WHO). 

“Moving towards scaling up clean and sustainable energy is key to protect human health and to promote healthier populations, particularly in remote and rural areas”, said Maria Neira, WHO Director of the Department of Environment, Climate Change and Health.  

COVID setbacks 
The report outlines significant but unequal progress on SDG7, noting that while more than one billion people globally gained access to electricity over the last decade, COVID’s financial impact so far, has made basic electricity services unaffordable for 30 million others, mostly in Africa, intensifying calls for funding for access to electricity across the region.  

“The Tracking SDG7 report shows that 90 per cent of the global population now has access to electricity, but disparities exacerbated by the pandemic, if left unaddressed, may keep the sustainable energy goal out of reach, jeopardizing other SDGs and the Paris Agreement’s objectives”, said Mari Pangestu, Managing Director of Development Policy and Partnerships at the World Bank. 

While the report also finds that the COVID-19 pandemic has reversed some progress, Stefan Schweinfest, DESA’s Director of the Statistics Division, pointed out that this has presented “opportunities to integrate SDG 7-related policies in recovery packages and thus to scale up sustainable development”. 

Modernizing renewables 
The publication examines ways to bridge gaps to reach SDG7, chief among them the scaling up of renewables, as outlined in the IRENA renewables report, which have proven more resilient than other parts of the energy sector during the COVID-19 crisis. 

While sub-Saharan Africa, facing a major electricity challenge, has the largest share of renewable sources in its energy supply, they are far from “clean” – 85 per cent use biomass, such as burning wood, crops and manure. 

“On a global path to achieving net-zero emissions by 2050, we can reach key sustainable energy targets by 2030, aligning with renewable ambition in NDCs as we expand renewables in all sectors and increase energy efficiency”, said IAE Executive Director, Fatih Birol.  

And although the private sector continues to source clean energy investments, the public sector remains a major financing source, central in leveraging private capital, particularly in developing countries, including efforts to put Africa on a path to universal electricity access, and in a post-COVID context. 

Amid the COVID-19 pandemic, which has dramatically increased investors’ risk perception and shifting priorities in developing countries, international financial flows in public investment terms, are more critical than ever to underpin a green energy recovery that can leverage the investment levels needed to reach SDG 7, according to the report.   

“Greater efforts to mobilize and scale up investment are essential to ensure that energy access progress continues in developing economies”, he added.  

Scaling up clean and sustainable energy is key to protect human health -- WHO's Maria Neira

Other key targets 
The report highlighted other crucial actions needed on clean cooking, energy efficiency and international financial flows. 

A healthy and green recovery from COVID-19 includes the importance of ensuring a quick transition to clean and sustainable energy”, said Dr. Neira. 

Feeding into autumn summit 
This seventh edition of the report formerly known as the Global Tracking Framework comes at a crucial time as Governments and others are gearing up for the UN High-level Dialogue on Energy in September 2021 aimed to examine what is needed to achieve SDG7 by 2030, including discussions on fossil fuel phase-out strategies, and mobilize voluntary commitments and actions through Energy Compacts.  

The report will inform the summit-level meeting on the current progress towards SDG 7, “four decades after the last high-level event dedicated to energy under the auspices of UN General Assembly”, said Mr. Schweinfest. 

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Automaker EV Fast-Charging Network will deploy 30,000 DC fast chargers across US and Canada, supporting CCS and NACS, integrating Tesla compatibility, easing range anxiety, and expanding highway and urban charging infrastructure with amenities and uptime.

Key Points

A $1B joint venture by seven automakers to build 30,000 DC fast chargers with CCS and NACS across the US and Canada.

✅ 30,000 DC fast chargers by 2030 across US and Canada

✅ Supports CCS and NACS; Tesla compatibility planned

✅ Launching mid-2024; focus on highways, urban hubs, amenities

Seven major automakers announced a plan on Wednesday to nearly double the number of fast chargers in the United States in an effort to address one of the main reasons that people hesitate to buy electric cars, even as the age of electric cars accelerates.

The carmakers — BMW Group, General Motors, Honda, Hyundai, Kia, Mercedes-Benz Group and Stellantis — will initially invest at least $1 billion in a joint venture that will build 30,000 charging ports on major highways and other locations in the United States and Canada.

The United States and Canada have about 36,000 fast chargers — those that can replenish a drained battery in 30 minutes or less. In some sparsely populated areas, such chargers can be hundreds of miles apart. Surveys show that fear about not being able to find a charger during longer journeys is a major reason that some car buyers are reluctant to buy electric vehicles.

Sales of electric vehicles have risen quickly in the United States as the market hits an inflection point, but there are signs that demand is softening. As a result, Tesla, Ford and other carmakers have cut prices in recent months and are offering incentives. Popular models that had long waiting lists last year are now available in a few days or weeks.

