Advertise on Plumbing Online

Ingula finally set to come on-streamy

Martin Czernowalow

Africa’s newest and largest pumped storage scheme is about to go into commercial operation this year — four years behind schedule and just about R27-billion over budget.

 Eskom’s Ingula Pumped Storage Scheme power station of 1 332MW was initially supposed to have become fully operational in 2013; however, the project suffered numerous delays and costs are said to have spiralled to roughly R35-billion from an initial budget of R8.9-billion.

The escalating cost of the project was first reported by investigative journalism television programme Carte Blanche last year, and these claims were seemingly backed up by Eskom spokesperson Khulu Phasiwe, who confirmed in media reports that the project had been plagued by unexpected costs and delays.

“So far we are doing everything possible to exceed the current amount that has been flaunted about. All we know at this stage is that the audited figures for the project is just over R26.8-billon,” he said, adding that a number of lessons had been learnt.

However, outgoing Eskom CEO Brian Molefe has rubbished the Carte Blanche report, describing it as a “hopelessly inaccurate story” that failed to present the power utility’s side. However, Molefe did not provide any clarity on the alleged irregularities or correct the budget amount presented by the programme.

Molefe subsequently resigned from Eskom towards the end of last year, amid the release of former public protector Thuli Madonsela’s report on state capture.

Meanwhile, commentators have pointed out that the cost of the Ingula delay is having a huge impact on South Africa’s economy.

The hydropower station is planned to function as a peaker plant, generating 1 332MW of electricity during peak periods. It would have reduced Eskom’s costly reliance on its diesel-powered open cycle gas turbines or, alternatively, reduced the need to revert to load-shedding had it been ready in 2012/13. Eskom’s diesel bill in 2015 was said to have been about R1-billion per month and necessitated further tariff increases.

The final unit — Unit 3 — of the Ingula Pumped Storage Scheme was synchronised to the national grid late last year. Eskom revealed that Unit 3 was previously synchronised to the national grid in March 2016 and supported the grid until 6 April 2016, when an ‘electrical incident’ occurred.

The synchronisation process entails the generator in the unit being electrically connected to the national power grid in such a way that its power is perfectly aligned with all the other generators to generate and deliver electricity into the country’s power grid.

 


 The power utility has previously stressed that it remains committed to bringing new capacity online, with 9 104MW to be commissioned over the next six years.


 

Expanding capacity

Ingula’s Unit 4 went into commercial operation on 10 June 2016, while Units 2 and 1 were put into commercial operation on 22 and 30 August 2016, respectively. The four units are located 350m underground in the world’s largest machine hall in mud-rock.

The Ingula hydropower station forms part of Eskom’s capacity expansion programme, along with the Kusile and Medupi coal-fired power stations, which are expected to become fully commercially operative in 2018.

The power utility has previously stressed that it remains committed to bringing new capacity online, with 9 104MW to be commissioned over the next six years.

This comes as Eskom is under increasing pressure to up its electricity generation capacity, with latest figures showing that the fundamentals of the business are not in a healthy state. The state-owned entity’s electricity output has been falling every year for almost a decade.

A recent report released by Stats SA shows that Eskom produced and sold 171 186 gigawatt hours (GWh) of power in the nine months ended September — against 173 689GWh in the first nine months of 2015. Furthermore, the Stats SA numbers (based on Eskom data) show its production has decreased every year since 2007, when it hit 241 170GWh. For all of last year, Eskom generated 230 000GWh.

The Ingula pumped-storage project is located on the Great Escarpment geological formation in the Little Drakensberg range and straddles the border of the Free State and KwaZulu-Natal provinces.

According to Eskom, to build a pumped storage scheme requires a specific combination of factors to be just right, including the right geology, enough available water, and two sites to build dams close enough together, but with at least 400m difference in altitude.

The scheme also needs to be close to the national grid and existing infrastructure. The utility started looking for such sites in the 1980s. Initially, more than 90 potential sites were investigated, resulting in the shortlisting of three. The best site was selected north-east of Van Reenen’s Pass, spanning the escarpment of the Little Drakensberg, and straddling the provincial boundary of the Free State and KwaZulu-Natal.

This is also the continental watershed between the Vaal River catchment, flowing into the Atlantic Ocean, and the Tugela River catchment, flowing into the Indian Ocean.

The pumped storage scheme consists of an upper and a lower dam, each capable of holding more than 20-million cubic metres of water. The dams, 4.6km apart, are connected by underground waterways passing through a subterranean powerhouse with four 333MW generators.

 


 Upon completion, Ingula will be Africa’s newest and largest pumped storage scheme and the nineteenth largest in the world.


 

Peak demand

The plant uses water from the upper reservoir to generate electricity when there is peak demand during the day. At night, excess power on the grid, generated by conventional coal and nuclear plants, is used to pump water to the upper reservoir.

The upper Bedford Dam, on Bedford stream — a tributary of the Wilge River — was completed in April 2011. It is a 39m tall concrete-face rock-fill dam. It has a 22.4-million cubic metre water storage capacity, of which 19.2-million cubic metres can be used for power generation.

The lower Braamhoek Dam, on Braamhoek stream — a tributary of the Klip River — was completed in November 2011. It is a 41m tall roller-compacted concrete gravity dam. It has a 26.3-million cubic metre water storage capacity, of which 21.9-million cubic metres can be pumped up to the upper reservoir.

A 2km long headrace tunnel connects the upper reservoir to the underground power station, which will house 4 × 333 megawatts (447 000hp) reversible Francis pump-turbines. The elevation between the two reservoirs affords a hydraulic head (water drop) of 480m (0.30mi). Water from the power station is discharged down a 2.5km (1.6mi) long tailrace tunnel to the lower reservoir

To generate electricity during times of peak demand, water is released from the upper dam, passing through the pump/turbines, into the lower dam. During times of low energy demand, the pump/turbines are used to pump the water from the lower dam, back to the upper dam.

“Water flows at high speed down to the turbines at around 60km/h, with enough water passing through each turbine to fill an Olympic-sized swimming pool in six seconds. Rotating at 428 revolutions per minute, each unit will produce 333MW, giving a total of 1 332MW for the station,” Eskom explains.

“On completion of all four units, Ingula will be part of Eskom’s peaking fleet of power stations. It can respond to demand increases on the national grid within two-and-a-half minutes. Upon completion, Ingula will be Africa’s newest and largest pumped storage scheme and the nineteenth largest in the world.”

Pin It
PA PD TP PO SA Plumbers Handbook Logo Plumbing newsletter

Talk to us

AVAILABLE MONDAY - FRIDAY, 8 AM - 4 PM

Connect with us

Keep in touch via your favourite social media