Abstract
M.Sc.
Mercury is a persistent and toxic substance that can be bio-accumulated in the food
chain. Natural and anthropogenic sources contribute to the mercury emitted in the
atmosphere. Eskom’s coal-fired power stations in South Africa comprised 92.8 % of the
total electricity produced in 2010/2011 (Eskom, 2011). Trace amounts of mercury can
be found in coal, mostly combined with sulphur, and can be released into the
atmosphere upon combustion. Coal-fired electricity generation plants are the highest
contributors to mercury emissions in South Africa. A major factor affecting the amount
of mercury emitted into the atmosphere is the type and efficiency of emission
abatement equipment at a power station. Eskom employs particulate emission control
technology at all its currently operating coal-fired power stations, and new power
stations are being built with sulphur dioxide abatement technology. A co-beneficial
reduction of mercury emissions exists as a result of the implementation of emission
control technology. The amount of mercury emitted from each of Eskom’s coal-fired
power stations is calculated, based on the amount of coal burnt and the mercury
content in the coal. Emission reduction factors are taken into consideration to reflect
the possible co-benefit received from the installed particulate control technologies at
the stations. Estimates are provided for different scenarios where the current
technology is replaced or additional emission control technology is added to the
existing technology. An average of 19.8 tons of mercury is calculated in this study to
have been emitted from the currently operating coal-fired power stations in 2010. The
total annual mercury emitted from 2006 to 2021 does not show a decreasing nor
increasing trend based on the currently implemented technology at the coal-fired
power stations. If all the power stations (that currently do not have fabric filter plants
as a particulate emission control) were retrofitted with fabric filter plants, a potential
76.9% reduction of the total mercury emissions from the fleet would result.