238 publications from this institution
This analysis proposes a modified A* routing algorithm for the routing of networked rural electrification systems in areas with substantial topological variation. Due to geographical complexity, using standard A* algorithm for optimal routing is very inefficient. This new algorithm utilizes a modified heuristic to reduce computational time while achieving near-optimal routing results. The modified algorithm is also more suitable for use in routing studies where inputs are uncertain, requiring Monte Carlo simulations to assess the robustness of proposed routes.
Meter-level data, such as those available through advance metering infrastructures (AMI), have enabled extensive monitoring and control of the electric distribution system. In this work, we develop and apply a physics-based model to simulate the heat transfer dynamics for distribution transformers in underground enclosed vaults with no ventilation. The resulting model compares well with predictions from an established semi-empirical model and in field measurements. The model suggests that the transformer aging may be significantly under-estimated, by as much as a factor of ~4, by well-established semi-empirical models for these enclosed submersible transformer applications. Results also show that system-wide application of the model provides transformer-specific insights which should help guide planning and maintenance.
Global efforts to track methane emissions from oil and natural gas operations have recently converged around measures of methane emissions intensity, including emergent requirements for reporting as part of import standards. However, multiple definitions of methane intensity have led to conflicting approaches that hinder clear comparisons among regions and obstruct the development of effective policy. This study analyzes six of the predominant methane intensity metrics and shows how half, by attributing methane exclusively to gas production while overlooking co-produced oil and liquids, can bias comparisons among jurisdictions and have limited practical utility. These naïve loss rates are strongly dependent on gas-oil ratios and tend toward meaningless infinite methane intensities in oil-dominant operations. The three remaining metrics overcome this limitation and are recommended as unbiased and directly intercomparable measures of methane performance. We further show how these latter metrics, which effectively benchmark methane emissions against total energy production, are computationally and functionally equivalent when emissions are allocated to oil and gas operations using energy production. Finally, we address the challenge of propagating emissions through the supply chain, and demonstrate how, for the recommended intensity metrics, embodied intensities of any facility’s outputs can be easily calculated from feeder-facility intensities and energy production.
This document is the nal report to the U.S. Department of Energy (DOE) for contract DE- FE0029068 awarded to Colorado State University (CSU). CSU and subcontractor AECOM partnered with nine U.S. midstream operators to characterize emissions from natural gas gathering and boosting stations (\gathering stations") { a sector of the natural gas supply chain where few measurements have been made and little data are available for component emissions.
