Analysis: Measuring the Carbon Impact of Battery Energy Storage Systems

Measuring the Carbon Impact of Battery Energy Storage Systems white paper cover with the background image of battery storage

Download the white paper PDF:
Measuring the Carbon Impact of Battery Energy Storage Systems

Executive Summary

As the deployment of commercial-scale battery energy storage systems (BESS) accelerates, companies are seeking a common standard for quantifying the system-wide emissions impact that they cause.Companies that operate BESS are also integrating real-time emissions forecasts as signals to optimize the timing of charge/discharge cycles. To the extent that the goal of this strategy is to measure and reduce CO2 emissions into the atmosphere, both the measurement and control signals must use consequential emissions factors to measure and achieve the desired outcome.

This study assesses an Amazon-enabled BESS in California to demonstrate a practical way of estimating the atmospheric CO2 emissions caused by a BESS (including the system-wide short- and long-run impacts) using freely and globally available data. This study also showed that a battery can be operated to achieve multiple objectives (revenue and CO2 avoidance) by very simply combining both objectives into the control signal. It also shows the high cost that can come from using a CO2 signal that doesn’t measure consequential atmospheric emissions impact (e.g., hourly average emissions rates as used in GHG Protocol Corporate Standard Scope 2 reporting).

Estimating the Impact of BESS is Practical

WattTime analyzed an Amazon-enabled BESS in California as a case study to demonstrate a practical method for estimating the consequential emissions impact of a BESS. We used an approach consistent with well-established guidelines and standards for consequential analysis and emissions factors that are freely and globally available. This approach is accessible to any party operating a BESS today.

BESS Can Achieve Multiple Objectives

We found that when the BESS had been operated to maximize revenue, it also avoided substantial CO2 emissions. This outcome would not occur everywhere; it is more likely in places with surplus renewables whose curtailment aligns with negative wholesale prices.

We also analyzed several theoretical scenarios for dispatching the BESS for multiple objectives. We found that there was significant additional potential to avoid CO2—up to 45% more—by combining emissions and price signals when optimizing the dispatch timing of the BESS (this technique is applicable everywhere, with varying degrees of emissions upside).

Different companies may have different budgets and different ideal outcomes. We demonstrated that the objective outcomes can be balanced by customizing the weight of each. There’s a wide range of CO2 abatement costs, from $45 to $170 per tonne, that achieve better than 85% of the best-case outcomes for both objectives. For example, the BESS could avoid 30% more CO2 emissions, while only giving up 4% of maximum revenue, at an abatement cost of $68 per tonne.


The Risks of Optimizing to Reduce Hourly Scope 2 Footprint

Many companies produce annual carbon accounting inventory reports using the GHG Protocol Corporate Standard under Scope 2 for electricity, using data of annual granularity. For BESS to be reflected in this inventory, hourly accounting is necessary. However, this shift to hourly Scope 2 accounting using an attributional framework could incentivize BESS optimization using an attributional signal (i.e., average emissions rates). There are significant climate, health, and financial risks to companies using this attributional framework to guide operational strategy or decision-making. To quantify those risks, we analyzed the outcomes for a hypothetical case where the BESS was optimized to minimize a Scope 2 carbon footprint, measured hourly.

Optimizing the BESS to reduce a company’s Scope 2 hourly carbon footprint would cost $657 per tonne of CO2 inventory reduction. While it would reduce carbon footprint on paper, it would cause an increase in CO2 in Earth’s atmosphere by an estimated 3,509 tonnes. The real-world impact of such an approach extends beyond GHG emissions. On coal-powered grids this increase in CO2 emissions would be coupled with an increase in co-pollutants(e.g., particulate) emissions, which are damaging to human health and cause premature death. This shows the high cost that would come with operating a BESS to reduce a company’s attributional carbon footprint on paper instead of aiming to reduce atmospheric CO2.

Download the white paper PDF: Measuring the Carbon Impact of Battery Energy Storage Systems

More than one billion smart devices now using marginal emissions data to slash power grid pollution with WattTime's 'AER'

As Automated Emissions Reduction (AER) technology continues to scale in smart devices across the globe — including Toyota and BMW EVs, Amazon and Google Nest smart thermostats, Apple iPhones, and more — it has the potential to reduce three billion tonnes of carbon emissions per year by 2030.  

Oakland, Calif. — 14 October 2025 /PRNewswire-PRWeb/ — Environmental tech nonprofit WattTime today announced that more than one billion smart devices globally are now using its marginal emissions data to reduce greenhouse gas emissions from electricity use, in what WattTime calls Automated Emissions Reduction (AER) technology. For context, that’s about twice the combined global subscriber base of Netflix and Amazon Prime, and roughly half the number of Instagram users worldwide.

AER enables electric vehicles (EVs), thermostats, smartphones, and other internet-connected devices to automatically use electricity at times that will cause less pollution, which can vary significantly by location and time of day. This means avoiding the use of electricity when it requires a dirty, fossil fuel power plant to meet that need and instead using more power at times when excess renewable energy is available. 

“What matters to me is stopping climate change, not actually whether people do it with WattTime’s data or someone else’s,” said Gavin McCormick, WattTime Founder and Executive Director. “What’s important here is that so many people are now shifting electricity from times that genuinely make fossil fuel plants run, to times that don’t. I would be so thrilled if, next, someone else announces they’ve enabled even more AER users than we have.”

AER continues to be recognized for its positive climate impact and easy implementation, most recently earning a spot on TIME’s 2025 Best Inventions list last week. McCormick has similarly been awarded for his impact-focused efforts, including his work with AER. Last month, McCormick was featured on Forbes’ 2025 Sustainability Leaders List and named a winner of global philanthropy nonprofit Climate Breakthrough’s 2025 Climate Breakthrough Award.

