Schwarzenegger boosts clean energy plan

U.S. Transmission Grid Modernization underscores FERC policy certainty, high-voltage infrastructure upgrades, renewables integration, electrification, and grid resilience to cut congestion and enable distributed energy resources, safeguarding against extreme weather, cyber threats, and market volatility.

Key Points

A plan to expand, upgrade, and secure high-voltage networks for renewables integration, electrification, reliability.

✅ Replace aging lines to cut congestion and customer costs

✅ Integrate renewables and distributed energy resources at scale

✅ Enhance resilience to weather, cyber, and physical threats

Today, in a high-visibility hearing on U.S. energy delivery infrastructure before the United States Senate Committee on Energy and Natural Resources, WIRES Executive Director and Former FERC Chairman Jim Hoecker addressed the challenges and opportunities that confront the modern high-voltage grid as the industry strives to upgrade and expand it to meet the demands of consumers and the economy.

In prepared testimony and responses to Senators' questions, Hoecker urged the Committee to support industry efforts to expand and upgrade the transmission network and to help regulators, especially the Federal Energy Regulatory Commission (FERC action on aggregated DERs), promote certainty and predictability in energy policy and regulation. 

His testimony stressed these points:

Significant transmission investment is needed now to replace aging infrastructure like the aging grid risks to clean energy, reduce congestion costs, and deliver widespread benefits to customers.

Increasingly, the role of the transmission grid is to integrate new distributed resources and renewable energy into the electric system and make them available to the market.

The changing electric generation mix, including needed nuclear innovation, and the coming electrification of transportation, heating, and other segments of the American economy in the next quarter century will depend on a strong and adaptable electric system. A robust transmission grid will be the linchpin that will enable us to meet those demands.

"Transmission is the common element that will support all future electricity needs and provide a hedge against uncertainties and potential costly outcomes. The time is now to be proactive in encouraging additional investments in our nation's most crucial infrastructure: the electric transmission system," Hoecker said. 

Hoecker's testimony also emphasized that transmission investment will contribute to the overall resilience of the electric system by bringing multiple resources and technologies to bear on threats to the power system, including extreme weather and proposals like a wildfire-resilient grid bill, cyber or physical attacks, or other events. Visit WIRES website for recently filed comments on the subject (supported by a Brattle Group study). 

"Transmission gives us the optionality to adapt to whatever the future holds, and a modern and resilient transmission system, informed by Texas reliability improvements, will be the most valuable energy asset we have," says Nina Plaushin, president of WIRES and vice president of federal affairs, regulatory and communications for ITC Holdings Corp. 

Hoecker closed his testimony by emphasizing that the "electrification" scenario that is being discussed across multiple industries demands action now in order to ensure policy and regulatory certainty that will support needed transmission investment. More studies need to be conducted to better understand and define how this delivery network must be configured and planned in anticipation of this potential transformation in how we use electrical energy. A full copy of the WIRES testimony can be found here.

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California Biofuels vs EV Subsidies examines tradeoffs in decarbonization, greenhouse gas reductions, clean energy deployment, charging infrastructure, energy security, lifecycle emissions, and transportation sector policy to meet climate goals and accelerate sustainable mobility.

Key Points

Policy tradeoffs weighing biofuels and EVs to cut GHGs, boost energy security, and advance clean transportation.

✅ Near-term blending cuts emissions from existing fleets

✅ EVs scale with a cleaner grid and charging buildout

✅ Lifecycle impacts and costs guide optimal subsidy mix

California is at the forefront of the transition to a greener economy, driven by its ambitious goals to reduce greenhouse gas emissions and combat climate change. As part of its strategy, the state is grappling with the question of whether it should subsidize out-of-state biofuels or in-state electric vehicles (EVs) to meet these goals. Both options come with their own sets of benefits and challenges, and the decision carries significant implications for the state’s environmental, economic, and energy landscapes.

The Case for Biofuels

Biofuels have long been promoted as a cleaner alternative to traditional fossil fuels like gasoline and diesel. They are made from organic materials such as agricultural crops, algae, and waste, which means they can potentially reduce carbon emissions in comparison to petroleum-based fuels. In the context of California, biofuels—particularly ethanol and biodiesel—are viewed as a way to decarbonize the transportation sector, which is one of the state’s largest sources of greenhouse gas emissions.

Subsidizing out-of-state biofuels can help California reduce its reliance on imported oil while promoting the development of biofuel industries in other states. This approach may have immediate benefits, as biofuels are widely available and can be blended with conventional fuels to lower carbon emissions right away. It also allows the state to diversify its energy sources, improving energy security by reducing dependency on oil imports.

