Solar energy plants use too much water

World Bank Energy Policy debates financing for coal, oil, gas, and renewables to fight energy poverty, expand grid reliability, ensure baseload power, and balance climate goals with development finance for affordable, reliable electricity access.

Key Points

It outlines the bank's stance on financing fossil fuels and renewables to expand affordable, reliable electricity.

✅ Focus on energy access, baseload reliability, and poverty alleviation

✅ Debate over coal, gas, and renewables in development finance

✅ Geopolitics: China and Russia fill funding gaps, raising risks

Why isn’t the World Bank using all available energy resources in its global efforts to fight poverty? That’s the question I’ve asked World Bank President David Malpass. Nearly two years ago, the multilateral development bank decided to stop supporting critical coal, oil and gas projects that help people in developing countries escape poverty.

Along with 11 other senators, and as a member who votes on whether to give U.S. taxpayer dollars to the World Bank, I am pressing the bank to lift these restrictions. Developing countries desperately need access to a steady supply of affordable, reliable clean electricity to support economic growth.

The World Bank has pulled funding for critical electricity projects in poor countries, including high-efficiency power stations that are fueled by coal, even as efforts to revitalize coal communities with clean energy have grown.

Despite Kosovo having the world’s fifth-largest reserves of coal, the bank announced it would only support new energy projects from renewable sources going forward. Kosovo’s Minister of Economic Development Valdrin Lluka responded: “We don’t have the luxury to do such experiments in a poor country such as Kosovo. … It is in our national security interest to secure base energy inside our country.”

The World Bank’s misguided move comes as 840 million people worldwide are living without electricity, including 70 percent of sub-Saharan Africa, and as the fall in global energy investment may lead to shortages.

Even more troubling, nearly 3 billion people in developing countries rely on fuels like wood and other biomass for cooking and home heating, resulting in serious health problems and premature deaths, and the pandemic saw widespread electricity shut-offs that deepened energy insecurity. In 2016, household smoke killed an estimated 2.6 million people.

The World Bank’s mission is to lift people out of poverty. The bank is now compromising that mission in favor of a political agenda targeting certain energy sources.

With the World Bank blocking financing to affordable and reliable energy projects, Russia and China are stepping up their investments in order to gain geopolitical leverage.

President Vladimir Putin is pursuing Russian oil and gas projects in Mozambique, Gabon, and Angola. China’s Belt and Road Initiative is supporting traditional energy resources, with 36 percent of its power projects from 2014 to 2017 involving coal. South Africa had to turn to the China Development Bank to fund its $1.5 billion coal-fired power plant.

There are real risks for countries partnering with China and Russia on these projects. Developing countries are facing what some are calling China’s “debt trap” diplomacy. These nations have also raised concerns over safety compliance, unfair business practices, and labor standards.

As the bank’s largest contributor, the United States has a duty to make sure U.S. taxpayer dollars are used wisely and effectively. Every U.S. dollar at the World Bank should make a difference for people in the developing world.

My colleagues and I have asked the bank to pursue an all-of-the-above energy strategy as it strives to achieve its mission to end extreme poverty and promote shared prosperity. We will take the bank’s response into account during the congressional appropriations process.

The United States is a top global energy producer. And yet Democrats running for president are pursuing anti-energy policies that would hurt not only the United States but the entire world, with implications for U.S. national security as well.

Utilizing our abundant energy resources has fueled an American energy renaissance and a booming U.S. economy, even as disruptions in coal and nuclear have strained the grid, with millions of new jobs and higher wages.

People who are struggling to survive and thrive in developing countries deserve the same opportunity to access affordable and reliable sources of power.

As Microsoft founder and global philanthropist Bill Gates has noted of renewables: "Many people experiencing energy poverty live in areas without access to the kind of grids that are needed to make those technologies cheap and reliable enough to replace fossil fuels."

Ultimately, there is a role for all sources of energy to help countries alleviate poverty and improve the education, health and wellbeing of their people.

The solution to ending energy poverty does not lie in limiting options, but in using all available options. The World Bank must recommit to ending extreme poverty by helping countries use all of the world’s abundant energy resources. Let’s end energy poverty now.

