South Africa is at the forefront of research into so-called clean-coal technology, aimed at reducing the huge volumes of greenhouse gases emitted by its power stations, MPs heard on Wednesday.
The country’s high-quality coal was mined out, leaving more environmentally harmful, lower-grade coal for use in the country’s power plants, the South African National Energy Research Institute’s chief executive, Kadri Nassiep, told members of Parliament’s minerals and energy portfolio committee.
”The focus is on how do we introduce cleaner coal technology … recognising the fact that we have ‘cherry picked’ the better quality coal and we’re left with a lower grade that is probably going to have more harmful environmental impacts,” he said.
Among the research being carried out was an investigation into better ways of burning the coal.
”Here, for instance, Eskom has been looking at ways and means of, rather than actually mining the coal, actually burning it underground, and that forms the basis of the underground coal-gasification project, which they’ve established.
”From there it’s a natural extension to burn the gas in gas turbines, in an integrated gasification combined-cycle plant.
”We are at the forefront as a country in terms of looking at clean-coal technology from that perspective, but a lot more needs to be done,” he said.
Earlier this year, Eskom reported it had carried out the first ”flaring” of gas from its underground coal gasification (UCG) pilot project at its Majuba power station in Mpumalanga.
UCG is a process where coal is converted underground into a synthetic gas, which can be used as fuel for power generation. A network of wells is drilled into the coal seam, and the coal is ignited with air that is pumped underground.
”Fire is essentially used to ‘mine’ the coal, which Eskom plans to use initially as a fuel for Majuba power station’s boilers,” the utility said in a statement at the time.
Nassiep said another research focus area was carbon capture and storage, where carbon dioxide — a major greenhouse gas — was stored underground in aquifers, in the sea or in disused mines.
”Now South Africa might have a problem with using disused mines because there are still some reserves down there. The question is how much of that … will be sterilised by introducing carbon dioxide on a permanent basis.
”The next step would be to look at operationalising our own research facilities that will look at new combustion techniques, such as fluidised bed combustion and super-critical boilers that will enhance the combustion process [at power stations],” he said.
Fluidised bed combustion involves ”suspending” the fuel used in a rising column of air, thereby vastly improving the combustion efficiency. Super-critical boilers operate more efficiently, resulting in lower emissions of greenhouse gases.
Eskom’s coal-fired power stations are the mainstay of the South African economy. In 2004, about 75% of the country’s total energy consumption was from coal.
They also pump millions of tons of carbon dioxide into the atmosphere, and are one of the main reasons the country is the largest contributor to greenhouse gas emissions in Africa. — Sapa