Energy Optimizer Program continues success

Ontario Global Adjustment and ICI balance hydro rates, renewable cost shift, and peak demand. Class A and Class B customers face demand response decisions amid pandemic occupancy uncertainty and volatile GA charges through 2022.

Key Points

A pricing model where GA costs and ICI peak allocation shape Class A/B bills, driven by renewables cost shifts.

✅ Renewable cost shift trims GA; larger Class A savings expected.

✅ Class A peak strategy returns; occupancy uncertainty persists.

✅ Class B faces volatile GA; limited levers beyond efficiency.

Ontario’s large commercial electricity customers can approach the looming annual decision about their billing structure for the 12 months beginning July 1 with the assurance of long-term relief on a portion of their costs, amid changes coming for electricity consumers that could affect planning. That’s to be weighed against uncertainties around energy demand and whether a locked-in cost allocation formula that looked favourable in pre-pandemic times will remain so until June 30, 2022.

“The biggest unknown is we just don’t know when the people are coming back,” Jon Douglas, director of sustainability with Menkes Property Management Services, reflected during a webinar sponsored by the Building Owners and Managers Association (BOMA) of Greater Toronto last week. “The occupancy in our office buildings this fall, and going into the new year, could really impact the outcome of the decision.”

After a year of operational upheaval and more modifications to provincial electricity pricing policies, BOMA Toronto’s regularly scheduled workshop ahead of the June 15 deadline for eligible customers to opt into the Industrial Conservation Initiative (ICI) program had a lot of ground to cover. Notably, beginning in January, all commercial customers have seen a reduction in the global adjustment (GA) component of their monthly hydro bills after the Ontario government shifted costs associated with contracted non-hydroelectric renewable supply to reduce the burden on industrial ratepayers from electricity rates to the general provincial account — a move that trims approximately $258 million per month from the total GA charged to industrial and commercial customers. However, they won’t garner the full benefit of that until 2022 since they’re currently repaying about $333 million in GA costs that were deferred in April, May and June of 2020.

Renewable cost shift pares the global adjustment
For now, Ontario government officials estimate the renewable cost shift equates to a 12 per cent discount relative to 2020 prices, even as typical bills may rise about 2% as fixed pricing ends in some cases. Once last year’s GA deferral is repaid at the end of 2021, they project the average Class A customer participating in the ICI program should realize a 16 per cent saving on the total hydro bill, while Class B customers paying the GA on a volumetric per kilowatt-hour (kWh) basis will see a slightly more moderate 15 per cent decrease.

“This is the biggest change to electricity pricing that’s happened since the introduction of ICI,” Tim Christie, director of electricity policy, economics and system planning for Ontario’s Ministry of Energy, Northern Development and Mines, told online workshop attendees. “The government is funding the out-of-market costs of renewables. It does tail off into the 2030s as those contracts (for wind, solar and biomass generation) expire, but over the next eight-ish years, it’s pretty steady at around just over $3 billion per year.”

Extrapolating from 2020 costs, he pegged average electricity costs at roughly 9.1 cents/kWh for Class A commercial customers and 13.2 cents/kWh for Class B, a point of concern for Ontario manufacturers facing high rates as well. However, energy management specialists suggest actual 2021 numbers haven’t proved that out.

“In commercial buildings, we’re averaging 10 to 12 cents for Class A in 2021, and we’re seeing more than that for about 14, 15 cents for Class B,” reported Scott Rouse, managing partner with the consulting firm, Energy@Work.

GA costs for Class B customers dropped nearly 30 per cent in the first four months of 2021 compared to the last four months of 2020, when they averaged 11.8 cents/kWh. Thus far, though, there have been significant month-to-month fluctuations, with a low of 5.04 cents/kWh in February and a high of 10.9 cents/kWh in April contributing to the four-month average of 8.3 cents/kWh.

“In 2020, system-wide GA very often averaged more than $1 billion per month,” Rouse said. “This February it dropped to $500 million, which was really quite surprising. So it is a very volatile cost.”

