The 4.8GW Kusile power station is expected to be one of the world’s largest coal-fired power plants upon completion.
The power station is being constructed by state-run electricity public utility Eskom Holdings SOC in Mpumalanga, South Africa.
The plant adopts supercritical-pressure technologies for more efficient generation of power than standard coal-fired systems, resulting in a significant reduction in CO₂ emissions.
The construction of the power plant began in August 2008. Units one and two were synchronised to the national grid in March and July 2017. Unit one was brought into full commercial operation in August 2017.
The third unit was synchronised by March 2019. Units two and three started full commercial operations in October 2020 and March 2021.
Unit four was synchronised to the grid in December 2021 and brought into full commercial operation in June 2022. Units five and six are expected to come online in December 2023 and May 2024.
The total planned operational life of the power plant is 50 years. Once all six units are complete the plant will generate enough electricity to power 3.5 million South African households.
Chimney failure at the Kusile power station
In October 2022, the Kusile Unit one flue gas desulphurisation (FGD) duct collapsed due to an excessive weight of slurry deposited in the flue, resulting in the failure of the flue chimney that also houses the units two and three flue gas ducts.
Units one, two and three had to be brought offline for the repair and maintenance of the damaged stacks, which is expected to be completed by December 2024.
In March 2023, Eskom was granted the exemption by the Department of Environment, Forestry and Fisheries (DEFF) of the South African Government. This exemption allowed Eskom to amend its atmospheric emission licence and temporarily bypass pollution regulations at Kusile to restart the three affected units a year sooner.
Eskom can seek regulatory approval to construct temporary stacks and operate the three units without the use of the FGD mechanism from November 2023 until the permanent stacks are repaired and restored in 2024.
Location of the Kusile power station
The 5,200ha site that hosts the plant is located between freeways N4 and N12 in Mpumalanga. It is situated west of the R545 and has the Kendal power station in its vicinity.
The plant is being constructed on the Hartbeesfontein and Klipfontein farms, which were once used for agriculture and cattle grazing.
Kusile power station details and technology
The Kusile power plant is designed to integrate six generating units, each with an 800MW capacity. Kusile is the first South African coal-fired power facility to incorporate state-of-the-art wet FGD technology.
The FGD technology is used to extract sulphur oxides (SOₓ) from the flue gases of the power plant, which burns fossil fuels. It will help in removing 90% of the sulphur oxide produced by the boilers. The technology is also an atmospheric emission abatement technology in line with current international practice.
FGD is being implemented in Kusile to meet air quality standards, as the plant is based in a priority airshed. It utilises limestone as the raw material for desulphurisation and produces gypsum as a by-product.
The power plant will comprise six STF100 steam turbines and six GIGATOP generators. The hydrogen-cooled generators will increase the efficiency of the power plant. Each supercritical tower boiler is approximately 115m high. The 300t 910MVA generator step-up transformer was put on its foundation in October 2014. An air-cooling system is used in the plant to conserve water.
The fossil fuel coal is used to produce the steam that drives the steam turbine and connected electricity generators and associated air-cooled condensers are supported by 60m-high concrete columns. The plan will also include turbine island auxiliary equipment, along with six feedwater heating plants.
Other associated infrastructure for the power station include administrative buildings, a coal stockyard, coal and ash conveyors and water-supply pipelines. There will also be water and wastewater treatment facilities, ash disposal systems, a railway line, a high-voltage yard, limestone offloading facilities, access roads and dams for water storage.
Power station financing
Funds of R31bn ($2.3bn) are being provided by French banks, including Calyon, BNP Paribas, Societe Generale, Natixis and CIC. BNP Paribas is serving as a documentation bank, as well as a facility and export credit agency (ECA) agent.
The funds are provided through a fixed-interest rate loan covered by COFACE, the French ECA. The loan can be repaid over 12 years, after the commissioning of relevant units of the power plant.
In May 2011, Eskom received an R5.7bn ($805.6m) loan from the Export-Import Bank of the US.
As of early 2015, the estimated cost of the project excluding interest was R82bn ($6.04bn). Furthermore, it was estimated that the project would require a total of R118bn ($8.7bn) till completion.
In July 2018, Eskom secured a $2.5bn loan from China Development Bank to complete the Kusile power station project.
The R2.9bn ($213m) main civil works contract was awarded to the Kusile Civil Works joint venture (JV) in 2008. Construction companies, including Stefanutti Stocks, Group five, Basil Read and WBHO Construction, are part of the JV.
In 2007, Eskom awarded an R31bn ($2.3bn) contract to acquire the boilers for the plant to Hitachi Power Africa, now Mitsubishi Hitachi Power Systems Americas, and the plant’s steam turbines to Alstom. In 2008, a contract that involved the supply of generation transformers was awarded to Siemens.
Murray & Roberts Power & Energy (MRPE), a subsidiary of South African engineering and contracting group Murray & Roberts, was contracted to erect the boiler structures, related pressure parts, supplementary piping, coal bunkers, fuel burners, ducting systems and associated mechanical systems to feed coal and reticulate air.
RIB CCS, a subsidiary of Germany-based RIB Software, provides engineering and construction management software solutions to MRPE for the project.
A $122.4m contract for the plant automation was awarded to Alstom in February 2010. Under the contract, the ALSPA Series 6 distributed control system (DCS) from Alstom is installed in the power plant. The system controls all the plant’s equipment, including turbines, generators and other components.
In February 2011, the Cosira Group and Alstom S&E (Alstom) consortium were contracted to provide the FGD technology for all six boilers of the plant.
Anglo Coal’s subsidiary, Anglo Inyosi Coal, was contracted to supply the necessary fuel to the Kusile power plant. Approximately 17 million tons of coal will be supplied by Anglo Inyosi Coal for a period of 47 years. In addition, the fuel will be supplied from the New Largo reserve.
General Electric (GE) was contracted for the engineering, procurement and construction (EPC) of six turbine islands, air-cooled condensers and the FGD plant of unit one in September 2017. Mitsubishi Hitachi Power Systems, the main boiler contractor, completed the delivery of the first supercritical-pressure boiler for the plant in the same month.
Bateman Engineering Group was contracted to carry out materials handling work at the plant. The scope of work includes the construction of the overland and in-plant conveyors, stockyards, civil works and electrical and instrumentation work. Bateman is also responsible for installing stacking and reclaiming equipment.
Black & Veatch had secured the contract to design the Kusile power station. As Eskom’s execution partner for the project, its services include planning, engineering and design, construction management, contracts management and claims and procurement management. Black & Veatch services also include health and safety management.
Kusile power plant environmental programme
An environmental impact assessment programme was conducted in March 2006 and received the Record of Decision (ROD) in June 2007. However, the Minister of Environmental Affairs and Tourism revised the ROD and issued environmental authorisation for the project in March 2008.