VANADIUM REDOX FLOW BATTERY Sizing of VRB in electrified heavy construction equipment NATHAN ZIMMERMAN School of Business, Society and Engineering Supervisor: Javier Campillo, Bobbie Frank Course: Degree Project Date: 2014-07-13 Course code: ERA401 Email: [email protected] Subject: Energy Engineering HE credits: 30 Program: Master of Science Program in Sustainable Energy Systems ABSTRACT In an effort to reduce global emissions by electrifying vehicles and machines with internal combustion engines has led to the development of batteries that are more powerful and efficient than the common lead acid battery. One of the most popular batteries being used for such an installation is lithium ion, but due to its short effective usable lifetime, charging time, and costs has driven researcher to other technologies to replace it. Vanadium redox flow batteries have come into the spotlight recently as a means of replacing rechargeable batteries in electric vehicles and has previously be used mainly to store energy for load leveling. It possesses many qualities that would be beneficial to electrify vehicles. The battery has the ability for power and energy to be sized independently which is not dissimilar to internal combustion vehicles. It also has the potential for a tolerance to low discharges, fast response time, and can quickly be refueled by replacing the electrolyte; just like is done when a car refuels at the gas station. The purpose of the study is to determine the possibility of using vanadium redox flow batteries to power heavy construction equipment, a wheel loader, with a finite amount of space available for implementation. A model has been designed in MATLAB to determine how long the battery could last under typically applications for the wheel loader which needs a peak power of 200 kW. From the volume available it has been determined that the battery can be installed with an energy capacity of 148 kWh. The results of the model show that vanadium redox flow batteries can be used to power a wheel loader but due to the limiting energy density and cell components it remains to be impractical. Keywords: All-vanadium redox flow battery, Vanadium, Energy storage, Batteries, Electric vehicle electrification. ii TABLE OF CONTENTS 1 INTRODUCTION .............................................................................................................1 Rechargeable Electrical Energy Storage ............................................................... 1 Batteries in Vehicles ........................................................................................ 2 Types of Batteries ............................................................................................ 2 1.1.2.1 Lead-Acid ....................................................................................................2 1.1.2.2 Sodium-X ....................................................................................................3 1.1.2.3 Nickel-metal Hydride ...................................................................................3 1.1.2.4 Lithium-ion ..................................................................................................3 1.1.2.5 Energy Storage Comparison .......................................................................3 Redox Flow Batteries .............................................................................................. 5 Electrochemistry .............................................................................................. 6 1.2.1.1 Redox Reactions and the Galvanic Cell ......................................................6 Vanadium Redox Flow Battery ............................................................................... 7 VRB System .................................................................................................... 8 The Advantages and Disadvantages of VRB Technology ................................ 9 Power & Energy ..............................................................................................10 1.3.3.1 Equilibrium Potential – Nernst Equation .................................................... 10 1.3.3.2 Standard Potential..................................................................................... 11 Cell, Module, Pack ..........................................................................................13 1.3.4.1 Cell Stack/Module ..................................................................................... 13 VRB Performance Aspects ....................................................................................15 Battery performance .......................................................................................15 Vanadium ................................................................................................................16 Vanadium Procurement ..................................................................................16 Vanadium Health and Environmental Impact ..................................................16 Purpose ...................................................................................................................17 Scope and limitations .............................................................................................18 2 DESCRIPTION OF CURRENT STUDY ......................................................................... 18 3 METHOD ....................................................................................................................... 19 VRB Sizing ..............................................................................................................19 SOC and Vanadium Concentration .................................................................20 Cell Stack ........................................................................................................22 Tank size ........................................................................................................22 iii Pump sizing ....................................................................................................23 4 SIMULATION AND RESULTS ...................................................................................... 24 Model 1 – Constant Current and Flow Rate ..........................................................25 Flow rate and Pumps ......................................................................................25 Cell Stack ........................................................................................................27 Power .............................................................................................................28 Volume ...........................................................................................................30 Energy ............................................................................................................31 Efficiency ........................................................................................................33 Model 1 Optimal Parameters Results ..............................................................34 Model 2 – Varying Current and Flow Rate ............................................................34 Varying load ....................................................................................................37 System Breakdown ................................................................................................40 Cost Analysis ..........................................................................................................41 Refuelling ................................................................................................................48 5 DISCUSSION................................................................................................................. 49 Model Limitations with Improvements ..................................................................49 Vanadium Concentration .................................................................................49 SOC ................................................................................................................50 Flow rate .........................................................................................................50 Increasing Power Density ......................................................................................50 Reducing Costs ......................................................................................................51 Comparison to the Industrial Standard – Li-ion ...................................................51 Semi-Solid Flow Cells .....................................................................................53 6 CONCLUSIONS ............................................................................................................ 54 7 SUGGESTIONS FOR FURTHER WORK ...................................................................... 54 iv LIST OF FIGURES Figure 1: Battery Comparison1. .................................................................................................. 5 Figure 2: Simplified Redox Reaction. ........................................................................................ 7 Figure 3: Vanadium Redox Flow Battery. .................................................................................. 9 Figure 4: VRB Cell Stack. .......................................................................................................... 13 Figure 5: VRB zero-gap cell stack..............................................................................................14