MERCURY EMISSIONS FROM COAL-FIRED POWER STATIONS IN SOUTH AFRICA By BELINDA LISA ROOS MINOR DISSERTATION Submitted in partial fulfilment of the requirements for the Degree MAGISTER SCIENTAE In ENVIRONMENTAL MANAGEMENT In the FACULTY OF SCIENCE At the UNIVERSITY OF JOHANNESBURG Supervisors: Mrs Thea Schoeman1 Dr Kristy Ross2 University of Johannesburg1 Eskom Holdings SOC Limited2 2011 Mercury emissions 2011 T ABLE OF CONTENTS ACKNOWLEDGEMENTS ...................................................................................................... IV LIST OF FIGURES ................................................................................................................. V LIST OF TABLES .................................................................................................................. VI ABSTRACT ........................................................................................................................... 1 CHAPTER 1 .......................................................................................................................... 2 1. INTRODUCTION ................................................................................................................. 2 1.1. Rationale and objectives ........................................................................................... 4 CHAPTER 2 .......................................................................................................................... 7 2. LITERATURE REVIEW ......................................................................................................... 7 2.1 South Africa and the electricity production sector ................................................... 7 2.1.1 Coal-fired power production .................................................................................... 8 2.1.2 Mercury in coal ....................................................................................................... 10 2.1.3 Eskom’s coal-fired power stations ......................................................................... 11 2.2 Mercury and the effects on human health and the environment .......................... 14 2.3 The speciation and cycle of mercury in the environment ....................................... 15 2.4 Sources of mercury emissions: Anthropogenic versus Natural .............................. 18 2.5 Mercury emissions from coal-fired power stations ................................................ 23 2.6 Factors that affect the capture of mercury in a coal-fired power station .............. 26 2.6.1 Coal Rank ................................................................................................................ 27 2.6.2 Temperature .......................................................................................................... 29 2.6.3 Efficiency of the plant............................................................................................. 29 2.6.4 Emission abatement technology ............................................................................ 30 2.7 Mercury speciation in coal-fired power stations .................................................... 30 2.8 Emission abatement technology in Eskom coal-fired power stations .................... 32 2.8.1 Pre-combustion control ......................................................................................... 34 2.8.2 Post-combustion control mechanisms ................................................................... 34 B L Roos i Mercury emissions 2011 2.9 Mercury Legislation ................................................................................................. 36 CHAPTER 3 ........................................................................................................................ 40 3. METHODOLOGY .............................................................................................................. 40 3.1 Data sources .................................................................................................................. 40 3.1.1 The amount of coal burnt................................................................................ 40 3.1.2 Mercury content in coal (ppm) ....................................................................... 41 3.1.3 Mercury emission reduction factors (ERFs) .................................................... 41 3.2 Data analysis methods .................................................................................................. 43 3.2.1 Annual mercury emitted from 2006 to 2021 ......................................................... 44 3.2.2 Mercury emissions inventory for 2010 .................................................................. 44 3.3 Limitations ..................................................................................................................... 45 3.4 Predictions: mercury emission reductions .................................................................... 45 CHAPTER 4 ........................................................................................................................ 49 4. RESULTS AND DISCUSSION .............................................................................................. 49 4.1 Mercury emissions inventory for 2010 ......................................................................... 49 4.2 Annual mercury emitted from 2006 to 2021 ................................................................ 53 4.3 Co-benefit from the existing particulate control technology ....................................... 56 4.3.1 FFPs versus CS-ESPs ................................................................................................ 56 4.4 Predictions: mercury emissions reduction .................................................................... 58 4.4.1 Scenario 1: FFP Retrofit .......................................................................................... 64 4.4.2 Scenario 2: Wet FGD retrofits ................................................................................ 64 4.4.3 Scenario 3: Wet FGD + SCR..................................................................................... 65 4.4.4 Scenario 4: FFP retrofits, Wet FGD ......................................................................... 66 4.4.5 The implementation of mercury specific technology ............................................ 69 4.4.6 Chemical additives ................................................................................................. 70 4.5 A comparison of the ERFs and the results from the EPAs 2010 investigations. ........... 72 4.6 Mercury regulation for South Africa ............................................................................. 74 B L Roos ii Mercury emissions 2011 CHAPTER 5 ........................................................................................................................ 76 5. CONCLUSION AND RECOMMENDATIONS ....................................................................... 76 REFERENCES ...................................................................................................................... 79 B L Roos iii Mercury emissions 2011 Acknowledgements It is with sincere gratitude that I acknowledge the following: • Eskom Holdings SOC Limited and the University of Johannesburg for allowing me to conduct this study; • my supervisors Mrs Thea Schoeman and Dr Kristy Ross for their support and guidance; • all Eskom staff that contributed to this study; and • my family and friends for their continuous encouragement and motivation. B L Roos iv Mercury emissions 2011 List of Figures Figure 1: The generation of electricity from a coal-fired power station (Miller, 2007b) .............. 9 Figure 2: South African coal fields (Wagner and Hlatshwayo, 2005) .......................................... 10 Figure 3: Stages of the formation of coal: From least desirable (left) to most desirable (right) fuel sources (Miller, 2007a) ........................................................................................................ 11 Figure 4: The location of Eskom coal-fired power Stations (Eskom, 2008)................................. 13 Figure 5: The transport and speciation of mercury in the environment (adapted from Cheng et al., 2009; EPA, 2011a; Miller, 2007b; VanLoon and Duffy 2005). ............................................... 15 Figure 6: South African sources of mercury emissions in 2004 (Pirrone et al., 2009) ................ 23 Figure 7: Emission by products as a result of the combustion of coal in the electricity generation process ...................................................................................................................... 24 Figure 8: Species of mercury that can be formed as a result of coal combustion process at a coal-fired power station (adapted from UNEP, 2010) ................................................................ 30 Figure 9: Emission control technologies at the Eskom coal-fired power stations ...................... 32 Figure 10: The total mercury emissions (kg) from each power station (2010) ........................... 52 Figure 11: Monthly mercury emissions from Eskom’s coal-fired power stations in 2010 .......... 53 Figure 12: Annual mercury emissions from the 2006/07 to the 2020/2021 financial year (based on coal burnt projections from Eskom’s 10-year Production Plan, as on July 2011) .................. 55 Figure 13: Relative mercury emissions from each station (kg mercury emitted/GWh) ............ 58 Figure 14: Possible co-beneficial