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Ukraine nuclear safety risks escalate as IAEA warns of power grid attacks threatening reactor cooling, diesel generators, and Zaporizhzhia oversight, prompting UN calls for demilitarized zones to prevent radioactive releases and accidents.

Key Points

Escalating threats from grid attacks and outages that jeopardize reactor cooling, IAEA oversight, and public safety.

✅ Power grid strikes threaten reactor cooling systems.

✅ Emergency diesel generators are last defense lines.

✅ Calls grow for demilitarized zones around plants.

In early February 2025, Rafael Grossi, Director General of the International Atomic Energy Agency (IAEA), expressed grave concerns regarding the safety of Ukraine's nuclear facilities amid ongoing Russian attacks on the country's power grids, as Kyiv warned of a difficult winter without power after deadly strikes on energy infrastructure. Grossi's warnings highlight the escalating risks to nuclear safety and the potential for catastrophic accidents.

The Threat to Nuclear Safety

Ukraine's nuclear infrastructure, including the Zaporizhzhia Nuclear Power Plant—the largest in Europe—relies heavily on a stable power supply to maintain critical cooling systems and other safety measures. Russian military operations targeting Ukraine's energy infrastructure have led to power outages, and created hazards akin to those highlighted in downed power line safety guidance during emergency repairs, jeopardizing the safe operation of these facilities. Grossi emphasized that such disruptions could result in severe nuclear accidents if cooling systems fail.

IAEA's Response and Actions

In response to these threats, the IAEA has been actively involved in monitoring and assessing the situation. Grossi visited Kyiv to inspect electrical substations and discuss safety measures with Ukrainian officials. He underscored the necessity of ensuring uninterrupted power to nuclear plants and the critical role of emergency diesel generators as a last line of defense, and noted that maintaining staffing continuity, including measures such as staff living on site at critical facilities, may be necessary. The IAEA has also postponed the rotation of its mission at the Zaporizhzhia plant due to security concerns, as reported by Reuters.

International Concerns and Diplomatic Efforts

The international community has expressed deep concern over the potential for nuclear accidents in Ukraine, echoing earlier grid overseer warnings about systemic risks in other crises that stress energy systems. The United Nations and various countries have called for the establishment of a demilitarized zone around nuclear facilities to prevent military activities that could compromise their safety. Diplomatic efforts are ongoing to facilitate dialogue between Russia and Ukraine, aiming to ensure the protection of nuclear sites and the safety of surrounding populations.

The Zaporizhzhia Nuclear Power Plant

The Zaporizhzhia Nuclear Power Plant, located in southeastern Ukraine, has been under Russian control since early in the conflict, with Rosatom cooperation agreements reflecting broader nuclear policy priorities that frame Moscow's approach to the sector. The plant consists of six reactors and has been a focal point of international concern due to its size and the potential consequences of any incident. The IAEA has been working to maintain oversight and ensure the plant's safety amid the ongoing conflict.

Potential Consequences of Nuclear Accidents

A nuclear accident at any of Ukraine's nuclear facilities could have catastrophic consequences, including the release of radioactive materials, displacement of populations, and long-term environmental damage, with communities potentially facing weeks without electricity and basic services in the aftermath. The proximity of these plants to densely populated areas further amplifies the risks. The international community continues to monitor the situation closely, emphasizing the need for immediate action to safeguard nuclear facilities.

The ongoing conflict in Ukraine has introduced unprecedented challenges to nuclear safety. The IAEA's warnings and actions underscore the critical need for international cooperation to protect nuclear facilities from the dangers posed by military activities. Ensuring the safety of these sites is paramount to prevent potential disasters that could have far-reaching humanitarian and environmental impacts, and sustained attention to nuclear workers' safety concerns helps maintain operational readiness under strain.

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Smart EV Charging orchestrates vehicle-to-grid (V2G), demand response, and fast charging to balance the power grid, integrating renewables, electrolyzers for hydrogen, and megawatt chargers for fleets with advanced control and co-optimization.

Key Points

Smart EV charging coordinates EV load to stabilize the grid, cut peaks, and integrate renewable energy efficiently.