As for success in the field, many of the world’s largest corporations have already adopted AER, in some cases adding it to more than 100 million new devices in one day. 

Some companies and products that have deployed WattTime’s AER thus far include:

For a detailed list of AER implementations, click here.

EV charging has been an especially impactful use case, due to its flexibility and high energy use. EV companies with AER-enabled charging deployed or in development make up 20% of the global EV market as of 2024. The ubiquity of AER for EVs continues to gain momentum, as WattTime’s partner Rivian is currently integrating WattTime’s marginal emissions data.

Other examples of the many flexible, internet-connected devices and services that can leverage AER include heat pumps, home appliances, battery-powered tools, building energy management software, data centers, virtual computing, and AI training jobs.

“AER is a force multiplier for building decarbonization. Together, our autonomous AI tech and AER demonstrated their positive impact on grid energy use. By shifting building electricity consumption to smarter times, we achieved two key outcomes: reduced emissions and greater use of renewable energy that would otherwise be wasted,” said Jean-Simon Venne, President and Founder at BrainBox AI.

AER’s growing reach has been bolstered by WattTime’s October 2024 global expansion of the first-ever real-time electricity marginal emissions dataset, which made AER available for nearly every country worldwide. After talking with its existing partners about their expansion plans, WattTime believes AER availability will likely double to reach two billion devices in about nine months. 

“Flexible loads like AI and electric vehicles are growing so fast. Based on the US Department of Energy’s projections of growth rates, if everyone adopted this simple, nearly free technology, AER could prevent three billion tonnes of carbon dioxide annually by 2030. That’s about 8% of all greenhouse gas emissions, or larger than any country’s emissions worldwide except China, the US, India, or Russia,” said McCormick.

For EVs in particular, AER can reduce grid emissions from charging by up to 18% annually, and more than 90% on individual days. In other technologies, use of AER has achieved reductions of 25–90%, depending on the device, time of day, and grid region. 

WattTime and others continue to develop new innovations in AER. Most recently, grid operators such as PJM, MISO, and NYISO have joined California in releasing official marginal emissions datasets that make it possible to measure the impact of AER using data straight from the local grid operator or government.

AER can also be programmed to reduce not only carbon dioxide emissions, but also health-damaging air pollutants. For example, companies like Toyota have integrated AER in their app software to create a charging schedule that is likely to reduce both the health and climate impacts of charging with grid electricity. AER can also optimize for the reduction of renewable energy waste, enabling power grids to absorb up to 20% more clean electricity from solar and wind farms.

The other key technology WattTime deploys using marginal emissions, Emissionality, also continues to scale rapidly, having grown from one billion watts to fifteen billion watts in the last twelve months. 

Learn more about AER here. And connect with the WattTime team by sending a message here.   

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About WattTime
WattTime is an environmental tech nonprofit that empowers all people, companies, policymakers, and countries to slash emissions and choose cleaner energy. Founded by UC Berkeley researchers, we develop data-driven tools and policies that increase environmental and social good. During the energy transition from a fossil-fueled past to a zero-carbon future, WattTime 'bends the curve' of emissions reductions to realize deeper, faster benefits for people and planet. Learn more at www.WattTime.org. 

Media contact
Nikki Arnone, Inflection Point Agency for WattTime
nikki@inflectionpointagency.com

WattTime’s Gavin McCormick Wins 2025 Climate Breakthrough Award to Offer Free Impact Analysis for Carbon Accounting Standards

McCormick’s new initiative is one of five selected for its potential to achieve dramatic gigaton-scale “breakthrough” climate impact. 

Oakland, Calif. — 15 September 2025 — Environmental tech nonprofit WattTime today announced that its cofounder and executive director, Gavin McCormick, has been named a winner of global philanthropy nonprofit Climate Breakthrough’s 2025 Climate Breakthrough Award. Climate Breakthrough recognized McCormick for a new initiative that will offer free impact analysis to any interested government and private sector organizations developing carbon accounting systems.

Climate Breakthrough provides $4 million in multiyear, flexible funding — the largest climate award for individuals — for experienced environmental and social change leaders to develop, launch, and scale new high-impact initiatives that Climate Breakthrough concludes could significantly reduce global annual greenhouse gas emissions. All Climate Breakthrough awards must have the potential to materially change the lives of tens of millions and reduce at least 500 million tons of emissions within ten years of launch. 

Through this new initiative, McCormick and his team will help facilitate groups of independent scientists to provide free impact analysis of potential carbon accounting systems and policies before they are completed. The work will combine McCormick’s prior experience individually conducting such analyses at WattTime and the US Department of Energy, with his current experience in the Climate TRACE coalition facilitating groups of independent experts from many organizations in reaching consensus. 

Climate Breakthrough’s analysis concluded this initiative could exceed 2.9 gigatons of annual pollution reduction by 2036. Such large potential is driven by three trends: 

Many policymakers and standards bodies have expressed particular interest in impact analysis jointly conducted by groups of experts from multiple independent institutions. To that end, the new initiative will focus on metastudies, which review and analyze a set of existing studies to synthesize their findings, that examine varying results and explore where there is — and where there is not — consensus on which options would drive the most impact. 

Climate Breakthrough selected McCormick partly due to his technical expertise, but also his proven ability to gather diverse stakeholders and his exceptional talent for helping different technical communities understand one another.

For a full list of 2025 Awardees, read the Climate Breakthrough announcement here. And connect with the WattTime team by sending a message here.   

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About WattTime
WattTime is an environmental tech nonprofit that empowers all people, companies, policymakers, and countries to slash emissions and choose cleaner energy. Founded by UC Berkeley researchers, we develop data-driven tools and policies that increase environmental and social good. During the energy transition from a fossil-fueled past to a zero-carbon future, WattTime 'bends the curve' of emissions reductions to realize deeper, faster benefits for people and planet. Learn more at www.watttime.org. 