Although welcome, the renewable cost shift does alter the payback on energy-saving investments, particularly for demand response mechanisms like energy storage. When combined with pandemic-related uncertainty and a series of policy and program reversals alongside calls to clean up Ontario’s hydro policy in recent years, the industry’s appetite for some more capital-intensive technologies appears to be flagging.

“Volatility puts a pause on some of the innovation,” said Terry Flynn, general manager with BentallGreenOak and chair of BOMA Toronto’s energy committee. “It could be a leading edge, but it might be a bleeding edge that won’t bear any fruit because the way the commodity costs are structured will change.”

“There’s kind of a wait-and-see approach on some of these bigger investments,” Douglas concurred.

Industrial Conservation Initiative underpins commercial class divide
Turning to the ICI, Class A customers — defined as those with average monthly energy demand of at least 1 megawatt (MW) — encountered some unexpected changes to the program rules during 2020. Meanwhile, Class B customers — encompassing the vast share of commercial properties smaller than about 350,000 square feet — confront the persistent reality of electricity cost allocation that offloads the burden from larger players onto them.

Through the ICI, participating Class A customers pay a share of the global adjustment that’s prorated to their energy use during the five hours of the period from May 1 to April 30 when the highest overall system demand is recorded. This gives Class A customers the opportunity to lock in a favourable factor for calculating their share of monthly system-wide global adjustment costs if they can successful project and curtail energy loads during those five hours of peak demand. On the flipside, Class B customers pay the remainder of those system-wide costs, on a straightforward per-kWh basis, once Class A payments have been reconciled.

“Class B has sometimes been regarded as the forgotten middle child of the customer classes in Ontario where all the shifted costs in the system kind of pile up,” acknowledged Mark Olsheski, vice president, energy and environment, with Sussex Strategy Group. “Likewise, there can be big unpredictable and uncontrollable swings in the global adjustment rate from month to month and, outside of pure energy efficiency, there really is precious little opportunity or empowerment for a Class B customer to take actions to lower their bills.”

Nevertheless, COVID-19 presents a few extra hiccups for Class A customers this year. Conventionally, late May is when they receive notification of the cost allocation factor that would be used to determine their GA for the upcoming July 1 to June 30 period. This year, though, all current ICI participants will retain the factor they secured by responding to the five hours of peak demand during the 12 months from May 1, 2019 to April 30, 2020 after the Ontario government placed a temporary halt on the peak demand response aspect of the program last summer. Regardless, eligible ICI participants must formally opt into the program by June 15 or they will be billed as Class B customers.

Peak chasing resumes for summer 2021
Since peak demand hours conventionally occur from June to September, Class A customers will once again be studying forecasts intently and preparing to respond via Peak Perks as the heat wave season sets in. That should help alleviate some of the system stresses that arose last summer — prompting policy-makers to reject lobbying for a continued pause on peak demand response.

“The policy rationale was to allow consumers to focus on their operations when recovering from COVID as opposed to reducing peaks. The other issue was that we did not expect the peaks to be high last summer given COVID shutdowns,” Christie recounted. “But due to some hot weather, more people at home and also the lack of ICI response, we saw peaks we haven’t seen in many, many years come up last summer. So the peak hiatus has ended and this summer we’ll be back to responding to ICI as per normal.”

Among Class A customers, owners/managers of office and retail facilities generally have the most to lose from a billing formula tied to the energy demand of more densely occupied buildings in the summer of 2019. However, they could be much more competitively positioned for 2022-23 if their buildings remain below full occupancy and energy demand stays lower than usual this summer.

“Where we can improve is the IESO (Independent Electricity System Operator) and the LDCs (local distribution companies) need to help customers get their real-time data, especially in light of the phantom demand issue, interpret their bills and their Class A versus B scenarios much more easily and comprehensively,” urged Lee Hodgkinson, vice president, technical services, sustainability and ESG, with Dream Unlimited. “ I look for APIs (application programming interface) and direct data flow from the LDCs to the building owners so that we can access that data really easily.”

Given Class A’s historic advantages, few eligible ICI participants are expected to migrate out to Class B. From a sustainability perspective, there’s perhaps more cause to question how the ICI’s 1-MW threshold encourages strategies to move in the other direction.

