Coal — the doomed energy resource, great polluter and contributor to global warming — might just have a brighter future. This is if a new technology that captures carbon dioxide from coal plants can be fine-tuned in the next few years.
South Africa has an abundance of coal, but the environmental problems coal plants cause is dampening the future of the mineral. But the new technology, called carbon capture and storage, might just ensure that it becomes environmentally sustainable.
Already South African coal-based energy giants Sasol and Eskom are eyeing carbon-capture technologies, which are designed to capture carbon dioxide from their plants for underground storage such as in disused mines. But while Sasol intends implementing the new technology in future plants, Eskom says the technology is still too expensive to implement at its power stations.
At present, no power plant in the world operates with a full carbon-capture and storage system.
Carbon capture and storage currently costs about R1 000 a ton of carbon, much too high for it to be viable in South Africa. The energy watchdog International Energy Agency (IEA), however, predicts that as technology progresses the price could fall to below R200 a ton in 2030, making it more affordable to Eskom.
The steep price of carbon capture arises from the fact that before carbon dioxide that is produced by power plants can be stored, it must be captured as a relatively pure gas.
It is routinely separated and captured as a by-product from industrial processes, but existing capture technologies are not economically viable for power plants.
Eskom, which produces 92% of South Africa’s electricity, mostly from coal-burning power stations, emitted 247 metric tons of carbon from January 2004 to March last year.
An Eskom executive, Steve Lennon, said in an interview with Engineering News that Eskom had to consider carbon capture and storage, but that it was just too expensive at present. But the energy provider will be tracking carbon-capture technology developments round the world with keen interest.
”The Eskom of today is no longer in position to say that it is just going to thunder ahead and build coal-fired power stations without stopping to consider environmental constraints,” he said.
”Any coal plant installed will need to be based on state-of-the-art clean-coal technology and high efficiency to ensure that less CO2 is emitted per unit of production,” Lennon said, adding that ”carbon capture and storage is an established technology, which is just not economically viable at the moment and which is very expensive, using something like 40% of the energy produced just to remove CO2”.
He said Eskom will be looking at what is happening globally and possibly post-2020, and whether carbon capture and storage can be a commercial technology in which CO2 will be extracted from flue gas and stored in underground storage systems or in deep-bed undersea storage.
Carbon capture is also part of Sasol’s future plans. The fuel giant is busy incorporating carbon storage into its operations.
It says new-generation technology now makes it possible to build coal-to-liquids (CTL) with clean-coal technologies.
”Sasol’s research and development (R&D) activities include research opportunities for reducing the environmental footprint of our products and processes,” said Sasol’s Elton Fortuyn.
”An important current focus area is the identification of practical opportunities for the capturing and storing of carbon dioxide.”
But he said that Sasol produces carbon dioxide in a concentrated form, making carbon capture less expensive.
While the South African-based CTL plant in Secunda is not yet carbon-capture ready, the company’s strategic intent will be that all its future CTL facilities are designed for this.
Carbon capture and storage plants have received the most support from China, which uses the European Union’s emission trading scheme to help it build the expensive plants.
According to the scheme, European companies earn emission credits if they invest in clean-energy technologies in developing countries such as China and South Africa. These partnerships are called Clean Development Mechanisms (CDM). The companies then use these credits to meet their own pollution targets back in Europe.
Jurgen Lefevre, an EU lawyer who works on CDM deals, says China has been very enthusiastic about implementing the EU’s proposed carbon-capture schemes. The two parties have signed a memorandum of understanding on the technology and are currently negotiating on where to start a pilot project.
”But South Africa has also expressed interest, although no formal negotiations are happening,” he said. At present, only two CDM projects exist in South Africa in contrast to China’s 11 and India’s 72, a fact that has been blamed on the bureaucratic difficulties in South Africa in setting up the projects.
Scientists speculate that carbon capture and storage, if applied to a modern conventional power plant, could reduce emissions by up to 90% when compared to plants without the process.
Power plants would use a post-combustion process where the carbon dioxide is removed after combustion of the fossil fuel.
Here, carbon dioxide is captured from flue gases at power stations. It would then be transported into underground geological formations such as oil fields, gas fields, saline formations and unmine-able coal seams.
According to the IEA’s technology perspectives report, carbon capture and storage technologies are the only way in which coal can still be used without severe environmental degradation.
The agency predicts that carbon capture and storage technologies will contribute between 20% and 28% of total emission reductions by 2050, adding that clean-coal technologies with carbon storage offer a particular important opportunity to constrain emission in rapidly growing economies with large coal reserves such as China, South Africa and India.
It said all the individual elements needed for carbon capture and storage have been demonstrated, but there is an urgent need for an integrated full-scale demonstration plant.
”Carbon capture and storage is indispensable for the role that coal can play in providing low-cast electricity in a carbon-dioxide constrained world,” the agency said.