Media contact
Nikki Arnone, Inflection Point Agency for WattTime
nikki@inflectionpointagency.com  
Logan Varsano, Inflection Point Agency for WattTime
logan@inflectionpointagency.com

Case study: carbon accounting approaches and an analysis of Meta’s 2023 data center electricity consumption and clean energy procurement

Download the case study PDF:
How carbon accounting approaches do (or don’t) reveal real-world impacts: An analysis of three methodologies to report emissions from Meta’s 2023 data center electricity consumption and clean energy procurement.

Executive Summary

Since 2020 Meta has matched 100% of its electricity use with more than 15 gigawatts of long-term clean energy purchase commitments, making it one of the world’s largest corporate buyers of clean energy. As a result, Meta has reduced its electricity-associated emissions reported under the current industry standard, the Greenhouse Gas Protocol’s (GHGP) market-based method, to nearly zero. But how well do these standard reported methodologies capture Meta’s physical emissions in the real world?

The GHGP has played a key role in driving over 200 gigawatts of corporate clean energy purchases. But today it is undergoing a major revision — its first in over a decade. Since it was last updated, many power grid operators and third-party providers started releasing far more granular and complete emissions data than were available at the time the current system was devised.

These new data show that the carbon intensity of electricity varies substantially by time and exact location. The emissions impact of using or generating electricity depends not just on how much is consumed, but also on when and where — and what technologies (coal, natural gas, hydropower, etc.) are on the grid at that moment. These variations in emissions impact have become even more pronounced in recent years due to the widespread deployment of clean energy. In certain times and places electricity has become very clean — for example, in West Texas when the wind is blowing — while others have changed little.

If we’re serious about reducing pollution from electricity grids and power sector decarbonization, then we need to measure the emissions impact of electricity consumption and clean energy generation more accurately, enabling companies to make informed decisions about where and when clean energy investments can have the greatest impact. The GHGP revision process currently underway provides a critical opportunity to ensure this foundational global standard better reflects real-world variations in electricity’s carbon intensity across time and place.

A key element of past GHGP updates has been examining case studies. At this pivotal moment in the GHGP’s evolution, Meta engaged WattTime to analyze its 2023 data center operations and clean energy procurement using three different methodologies currently under consideration by the GHGP. The goal was to use Meta’s real-world data as a test case for the potential implications of different approaches for all companies.

The three methodologies examined in the case study were: 1) Annual Matching (current GHGP methodology), 2) Hourly Matching (24/7 CFE methodology), and 3) Carbon Matching (emissions matching methodology). This analysis strongly suggests a need for the GHGP (and other carbon accounting frameworks) to adopt more accurate carbon accounting methodologies such as Carbon Matching that more accurately reflect real-world emissions impact and empower companies to make more targeted, better informed, and higher-impact clean energy investments. Methodologies such as carbon matching are well aligned with the three main criteria of the GHGP Scope 2 revisions: scientific rigor, will drive ambition in climate action, and feasibility.

Download the case study PDF:
How carbon accounting approaches do (or don’t) reveal real-world impacts: An analysis of three methodologies to report emissions from Meta’s 2023 data center electricity consumption and clean energy procurement.

REsurety and WattTime announce release of free electricity marginal emissions data platform to drive more impactful climate action

The global power grid emissions data required to take an impact-based approach to carbon accounting and decision making are now freely available for smaller organizations, ensuring that all institutions that can benefit from the data can access it.

BOSTON and OAKLAND, Calif., March 6, 2025 /PRNewswire-PRWeb/ -- REsurety, Inc., the leading provider of software, services, and marketplace solutions empowering the future of energy, and WattTime, an environmental tech nonprofit working to multiply positive climate impact, have today announced the launch of the Grid Emissions Data platform — a free and open resource which provides high-quality marginal emissions data covering the entire globe to qualified end users worldwide to enable an impact-based approach to carbon accounting and decision making.

Marginal emissions data, which measure the carbon impact of consuming or generating electricity at a given time and location, are a critical tool for maximizing and accurately measuring real-world carbon impacts. For example, marginal emissions data enable a strategic approach to clean energy procurement like the one McKinsey & Company recently found to be most effective at reducing emissions. But high-quality data of this nature can sometimes be difficult to access for companies without the budget to pay for it.

"...using data like these to optimize electricity procurement, load shifting, and siting decisions at scale is the only climate solution we've seen with the potential to rapidly reduce over 8 billion tons of carbon dioxide equivalent per year." —Gavin McCormick, WattTimePost this

The Grid Emissions Data platform was made to serve small corporate buyers of clean energy and industry researchers with freely accessible, high-quality, accurate, and granular marginal emission data via a single, third-party website and database.

"More and more organizations are committed to accurately reporting the real-world impacts of their clean energy procurements," said Lee Taylor, CEO of REsurety. "The Grid Emissions Data platform will support and accelerate that trend by offering the highest quality data available, free from the constraints of a paywall."

The marginal emissions data provided on the new platform are consistent with the operating margin data guidelines established in the Guidelines for Quantifying GHG Reductions from Grid-Connected Electricity Projects — part of the The GHG Protocol for Project Accounting published by World Resources Institute (WRI) and The World Business Council for Sustainable Development (WBCSD). In addition, the platform directly supports the kind of approach espoused by the Emissions First Partnership; the group of corporate and tech leaders has called for a shift in corporate carbon accounting standards away from megawatt-hour matching and toward an emissions impact-centric system that maximizes greenhouse gas reductions.

"Slashing emissions is more urgent than ever. And using data like these to optimize electricity procurement, load shifting, and siting decisions at scale is the only climate solution we've seen with the potential to rapidly reduce over 8 billion tons of carbon dioxide equivalent per year," said Gavin McCormick, founder and executive director of WattTime. "That's why we knew — as two mission-driven organizations — that giving away these free data was just the right thing to do."

