California Residential Methane Emissions Characterization (CARMEC)
Research will improve California’s methane emission inventory, quantify benefits of building decarbonization and inform the development of cost-effective strategies to reduce methane emissions from residential buildings.
Lawrence Berkeley National Laboratory
Recipient
Berkeley, CA
Recipient Location
9th
Senate District
15th
Assembly District
$762,051
Amount Spent
Active
Project Status
Project Update
Substantial progress has been made on Task 2 (Synthesize Existing Information and Identify Data Priorities) and Task 3 (Measurement Methods and Field Study Preparations). LBNL and PSE Healthy Energy (PSE) have designed and populated a database that compiles existing measurements of post-meter methane leakage, including from home distribution systems and from individual appliances. The database includes measurements made by teams from LBNL, Stanford University, PSE, and University of Illinois Urbana-Champaign (UIUC) that were collected with methods that were reviewed for validity and accuracy. LBNL and PSE are continuing to investigate the suitability and comparability of various measurement methods. Discussion with Stanford researchers is underway to include measurements that they have and are collecting as part of the CEC-funded project "SUper-eMitters of Methane detection using Aircraft, Towers, and Intensive Observational Network" (SUMMATION, PIR-17-015). LBNL and UC Berkeley (UCB) have adapted methods used previously to measure methane leakage from several fossil gas appliances that had not been previously measured: two clothes dryers, two outdoor grills, and a pool heater. LBNL and UCB are developing and demonstrating measurement methods for other gas appliances, such as fireplaces and wall furnaces that will be used in field sampling. The first Technical Advisory Committee meeting for the project was held on May 31, 2024.
The Issue
Leakage of fossil gas from infrastructure and appliances within residential buildings releases methane, a greenhouse gas that has a warming effect 25 times as potent as that of carbon dioxide over a 100-year time horizon. Methane leakage occurs when equipment is off (quiescent or resting conditions), when burners start and stop, and during steady burner operation. Emissions during resting conditions and during steady burner operation were measured in a pioneering study led by Lawrence Berkeley National Laboratory (LBNL, Recipient) with help from Richard Heath & Associates, Inc. (RHA). In a previous study, the Recipient and RHA measured emissions from 75 houses located throughout coastal and central California and from over 100 appliances in the homes. Subsequent studies have measured emissions during start/stop events, steady burner operation, and in some cases also resting emissions for hundreds of burners on various types of fossil gas appliances in California, Boston, Illinois, Indiana, and New York. These studies have consistently found that methane emission rates are highly skewed, which means that overall emissions from the population are driven by very high emissions from a small fraction of the homes and appliances. The skewed nature of the emission distribution means that an accurate estimate of the overall emission inventory requires more robust data about the frequency and magnitude of high emission equipment. Knowledge of the factors that predict or are associated with high emissions could be used to develop cost-effective programs to identify and replace high-emitting equipment. Accurate emissions data are also important for quantifying the expected benefits of policies that accelerate replacement or avoidance of fossil gas infrastructure, e.g., through electrification retrofits or via restrictions on fossil gas in new construction. Critical deficiencies in the data that have been collected to date limit our knowledge of overall methane emissions from the residential sector and the best approaches to reducing these emissions.
Project Innovation
The project will quantify and elucidate the sources of methane emissions from post-meter fossil gas infrastructure in California’s residential sector. The foundation of the study will be a field sampling campaign in a large and diverse sample of homes that include owner- and renter-occupied houses and multifamily units in the Los Angeles and San Francisco Bay Area urban centers as well as Fresno, Stockton, Sacramento, and Chico, with at least 50 percent of the sample in disadvantaged communities. The study will synthesize methane emissions data that have been collected previously in homes and coordinate with an ongoing study of methane emissions in Bakersfield. The study will greatly expand and improve the quality of available data on emissions from residential gas distribution systems and equipment used for space heating, water heating, cooking, clothes drying, aesthetics, and leisure. Data collection and analysis will aim to identify building, appliance technology, and household characteristics that can be used to screen for high emissions to design efficient decarbonization programs and improve the state’s methane inventory.
Project Goals
Project Benefits
This project will result in the ratepayer benefits of lower costs and increased safety by providing the data and analysis needed to improve cost-effectiveness of programs designed to reduce greenhouse gas emissions, support targeted residential electrification retrofits that will reduce harmful air pollutant emissions inside homes and in neighborhoods, and quantify the benefits of accelerating all-electric new construction standards.
Environmental Sustainability
The project will provide improved information for California’s methane emission inventory, providing better information on emissions from all subsectors, including multifamily and other rental units and homes in disadvantaged communities. The project will also provide solid data to quantify the benefits of transitioning from mixed-fuel to all-electric homes.
Key Project Members
Brett Craig Singer
Wanyu Rengie Chan
Subrecipients
The Regents of the University of California on behalf of the Berkeley campus
Richard Heath and Associates, Inc.
Physicians, Scientists, and Engineers for Healthy Energy
Match Partners
U.S. Department of Energy