Moreover, biofuels can be produced in many regions across the United States, including rural areas. By subsidizing out-of-state biofuels, California could foster economic development in these regions, creating jobs and stimulating agricultural innovation. This approach could also support farmers who grow the feedstock for biofuel production, boosting the agricultural economy in the U.S.

However, there are drawbacks. The environmental benefits of biofuels are often debated. Critics argue that the production of biofuels—particularly those made from food crops like corn—can contribute to deforestation, water pollution, and increased food prices. Additionally, biofuels are not a silver bullet in the fight against climate change, as their production and combustion still release greenhouse gases. When considering whether to subsidize biofuels, California must also account for the full lifecycle emissions associated with their production and use.

The Case for Electric Vehicles

In contrast to biofuels, electric vehicles (EVs) offer a more direct pathway to reducing emissions from transportation. EVs are powered by electricity, and when coupled with renewable energy sources like solar or wind power, they can provide a nearly zero-emission solution for personal and commercial transportation. California has already invested heavily in EV infrastructure, including expanding its network of charging stations and exploring how EVs can support grid stability through vehicle-to-grid approaches, and offering incentives for consumers to purchase EVs.

Subsidizing in-state EVs could stimulate job creation and innovation within California's thriving clean-tech industry, with other states such as New Mexico projecting substantial economic gains from transportation electrification, and the state has already become a hub for electric vehicle manufacturers, including Tesla, Rivian, and several battery manufacturers. Supporting the EV industry could further strengthen California’s position as a global leader in green technology, attracting investment and fostering growth in related sectors such as battery manufacturing, renewable energy, and smart grid technology.

Additionally, the environmental benefits of EVs are substantial. As the electric grid becomes cleaner with an increasing share of renewable energy, EVs will become even greener, with lower lifecycle emissions than biofuels. By prioritizing EVs, California could further reduce its carbon footprint while also achieving its long-term climate goals, including reaching carbon neutrality by 2045.

However, there are challenges. EV adoption in California remains a significant undertaking, requiring major investments in infrastructure as they challenge state power grids in the near term, technology, and consumer incentives. The cost of EVs, although decreasing, still remains a barrier for many consumers. Additionally, there are concerns about the environmental impact of lithium mining, which is essential for EV batteries. While renewable energy is expanding, California’s grid is still reliant on fossil fuels to some degree, and in other jurisdictions such as Canada's 2019 electricity mix fossil generation remains significant, meaning that the full emissions benefit of EVs is not realized until the grid is entirely powered by clean energy.

A Balancing Act

The debate between subsidizing out-of-state biofuels and in-state electric vehicles is ultimately a question of how best to allocate California’s resources to meet its climate and economic goals. Biofuels may offer a quicker fix for reducing emissions from existing vehicles, but their long-term benefits are more limited compared to the transformative potential of electric vehicles, even as some analysts warn of policy pitfalls that could complicate the transition.

However, biofuels still have a role to play in decarbonizing hard-to-abate sectors like aviation and heavy-duty transportation, where electrification may not be as feasible in the near future. Thus, a mixed strategy that includes both subsidies for EVs and biofuels may be the most effective approach.

Ultimately, California’s decision will likely depend on a combination of factors, including technological advancements, 2021 electricity lessons, and the pace of renewable energy deployment, and the state’s ability to balance short-term needs with long-term environmental goals. The road ahead is not easy, but California's leadership in clean energy will be crucial in shaping the nation’s response to climate change.

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Summerside Wind Power reached 61% in May, blending renewable energy, municipal utility operations, and P.E.I. wind farms, driving city revenue, advancing green city goals, and laying groundwork for smart grid integration.

Key Points

Summerside Wind Power is the city utility's wind supply, 61% in May, generating revenue that supports local services.

✅ 61% of electricity in May from wind; annual target 45%.

✅ Mix of city-owned farm and West Cape Wind Farm contract.

✅ Revenues projected at $2.9M; funds municipal budget and services.

During the month of May, 61 per cent of the electricity Summerside's homes, businesses and industries used came from wind power sources.

25 per cent was purchased from the West Cape Wind Farm in West Point, P.E.I. — the city has had a contract with it since 2007. The other 36 per cent came from the city's own wind farm, which was built in 2009. 

"One of the strategic goals that was planned for by the city back in 2005 was to try to become a 100 per cent green city," said Greg Gaudet, Summerside's director of municipal services.

"The city started looking at ways it could adopt green practices into its operations on everything it owns and operates and provides services to the community."