Designed, developed, and maintained jointly by WattTime and REsurety, the Grid Emissions Data platform offers hourly marginal emissions data on a global scale from the prior three complete years in CSV download format. Users can retrieve data by node, region, or sub-region, where available, and data will be updated at least annually.

Qualified end users — including most smaller buyers of clean energy, auditors, academics, and regulators — can download their selected data at GridEmissionsData.io after completing a simple, free data-use agreement.

For additional questions, email contact@gridemissionsdata.io.

About REsurety
REsurety is the leading provider of data, software, and services to the clean energy economy, and operates the only transactional marketplace for clean power. Trusted by the industry's leading buyers, sellers, and investors, REsurety's proprietary data models, powerful technology platforms, and deep domain expertise empower confident, impactful decision-making and efficient, effective portfolio management. For more information, visit www.resurety.com or follow REsurety on LinkedIn.

About WattTime
WattTime is an environmental tech nonprofit that empowers all people, companies, policymakers, and countries to slash emissions and choose cleaner energy. Founded by UC Berkeley researchers, we develop data-driven tools and policies that increase environmental and social good. During the energy transition from a fossil-fueled past to a zero-carbon future, WattTime 'bends the curve' of emissions reductions to realize deeper, faster benefits for people and planet. Learn more at www.WattTime.org.

Media Contact
Nikki Arnone, Inflection Point Agency for REsurety and WattTime, 1 (719) 357-8344, nikki@inflectionpointagency.com, gridemissionsdata.io

SOURCE REsurety and WattTime

The methodology behind our latest global data expansion

This week we’re excited to announce a major, global geographic expansion of our flagship Marginal Operating Emissions Rate (MOER) carbon data signal — growing from 40 to 210 total countries and territories. You can read the full press release here. With this expansion to ~170 new geographies, WattTime now offers actionable marginal emissions data — available with 5-minute granularity and a combination of historical, real-time, and rolling 3-day forecast perspectives — for 99% of the world's electricity consumption.

MOER coverage map

Accurate, location-specific, timely, and granular MOER signals are central to a trio of solutions — carbon-aware load shifting, emissionality-based renewables siting and procurement, and supply chain decarbonization — that can save more than 9 gigatons of emissions every year. That’s equal to nearly 20% of total global carbon emissions. These solutions also accelerate the reduction of harmful air pollution that disproportionately affects the developing countries that often are last to gain access to technological solutions that improve their lives.

Adopting those three solutions at scale (and unlocking those 9+ gigatons of emissions reductions) depends on a truly global MOER signal. Which is why this week’s announcement represents an enormous step-change for what’s possible.

In this article, we’ll take a closer look at the foundational methodology driving our MOER models thus far, as well as the new methodologies that allowed our team to expand to substantially global data coverage.

The science behind WattTime’s current MOERs

When electricity demand rises or falls, or new wind or solar capacity gets built, which generators respond varies. Namely, a certain generator (or generators) ramp up or down — or turn on or off — in response to changes in load or new renewables added to the grid mix. These power plants on the edge of the dispatch stack order are what’s known as marginal generators, and their associated emissions are what’s described by our MOER signal. Sometimes polluting, fossil-fueled peaker plants might set the marginal emissions rate; at other times, surplus renewables being curtailed might be on the margin.

Scientists agree that such a marginal signal is the best way to guide (and measure the impact of) interventions such as cleaner EV charging to reduce emissions or the avoided emissions of building a new wind farm on a coal-heavy grid.

Our current-best MOER — with foundations in academic literature and iterated on by WattTime for over ten years — is based on causal, empirical modeling. In the grid regions of North America and Europe, we use robust, detailed, generator-level data inputs to refine and train our algorithms. For example, we incorporate generation and emissions data from individual power plants via the US EPA’s Continuous Emissions Monitoring System (CEMS). We get demand, interchange, and generation by fuel type data from the US Energy Information Administration (EIA) and European Network of Transmission System Operators for Electricity (ENTSO-E). We also integrate myriad other data sources into our overall modeling. For regions where these data are available, we feed it all into a binned regression model. The result is today considered WattTime's highest-quality methodology for the MOER signal type.

In regions where we have access to partial real-time and forecasted information about the status of the grid (such as demand or energy prices), but are lacking specific ground truth time series data such as emissions or generation by fuel type required to train a binned regression model, we use a proxy regression model where we use machine learning to identify a data-rich grid with similar characteristics to use as a proxy for the grid with partial data. The power plants for the region of interest are characterized by Climate TRACE and assembled into a supply curve that resembles economic dispatch for the proxy region, which is then used to estimate the MOER based on the real-time demand in the region. MOER data from this “Proxy Regression” model is available in countries such as Brazil, India, Chile, and Turkey. (Longtime WattTime partner Microsoft helped fund development of this method.)

But after deploying these higher-quality MOER signals for the grids of all countries with the necessary data, we still had not covered about 170 countries of the world. Yet many of these are the same countries where emissions are not yet falling, and it’s not good enough to just ignore them. Our latest MOER expansion fixes that in big ways, thanks to a novel modeling approach from our team.

Inside the methodology powering our global MOER expansion

With the goal of making MOER data truly global, we’ve employed a synthetic demand model for countries where we lack historical and real-time grid information. It extends and improves upon the 2021 work of Mattsson et al.

In lieu of actual real-time demand data (like those used in our proxy regression models), the Mattsson framework uses atmospheric estimations derived from ERA5 climate and weather data, along with demographic information, to model synthetic power demand with a mean absolute percentage error of only 8% when averaged by month and hour.