“You could jack up demand in some buildings and get them into Class A basically by firing up the chillers on the weekend and then pouring cooling outside to get rid of it,” Douglas noted. “That has nothing to do with climate change strategy or sustainability, but it’s a cost- saving strategy, and, sometimes, when you look at the math, it’s hundreds of thousands of dollars you can save.”

Brian Hewson, vice president, consumer protection and industry performance with the Ontario Energy Board (OEB), confirmed the OEB is currently scrutinizing the discrepancy that leaves Class B as the only consumer group with no flexibility to curtail energy load during higher-priced periods, and will be providing advice to the Ministry of Energy. In the interim, that status does, at least, simplify tactics.

“Just reduce your kWh and it doesn’t matter what time of day because you’re paying that fixed rate for 24 hours a day. So if you can curb your demand at night, you get a big bang for your dollar,” Rouse advised.

“We do talk about rates a lot, but if you’re not using it, you’re not paying for it,” Flynn agreed. “A lot of our focus is still on really to try to reduce the number of kilowatts that we use. That seems to be the best thing to do.”

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PG&E 2024 Rate Hikes signal sharp increases to fund wildfire safety, infrastructure upgrades, and CPUC-backed reliability, with rates expected to stabilize in 2025, affecting rural residents, businesses, and high-risk zones across California.

Key Points

PG&E’s 2024 hikes fund wildfire safety and grid upgrades, with pricing expected to stabilize in 2025.

✅ Driven by wildfire safety, infrastructure, and reinsurance costs

✅ Largest impacts in rural, high-risk zones; business rates vary

✅ CPUC oversight aims to ensure necessary, justified investments

Pacific Gas and Electric (PG&E) is expected to implement a series of rate hikes that, amid analyses of why California electricity prices are soaring across the state, will significantly impact California residents. These increases, while substantial, are anticipated to be followed by a period of stabilization in 2025, offering a sense of relief to customers facing rising costs.

PG&E, one of the largest utility providers in the state, announced that its 2024 rate hikes are part of efforts to address increasing operational costs, including those related to wildfire safety, infrastructure upgrades, and regulatory requirements. As California continues to face climate-related challenges like wildfires, utilities like PG&E are being forced to adjust their financial models to manage the evolving risks. Wildfire-related liabilities, which have plagued PG&E in recent years, play a significant role in these rate adjustments. In response to previous fire-related lawsuits, including a bankruptcy plan supported by wildfire victims that reshaped liabilities, and the increased cost of reinsurance, PG&E has made it clear that customers will bear part of the financial burden.

These rate hikes will have a multi-faceted impact. Residential users, particularly those in rural or high-risk wildfire zones, will see some of the largest increases. Business customers will also be affected, although the adjustments may vary depending on the size and energy consumption patterns of each business. PG&E has indicated that the increases are necessary to secure the utility’s financial stability while continuing to deliver reliable service to its customers.

Despite the steep increases in 2024, PG&E's executives have assured that the company's pricing structure will stabilize in 2025. The utility has taken steps to balance the financial needs of the business with the reality of consumer affordability. While some rate hikes are inevitable given California's regulatory landscape and climate concerns, PG&E's leadership believes the worst of the increases will be seen next year.

PG&E’s anticipated stabilization comes after a year of scrutiny from California regulators. The California Public Utilities Commission (CPUC) has been working closely with PG&E to scrutinize its rate request and ensure that hikes are justifiable and used for necessary investments in infrastructure and safety improvements. The CPUC’s oversight is especially crucial given the company’s history of safety violations and the public outrage over past wildfire incidents, including reports that its power lines may have sparked fires in California, which have been linked to PG&E’s equipment.

The hikes, though significant, reflect the broader pressures facing utilities in California, where extreme weather patterns are becoming more frequent and intense due to climate change. Wildfires, which have grown in severity and frequency in recent years, have forced PG&E to invest heavily in fire prevention and mitigation strategies, including compliance with a judge-ordered use of dividends for wildfire mitigation across its service area. This includes upgrading equipment, inspecting power lines, and implementing more rigorous protocols to prevent accidents that could spark devastating fires. These investments come at a steep cost, which PG&E is passing along to consumers through higher rates.