Summerside Electric powers about 6,200 residential, 970 commercial and 30 industrial customers and also sells to NB Power, while Nova Scotia Power now generates 30 per cent of its electricity from renewables.

The Summerside Wind Farm is owned by the City of Summerside, which then sells the electricity to Summerside Electric, which it also owns, for profit. 

For the months of April and May, the wind farm generated $630,000 for the city. Last year, it was $507,000 over the same time frame, which does not include a 2 per cent rate increase imposed this year.

"We had a lot of good, strong days of wind for the month of May over other years. So normally we'd be on average somewhere in the range of the 45 per cent range for those months," said Gaudet. 

The city's annual target for wind generation is also 45 per cent, which aligns with the view that more energy sources make better projects. Gaudet said it balances out over the year, with winter being the best and production dropping as low as 25 per cent in the summer months.

At Summerside council's monthly meeting on Monday, May's 61 per cent figure was touted as one of the highest months on record.

"To have one at 61 per cent means we had great production from our wind facilities and contracts, though communities such as Portsmouth have raised turbine noise and flicker concerns in other contexts," Gaudet said.

The utility also owns and provides power through a diesel generation plant.

Municipal money maker
The municipality projects its wind energy production will generate $2.9 million for the city in its current fiscal year, which began April 1, paralleling job gains seen in Alberta's renewables surge this year.

"Any revenues that are received from the wind farm facility goes into the City of Summerside budget," Gaudet said. "Then the council decides on how that money is accrued and where it goes and what it supports in the community."

Wind power generated $2.89 million for the city in the 2019-2020 fiscal year. The budget originally projected $3.2 million in revenue, but blade damage sustained during post-tropical storm Dorian put two turbines out of commission for a few weeks.

Gaudet called this their "only bad year" and officials said they see this year's target to be a bit more conservative and achievable regardless of hiccups and uncontrollable forces, such as the wind they're harnessing.

"It's performed outstandingly well," said Gaudet of the operation.

"There's been no huge, major cost factors with the wind farm to date ... its production has been fairly consistent from year to year." 

Gaudet said the technology has already been piloted at a smaller operation at Credit Union Place, aligning with municipal solar power projects elsewhere.

The goal of the project is to bring Summerside's renewable portfolio up to a yearly average of 62 per cent. Gaudet said it's expected to be commissioned by May 2022 at the latest and after that, the city hopes to focus on smart grid technology.

"It's a long-term goal and I think it's the right [investment] to make," he said. "You have to be environmentally conscious and a steward of your community.

"I think Summerside is that and does that ... a model for North America to look at how a city can work a relationship with an electric utility for the betterment."

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Wildfire Resilient Power Grid Act proposes DOE grants for utility companies to fund wildfire mitigation, grid resilience upgrades, undergrounding power lines, fast-tripping protection, weather monitoring, and vegetation management, prioritizing rural electric cooperatives.

Key Points

A federal bill funding utility wildfire mitigation and grid hardening via DOE grants, prioritizing rural utilities.

✅ $1B DOE matching grants for grid upgrades and wildfire mitigation.

✅ Prioritizes rural utilities; supports undergrounding and hardening.

✅ Funds fast-tripping protection, weather stations, vegetation management.

U.S. Sens. Ron Wyden and Jeff Merkley today introduced new legislation, amid transmission barriers that persist, to incentivize utility companies to do more to reduce wildfire risks as aging power infrastructure ignite wildfires in Oregon and across the West.

Wyden and Merkley's Wildfire Resilient Power Grid Act of 2020 would ensure power companies do their part to reduce the risk of wildfires through power system upgrades, even as California utility spending crackdown seeks accountability, such as the undergrounding of power lines, fire safety equipment installation and proper vegetation management.

"First and foremost, this is a public safety issue. Fire after fire ignited this summer because the aging power grid could not withstand a major windstorm during the season's hottest and driest days," Wyden said. "Many utility companies are already working to improve the resiliency of their power grid, but the sheer costs of these investments must not come at the expense of equitable regulation for rural utility customers. Congress must do all that it can to stop the catastrophic wildfires decimating the West, and that means improving rural infrastructure. By partnering with utilities around the country, we can increase wildfire mitigation efforts at a modest cost -- a fire prevention investment that will pay dividends by saving lives, homes and businesses."

"When this year's unprecedented wildfire event hit, I drove hundreds of miles across our state to see the damage firsthand and to hear directly from impacted communities, so that I could go back to D.C. and work for the solutions they need," said Merkley. "What I saw was apocalyptic--and we have to do everything we can to reduce the risk of this happening again. That means we have to work with our power companies to get critical upgrades and safety investments into place as quickly as possible."