✅ Reduces peak demand via coordinated, flexible load control

✅ Enables V2G services with renewables and battery storage

✅ Supports megawatt fast charging for heavy-duty fleets

As electric vehicle (EV) sales continue to rev up in the United States, the power grid is in parallel contending with the greatest transformation in its 100-year history: the large-scale integration of renewable energy and power electronic devices. The expected expansion of EVs will shift those challenges into high gear, causing cities to face gigawatt-growth in electricity demand, as analyses of EV grid impacts indicate, and higher amounts of variable energy.

Coordinating large numbers of EVs with the power system presents a highly complex challenge. EVs introduce variable electrical loads that are highly dependent on customer behavior. Electrified transportation involves co-optimization with other energy systems, like natural gas and bulk battery storage, including mobile energy storage flexibility for new operational options. It could involve fleets of automated ride-hailing EVs and lead to hybrid-energy truck stops that provide hydrogen and fast-charging to heavy-duty vehicles.

Those changes will all test the limits of grid integration, but the National Renewable Energy Laboratory (NREL) sees opportunity at the intersection of energy systems and transportation. With powerful resources for simulating and evaluating complex systems, several NREL projects are determining the coordination required for fast charging, balancing electrical supply and demand, and efficient use of all energy assets.

Smart and Not-So-Smart Control
To appreciate the value of coordinated EV charging, it is helpful to imagine the opposite scenario.

"Our first question is how much benefit or burden the super simple, uncoordinated approach to electric vehicle charging offers the grid," said Andrew Meintz, the researcher leading NREL's Electric Vehicle Grid Integration team, as well as the RECHARGE project for smart EV charging. "Then we compare that to the 'whiz-bang,' everything-is-connected approach. We want to know the difference in value."

In the "super simple" approach, Meintz explained that battery-powered electric vehicles grow in market share, exemplified by mass-market EVs, without any evolution in vehicle charging coordination. Picture every employee at your workplace driving home at 5 p.m. and charging their vehicle. That is the grid's equivalent of going 0 to 100 mph, and if it does not wreck the system, it is at least very expensive. According to NREL's Electrification Futures Study, a comprehensive analysis of the impacts of widespread electrification across all U.S. economic sectors, in 2050 EVs could contribute to a 33% increase in energy use during peak electrical demand, underscoring state grid challenges that make these intervals costly when energy reserves are procured. In duck curve parlance, EVs will further strain the duck's neck.

The Optimization and Control Lab's Electric Vehicle Grid Integration bays allow researchers to determine how advanced high power chargers can be added safely and effectively to the grid, with the potential to explore how to combine buildings and EV charging. Credit: Dennis Schroeder, NREL
Meintz's "whiz-bang" approach instead imagines EV control strategies that are deliberate and serve to smooth, rather than intensify, the upcoming demand for electricity. It means managing both when and where vehicles charge to create flexible load on the grid.

At NREL, smart strategies to dispatch vehicles for optimal charging are being developed for both the grid edge, where consumers and energy users connect to the grid, as in RECHARGEPDF, and the entire distribution system, as in the GEMINI-XFC projectPDF. Both projects, funded by the U.S. Department of Energy's (DOE's) Vehicle Technologies Office, lean on advanced capabilities at NREL's Energy Systems Integration Facility to simulate future energy systems.

At the grid edge, EVs can be co-optimized with distributed energy resources—small-scale generation or storage technologies—the subject of a partnership with Eaton that brought industry perspectives to bear on coordinated management of EV fleets.

At the larger-system level, the GEMINI-XFC project has extended EV optimization scenarios to the city scale—the San Francisco Bay Area, to be specific.

"GEMINI-XFC involves the highest-ever-fidelity modeling of transportation and the grid," said NREL Research Manager of Grid-Connected Energy Systems Bryan Palmintier.

"We're combining future transportation scenarios with a large metro area co-simulationPDF—millions of simulated customers and a realistic distribution system model—to find the best approaches to vehicles helping the grid."

GEMINI-XFC and RECHARGE can foresee future electrification scenarios and then insert controls that reduce grid congestion or offset peak demand, for example. Charging EVs involves a sort of shell game, where loads are continually moved among charging stations to accommodate grid demand.

