Mohit Dubey and Yuanrui Zhu: Lightning talks on solar spectrometer networks and geospatial LCA models

Mohit Dubey

Abstract

Despite advances in satellite technology and retrieval algorithms, there is still no existing method that reliably measures methane sources on the order of 1 km spatial scale at leak rates below 100 kg/hr. Furthermore, a large majority of known methane sources including landfills, wetlands, and agriculture fall under this category of undetected “diffuse” emissions, due to the non point-like nature of their plumes. We propose a potential solution to this data gap via a network of affordable (<$10,000) Butterfly solar spectrometers, which will enable dense networks of slant column measurements and provide a novel method for monitoring emissions. Improving upon previous studies which used sparse networks of compact Bruker solar Fourier Transform Spectrometers (EM27/SUN, $150,000), our proposed dense network will generate columns that “sweep” across the entire emission landscape and will provide more robust spatial information and greater overall sensitivity. By enabling footprint estimates along the slant columns via emulators, we can decrease the computational cost of converting total column concentration to flux estimates. These emulators will approximate Lagrangian particle dispersion trajectories (similar to those of WRF-STILT) on spatial resolutions from 100 m up to 3 km, resulting in novel estimates of methane emissions from previously poorly characterized sources.

Bio

Mohit Dubey is a PhD Student in the Department of Environmental Engineering at UC Berkeley, advised by Tina Chow (UCB) and Sebastien Biraud (LBNL). Dubey researches the measuring and monitoring of methane emissions across multiple scales using a variety of remote sensing and in situ methods. His recent work, in collaboration with researchers at LBNL, was helping to develop the FAST method for estimating emission rates from orphaned wells. He is currently investigating the estimation of basin-scale methane emissions using a novel solar spectrometer network in collaboration with Butterfly Photonics.

Yuanrui Zhu

Abstract:

Growth in US liquefied natural gas (LNG) exports has increased concerns about the climate impacts of methane leakage along LNG supply chains. Given the underestimation of official inventory and observed significant emission variation across oil and gas basin, we develop a geospatial, measurement-informed life cycle analysis (LCA) model that incorporates recent top-down methane measurements to examine regional differences in greenhouse gas (GHG) emissions intensity of US LNG supply chains for delivery to Europe and Asia.  For every megajoule of LNG shipped from the US, the energy allocated GHG emissions intensity of the Permian-UK LNG supply chain is 42% higher compared to the Marcellus-UK LNG supply chain. Differences in basin-specific, measurement informed inventories are a key driver of disparities in supply chain LNG emissions intensity. Developing measurement-informed, supply-chain-specific lifecycle GHG emissions assessments is critical to enabling a global market for differentiated natural gas.

Bio:

Yuanrui Zhu (yuanruizhu@utexas.edu) is a PhD candidate in the Department of Petroleum and Geosystems Engineering at the University of Texas at Austin. Her research focuses on enhancing the accuracy of greenhouse gas emission estimation across oil and natural gas supply chains. She has received the 2023-2024 Chevron Energy Graduate Fellows Award. She has published two journal papers and presented in more than five conferences, contributing to advancing methods for more precise environment impact assessments in the energy sector.