To model the MOER, we expanded upon Mattsson’s academic model to account for more geographic and economic diversity. This enabled us to produce estimates of real-time and forecasted demand. To productionize this, we needed to build a sophisticated weather data modeling pipeline, ingesting gigabytes of global weather data four times a day, thus producing timely synthetic demand estimates. Currently, we’re using these synthetic demand estimates as inputs to our existing proxy regression models in order to produce MOERs using a model we are calling the “Synthetic Demand Proxy Regression” model, or “Synthetic Proxy” for short.

While the MOER signals resulting from this method are inherently less accurate than those that we can derive using the binned regression model, they’re nevertheless useful for both carbon-aware load shifting and renewables siting — which unlocks significant emissions-reduction potential. Of course, data transparency will only increase in regions across the globe. As it does, we will vigilantly be upgrading our MOER signals according to higher-quality binned regression methodologies.

Putting global MOER data into action 

The MOER signals generated via our synthetic proxy regression models unlock potential to enable much more strategic emissions reductions decisions and automations, and in regions that have never before enjoyed access to such actionable data. Historically, granular and accessible emissions data have been far more accessible for countries in the Global North. This release is a major step in closing this gap, and opens up opportunities to drive emissions reductions and new solution possibilities across the Global South.

All WattTime data can be accessed through our API. Basic access is available for free to all users. Partners on our Pro data plan get full access to historical and forecast data, including premium support. Our partners with a global data license will automatically gain access to these new grid regions. Contact our team to learn more.

WattTime expands marginal emissions dataset globally to cover nearly 100% of world's electricity consumption

The nonprofit is working to eliminate the world's emissions data divide — and the inequitable approach to the energy transition — with the first-ever electricity marginal emissions dataset covering nearly every country and region, which can be leveraged to save the world more than 9 gigatons of carbon emissions annually.

OAKLAND, Calif., Oct. 23, 2024 /PRNewswire-PRWeb/ -- Environmental tech nonprofit WattTime has announced the completion of the first-ever hourly electricity marginal emissions dataset for nearly every country worldwide. Today's data release expands the availability of hourly marginal emissions data to 210 countries and territories, covering nearly 100% of global electricity consumption on the world's power grids. Previously, only around 40 countries had such data. WattTime developed this dataset to enable more strategic climate action and emissions reductions decisions, particularly in regions that never had access to such granular and actionable data before.

These data allow users to estimate emissions based on when and where electricity is used, as well as the avoided emissions that can be achieved by investing in renewable energy projects in specific locations. Marginal emissions data empower corporate leaders, policymakers, and consumers to make decisions that reduce or avoid the most emissions.

Historically, a lack of accurate and actionable marginal emissions data has hindered climate action in much of the Global South and other developing countries. This data divide has slowed meaningful climate progress and clean energy deployments in the regions where it is needed most.

"Climate progress is needed worldwide, but all too often, the most cutting-edge, data-driven solutions are only made available in a select few wealthy countries," said Gavin McCormick, founder and executive director of WattTime. "But we will never beat climate change if emissions data experts keep ignoring the rest of the world — because frankly, that's where most emissions are. We're beyond excited to be leaping forward in our mission to give anyone, anywhere the tools needed to slash the emissions. Because we're all in this together."

"At Meta, we believe that using more accurate emissions data drives more informed and impactful climate action. The emissions from a megawatt-hour of electricity can vary widely by time and location, both within and across grids. WattTime's vastly expanded dataset will help all grid participants more accurately assess their carbon footprints and make more targeted climate investments to accelerate grid decarbonization globally," said Brent Morgan, Principal, Energy Strategy at Meta.

"Amazon is committed to making the global power grid carbon-free and more reliable for everyone. We recognize that carbon emissions from electricity generation vary by time and location, making accurate measurement complex. With the right data, we can now better understand the emissions impact of our energy consumption and clean energy purchases. The expanded data from WattTime offers crucial insights to target energy projects where they can have the greatest impact, helping to decarbonize the grid and make it more reliable for all," said Jake Oster, Amazon Web Services (AWS) Director of Energy, Environment and Sustainability Policy.

Marginal emissions data have many uses, but three use cases in particular have dramatic potential to reduce global emissions. Using data from the U.S. Department of Energy, the United Nations, and its own work, WattTime estimates that full global adoption of these three techniques alone could save the world over 9 gigatons of carbon emissions annually:

Renewables siting

Also referred to as "emissionality," this approach uses granular marginal emissions data to help renewable energy buyers target the dirtiest hours and locations on the grid. This approach allows buyers to maximize the climate benefit of their investments by displacing more carbon-intensive power.

WattTime has worked with partners like Apple, Boston University, Clearloop, General Motors (GM) Meta, Nucor, Salesforce, and The Nature Conservancy to enable emissionality-based procurement.

"You can't fix what you can't measure. At Salesforce, we use marginal emissions data to guide our procurement of renewables in locations around the world that can maximize emissions impact," said Megan Lorenzen, Director, Climate & Energy, Salesforce. "The expansion of this dataset will accelerate that work and help close the global data divide — a critical step in reaching our collective climate goals."

"In addition to speeding global emissions reductions, building more renewables in lower-income countries can provide concrete benefits for promoting peace in fragile regions. We at Energy Peace Partners know firsthand the power of expanding clean energy access among vulnerable populations. This dataset — if used well — will help corporate buyers better optimize their procurement and send stronger demand signals for clean energy projects that deliver decarbonization and social benefits together," said Doug Miller, director of market development at Energy Peace Partners.

Now that an emissionality-based approach is possible on a global scale, cloud computing company and WattTime partner PagerDuty has provided WattTime with a grant to help raise awareness of the solution among decision-makers in Global South countries.