But for heavy-duty vehicles, the load is harder to hide. Electrified truck fleets will hit the road soon, creating power needs for electric truck fleets that translate to megawatts of localized demand. No amount of rerouting can avoid the requirements of charging heavy-duty vehicles or other instances of extreme fast-charging (XFC). To address this challenge, NREL is working with industry and other national laboratories to study and demonstrate the technological buildout necessary to achieve 1+ MW charging stationsPDF that are capable of fast charging at very high energy levels for medium- and heavy-duty vehicles.

To reach such a scale, NREL is also considering new power conversion hardware based on advanced materials like wide-bandgap semiconductors, as well as new controllers and algorithms that are uniquely suited for fleets of charge-hungry vehicles. The challenge to integrate 1+ MW charging is also pushing NREL research to higher power: Upcoming capabilities will look at many-megawatt systems that tie in the support of other energy sectors.

Renewable In-Roads for Hydrogen

At NREL, the drive toward larger charging demands is being met with larger research capabilities. The announcement of ARIES opens the door to energy systems integration research at a scale 10-times greater than current capabilities: 20 MW, up from 2 MW. Critically, it presents an opportunity to understand how mobility with high energy demands can be co-optimized with other utility-scale assets to benefit grid stability.

"If you've got a grid humming along with a steady load, then a truck requires 500 kW or more of power, it could create a large disruption for the grid," said Keith Wipke, the laboratory program manager for fuel cells and hydrogen technologies at NREL.

Such a high power demand could be partially served by battery storage systems. Or it could be hidden entirely with hydrogen production. Wipke's program, with support from the DOE's Hydrogen and Fuel Cell Technologies Office, has been performing studies into how electrolyzers—devices that use electricity to break water into hydrogen and oxygen—could offset the grid impacts of XFC. These efforts are also closely aligned with DOE's H2@Scale vision for affordable and effective hydrogen use across multiple sectors, including heavy-duty transportation, power generation, and metals manufacturing, among others.

"We're simulating electrolyzers that can match the charging load of heavy-duty battery electric vehicles. When fast charging begins, the electrolyzers are ramped down. When fast charging ends, the electrolyzers are ramped back up," Wipke said. "If done smoothly, the utility doesn't even know it's happening."

NREL Researchers Rishabh Jain, Kazunori Nagasawa, and Jen Kurtz are working on how grid integration of electrolyzers—devices that use electricity to break water into hydrogen and oxygen—could offset the grid impacts of extreme fast-charging. Credit: National Renewable Energy Laboratory
As electrolyzers harness the cheap electrons from off-demand periods, a significant amount of hydrogen can be produced on site. That creates a natural energy pathway from discount electricity into a fuel. It is no wonder, then, that several well-known transportation and fuel companies have recently initiated a multimillion-dollar partnership with NREL to advance heavy-duty hydrogen vehicle technologies.

"The logistics of expanding electric charging infrastructure from 50 kW for a single demonstration battery electric truck to 5,000 kW for a fleet of 100 could present challenges," Wipke said. "Hydrogen scales very nicely; you're basically bringing hydrogen to a fueling station or producing it on site, but either way the hydrogen fueling events are decoupled in time from hydrogen production, providing benefits to the grid."

The long driving range and fast refuel times—including a DOE target of achieving 10-minutes refuel for a truck—have already made hydrogen the standout solution for applications in warehouse forklifts. Further, NREL is finding that distributed electrolyzers can simultaneously produce hydrogen and improve voltage conditions, which can add much-needed stability to a grid that is accommodating more energy from variable resources.

Those examples that co-optimize mobility with the grid, using diverse technologies, are encouraging NREL and its partners to pursue a new scale of systems integration. Several forward-thinking projects are reimagining urban mobility as a mix of energy solutions that integrate the relative strengths of transportation technologies, which complement each other to fill important gaps in grid reliability.

The Future of Urban Mobility
What will electrified transportation look like at high penetrations? A few NREL projects offer some perspective. Among the most experimental, NREL is helping the city of Denver develop a smart community, integrated with electrified mobility and featuring automated charging and vehicle dispatch.

