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1DWVXUY :DWHUDQG:DVWHZDWHU 0DQDJHPHQWLQWKH SRZHUJHQHUDWLQJLQGXVWU\ (GLWLRQ 77 NATSURV 16 WATER AND WASTEWATER MANAGEMENT IN THE POWER GENERATING INDUSTRY (Edition 2) Report to the Water Research Commission by Gina Pocock, Waterlab (Pty) Ltd Hannes Joubert, VitaOne8 (Pty) Ltd WRC Report No. TT 853/21 July 2021 Obtainable from Water Research Commission Private Bag X03 Gezina, 0031 [email protected] or download from www.wrc.org.za The publication of this report emanates from a project entitled Natsurv 16: Water and wastewater management in the power generating industry (Edition 2) (WRC Project No. K5/2847//3) DISCLAIMER This report has been reviewed by the Water Research Commission (WRC) and approved for publication. Approval does not signify that the contents necessarily reflect the views and policies of the WRC, nor does mention of trade names or commercial products constitute endorsement or recommendation for use. ISBN 978-0-6392-0261-7 Printed in the Republic of South Africa © WATER RESEARCH COMMISSION EXECUTIVE SUMMARY This project aimed to review Natsurv 16: Water and Wastewater Management in the Power Generating Industry, to obtain an overview of operations, specific water use, specific effluent volume, and the extent to which best practice is being implemented, when compared to international benchmarks. The previous edition of the power generation Natsurv compiled by van Zyl & Premlall was published relatively recently (2005) compared with many other Natsurvs that were published in the 1980s. At the time that the previous Natsurv was written, the industry was starting to show a greater commitment to taking measures to reduce the water intake and pollution potential of power generating stations, including the installation of dry cooling and dry ashing systems, the installation of desalination plants to treat mine water which can be used to supplement raw water sources, as well as improved management and operation of processes such as the Zero Liquid Effluent Discharge philosophy that encompasses a number of measures such as reuse, recycling and cascading water use. Water use and comparison with previous Natsurv Conventional fuels (nuclear and fossil fuels) withdraw significant quantities of water (this is seawater in the case of nuclear) over the life cycle of energy production, especially for thermoelectric power plants operated with a wet-cooling system. In 2005 when the previous Natsurv was published, South Africa produced 192 000 GWh of electricity, consuming approximately 245 000 Ml of water. The specific raw water consumption in 2005 was found to be 1.95 l/kWh for recycling wet-cooled coal-fired plants, 0.09 l/kWh for dry-cooled coal fired plants and 0.258-0.306 l/kWh for nuclear: an average specific water consumption of 1.28 l/kWh over all technologies. In 2018/2019, South Africa produced a total of 234 407 GWh for distribution, over 42 000 GWh (18%) more than in 2005, consuming 292 344 Ml of water; 47 344 Ml more than in 2005. In 2013/2014, the specific raw water consumption was 2.2 l/kWh for wet-cooled stations, and 0.12 l/kWh for dry cooled stations. Overall power generating and cooling technologies, the 2013/2014 specific water consumption was 1.35 l/kWh, which was in line with Eskom’s water use target. From 2014/2015 to 2016/2017 the specific water consumption increased above Eskom’s target of 1.35 l/kWh, but this reduced to 1.3 l/kWh in 2017/2018. Unfortunately, the good progress made in 2017/2018 was not realised over the 2018/2019 year with a specific water consumption of 1.41 l/kWh, which missed the target of 1.36. This was attributed to poor water management practices and operational inefficiencies at power stations due to water leaks, water wastage through overflowing tanks, low load factors, several unit trips and boiler filling, as well as slow implementation of water strategy action plans aimed at addressing poor water management practices at the stations. There has therefore been an increase in specific water use of 0.27 l/kWh (9.2%) since the 2005 Natsurv. In 2005, the total dry-cooled installed capacity in South Africa was 10 477 MW, which was approximately 33% of the total installed capacity for coal fired stations. As of March 2019, the installed dry-cooled capacity for the coal fired power stations was 13 806 MW, 34% of the total installed coal fired capacity of 40 170 MW. Once the New Build plants Kusile and Medupi are fully commissioned, the installed dry-cooled coal-fired capacity will increase to 20 188 MW, 50% of the installed coal fired capacity. In 2005, a maximum specific water intake of 2.5 l/kWh at wet-cooled power stations and 0.8 l/kWh at dry- cooled power stations was recommended. 