The Wildfire Resilient Power Grid Act of 2020:

* Establishes a $1 billion-per-year matching grant program for power companies through the Department of Energy, even as ACORE opposed DOE subsidy proposals, to reduce the risk of power lines and grid infrastructure causing wildfires.

* Gives special priority to smaller, rural electric companies to ensure mitigation efforts are targeted to forested rural areas.

* Promotes proven methods for reducing wildfire risks, including undergrounding of lines, installing fast-tripping protection systems, and constructing weather monitoring stations to respond to electrical system fire risks.

* Provides for hardening of overhead power lines and installation of fault location equipment where undergrounding of power lines is not a favorable option.

* Ensures fuels management activities of power companies are carried out in accordance with Federal, State, and local laws and regulations.

* Requires power companies to have "skin in the game" by making the program a 1-to-1 matching grant, with an exception for smaller utilities where the matching requirement is one third of the grant.

* Delivers accountability on the part of utilities and the Department of Energy by generating a report every two years on efforts conducted under the grant program.

Portland General Electric President and CEO Maria Pope: "We appreciate Senator Wyden's and Senator Merkley's leadership in proposing legislation to provide federal funding that will help protect Oregon from devastating wildfires. When passed, this will help make Oregon's electric system safer, faster, without increasing customer prices. That is especially important given the economy and hotter, drier summers and longer wildfire seasons that Oregon will continue to face."

Lane County Commission Chair Heather Butch: " In a matter of hours, the entire Lane County community of Blue River was reduced to ashes by the Holiday Farm Fire. Since the moment I first toured that devastation I've been committed to building it back better. I applaud Senators Wyden and Merkley for drafting the Wildfire Resilient Power Grid Act, as it could well provide the path towards meeting this important goal. Moreover, the resultant programs will better protect rural communities from the increasing dangers of wildfires through a number of preventative measures that would otherwise be difficult to implement."

Linn County Commissioner Roger Nyquist: "This legislation is a smart strategic investment for the future safety of our residents as well as the economic vitality of our community."

Marion County Commissioner Kevin Cameron: "After experiencing a traumatic evacuation during the Beachie Creek and Lion's Head wild fires, I understand the need to strengthen the utility Infrastructure. The improvements resulting from Senator Wyden and Merkley's bill will reduce disasters in the future, but improve everyday reliability for our citizens who live, work and protect the environment in potential wildfire areas."

Edison Electric Institute President Tom Kuhn: "EEI thanks Senator Wyden and Senator Merkley for their leadership in introducing the Wildfire Resilient Power Grid Act. This bill will help support and accelerate projects already planned and underway to enhance energy grid resiliency and mitigate the risk of wildfire damage to power lines. Electric companies across the country are committed to working with our government partners and other stakeholders on preparation and mitigation efforts that combat the wildfire threat and on the rapid deployment of technology solutions, including aggregated DERs at FERC, that address wildfire risks, while still maintaining the safe, reliable, and affordable energy we all need."

Oregon Rural Electric Cooperative Association Executive Director Ted Case: "Oregon's electric cooperatives support the Wildfire Resilient Power Grid Act and appreciate Senator Wyden's and Senator Merkley's leadership and innovative approach to wildfire mitigation, particularly for small, rural utilities. This legislation includes targeted assistance that will help us to continue to provide affordable, reliable and safe electricity to over 500,000 Oregonians."

Sustainable Northwest Director of Government Affairs & Program Strategy Dylan Kruse: "In recent years, the West has seen too many wildfires originate due to poorly maintained or damaged electric utility transmission and distribution infrastructure. This legislation plays an important role to ensure that power lines do not contribute to wildfire starts, while providing safe and reliable power to communities during wildfire events. Utilities must, even as Wyoming clean energy bill proposals emerge, live up to their legal requirements to maintain their infrastructure, but this bill provides welcome resources to expedite and prioritize risk reduction, while preventing cost increases for ratepayers."

Oregon Wild Wilderness Program Manager Erik Fernandez: "2020 taught Oregon the lesson that California learned in the Paradise Fire, and SCE wildfire lawsuits that followed underscore the stakes. Addressing the risk of unnaturally caused powerline fires is an increasingly important critical task. I appreciate Senator Ron Wyden's efforts to protect our homes and communities from powerline fires."

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Sunrun-Tesla Virtual Power Plant Texas leverages residential solar, Tesla Powerwall battery storage, and ERCOT demand response to enhance grid resilience, cut emissions, and supply backup power via a coordinated distributed energy resources network.

