Over the last decade, there has been a growing cognizance concerning the environmental degradation caused by the greenhouse gases emissions release during the production of electricity. This awareness along with the issue surrounding the depletion of natural resources, has led many countries across the world, comprising South Africa to explore the alternatives for mitigating this situation and developing strategies to move away from conventional electricity generating sources towards ‘’low-emissions’’ electricity technologies. However, with the current economic growth and increased of population, ‘’high-carbon emissions’’ electricity technologies are expected to be used for many decades to come, especially in South Africa where roughly 88% of energy are being generated from fossil fuels. Keeping this in mind, this paper aimed at measuring and comparing the environmental impact between coal and biomass based power plants in the context of the South African energy sector. The assessments were conducted by means of fourteen environmental indicators. The results of the assessments indicate that the coalfired power plant has significant ecological impacts regarding the global warming, freshwater eutrophication, and fossil depletion categories than the biomass electricity generating source.