On another path to advanced mobility, Los Angeles has embarked on a plan to modernize its electricity system infrastructure, reflecting California EV grid stability goals—aiming for a 100% renewable energy supply by 2045, along with aggressive electrification targets for buildings and vehicles. Through the Los Angeles 100% Renewable Energy Study, the city is currently working with NREL to assess the full-scale impacts of the transition in a detailed analysis that integrates diverse capabilities across the laboratory.

The transition would include the Port of Long Beach, the busiest container port in the United States.

At the port, NREL is applying the same sort of scenario forecasting and controls evaluation as other projects, in order to find the optimal mix of technologies that can be integrated for both grid stability and a reliable quality of service: a mix of hydrogen fuel-cell and battery EVs, battery storage systems, on-site renewable generation, and extreme coordination among everything.

"Hydrogen at ports makes sense for the same reason as trucks: Marine applications have big power and energy demands," Wipke said. "But it's really the synergies between diverse technologies—the existing infrastructure for EVs and the flexibility of bulk battery systems—that will truly make the transition to high renewable energy possible."

Like the Port of Long Beach, transportation hubs across the nation are adapting to a complex environment of new mobility solutions. Airports and public transit stations involve the movement of passengers, goods, and services at a volume exceeding anywhere else. With the transition to digitally connected electric mobility changing how airports plan for the future, NREL projects such as Athena are using the power of high-performance computing to demonstrate how these hubs can maximize the value of passenger and freight mobility per unit of energy, time, and/or cost.

The growth in complexity for transportation hubs has just begun, however. Looking ahead, fleets of ride-sharing EVs, automated vehicles, and automated ride-sharing EV fleets could present the largest effort to manage mobility yet.

A Self-Driving Power Grid
To understand the full impact of future mobility-service providers, NREL developed the HIVE (Highly Integrated Vehicle Ecosystem) simulation framework. HIVE combines factors related to serving mobility needs and grid operations—such as a customer's willingness to carpool or delay travel, and potentially time-variable costs of recharging—and simulates the outcome in an integrated environment.

"Our question is, how do you optimize the management of a fleet whose primary purpose is to provide rides and improve that fleet's dispatch and charging?" said Eric Wood, an NREL vehicle systems engineer.

HIVE was developed as part of NREL's Autonomous Energy Systems research to optimize the control of automated vehicle fleets. That is, optimized routing and dispatch of automated electric vehicles.

The project imagines how price signals could influence dispatch algorithms. Consider one customer booking a commute through a ride-hailing app. Out of the fleet of vehicles nearby—variously charged and continually changing locations—which one should pick up the customer?

Now consider the movements of thousands of passengers in a city and thousands of vehicles providing transportation services. Among the number of agents, the moment-to-moment change in energy supply and demand, and the broad diversity in vendor technologies, "we're playing with a lot of parameters," Wood said.

But cutting through all the complexity, and in the midst of massive simulations, the end goal for vehicle-to-grid integration is consistent:

"The motivation for our work is that there are forecasts for significant load on the grid from the electrification of transportation," Wood said. "We want to ensure that this load is safely and effectively integrated, while meeting the expectations and needs of passengers."

The Port of Long Beach uses a mix of hydrogen fuel-cell and battery EVs, battery storage systems, on-site renewable generation, and extreme coordination among everything. Credit: National Renewable Energy Laboratory
True Replacement without Caveats

Electric vehicles are not necessarily helpful to the grid, but they can be. As EVs become established in the transportation sector, NREL is studying how to even out any bumps that electrified mobility could cause on the grid and advance any benefits to commuters or industry.

"It all comes down to load flexibility," Meintz said. "We're trying to decide how to optimally dispatch vehicle charging to meet quality-of-service considerations, while also minimizing charging costs."

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Hydro One-Avista Acquisition secures U.S. antitrust clearance under Hart-Scott-Rodino, pending approvals from state utility commissions, the FCC, and CFIUS, with prior FERC approval and shareholder vote supporting the cross-border utility merger.

Key Points

A $6.7B cross-border utility merger cleared under HSR, still awaiting state, FCC, and CFIUS approvals; FERC approved earlier.