Load shifting

Marginal emissions data can be used to power automated emissions reduction (AER) technology and other features that allow for the scheduling of flexible energy demand to reduce electricity-related emissions. Internet-connected devices, like smart thermostats and EV chargers, can use the data to forecast when energy consumption will be cleanest and shift power use to align with those times.

WattTime has worked with companies like Amazon, Apple, BMW, Microsoft, and Toyota to deploy load-shifting solutions driven by marginal emissions data.

Supply chain decarbonization

WattTime's marginal emissions data can also be used to better understand the electricity-related emissions of a company's suppliers, allowing them to make better supplier decisions that contribute to decreases in Scope 3 emissions. WattTime is advancing this use case rapidly in its work with Climate TRACE — a global nonprofit coalition that provides open access to source-level emissions data for every sector and country in the world.

The full dataset is now available to WattTime partners through licensing agreements. A free and simplified version of the dataset suited for many emissions reduction use cases can be accessed by anyone via the WattTime API.

To learn more about opportunities to support or partner with WattTime, contact the team here.

About WattTime
WattTime is an environmental tech nonprofit that empowers all people, companies, policymakers, and countries to slash emissions and choose cleaner energy. Founded by UC Berkeley researchers, we develop data-driven tools and policies that increase environmental and social good. During the energy transition from a fossil-fueled past to a zero-carbon future, WattTime 'bends the curve' of emissions reductions to realize deeper, faster benefits for people and planet. Learn more at www.watttime.org.

Media Contact
Nikki Arnone, Inflection Point Agency for WattTime, 1 (719) 357-8344, nikki@inflectionpointagency.com, www.watttime.org

Is battery energy storage (finally) living up to its promise of enabling a net-zero grid?

From the World Economic Forum to utility industry magazines to the US Department of Energy, in recent years there’s been a growing refrain: how batteries can enable a net-zero electricity grid. Implicit in that statement is the idea that batteries can (and should) help lower grid emissions, increase the integration of zero-emissions renewable energy sources, and support overall power sector decarbonization. Yet battery energy storage is sometimes finding itself in the hot seat for exactly the opposite reason.

Earlier this year, a University of Michigan study focused on the PJM market (the large regional transmission organization covering all or part of 13 U.S. states plus Washington, D.C.) found that batteries sometimes increased grid emissions. While the U-M study was based on older data (from 2012 to 2014), its takeaways echo concerns we’ve heard before. 

In the early 2010s, California’s Self-Generation Incentive Program (SGIP) — a major driver of the state’s behind-the-meter battery energy storage market — shifted its focus to specifically prioritize greenhouse gas reductions for the Golden State’s power grid. But then circa 2018 and 2019, analysis found that batteries were often increasing, rather than decreasing, grid emissions.

Batteries are only as clean as the electricity used to charge them

For the better part of a decade, batteries have been described as a Swiss Army knife of the power grid, capable of performing myriad functions — from customer-centric services such as backup power, peak shaving, solar self-consumption, and time-of-use energy arbitrage to grid-centric services such as frequency and voltage regulation, demand response, and mitigating renewables curtailment.

Ultimately, doing all of that involves software algorithms that dictate when a battery energy storage system charges and discharges. Those algorithms typically co-optimize around various price signals. But it’s the marginal emissions of the power grid at the times a battery is charging vs. discharging that determines whether the battery causes a net decrease (or increase) in grid emissions.

Unless energy storage considers emissions in their control approach, there’s no guarantee that they’ll help decarbonize power grids. Energy journalist David Roberts summed it up well: “It’s a mistake to deploy batteries … as though they will inevitably reduce emissions. They’re a grid tech, not a decarbonization tech,” more akin to transmission lines that can equally carry dirty or clean power, agnostic to the electricity’s generation source and the associated carbon emissions. So, too, with batteries in the absence of the right signals.

California’s battery emissions success story

To address the emissions increase caused by energy storage participating in SGIP, the rules of the program were revised with the goal of enabling the state’s participating behind-the-meter commercial and residential batteries to live up to their emissions-reducing promise. Almost immediately after the rule change, we started to see positive outcomes. A detailed impact evaluation published earlier this year by CPUC with analysis by Verdant gives a longer-term view of SGIP’s turnaround story.

Between 2018 and 2022 (the period covered by Verdant’s analysis), battery systems in California’s SGIP fully reversed course, flipping from causing a net increase in grid emissions to causing a significant net decrease in a resounding decarbonization success.

Now, energy storage has cemented its central role supporting California’s goal of achieving 100% carbon-free electricity by 2045. The state boasts more than 10 GW of installed battery capacity, and earlier this year, batteries became the single largest contributor to the state’s grid briefly during the evening peak. Grid-scale batteries charged on excess daytime solar are starting to displace natural gas power plants. And during this year’s solar eclipse, batteries charged on excess renewable energy carried California’s power sector through the temporary slump in solar PV generation.

Net GHG emissions of battery energy storage in CA's SGIP

A cautionary tale for other states

California may be the country’s most-prominent example, but it’s hardly the only US state setting combinations of both emissions-reduction / net-zero emissions targets as well as energy storage goals. For just four examples, Connecticut, Massachusetts, New Jersey, and New York — all members of the Regional Greenhouse Gas Initiative (RGGI) — each have robust energy storage targets tied to 100% clean energy and GHG reduction goals. So does Michigan.

For energy storage to help these and other states achieve their clean energy goals, it will be crucial to learn from California’s SGIP growing pains — and using a true marginal emissions GHG signal, rather than a proxy metric, to inform batteries’ duty cycles. Just look at what has transpired in Texas and the ERCOT market.

The Lone Star State has been called “the hottest grid battery market in the country.” But analysis from Tierra Climate published in June 2024 in collaboration with REsurety, Grid Status, Modo Energy, and WattTime found that 92% of batteries in ERCOT increased grid emissions in 2023. This is largely because those batteries are not co-optimizing their operation in coordination with a carbon signal like SGIP’s GHG signal. That same report found that co-optimization with a carbon signal (or a carbon price) would move these battery energy storage assets from carbon increasing to carbon decreasing.