Major carmakers are investing billions of dollars to manufacture electric vehicles and batteries and to establish supplier networks. Having staked their futures on the technology, they have a strong incentive to ensure that electric vehicles catch on with car buyers, even as gas-electric hybrids help bridge the transition.

The chargers installed by the joint venture will have plugs designed for the connections used by most carmakers other than Tesla, as well as the standard developed by Tesla, amid fights for control over charging, that Ford, G.M. and other companies have said they intend to switch to in 2025.

“The better experience people have, the faster E.V. adoption will grow,” Mary T. Barra, the chief executive of General Motors, said in a statement.

The seven automakers plan to formalize the joint venture and announce its name by the end of the year, Chris Martin, a Honda spokesman, said. The first chargers will begin operating around the middle of 2024, he said, with all 30,000 in place by the end of the decade.

The joint venture is open to adding other partners, he said. Among major automakers, Ford was a notable absence from the announcement on Wednesday. The company said in a statement on Wednesday that it would continue to iThe partnership also does not include Volkswagen. The company is a majority shareholder of Electrify America, one of the largest fast-charging providers.

Tesla accounts for more than half the fast chargers in the United States and has said it will open its networks to other car brands, though, so far, it has only made fewer than 100 ports available. Owners of Ford and G.M. vehicles, among others, will be able to connect to 12,000 Tesla fast chargers using an adapter beginning next year. In 2025, Ford and G.M. plan to make models designed to take the Tesla plug without an adapter.

The decision by the seven carmakers to form the joint venture is an indication that they do not intend to rely solely on Tesla, which dominates sales of electric vehicles, for charging.

The chargers being built by the joint venture will be concentrated in urban areas and along major highways, especially those used most heavily by vacationers and other travelers, the companies said in a joint statement. Charging stations will be close to restrooms, restaurants and other amenities. The partners said they would try to take advantage of federal and state funds available for charging infrastructure amid questions about whether the U.S. has the power to charge it at scale.

Most electric vehicle owners charge at home and rarely need to use public chargers. Home chargers typically replenish batteries overnight. Most public chargers, about 125,000 in the United States and Canada, also operate relatively slowly — taking four to 10 hours to do the job.nvest in its own network, which allows Ford owners to charge from a variety of providers with one mobile phone app.

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Clean Energy Tax Incentives could expand under Democratic proposals, including ITC, PTC, and EV tax credits, boosting renewable energy, energy storage, and grid modernization within a broader infrastructure package influenced by Green New Deal goals.

Key Points

Federal incentives like ITC, PTC, and EV credits that cut costs and speed renewables, storage, and grid upgrades.

✅ Proposes permanence for ITC, PTC, and EV tax credits

✅ Could accelerate solar, wind, storage, and grid upgrades

✅ Passage depends on bipartisan infrastructure compromise

The 115th U.S. Congress has not even adjourned for the winter, and already a newly resurgent Democratic Party is making demands that reflect its majority status in the U.S. House come January.

Climate appears to be near the top of the list. Last Thursday, Senator Chuck Schumer (D-NY), the Democratic Leader in the Senate, sent a letter to President Trump demanding that any infrastructure package taken up in 2019 include “policies and funding to transition to a clean energy economy and mitigate the risks that the United States is already facing due to climate change.”

And in a list of policies that Schumer says should be included, the top item is “permanent tax incentives for domestic production of clean electricity and storage, energy efficient homes and commercial buildings, electric vehicles, and modernizing the electric grid.”

In concrete terms, this could mean an extension of the Investment Tax Credit (ITC) for solar and energy storage, the Production Tax Credit (PTC) for wind and the federal electric vehicle (EV) tax credit program as well.

Pressure from the Left

This strong statement on climate change, clean energy and infrastructure investment comes as at least 30 incoming members of the U.S. House of Representatives have signed onto a call for the creation of a committee to explore a “Green New Deal” and to move the nation to 100% renewable energy by 2030.*

It also comes as Schumer has come under fire by activists for rumors that he plans to replace Senator Maria Cantwell (D-Washington) with coal state Democrat Joe Manchin (D-West Virginia) as the top Democrat on the Senate Energy and Natural Resources Committee.

As such, one possible way to read these moves is that centrist leaders like Schumer are responding to pressure from an energized and newly elected Left wing of the Democratic Party. It is notable that Schumer’s program includes many of the aims of the Green New Deal, while avoiding any explicit use of that phrase.

Implications of a potential ITC extension

The details of levels and timelines are important here, particularly for the ITC.

The ITC was set to expire at the end of 2016, but was extended in legislative horse-trading at the end of 2015 to a schedule where it remains at 30% through the end of 2019 and then steps down for the next three years, and disappears entirely for residential projects. Since that extension the IRS has issued guidance around the use of co-located energy storage, as well as setting a standard under which PV projects can claim the ITC for the year that they begin construction.

