Integration and Dynamics of a Renewable Regenerative Hydrogen Fuel Cell System by Alvin Peter Bergen B.A.Sc., University of Victoria, 1994 M.A.Sc., University of Victoria, 1999 A Dissertation Submitted in Partial Fulfillment of the Requirements for the Degree of DOCTOR OF PHILOSOPHY in the Department of Mechanical Engineering © Alvin Bergen, 2008 University of Victoria All rights reserved. This thesis may not be reproduced in whole or in part, by photocopy or other means, without the permission of the author. ISBN: 978-0-494-41177-3 ii Supervisory Committee Integration and Dynamics of a Renewable Regenerative Hydrogen Fuel Cell System by Alvin Peter Bergen B.A.Sc., University of Victoria, 1994 M.Sc., University of University, 1999 Supervisory Committee Dr. Ned Djilali, Department of Mechanical Engineering Supervisor Dr. Peter Wild, Department of Mechanical Engineering Supervisor Dr. Andrew Rowe, Department of Mechanical Engineering Departmental Member Dr. Tom Fyles, Department of Chemistry Outside Member Dr. Brant Peppley, Department of Chemical Engineering, Queen’s University External Examiner iii Abstract Supervisory Committee Dr. Ned Djilali, Department of Mechanical Engineering Supervisor Dr. Peter Wild, Department of Mechanical Engineering Supervisor Dr. Andrew Rowe, Department of Mechanical Engineering Departmental Member Dr. Tom Fyles, Department of Chemistry Outside Member Dr. Brant Peppley, Department of Chemical Engineering, Queen’s University External Examiner This thesis explores the integration and dynamics of residential scale renewable- regenerative energy systems which employ hydrogen for energy buffering. The development of the Integrated Renewable Energy Experiment (IRENE) test-bed is presented. IRENE is a laboratory-scale distributed energy system with a modular structure which can be readily re-configured to test newly developed components for generic regenerative systems. Key aspects include renewable energy conversion, electrolysis, hydrogen and electricity storage, and fuel cells. A special design feature of this test bed is the ability to accept dynamic inputs from and provide dynamic loads to real devices as well as from simulated energy sources/sinks. The integration issues encountered while developing IRENE and innovative solutions devised to overcome these barriers are discussed. Renewable energy systems that employ a regenerative approach to enable intermittent energy sources to service time varying loads rely on the efficient transfer of energy through the storage media. Experiments were conducted to evaluate the performance of the hydrogen energy buffer under a range of dynamic operating conditions. Results indicate that the operating characteristics of the electrolyser under transient conditions iv limit the production of hydrogen from excess renewable input power. These characteristics must be considered when designing or modeling a renewable-regenerative system. Strategies to mitigate performance degradation due to interruptions in the renewable power supply are discussed. Experiments were conducted to determine the response of the IRENE system to operating conditions that are representative of a residential scale, solar based, renewable- regenerative system. A control algorithm, employing bus voltage constraints and device current limitations, was developed to guide system operation. Results for a two week operating period that indicate that the system response is very dynamic but repeatable are presented. The overall system energy balance reveals that the energy input from the renewable source was sufficient to meet the demand load and generate a net surplus of hydrogen. The energy loss associated with the various system components as well as a breakdown of the unused renewable energy input is presented. In general, the research indicates that the technical challenges associated with hydrogen energy buffing can be overcome, but the round trip efficiency for the current technologies is low at only 22 percent. v Table of Contents Supervisory Committee ...................................................................................................... ii Abstract..............................................................................................................................iii Table of Contents................................................................................................................ v List of Tables ...................................................................................................................viii List of Figures.................................................................................................................... ix Acknowledgments............................................................................................................. xii Dedication........................................................................................................................xiii Chapter 1 Introduction ....................................................................................................... 1 1.1 Background.......................................................................................................... 1 1.2 Renewable Energy and Resource Buffering........................................................ 2 1.3 Literature Review Summary................................................................................ 7 1.4 Objectives and Scope of Thesis ........................................................................... 9 Chapter 2 Literature Review............................................................................................ 12 2.1 Modeling of Hydrogen Buffered Renewable Energy Systems.......................... 12 2.2 First Generation Hydrogen Renewable Energy Systems................................... 16 2.3 Second Generation Hydrogen Renewable Energy Systems .............................. 31 2.4 Summary............................................................................................................ 41 PART I : IRENE System Development......................................................................... 43 Chapter 3 IRENE Component Selection and Implications.............................................. 44 3.1 IRENE Design Criteria ...................................................................................... 44 3.2 IRENE System Sizing and Initial Configuration............................................... 45 3.3 Commercial Component Overview ................................................................... 47 3.3.1 Input Power Supply.................................................................................. 47 3.3.2 Short Term Energy Storage ..................................................................... 48 3.3.3 AC Inversion Hardware ........................................................................... 49 3.3.4 AC Load Devices..................................................................................... 51 3.3.5 Hydrogen Generation............................................................................... 52 3.3.6 Hydrogen Storage .................................................................................... 53 vi 3.3.7 Hydrogen Regeneration ........................................................................... 54 3.3.8 Data Acquisition ...................................................................................... 55 3.4 Initial Component Testing ................................................................................. 55 3.4.1 Power Supply Trials................................................................................. 56 3.4.2 AC Inverter and Battery Trials ................................................................ 57 3.4.3 AC Load Bank Trials............................................................................... 59 3.4.4 Electrolyser Commissioning.................................................................... 60 3.4.5 Hydrogen Storage .................................................................................... 64 3.4.6 Fuel Cell Trials ........................................................................................ 65 3.4.7 Data Acquisition and Control Trials........................................................ 66 3.5 Summary............................................................................................................ 67 Chapter 4 System Integration........................................................................................... 68 4.1 General Component Integration......................................................................... 68 4.2 Electrolyser Integration Phase 1 ........................................................................ 73 4.3 Electrolyser Integration Phase 2 ........................................................................ 78 4.4 Hydrogen Storage System Integration............................................................... 83 4.5 Fuel Cell Integration .......................................................................................... 84 4.6 Instrumentation and Control System Integration............................................... 88 4.7 Summary............................................................................................................ 93 PART II : Dynamic Operation of the IRENE System................................................... 95 Chapter 5 Hydrogen Buffer Response to Dynamic Operation ........................................ 96 5.1 Electrolyser Temperature