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Topic

Modeling and optimization of a gas transmission network for supplying natural gas with hydrogen injection

Department of Mechanical Engineering

Date & location

• Thursday, August 1, 2024
• 11:30 A.M.
• Engineering Office Wing, Room 106

Examining Committee

Supervisory Committee

• Dr. Andrew Rowe, Department of Mechanical Engineering, ·¬ÇÑÉçÇø (Supervisor)
• Dr. Peter Wild, Department of Mechanical Engineering, UVic (Member)

External Examiner

• Dr. Phalguni Mukhopadhyaya, Department of Civil Engineering, UVic

Chair of Oral Examination

• Dr. Simon Devereaux, Department of History, UVic

Abstract

This study focuses on optimizing natural gas transmission pipelines transporting methane hydrogen mixtures. The optimization problem employs MATLAB and genetic algorithm to minimize compressor fuel consumption. The optimization targets both single and multi-delivery pipelines. For an 800 km pipeline, the fuel consumption for delivering 8 GW of power is 2.98% for single delivery, and 2.7% for multi-delivery pipelines. Introducing hydrogen into the natural gas mixture increases fuel consumption proportionally, with 5-20vol% hydrogen injections resulting in fuel consumptions of 3-3.8%, respectively, for multi-delivery pipelines. Pure hydrogen (100% H₂) injection leads to a significant increase in fuel consumption up to 19.9%. The study also explores the impact of maximum allowable operating pressure (MAOP) on pipeline performance. In case of multi-delivery pipelines, the maximum operating pressures for natural gas, 10% H₂, 20% H₂, and 100% H₂ are 8.26 MPa, 8.39 MPa, 8.49 MPa, and 8.59 MPa, respectively, when the MAOP is 8.6 MPa. This highlights the need for higher pressures to transport hydrogen enriched natural gas efficiently. Furthermore, the pressure drop is more pronounced for gases with lower molar mass; natural gas exhibits a pressure drop of 6.9%, whereas 5%, 10%, 15%, and 20% hydrogen mixtures show drops of 0.82%, 0.84%, 0.86%, and 0.88%, respectively. The study finds that blending hydrogen reduces CO₂ emissions significantly, with reductions of 1.85-7.25% for 5-20vol% hydrogen injections, respectively. In terms of economic implications, transitioning from natural gas to electric compressors reduces emissions from 430 ktCO₂/year to 31.9 ktCO₂/year, albeit with a cost increase from $15.39 million to $178 million annually. The results underscore the usefulness of the optimization approach in enhancing fuel efficiency and reducing emissions.