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Available electricity generation reduced or left unused because the power system cannot accommodate it.
Save conceptElectricity curtailment occurs when a source could generate power but the system cannot accommodate all of it. The energy department identifies network constraints and operating conditions, including supply exceeding demand, as reasons. It differs from a plant being unable to produce because wind, fuel or equipment is unavailable.
Electricity must be balanced with demand while networks remain within safe operating limits. If generation exceeds what consumers and available storage can take, or a line cannot carry the required flow, output may be reduced. Different causes require different solutions: shifting energy in time does not automatically resolve a bottleneck in its location.
Suppose a wind farm can produce 100MW, but its connection can safely carry only 80MW. If output is reduced to that limit, 20MW is curtailed at that moment. Over two hours at the same rates, the unused potential energy is 40MWh. The example assumes constant output and is not a measurement of South Africa’s current curtailment.
A battery or scheme can absorb some surplus and deliver it later. It must be able to access that electricity and discharge without recreating the network constraint. New transmission lines can address location constraints. Curtailment does not itself tell a reader that consumers have lost supply or that all unused generation could be recovered economically.
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