✅ HSR waiting period expired; U.S. antitrust clearance obtained

✅ Approvals pending: state commissions, FCC, and CFIUS

✅ FERC and Avista shareholders have approved the transaction

Hydro One Ltd. says it has received antitrust clearance in the United States for its deal to acquire U.S. energy company Avista Corp., even as it sought to redesign customer bills in Ontario.

The Ontario-based utility says the 30-day waiting period under the Hart-Scott-Rodino Antitrust Improvements Act expired Thursday night.

Hydro One announced the friendly deal to acquire Avista last summer, amid customer backlash in some service areas, in an agreement that valued the company at $6.7 billion.

The deal still requires several other approvals, including those from utility commissions in Washington, Idaho, Oregon, Montana and Alaska.

Analysts also warned of political risk for Hydro One during this period, reflecting concerns about provincial influence.

The U.S. Federal Communications Commission must also sign off on the transaction, and although U.S. regulators later rejected the $6.7B takeover following review, clearance is required by the Committee on Foreign Investment in the United States.

The agreement has received approval from the U.S. Federal Energy Regulatory Commission as well as Avista shareholders, and it mirrored other cross-border deals such as Algonquin Power's acquisition of Empire District that closed in the sector.

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Illinois Zero Emission Credits support nuclear plants via tradable credits tied to wholesale electricity prices, carbon costs, created by the Future Energy Jobs Bill to avert Exelon closures and sustain low-carbon power.

Key Points

State credits that value nuclear power's zero-carbon output, priced by market and carbon metrics to keep plants running.

✅ Pegged to wholesale prices, carbon costs, and state averages.

✅ Created by Future Energy Jobs Bill to prevent plant retirements.

✅ Supports Exelon Quad Cities and Clinton nuclear facilities.

Nuclear plants have produced over half of Illinois electricity generation since 2010, but the states two largest plants would have been retired amid the debate over saving nuclear plants if the state had not created a zero emission credit (ZEC) mechanism to support the facilities.

The two plants, Quad Cities and Clinton, collectively delivered more than 12 percent of the states electricity generation over the past several years. In May 2016, however, Exelon, the owner of the plants, announced that they had together lost over $800 million dollars over the previous six years and revealed plans to retire them in 2017 and 2018, similar to the Three Mile Island closure later announced for 2019 by its owner.

In December 2016, Illinois passed the Future Energy Jobs Bill, which established a zero emission credit (ZEC) mechanism

to support the plants financially. Exelon then cancelled its plans to retire the two facilities.

The ZEC is a tradable credit that represents the environmental attributes of one megawatt-hour of energy produced from the states nuclear plants. Its price is based on a number of factors that include wholesale electricity market prices, nuclear generation costs, state average market prices, and estimated costs of the long-term effects of carbon dioxide emissions.

The bill is set to take effect in June, but faces multiple court challenges as some utilities have expressed concerns that the ZEC violates the commerce clause and affects federal authority to regulate wholesale energy prices, amid gas-fired competition in nearby markets that shapes the revenue outlook.

Illinois ranks first in the United States for both generating capacity and net electricity generation from nuclear power, a resource many see as essential for net-zero emissions goals, and accounts for approximately one-eighth of the nuclear power generation in the nation.

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US SF6 Emissions Decline as NOAA analysis and EPA mitigation show progress, with atmospheric measurements and Greenhouse Gas Reporting verifying reductions from the electric power grid; sulfur hexafluoride's extreme global warming potential underscores inventory improvements.

Key Points

A documented drop in US sulfur hexafluoride emissions, confirmed by NOAA atmospheric data and EPA reporting reforms.

✅ NOAA towers and aircraft show 2007-2018 decline

✅ EPA reporting and utility mitigation narrowed inventory gaps

✅ Winter leaks and servicing signal further reduction options

A new NOAA analysis shows U.S. emissions of the super-potent greenhouse gas sulfur hexafluoride (SF6) have declined between 2007-2018, likely due to successful mitigation efforts by the Environmental Protection Agency (EPA) and the electric power industry, with attention to SF6 in the power industry across global markets. 