This language around construction means that projects can start work in 2019, complete in 2023 and still claim the 30% ITC, and this may be why we at pv magazine USA are seeing an unprecedented boom in project pipelines across the United States.

Of course, if the ITC were to become permanent some of those projects would be pushed out to later years. But as we saw in 2016, despite an extension of the ITC many projects were still completed before the deadline, leading to the largest volume of PV installed in the United States in any one year to date.

This means that if the ITC were extended by the end of 2020, we could see the same thing all over again – a boom in projects created by the expected sunset, and then after a slight lull a continuation of growth.

Or it is possible that a combination of raw economics, increased investor and utility interest, and accelerating renewable energy mandates will cause solar growth rates to continue every year, and that any changes in the ITC will only be a bump against a larger trend.

While the basis for expiration of the EV tax credit is the number of vehicles sold, not any year, both the battery storage and EV industries, which many see at an inflection point, could see similar effects if the ITC and EV tax credits are made permanent.

Will consensus be reached?

It is also unclear that any such infrastructure package will be taken up by Republicans, or that both parties will be able to come to a compromise on this issue. While the U.S. Congress passed an infrastructure bill in 2017, given the sharp and growing differences between the two parties, and divergent trade approaches such as the 100% tariff on Chinese-made EVs, it is not clear that they will be able to come to a meaningful compromise during the next two years.

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Nighttime thermoradiative power converts outgoing infrared radiation into electricity using semiconductor photodiodes, leveraging negative illumination and sky cooling to harvest renewable energy from Earth-to-space heat flow when solar panels rest, regardless of weather.

Key Points

Nighttime thermoradiative power converts Earth's outgoing infrared heat into electricity using semiconductor diodes.

✅ Uses negative illumination to tap Earth-to-space heat flow

✅ Infrared semiconductor photodiodes generate small nighttime current

✅ Theoretical output ~4 W/m^2; lab demo reached 64 nW/m^2

There's a stark contrast between the freezing temperatures of space and the relatively balmy atmosphere of Earth, and that contrast could help generate electricity, scientists say – and alongside concepts such as space-based solar power, utilizing the same optoelectronic physics used in solar panels. The obvious difference this would have compared with solar energy is that it would work during the night time, a potential source of renewable power that could keep on going round the clock and regardless of weather conditions.

Solar panels are basically large-scale photodiodes - devices made out of a semiconducting material that converts the photons (light particles) coming from the Sun into electricity by exciting electrons in a material such as silicon, while concepts like space solar beaming could complement them during adverse weather.

In this experiment, the photodiodes work 'backwards': as photons in the form of infrared radiation - also known as heat radiation - leave the system, a small amount of energy is produced, similar to how raindrop electricity harvesting taps ambient fluxes in other experiments.

This way, the experimental system takes advantage of what researchers call the "negative illumination effect" – that is, the flow of outgoing radiation as heat escapes from Earth back into space. The setup explained in the new study uses an infrared semiconductor facing into the sky to convert this flow into electrical current.

"The vastness of the Universe is a thermodynamic resource," says one of the researchers, Shanhui Fan from Stanford University in California.

"In terms of optoelectronic physics, there is really this very beautiful symmetry between harvesting incoming radiation and harvesting outgoing radiation."

It's an interesting follow-up to a research project Fan participated in last year: a solar panel that can capture sunlight while also allowing excess heat in the form of infrared radiation to escape into space.

In the new study, this "energy harvesting from the sky" process can produce a measurable amount of electricity, the researchers have shown – though for the time being it's a long way from being efficient enough to contribute to our power grids, but advances in peer-to-peer energy sharing could still make niche deployments valuable.

In the team's experiments they were able to produce 64 nanowatts per square metre (10.8 square feet) of power – only a trickle, but an amazing proof of concept nevertheless. In theory, the right materials and conditions could produce a million times more than that, and analyses of cheap abundant electricity show how rapidly such advances compound, reaching about 4 watts per square metre.

"The amount of power that we can generate with this experiment, at the moment, is far below what the theoretical limit is," says one of the team, Masashi Ono from Stanford.

When you consider today's solar panels are able to generate up to 100-200 watts per square metre, and in China solar is cheaper than grid power across every city, this is obviously a long way behind. Even in its earliest form, though, it could be helpful for keeping low-power devices and machines running at night: not every renewable energy device needs to power up a city.

Now that the researchers have proved this can work, the challenge is to improve the performance of the experimental device. If it continues to show promise, the same idea could be applied to capture energy from waste heat given off by machinery, and results in humidity-powered generation suggest ambient sources are plentiful.

"Such a demonstration of direct power generation of a diode facing the sky has not been previously reported," explain the researchers in their published paper.

"Our results point to a pathway for energy harvesting during the night time directly using the coldness of outer space."

The research has been published in Applied Physics Letters.

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