That equals about a third of the generating capacity of Africa's most industrialised country.
South Africa relies on Eskom for more than 90% of its electricity, which derives chiefly from 15 ageing coal-fired power stations, for which it has enjoyed waivers on emissions limits for soot, nitrogen oxides and sulphur dioxide.
The heavily-indebted provider says it cannot afford the technology required to meet them.
"If implemented, the decision will result in an immediate shutting down of 16,000 megawatts (MW) of installed coal fired capacity," Eskom said in a statement, adding that it would cost over R300bn to adhere to it.
Pollution in the coal belt is among the worst in the world, rivalling Beijing and Mumbai, and researchers estimate the smog there kills thousands of people a year, with one putting the cost at $2.37bn a year.
The government is fighting legal action with environmental groups over it.
Eskom said the Department of Environment allowed it to postpone meeting emissions standards on seven power stations, with five requests rejected and four only partially granted. Neither Eskom nor the department's spokespeople responded to requests for more details.
The utility is working on a plan with donors, agreed at the COP26 climate talks in November, to shut down its coal-fired power stations and replace them with renewables. It says it should seek to clean the air that way, not by expensively retrofitting old plants with pollution filters.
South Africa's over-reliance on coal has made it the world's 12th biggest greenhouse gas emitter, the Global Carbon Atlas says.
Eskom is due to close half its 46,000MW of nominal capacity by 2035, replacing some of that with gas and renewables, and allowing independent producers to make up the shortfall.
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