The US energy storage market is growing fast, with record-setting capacity additions in Q1 2024 and a staggering 75 GW of cumulative new capacity forecasted to come online during the period 2024–2028. If battery energy storage is to continue living up to its promise of enabling a net-zero grid, it’s more important than ever that state policies and battery control algorithms include a marginal emissions signal as part of their intelligence under the hood.

Inside Texas’s power sector paradox

The United States’ clean energy leader is also its number-one source of electricity emissions. Welcome to the Lone Star State, aka the China of the U.S. in terms of fossil fuel historical dominance — as well as record-setting wind and solar.

In March, Texas published its first-ever greenhouse gas (GHG) inventory, joining more than 20 other U.S. states in cataloging annual statewide emissions. This inventory, which covers the state’s 2021 GHG emissions, revealed the Lone Star State as the United States’ top emitter overall by state. Per both the U.S. EPA and Climate TRACE data from 2022, Texas’s overall, economy-wide GHG emissions were more than double that of America’s second-place emitter, California. 

According to its inaugural self-assessment, in 2021 Texas released more than 873 million tonnes (Mt) of GHG emissions. To put that in context, if Texas were its own country, it would rank 11th on a global scale — just ahead of Mexico and behind Saudi Arabia, according to Climate TRACE 2022 data.

There’s more to this story than meets the eye. Pop culture portrayals of the Lone Star State have long made ample use of oil barons and rigs dipping into dusty prairie, and for good reason… at least historically. While that fossil-fuel-happy reputation still applies — Texas remains America’s top producer of crude oil and natural gas — it’s also become America’s clean energy leader.

So let’s take a closer look at what WattTime knows best (electricity) and unpack Texas’s power sector energy and emissions data to better understand where it has been — and where it might be going.

Everything’s bigger in Texas — including appetite for renewables

The self-proclaimed “Energy Capital of the World,” Houston is fast becoming a clean hydrogen hub and currently ranks #1 on the EPA’s Green Power Partnership list — a program ranking organizations by their voluntary clean energy procurement — in the local government category. In fact, the top six slots nationwide include five Texan entities, including Dallas, DFW airport, Austin, and Harris County. Austin, Dallas, Houston, and San Antonio are all officially working toward net-zero-by-2050 goals. 

Since the early 2000s, Texas has famously led America’s wind energy pack, comfortably sitting in the top spot for installed wind capacity, according to U.S. DOE WINDExchange data. With more than 41 GW, the state is responsible for more than a quarter of all U.S. wind energy capacity, tripling silver-medal Iowa’s contribution of 13 GW. 

Solar PV is growing, too. Late last year, Texas overtook longtime solar leader California to capture the top spot among U.S. states for installed utility-scale solar capacity. And in early 2024 solar generation passed coal-fired electricity generation for the first time in Texas history. 
Although natural gas still leads the generation stack for ERCOT — the independent system operator (ISO) that balances supply and demand for 90% of Texas’s electricity — as of May 2024, wind and solar together are closing in on gas’s lead, with 38.4% of the state’s electric generating capacity, compared with natural gas at 44.3%.

Texas power sector emissions 2021

Texas’s fossil-burning power plants in focus

So with clean energy scaling rapidly, where exactly are all Texas’s electricity generation emissions coming from?

For starters, Texas has some 180 combustion power plants, per Climate TRACE and WattTime data. Most of those are gas–fired power plants. But data from the Texas Comptroller shows that 15 coal-fired plants are currently operational; a third of them are slated for retirement by 2030.
Among those 180 fossil-burning plants identified in Climate TRACE data, the biggest power sector culprit is the dual gas/coal-fired WA Parish Generating Station. With 3.9 GW capacity, the #5 emitter for power plants across the U.S. is notorious among environmental advocates and Texas media outlets, which have been raising alarms about the pollution and harm caused by the WA Parish plant.

power plant satellite image

However, while coal-fired power plants might be Texas’s dirtiest on a per-MWh basis, the sheer size (and policy support) of the state’s gas-fired fleet matters, too. In recent years, the Lone Star State has been digging in its spurs — or, at least, its heels — to prop up the gas fleet.

For instance, in early 2021 Winter Storm Uri infamously caused widespread blackouts across Texas and $195 billion in damages. The Texas PUC set an astronomical system-wide price cap of $9,000 ​​per MWh in a bid to bring more generation online (market-clearing prices were closer to $1,200 per MWh). In the wake of that catastrophe, Texas legislators introduced bills to bolster gas-fired generating resources and keep more fossil-burning power plants online, even though multiple Uri post-mortems found that gas infrastructure was the biggest failure during the winter storm; nearly twice as much gas-fired capacity went offline as wind capacity.

More recently, during April 2024’s total solar eclipse, gas proved Texas’s electricity generation fuel of choice, when ERCOT ramped up gas to make up for solar’s temporary dip.

Austin also illustrated this “can’t quit fossil” dynamic when it approved a plan in 2020 to shut down its greatest source of carbon emissions, the coal-fired Fayette Power Project plant. The decision was a boon to Austinites’ goal of producing wholly emissions-free electricity by 2035; however, the closure never came to pass and the Fayette Plant remains operational today. 

An hour south in San Antonio, CPS Energy — America’s largest municipally-owned electric and gas utility — has already acknowledged it won’t meet the Climate Action and Adaptation Plan the city adopted in late 2019, now that its customers owe $200 million-plus in late bills for natural gas purchased at elevated rates during winter 2021. And in late 2023, ERCOT asked CPS Energy to bring a coal plant it had recently shuttered back into operation in an effort to secure more reserve power ahead of winter.

