How Eskom avoided stage 9 load-shedding

Eskom avoided implementing stage 9 load-shedding on 9 December 2019 thanks to a combination of load curtailment and instructing industrial customers to reduce to essential load.

South Africa experienced stage 6 load-shedding – which requires the reduction of 6,000 MW of load – for the first time on 9 December 2019.

Former CEO Andre de Ruyter said stage 6 power cuts were precipitated by unusually high rains and flooding in Mpumalanga.

The rain impacted the coal supply and flooded two power stations, taking out about 4,000 MW of expected supply.

There was such a shock that the country was hit by stage 6 load-shedding that President Cyril Ramaphosa cut an Egypt state visit short to deal with the crisis.

What most South Africans don’t know is that the situation could have been significantly worse.

Eskom’s manual load-reduction data revealed that it cut 8,737 MW from the grid on 9 December 2019. This equates to stage 9 load-shedding.

However, thanks to a range of interventions by the power utility, it was able to contain load-shedding to stage 6.

Eskom explained that the system operator has a number of levers that can be used to reduce demand other than load-shedding.

In particular, load curtailment, which requires large industrial customers to reduce demand continuously for a period.

There are also several demand response products that may be dispatched that allow Eskom to reduce customer demand under contract. 

Together, these levers are used to minimise load-shedding while adhering to the contractual limits of the demand response contracts. 

Using many of these levers simultaneously with load-shedding can result in the required demand being reduced from the power system.

In December 2019, Eskom instructed its industrial customers to reduce to essential load, a process described in the NRS048-9 documentation. 

Essential load is the minimum safe demand that an industrial plant is able to operate at to ensure environmental matters and safety are not compromised.

It is not load curtailment. It is an instruction for industrial plants to shut down safely and cease production.

December 2019 was the first time in recent history that industrial customers were instructed to reduce to essential load.

The reduction was more than anticipated, and immediately after the evening peak, the demand was returned to the system.

This intervention helped Eskom to limit load-shedding to stage 6 despite cutting over 8,700 MW from the grid.