These simulators are fast, and if the input data is strongly representative of the simulated facilities, as accurate on average as traditional inventories using the same inputs. However, since these simulators rely on emission and activity distributions collected from previous studies, simulated sites lack site-specific behaviors. One 255 common example is that emissions do not scale with the throughput of sites, leading to cases where a small site may produce unrealistically high emissions, or the inverse, where emissions are unrealistically low for a high-throughput site. Additionally, this type of simulation cannot readily represent failure conditions coupled with other failures or process conditions. For example, when wells cycle between production and shut-in (a common production method), emissions from failure conditions typically cycle with the wells. Since these ulations. Mechanistic modeling retains the coupling between equipment units represented in physio-chemical models, retaining realism while gaining significant computational efficiencies. Conversely, for smaller emitters, or emitters which are not heavily impacted by mechanistic coupling, MAES utilizes time series variants of traditional inventory methods, similar to those used in purely stochastic simulators. SI Section S-5 describes both methodologies and specifies which method was utilized for each emission type (e.g., seal vents, 270 component leaks, tank thief hatch, etc.).