Complex sentence: When both 660 MW plants are complete, the estimated annual coal consumption for the plants will be 4.66 million tons, most of which will be imported from Indonesia, with South Africa, and Australia identified as suitable supplemental suppliers.
Split into simpler sentences: When both 660 MW plants are complete, the estimated annual coal consumption for the plants will be 4.66 million tons. Most of the coal used for the power plant will be imported from Indonesia, with South Africa and Australia identified as suitable supplemental suppliers.