Key Points

A Texas VPP using residential solar and Tesla Powerwall to aid ERCOT with grid services resilience, and less emissions.

✅ Aggregates Powerwall storage for ERCOT demand response.

✅ Enhances grid reliability with distributed energy resources.

✅ Cuts emissions by shifting solar to peak and outage periods.

In a significant development for renewable energy and grid resilience, Sunrun and Tesla have announced a groundbreaking partnership to establish a distributed power plant in Texas. This collaboration represents a major step forward in harnessing solar energy and battery storage, with advances in affordable solar batteries helping to create a more reliable and sustainable power system. The initiative aims to address the growing demand for clean energy solutions while enhancing grid stability and resilience in one of the largest and most energy-dependent states in the U.S.

The new distributed power plant, a joint venture between Sunrun, a leading residential solar provider, and Tesla, renowned for its advanced battery technology and electric vehicles, will leverage the strengths of both companies to transform how energy is generated and used. The project will deploy Tesla's Powerwall battery systems alongside Sunrun's solar panels to create a network of interconnected residential energy storage units. This network will function as a virtual power plant, aligned with emerging peer-to-peer energy sharing models that are capable of providing electricity back to the grid during periods of high demand or outages.

Texas, with its vast and growing population, has faced significant energy challenges in recent years. The state’s power grid, managed by the Electric Reliability Council of Texas (ERCOT), has experienced strain during extreme weather events and high demand periods, and instances of Texas wind curtailment during grid stress, leading to concerns about reliability and stability. The partnership between Sunrun and Tesla seeks to address these concerns by introducing a more flexible and resilient energy solution.

The distributed power plant will consist of thousands of residential solar installations, each equipped with Tesla Powerwall batteries, reflecting the broader trend of pairing storage with solar across the U.S. as it scales. These batteries store excess solar energy generated during the day and release it when needed, such as during peak demand times or power outages. By connecting these systems through advanced software, the project will create a coordinated network of distributed energy resources that can respond dynamically to fluctuations in energy supply and demand.

One of the key benefits of this distributed approach is its ability to enhance grid reliability. Traditional power plants are centralized and can be vulnerable to disruptions, whether from extreme weather, technical failures, or other issues. In contrast, a distributed power plant spreads the generation and storage capacity across numerous locations, a principle echoed by renewable power developers pursuing multi-resource projects today, reducing the risk of widespread outages and increasing the overall resilience of the power grid.

Additionally, the project will contribute to the reduction of greenhouse gas emissions. By increasing the use of solar energy and reducing reliance on fossil fuels, and amid ongoing work to improve solar and wind technologies, the distributed power plant supports Texas’s climate goals and contributes to broader efforts to combat climate change. The integration of renewable energy sources into the grid helps to decrease carbon emissions and promote a cleaner, more sustainable energy system.

The partnership between Sunrun and Tesla also underscores the growing role of technology in transforming the energy landscape. Tesla's Powerwall battery systems represent some of the most advanced energy storage technology available, and amid record solar and storage growth nationwide this decade they showcase the capability to store and manage energy efficiently. Sunrun’s expertise in residential solar installations complements this technology, creating a powerful combination that leverages the latest advancements in clean energy.

The project is expected to deliver several benefits to both individual homeowners and the broader community. Homeowners who participate in the program will have access to solar energy and battery storage at reduced costs, thanks to the economies of scale and innovative financing options provided by Sunrun and Tesla. Additionally, they will have the added security of backup power during outages, contributing to greater energy independence and resilience.

For the broader community, the distributed power plant offers a more reliable and sustainable energy system. The ability to generate and store energy at the residential level reduces the strain on traditional power plants and enhances the overall stability of the grid. Furthermore, the project will contribute to local job creation, as the installation and maintenance of solar panels and battery systems require skilled workers.

As the project moves forward, Sunrun and Tesla will work closely with local stakeholders, regulators, and utility providers to ensure the successful implementation and integration of the distributed power plant. Collaboration with these parties will be essential to addressing any regulatory, technical, or logistical challenges and ensuring that the project delivers its intended benefits.

In conclusion, the partnership between Sunrun and Tesla to create a distributed power plant in Texas represents a significant advancement in clean energy technology and grid resilience. By combining solar power with advanced battery storage, the project aims to enhance grid stability, reduce emissions, and provide reliable energy solutions for homeowners. As Texas continues to face energy challenges, this innovative initiative offers a promising model for the future of distributed energy and highlights the potential for technology-driven solutions to address pressing environmental and infrastructure issues.

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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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