America’s China?

The energy landscape within America’s second-largest GDP after California in many ways parallels that of the world’s second-largest economy — one similarly marked by massive ongoing power sector emissions, clean energy leadership, heavy industrial growth, surging populations, and uncertainty about how the future will unfold.

Like China, Texas’s key contributors to new emissions stem from the power and industrial sectors. Despite China’s role as the world’s leading deployer of renewable energy in electricity generation — it’s the only entity in the world that tops Texas in installed wind capacity — the production of fossil fuels continues to grow strongly in China, which is the world’s #1 emitter of GHGs. Still, coal’s share within China’s electricity generation mix has steadily declined — as it has in Texas — and the long-term plan is to phase it out. But over the near term, coal will retain its pivotal role within China’s generation mix, which could translate to bumps in its coal-fired emissions. 

Texas is a space to watch for that same phenomenon, especially this summer, as the window spanning May through August historically marks Texas’s high point for power generation and demand. And given the heat wave that slammed Texas over Memorial Day weekend, this summer looks to be a heat demand doozy, requiring fast-response power resources. 

Don’t mess with Texas’s clean energy leadership

On a more hopeful note, in addition to its greenhouse gas inventory, the Texas Commission on Environmental Quality used EPA grant funds to create an emissions reduction plan for Texas. According to its estimates, implementation of suggested measures — divvied into buckets tailored to each of the state’s highest-emitting sectors: industry, transportation, and electric power — could reduce GHG emissions in the Lone Star State by 174 Mt from 2025 through 2030 and 592 Mt from 2025 through 2050.

The plan spells out precise priority measures — voluntary, yet incentivized ones, created with extensive input from a variety of Texan stakeholders. And in 2027, the TCEQ will publish a status report detailing implementation progress, priority analyses, next steps, and future budget and staffing needs to continue deployment of the measures. So it seems Texas is taking its emissions reduction plan seriously.

A shining example of a power grid in the midst of a massive transition — wherein wind, solar, and battery energy storage are poised to together become the dominant wedge of the power generation pie, supplanting natural gas’s piece — Texas provides a valuable example for how grids across the country can tap wind, scale up solar, utilize existing energy infrastructure to generate clean hydrogen, and ultimately, decarbonize the power sector. Especially as coal-fired generation retires in the years ahead, Texas’s model, from a clean energy leadership perspective, is one not to be messed with.

WattTime selected for climate-focused Salesforce ‘AI for Impact’ accelerator program

Five nonprofits will receive support to further develop and scale AI-driven climate solutions and tools; WattTime will prioritize expanding user partnerships to maximize potential emissions reductions from its AI-powered tools.

Oakland, Calif. — 25 April 2024 — Environmental tech nonprofit WattTime today announced it has been selected by global software leader Salesforce as part of its new Salesforce Accelerator AI for Impact program — a philanthropic initiative to equip purpose-driven organizations with trusted generative AI technologies.

Salesforce selected five nonprofits to support through the accelerator, which is focused on AI-driven climate solutions. The technologies and teams selected are addressing a wide range of climate issues, from mitigation and adaptation to equitable climate finance. 

WattTime’s focus for the Salesforce accelerator program will be on scaling the reach of its marginal emissions data signal and API. Today, these tools allow WattTime partners to enable hundreds of millions of internet-connected devices to shift electricity usage to sync with clean power; they also allow corporate sustainability teams to strategize on the most impactful locations for renewable energy investments. However, these successful partnerships represent only a small fraction of what WattTime estimates could be more than 9 gigatons of carbon dioxide (CO2) reductions annually. With Salesforce’s support in AI technology, expertise, and resources, WattTime aims to greatly expand its partnerships to realize these  emissions reduction impacts. 

“We believe good data are the foundation of good climate decision making, which is why we’re so thrilled to have this new wave of support from Salesforce,” said Gavin McCormick, founder and executive director at WattTime. “With their help, we can improve our AI- and data-driven tools and get them into the hands of the world’s largest corporate leaders. We can enable even more users to reduce their emissions footprint quickly, affordably, and efficiently. Scaling these tools is a no-regrets option that can make a real difference for our climate future.” 

Salesforce will support each of the five nonprofits in the AI for Impact cohort with technology, investment, and philanthropy — including product donations and $2 million in shared funding — to help each team enrich the world’s climate action toolbox. Organizations will also receive a year of pro-bono consulting from Salesforce experts focused on strategy, planning, technical architecture, and more. 

In addition to WattTime, other nonprofit organizations selected for the accelerator include Climate Collective Foundation, Good360, Groundswell, and Ocean Risk and Resilience Action Alliance (ORRAA). 

In tandem with the accelerator, Salesforce also announced a new set of policy principles focused on the sustainable use of AI technology. The framework shares guidance on proposed AI regulations to minimize environmental impacts and drive stronger climate innovations. 

Becky Ferguson, CEO of the Salesforce Foundation and SVP of Philanthropy at Salesforce, shared: “Generative AI presents a massive and exciting opportunity for purpose-driven organizations to better serve and meaningfully engage with their communities. In this time of rapid innovation, we need to ensure no one gets left behind. This AI accelerator brings the full power of Salesforce with unrestricted grants, pro-bono expertise, and our technology to create a more equitable AI world.”

To learn more about opportunities to support or partner with WattTime, contact the team here. 

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About WattTime
WattTime is an environmental tech nonprofit that empowers all people, companies, policymakers, and countries to slash emissions and choose cleaner energy. Founded by UC Berkeley researchers, we develop data-driven tools and policies that increase environmental and social good. During the energy transition from a fossil-fueled past to a zero-carbon future, WattTime ‘bends the curve’ of emissions reductions to realize deeper, faster benefits for people and planet. Learn more at www.watttime.org. 

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