15 years later, despite inefficiencies and high consumption of the return to service stations, the specific water use for wet-cooled stations is still well within this target and far exceeds the dry-cooled target of 0.8 l/kWh, with the average dry-cooled water use at 0.12 l/kWh. In the previous Edition of Natsurv 16, renewable power generation such as wind turbines and solar was not considered. Due to the growing importance of these technologies and their potential future impact, a review i has also been conducted into their water use, even though it is comparatively small. Concentrating solar power plants have specific water use similar or in excess to that of coal fired power stations (0.3 l/kWh for dry cooling and 3 l/kWh for wet cooling) due to the requirement for cooling and location in areas with high temperatures. A summary of the water use per technology for South Africa’s power generation is presented below. Raw Water Boiler Water Climatic Power Plant Type Cooling Type Use WSR Use (l/kWh) Zone (L/kWh) Coal Fired Existing Wet closed cycle 2.04 to 2.38 0.062 to 0.12 Olifants Cold interior Coal Fired Existing Indirect-dry 0.12 0.07 Olifants Cold interior Coal Fired Existing Direct dry 0.12 0.02 Limpopo Hot Interior New super-critical coal-fired Direct dry 0.12 0.02 Limpopo Hot Interior New Coal-fired fitted with FGD Direct dry 0.32 0.02 Limpopo Hot Interior Open-cycle gas turbine NA 0.02 NA Combined-cycle gas turbine Direct dry 0.013 CSP Direct dry 0.3 0.06 Limpopo Hot Interior CSP Hybrid cycle 0.4 to 1.7 0.06 Limpopo Hot Interior CSP Wet closed cycle 3 0.06 Limpopo Hot Interior Solar PVa NA NA NA NA Distributed Wind NA NA NA NA Distributed Nuclear Once through seawater NA NA NA Coastal WSR = water supply region; FSD = flue gas desulfurization; CCS = carbon capture and sequestration; NA = not applicable; CSP = concentrating solar power. a. Water to wash solar PV panels is not considered. Solar photovoltaic (PV) and wind energy exhibit the lowest demand for water and could perhaps be considered the most viable renewable options in terms of water withdrawal and consumption. Moreover, the observed water usage in these renewable energy technologies is predominantly in the manufacturing processes and the abstraction of material for construction, such as rare earths. Comparison with international benchmarks South Africa’s water use for power generation was not benchmarked against international water use in the previous Natsurv. This was done in this revision. On average in South Africa, 1 kWh of electricity consumes about 1.4 l of water across all technologies. This is in line with the world average of 1.2-1.5 l/kWh. Water demands of between 2.04 and 2.38 from the predominantly wet-cooled closed loop thermal power plant fleet are somewhat above the typical mean intensity of 1.7 l/kWh reported by National Renewable Energy Laboratory (NREL) for subcritical coal power plants cooled with wet-recirculating systems; this can be attributed to the decreasing thermal efficiency and increasing age profile of the power plants. Water consumption figures for South Africa’s dry cooled power plants, however, are amongst the best performing in the world. Water use for the direct dry stations (Matimba and the New Build Plants Kusile and Medupi) of 0.12 l/kWh is in line with international estimates of 0.1 l/kWh. The lower water usage profiles for dry cooled power plants can be attributed to state-of-art cooling technologies and lower age profile of these power plants. Wet- cooled water consumption is bound to increase based on current trends; this can be mainly attributed to the decreasing efficiency of wet cooled power plants. ii Water supply and associated risks Water for Eskom’s coal fired power stations is sourced from several dams and supplied to the power stations through a series of supply schemes. The majority of South Africa’s WMAs are under severe duress. This issue gets worse when considering the fact that most of the coal-based power plants are within regions partially or severely constrained in terms of water. Eskom’s RTS power plants namely Camden, Komati and Grootvlei, which are water intensive power plants, are in the severely constrained WMAs namely Olifants and Inkomati. The RTS power plant water consumption factor and total water consumption profile are higher compared to the base load fleet primarily because of lower performance parameters, such as reduced efficiency. Measures aimed towards increasing the efficiency of the RTS or gradual decommissioning could bring considerable changes to the forecasted WMA deficits. The gradual retirement of the RTS fleet could provide added water capacity in these WMAs. The savings of roughly 35 gigalitres associated with the decommissioning of the RTS fleet and operation of the New Build power plants Medupi and Kusile, could account for almost 15% of the forecasted deficit of 234 gigalitres by 2025, which is roughly the amount of water used by one of the larger wet cooled power stations such as Kriel, Tutuka, Matla or Lethabo.

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