Wet coal, faulty flues and starting energy trading at Eskom

Eskom's fourth bout of stage six loadshedding for February is thanks to a confluence of bad weather creating wet coal exacerbating 21,243MW of breakdowns plus 4,566MW of planned breakdowns.

In a hastily convened media briefing, Eskom Group CEO Andre de Ruyter said the demand forecast of an evening peak of 27,282MW means a shortfall in generation capacity of 5,834MW for Monday night, "so you can see why we have to implement loadshedding stage 6."

"Given the fact that we are running our open cycle gas turbines hard, we have no option but to implement loadshedding stage 6," said de Ruyter.

He pointed out that Eskom has resolved its funding issue and can now procure diesel because National Treasury is guaranteeing any utility loans procured from local banks to buy fuel.

"That has given us the ability to ease the constraint and we’ve been able to purchase the necessary supplies from the OCGT," said de Ruyter.

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While Lethabo Power Station is usually one of the more stable Eskom power plants, they now have three units down thanks to coal supply issues and a boiler tube leak. The New Vaal Coal Mine is having trouble supplying Lethabo with the requisite amount of coal because heavy rain is pushing up the level of the river adjacent to the coal mining pit, leading to wet coal.

Lethabo is fairly removed from the Mpumalanga coalfields, which makes it difficult to change supplier at short notice, plus coal at Eskom's strategic coal stockpile is also wet.

"There is a lot of coal at Lethabo in the stockpile, it's just very wet. And, in transporting coal to the power station while it is raining, you run the risk of bringing a very wet product to the station, which defeats the object," said Thomas Conradie, acting head of generation.

He pointed out that Lethabo power station has 32.9 days of coal stock available, so still well within grid code requirements. But Eskom does not foresee the problem persisting for weeks on end. "It's a combination of plants not performing as we want them to in terms of the reliability of the fleet, combined with specific incidents we’ve had lately," said Conradie.

The high rainfall is also creating a situation at their pumped hydro schemes, particularly Ingula, which is a closed system "with no outflow apart from the wetlands downstream.

"So when both dams are full, it is impossible to generate electricity by letting water from the upper dam," explained de Ruyter.

Eskom has to gradually release the overflow from the lower dam to the wetland but doing that too quickly creates the risk of flowing downstream towns. Since the Drakensberg pumped storage scheme is connected to the Tugela river, it is not similarly constrained.

Then there is the very different climate problem currently encountered, but that, in de Ruyter's words, often goes undiscussed, is "the load losses due to the high ambient temperatures impacting the efficiency of our cooling system at Matimba".

"Currently, we are sitting with 600MW load loss because of the warm summer weather at Lephalale," explained the Group CEO.

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"The balance of the fleet is old and unreliable and consequently, when we have incidents like we had at Lethabo, where we lose two units to coal constraints and a further unit to a boiler tube leak, the shortfall in generation capacity becomes very urgent indeed," said de Ruyter.

Conradie said the EAF is currently sitting at 53% and Eskom does not anticipate reaching 60% by the end of this financial year thanks to the high unplanned unavailability of generating capacity.

De Ruyter said they did not anticipate going beyond stage 6 right now and the risk of reaching stage 8 is low. But, they do have plans in place for what level 8 would look like.

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De Ruyter said Isabel Fick, general manager: systems operator for Eskom, had assured him the probability of a total systems blackout remains very low thanks to not only the use of loadshedding but "the support of the major industrial and mining customers for load curtailment who assist us during peaks when we have high demand."

Eskom anticipates the current stage 6 loadshedding to remain in place until at least 5am Thursday morning at which time they will scale back to stage 4 and then hopefully stage 3 by the weekend.

"At this stage there is no need to contemplate going further than that," said de Ruyter.

Fick said they are currently in the process of reviewing the NERSA document guidelines governing loadshedding. That document is being put to the industry for comment. "We are still going through the governance processes but are looking at the different stages of loadshedding.

"In terms of contingency planning for stage 8, we do have a plan should we reach stage 8… but don't anticipate it at this stage," said Fick.

When questioned about the possibility of Eskom switching from diesel to gas, de Ruyter agreed that "based on prices, LNG would be more cost-effective than diesel."

"But in order for us to use LNG at scale we would need to import the LNG, gasify it again, transport it to probably Ankerlig, possibly Gourikwa… and that requires a significant investment into infrastructure," said de Ruyter.

"Because our likely consumption of natural gas is too low to warrant investment into import facilities, what we are looking for is an aggregator of demand to allow us to import gas in conjunction with other consumers of gas. That should assist in reducing the overall cost of importing," said de Ruyter.

Pursuing an open-cycle combined gas project at Richards Bay would justify the creation of a floating storage regasification unit (FSRU). However, Eskom would want to purchase their LNG at a contractually pre-determined price and not have to handle the importation themselves.

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The three units down at Kusile Power Station, as a result of the broken chimney, should get their new, temporary chimneys by the end of this year.

De Ruyter said they have asked the Forestry, Fisheries and Environment Minister to expedite the approval process. While they await the department's permission to build temporary chimneys, they are running various paperwork processes in parallel to be able to get the process started the second they have permission.

"We took the decision to place the order for the steel required to build the three temporary flues and are in urgent discussions with the contractor to ensure we can bring the three units back by commissioning the flues by December this year," said de Ruyter.

Did you know?Eskom creates three new electricity procurement programmes

Andrew Etzinger, general manager of energy market services in Transmission, said they are awaiting all necessary approvals to get started with the trade of electricity and expect the Standard Offer Programme to get going within the next week or so. "We are just finalising legal contracting between ourselves and the other parties," said Etzinger.

The Emergency Generator Programme will only be triggered when the system is under severe constraints, and the participants would effectively be able to bid in. Then Eskom would accept or reject the offer based on the pool rules. "That would be a good start to the competitive bidding process in the electricity market to be rolled out," said Etzinger.

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