For homeowners and businesses, the potential for future rate stabilization offers a glimmer of hope. However, the 2024 increases are still expected to hit consumers hard, especially those already struggling with high living costs. The steep hikes have prompted public outcry, with calls for action as bills soar amplifying advocacy group arguments that utilities should absorb more of the costs related to climate change and fire prevention instead of relying on ratepayers.

Looking ahead to 2025, the expectation is that PG&E’s rates will stabilize, but the question remains whether they will return to pre-2024 levels or continue to rise at a slower rate. Experts note that California’s energy market remains volatile, and while the rates may stabilize in the short term, long-term cost management will depend on ongoing investments in renewable energy sources and continued efforts to make the grid more resilient to climate-related risks.

As PG&E navigates this challenging period, the company’s commitment to transparency and working with regulators will be crucial in rebuilding trust with its customers. While the immediate future may be financially painful for many, the hope is that the utility's focus on safety and infrastructure will lead to greater long-term stability and fewer dramatic rate increases in the years to come.

Ultimately, California residents will need to brace for another tough year in terms of utility costs but can find reassurance that PG&E’s rate increases will eventually stabilize. For those seeking relief, there are ongoing discussions about increasing energy efficiency, exploring renewable energy alternatives, and expanding assistance programs for lower-income households to help mitigate the financial strain of these price hikes.

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Texas Energy Policy Debate centers on ERCOT and PUC directives, fossil fuels vs renewables, grid reliability, energy efficiency, battery storage, and blackout risks, shaping Texas power market rules, conservation alerts, and capacity planning.

Key Points

Policy fight over ERCOT/PUC rules weighing fossil fuels vs renewables and storage to bolster Texas grid reliability.

✅ ERCOT and PUC directives under political scrutiny

✅ Fossil fuel subsidies vs renewable incentives and storage

✅ Focus on grid reliability, efficiency, and blackout prevention

Earlier this week, Governor Abbott released a letter to the Public Utility Commission of Texas (PUC) and the Electric Reliability Council of Texas (ERCOT), demanding electricity market reforms that Abbott falsely claims will "increase power generation capacity and to ensure the reliability of the Texas power grid."

Unfortunately, Abbott's letter promotes polluting, unreliable fossil fuels, attacks safer clean energy options, and ignores solutions that would actually benefit everyday Texans.

"Governor Abbott, in a blatant effort to politicize Texans' energy security, wants to double down on fossil fuels, even though they were the single largest point of failure during both February's blackouts and June's energy conservation alerts," said Cyrus Reed, Interim Director & Conservation Director of the Lone Star Chapter of the Sierra Club.

"Many of these so-called solutions were considered and rejected most recently by the Texas Legislature. Texas must focus on expanding clean and reliable renewable energy, energy efficiency, and storage capacity, as voters consider funding to modernize generation in the months ahead.

"We can little afford to repeat the same mistakes that have failed to provide enough electricity where it is needed most and cost Texans billions of dollars. Instead of advocating for evidence-based solutions, Abbott wants to be a culture warrior for coal and gas, even as he touts grid readiness amid election season, even when it results in blackouts across Texas."

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Wind And Solar Energy Growth is reshaping the global power mix, accelerating grid decarbonization as coal declines; boosted by pandemic demand drops, renewables now supply near 10% of electricity, advancing climate targets toward net-zero trajectories.

Key Points

It is the rise in wind and solar's share of electricity, driving decarbonization and displacing coal globally.

✅ Share doubled in five years across 83% of global electricity

✅ Coal's share fell; renewables neared 10% in H1 2020

✅ Growth still insufficient for 1.5 C; needs ~13% coal cuts yearly

Wind and solar energy doubled its share of the global power mix over the last five years, with renewable power records underscoring the trend, moving the world closer to a path that would limit the worst effects of global warming.

