Citation:

Champion, W., M. MacDonald, I. George, J. Carpenter, R. Brown, D. Garver, B. Thomas, AND E. Thoma. Assessing fuel storage tank fugitive emissions using lower-cost sensors and triggered canisters: the Greensboro Storage Tank Assessment with Remote sensing Technologies (G-START) Project. AWMA: Air Quality Measurements, Durham, NC, November 14 - 16, 2023.

Impact/Purpose:

This is an abstract/presentation to be submitted to the Air & Waste Management Association’s Air Quality Measurement Methods and Technology conference, held November 14-16, 2023 in Durham, NC. The presentation will describe a 1.5 year-long monitoring campaign conducted near a fuel storage tank facility/farm in Greensboro, NC (2021-2023) using next generation emission measurement (NGEM) technologies. Although data analysis is on-going, we expect our results to support the use of lower-cost sensors to both inform best operating/maintenance practices for tanks and fuel terminals, and to provide information to nearby communities on their local airshed impacts from nearby fuel storage and distribution.

Description:

Above ground storage tanks/terminals provide an essential link in the transportation of fuel between national infrastructure (e.g., pipelines) and local distribution points (e.g., gas stations). As part of normal operations, volatile components of refined gasoline/fuels (including ozone precursors) are routinely emitted through atmospheric vents around upper perimeters of tanks at variable emission rates impacted by tank construction and configuration, tank condition and maintenance status, terminal activity (e.g., filling and dispensing cycles) and atmospheric factors such as temperature and wind speed. Although U.S. EPA’s AP-42 calculations provide an estimate of annualized emissions from storage tanks, variables such as internal floating roof integrity and penetration seal maintenance can significantly impact emissions. As such, past studies have found that some tanks emit at rates much higher than expected. Due to the complexities of safely measuring tank emissions, the data used to inform emissions inventories generally do not reflect this real-world variability between different in-use tanks. Additionally, since tank emissions include hazardous air pollutants (HAPs, e.g., benzene), near source population impacts may be affected by tank maintenance and operational factors. Use of emerging, next generation emission measurement (NGEM) techniques presents a lower-cost approach to monitor tank emissions from a remote vantage point, to both detect anomalous operation and to ground-truth inventory estimates. In this study, the U.S. EPA’s Office of Research and Development deployed commercially-available, solar-powered Sensit© SPods to measure real-time (0.1 Hz) airborne concentrations of organic vapors using 10.6 eV photoionization detectors (PIDs) at four sites around a cluster of fuel terminals situated along a pipeline in Greensboro, NC. Co-located SPods at each site ran continuously for 7-18 months. Local meteorology was also characterized using 2D sonic anemometers, allowing for development of ‘polar maps’ (and other algorithms) to identify potential source locations. Importantly, the use of ‘triggered’ 1.4 L evacuated canisters was included in the present study, which captured ~50 samples (for 20 seconds each) during periods of elevated VOC concentrations to be analyzed using EPA’s method TO-15. These canister data will provide detailed chemical speciation of the observed plumes, and when combined with the continuous VOC sensor and meteorology data, will allow the study team to better understand how VOC signal relates to HAP concentrations. An in-house data processing and quality assurance (QA) program, SENTINEL (soon to be made available to specified user groups), was used to process raw data and verify numerous QA procedures. Preliminary results are to be presented, evaluating the objectives of: 1) assessing this novel approach to monitor fugitive fuel tank emissions, 2) developing algorithms to identify specific sources, and 3) informing local communities of airshed impacts.

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