A new study in the United States that links hydraulic fracturing, or fracking, to high concentrations of methane in drinking wells has reignited the South African debate about the controversial technique for extracting natural gas.
South Africa's plan to drill for natural gas in the Karoo Basin, which could pave the way towards increasing its energy independence and boosting the economy, has been met with vociferous opposition from civil and environmental lobby groups.
They say that the government is bowing to big business and enslaving the country to another form of fossil fuel at the expense of the Karoo, one of the most biologically diverse areas in the world. South Africa has an estimated 390-trillion cubic feet in technically recoverable, but not proven, reserves of natural gas.
Last year, the Cabinet lifted its moratorium on natural gas exploration, saying that South Africa was an energy-poor country that needed to explore the possibility of natural gas reserves. The exploration could take up to a decade.
On Tuesday, US President Barack Obama threw Washington's weight behind natural gas in what is being called his "climate change" speech: "The bottom line is natural gas is creating jobs. It's lowering many families' heat and power bills. And it's the transition fuel that can power our economy with less carbon pollution even as our businesses work to develop and then deploy more of the technology required for the even cleaner energy economy of the future."
This comes in the same week that the US Environmental Protection Agency delayed the finalisation of a report claiming that fracking had contaminated groundwater in Wyoming with the chemical used to fracture the rock. Both natural gas critics and proponents claimed the move as a victory.
Karoo: A water-scarce area
However, the most recent study found no metal, radioactive or salt contamination of drinking water. The study, published in the Proceedings of the National Academy of Sciences, analysed 141 drinking water wells in the Marcellus Shale Formation, in north-eastern Pennsylvania, and found that "methane was detected in 82% of drinking water samples, with average concentrations six times higher for homes less than one kilometre from natural gas wells [and] ethane was 23 times higher in homes less than one kilometre from gas wells".
The distance to the wells was the most important factor in these readings as the gas signatures were of stray gases that came from the wells rather than naturally occurring ones, the authors write.
However, there has been very little research on whether consuming hydrocarbons, such as methane and ethane, in water is bad for human health.
Water is one of the major issues about extracting natural gas in the Karoo, a water-scarce area where the water that does exist is in underground aquifers.
'Potential for the emigration of gases'
Jonathan Deal of the Treasure the Karoo Action Group said hydrocarbons in the drinking water was "a serious cause for concern" because "it indicates the potential for the emigration of gases from far below the surface area where the gases are expected".
Saliem Fakir, head of the living planet unit at WWF, said that it raised questions about regulations and enforcement: "It depends on the regulatory regime that is able to set standards of how the wells should be capped or sealed."
However, natural gas resources, if they are realisable, offer the opportunity for South Africa to move away from dirty coal-based electricity and its high greenhouse gas emissions. But the questions of the environmental risk remain.
Fakir said it was a matter of managing these risks.
"What kinds of precautionary measures can one take in terms of both technology and management, and what are the cost implications of that?" he asked.
Karoo will demand its own extraction process
Although fracking appears to have attracted most of the attention, it is only one part of natural gas extraction and the other aspects also require close scrutiny. There are different processes for different kinds of rock. First, a well is drilled, using a combination of water, biocides and diesel-based lubricants. Most of this solution is regurgitated back up the well, forced to the surface by the gas in the ground.
Then explosive charges are inserted and detonated in the hole, fracturing the rock. Only then fracking takes place – a mixture of chemicals, sand and water is pumped down the well at high pressure, creating fissures up to three centimetres wide. Once again, the escaping gas forces most of this mixture to the surface.
According to experts from Shell in the United States, one fracking stage can use up to 2 000 barrels of water, and one well can have multiple fracking stages. But the chemicals and drilling processes depend on the terrain, geology and climate, which means that the process will have to be specifically developed for the Karoo.