The sources of renewable energy made up nearly 10% of power in most parts of the world in the first half of this year, according to analysis from U.K. environmental group Ember, while globally over 30% of electricity is renewable in broader assessments.

That decarbonization of the power grid was boosted this year as shutdowns to contain the coronavirus reduced demand overall, leaving renewables to pick up the slack.

Ember analyzed generation in 48 countries that represent 83% of global electricity. The data showed wind and solar power increased 14% in the first half of 2020 compared with the same period last year while global demand fell 3% because of the impact of the coronavirus.

At the same time that wind turbines and solar panels have proliferated, coal’s share of the mix has fallen around the world. In some, mainly western European countries, where renewables surpassed fossil fuels, coal has been all but eliminated from electricity generation.

China relied on the dirtiest fossil fuel for 68% of its power five years ago, and solar PV growth in China has accelerated since then. That share dipped to 62% this year and renewables made up 10% of all electricity generated.

Still, the growth of renewables may not be going fast enough for the world to hit its climate goals, even as the U.S. is projected to have one-fourth of electricity from renewables soon, and coal is still being burnt for power in many parts of the world.

Coal use needs to fall by about 79% by 2030 from last year’s levels - a fall of 13% every year throughout the decade to come, and in the U.S. renewable electricity surpassed coal in 2022, Ember said.

New installations of wind farms are set to hold more or less steady in the next five years, according to data from BloombergNEF on deployment trends. That will make it difficult to realize a sustained pace of doubling renewable power every five years.

“If your expectations are that we need to be on target for 1.5 degrees, clearly we’re not going fast enough,” said Dave Jones, an analyst at Ember. “We’re not on a trajectory where we’re reducing coal emissions fast enough.”

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Texas Heat Pump Electrification replaces natural gas furnaces with electric heating across ERCOT, cutting carbon emissions, lowering utility bills, shifting summer peaks to winter, and aligning higher loads with strong seasonal wind power generation.

Key Points

Statewide shift from gas furnaces to heat pumps in Texas, reducing emissions and bills while moving grid peak to winter.

✅ Up to $452 annual utility savings per household

✅ CO2 cuts up to 13.8 million metric tons in scenarios

✅ Winter peak rises, summer peak falls; wind aligns with load

What would happen if you converted all the single-family homes in Texas from natural gas to electric heating?

According to a paper from Pecan Street, an Austin-based energy research organization, the transition would reduce climate-warming pollution, save Texas households up to $452 annually on their utility bills, and flip the state from a summer-peaking to a winter-peaking system. And that winter peak would be “nothing the grid couldn’t evolve to handle,” according to co-author Joshua Rhodes, a view echoed by analyses outlining Texas grid reliability improvements statewide today.

The report stems from the reality that buildings must be part of any comprehensive climate action plan.

“If we do want to decarbonize, eventually we do have to move into that space. It may not be the lowest-hanging fruit, but eventually we will have to get there,” said Rhodes.

Rhodes is a founding partner of the consultancy IdeaSmiths and an analyst at Vibrant Clean Energy. Pecan Street commissioned the study, which is distilled from a larger original analysis by IdeaSmiths, at the request of the nonprofit Environmental Defense Fund.

In an interview, Rhodes said, “The goal and motivation were to put bounding on some of the claims that have been made about electrification: that if we electrify a lot of different end uses or sectors of the economy...power demand of the grid would double.”

Rhodes and co-author Philip R. White used an analysis tool from the National Renewable Energy Laboratory called ResStock to determine the impact of replacing natural-gas furnaces with electric heat pumps in homes across the ERCOT service territory, which encompasses 90 percent of Texas’ electricity load.

Rhodes and White ran 80,000 simulations in order to determine how heat pumps would perform in Texas homes and how the pumps would impact the ERCOT grid.

The researchers modeled the use of “standard efficiency” (ducted, SEER 14, 8.2 HSPF air-source heat pump) and “superior efficiency” (ductless, SEER 29.3, 14 HSPF mini-split heat pump) heat pump models against two weather data sets — a typical meteorological year, and 2011, which had extreme weather in both the winter and summer and highlighted blackout risks during severe heat for many regions.