At the same time, significant disparities that existed previously between NOAA’s estimates, which are based on atmospheric measurements, and EPA’s estimates, which are based on a combination of reported emissions and industrial activity, have narrowed following the establishment of the EPA's Greenhouse Gas Reporting Program. The findings, published in the journal Atmospheric Chemistry and Physics, also suggest how additional emissions reductions might be achieved. 

SF6 is most commonly used as an electrical insulator in high-voltage equipment that transmits and distributes electricity, and its emissions have been increasing worldwide as electric power systems expand, even as regions hit milestones like California clean energy surpluses in recent years. Smaller amounts of SF6 are used in semiconductor manufacturing and in magnesium production. 

SF6 traps 25,000 times more heat than carbon dioxide over a 100-year time scale for equal amounts of emissions, and while CO2 emissions flatlined in 2019 globally, that comparison underscores the potency of SF6. That means a relatively small amount of the gas can have a significant impact on climate warming. Because of its extremely large global warming potential and long atmospheric lifetime, SF6 emissions will influence Earth’s climate for thousands of years.

In this study, researchers from NOAA’s Global Monitoring Laboratory, as record greenhouse gas concentrations drive demand for better data, working with colleagues at EPA, CIRES, and the University of Maryland, estimated U.S. SF6 emissions for the first time from atmospheric measurements collected at a network of tall towers and aircraft in NOAA’s Global Greenhouse Gas Reference Network. The researchers provided an estimate of SF6 emissions independent from the EPA’s estimate, which is based on reported SF6 emissions for some industrial facilities and on estimated SF6 emissions for others.

“We observed differences between our atmospheric estimates and the EPA’s activity-based estimates,” said study lead author Lei Hu, a Global Monitoring Laboratory researcher who was a CIRES scientist at the time of the study. “But by closely collaborating with the EPA, we were able to identify processes potentially responsible for a significant portion of this difference, highlighting ways to improve emission inventories and suggesting additional emission mitigation opportunities, such as forthcoming EPA carbon capture rules for power plants, in the future.” 

In the 1990s, the EPA launched voluntary partnerships with the electric power, where power-sector carbon emissions are falling as generation shifts, magnesium, and semiconductor industries to reduce SF6 emissions after the United States recognized that its emissions were significant. In 2011, large SF6 -emitting facilities were required to begin tracking and reporting their emissions under the EPA Greenhouse Gas Reporting Program. 

Hu and her colleagues documented a decline of about 60 percent in U.S. SF6 emissions between 2007-2018, amid global declines in coal-fired power in some years—equivalent to a reduction of between 6 and 20 million metric tons of CO2 emissions during that time period—likely due in part to the voluntary emission reduction partnerships and the EPA reporting requirement. A more modest declining trend has also been reported in the EPA’s national inventories submitted annually under the United Nations Framework Convention on Climate Change. 

Examining the differences between the NOAA and EPA independent estimates, the researchers found that the EPA’s past inventory analyses likely underestimated SF6 emissions from electrical power transmission and distribution facilities, and from a single SF6 production plant in Illinois. According to Hu, the research collaboration has likely improved the accuracy of the EPA inventories. The 2023 draft of the EPA’s U.S. Greenhouse Gas Emissions and Sinks: 1990-2021 used the results of this study to support revisions to its estimates of SF6 emissions from electrical transmission and distribution. 

The collaboration may also lead to improvements in the atmosphere-based estimates, helping NOAA identify how to expand or rework its network to better capture emitting industries or areas with significant emissions, according to Steve Montzka, senior scientist at GML and one of the paper’s authors.

Hu and her colleagues also found a seasonal variation in SF6 emissions from the atmosphere-based analysis, with higher emissions in winter than in summer. Industry representatives identified increased servicing of electrical power equipment in the southern states and leakage from aging brittle sealing materials in the equipment in northern states during winter as likely explanations for the enhanced wintertime emissions—findings that suggest opportunities for further emissions reductions.

“This is a great example of the future of greenhouse gas emission tracking, where inventory compilers and atmospheric scientists work together to better understand emissions and shed light on ways to further reduce them,” said Montzka.

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