Emissions were calculated using Texas’ power sector data from 2017. For energy cost calculations, IdeaSmiths used 10.93 cents per kilowatt-hour for electricity and 8.4 cents per therm for natural gas.

Nothing the grid can't handle
Rhodes and White modeled six scenarios. All the scenarios resulted in annual household utility bill savings — including the two in which annual electricity demand increased — ranging from $57.82 for the standard efficiency heat pump and typical meteorological year to $451.90 for the high-efficiency heat pump and 2011 extreme weather year.

“For the average home, it was cheaper to switch. It made economic sense today to switch to a relatively high-efficiency heat pump,” said Rhodes. “Electricity bills would go up, but gas bills can go down.”

All the scenarios found carbon savings too, with CO2 reductions ranging from 2.6 million metric tons with a standard efficiency heat pump and typical meteorological year to 13.8 million metric tons with the high-efficiency heat pump in 2011-year weather.

Peak electricity demand in Texas would shift from summer to winter. Because heat pumps provide both high-efficiency space heating and cooling, in the scenario with “superior efficiency” heat pumps, the summer peak drops by nearly 24 percent to 54 gigawatts compared to ERCOT’s 71-gigawatt 2016 summer peak, even as recurring strains on the Texas power grid during extreme conditions persist.

The winter peak would increase compared to ERCOT’s 66-gigawatt 2018 winter peak, up by 22.73 percent to 81 gigawatts with standard efficiency heat pumps and up by 10.6 percent to 73 gigawatts with high-efficiency heat pumps.

“The grid could evolve to handle this. This is not a wholesale rethinking of how the grid would have to operate,” said Rhodes.

He added, “There would be some operational changes if we went to a winter-peaking grid. There would be implications for when power plants and transmission lines schedule their downtime for maintenance. But this is not beyond the realm of reality.”

And because Texas’ wind power generation is higher in winter, a winter peak would better match the expected higher load from all-electric heating to the availability of zero-carbon electricity.

A conservative estimate
The study presented what are likely conservative estimates of the potential for heat pumps to reduce carbon pollution and lower peak electricity demand, especially when paired with efficiency and demand response strategies that can flatten demand.

Electric heat pumps will become cleaner as more zero-carbon wind and solar power are added to the ERCOT grid, as utilities such as Tucson Electric Power phase out coal. By the end of 2018, 30 percent of the energy used on the ERCOT grid was from carbon-free sources.

According to the U.S. Energy Information Administration, three in five Texas households already use electricity as their primary source of heat, much of it electric-resistance heating. Rhodes and White did not model the energy use and peak demand impacts of replacing that electric-resistance heating with much more energy efficient heat pumps.

“Most of the electric-resistance heating in Texas is located in the very far south, where they don’t have much heating at all,” Rhodes said. “You would see savings in terms of the bills there because these heat pumps definitely operate more efficiently than electric-resistance heating for most of the time.”

Rhodes and White also highlighted areas for future research. For one, their study did not factor in the upfront cost to homeowners of installing heat pumps.

“More study is needed,” they write in the Pecan Street paper, “to determine the feasibility of various ‘replacement’ scenarios and how and to what degree the upgrade costs would be shared by others.”

Research from the Rocky Mountain Institute has found that electrification of both space and water heating is cheaper for homeowners over the life of the appliances in most new construction, when transitioning from propane or heating oil, when a gas furnace and air conditioner are replaced at the same time, and when rooftop solar is coupled with electrification, aligning with broader utility trends toward electrification.

More work is also needed to assess the best way to jump-start the market for high-efficiency all-electric heating. Rhodes believes getting installers on board is key.

“Whenever a homeowner’s making a decision, if their system goes out, they lean heavily on what the HVAC company suggests or tells them because the average homeowner doesn’t know much about their systems,” he said.

More work is also needed to assess the best way to jump-start the market for high-efficiency all-electric heating, and how utility strategies such as smart home network programs affect adoption too. Rhodes believes getting installers on board is key.

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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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