What is fracking?
“Fracking” is shorthand for hydraulic fracturing, a form of mining where cracks (fractures) are made in rock to access deposits of natural gas.
The process is “hydraulic” because it involves pumping liquid (water, sands and chemicals) down a well drilled into the rock: the pressure build-up from this causes cracks to form, releasing the gas for collection.
In some cases, it is possible to extract natural gas by drilling wells without resorting to fracking. But as conventional gas wells have started to run dry, as they have in the United States, the use of fracking has increased in order to mine less accessible gas deposits.
What is natural gas?
Like other fossil fuels (oil and coal), natural gas is formed from plant and animal matter compressed and heated in the earth's crust over millions of years. The energy of the sun originally stored by prehistoric plants can be converted into electrical energy for our use.
Natural gas is composed mainly of the gas methane.
Burning any kind of fossil fuel is polluting and contributes to climate change, but natural gas is relatively “cleaner” than oil or coal.
What is shale gas?
Shale gas is natural gas trapped in a kind of rock formation called shale that is often rich in fossils and fossil fuels.
Over the past decade, shale gas has become increasingly important to the United States' energy sector, now supplying over 20% of that country's energy needs.
Thus other countries like South Africa have also started looking to their natural gas deposits to supplement their energy supply.
Why do some people think we need to frack?
Our hunger for fossil fuels to drive our industries and transport systems, and keep our homes warm and well-lit, creates an ongoing demand for more to be extracted.
In South Africa, supply is not meeting the demand, and tapping our considerable reserves of natural gas more effectively is one way to do this. It is also advantageous to use a fuel source on home ground and reduce dependence on imports.
What's wrong with fracking?
All mining has environmental and health impacts. In the case of fracking, the primary concerns are as follows:
Some of the gas previously trapped underground may leak out during the fracking process. We don't want additional methane in the atmosphere because it's a potent greenhouse gas that contributes to climate change.
Much of the fluid injected into a fracking mine is recovered and stored on the surface in open reservoirs; these could potentially contaminate fresh water resources. Fracking fluid contains hundreds of chemicals, many toxic, and when these evaporate off they can be inhaled, or they can fall back to the surface and contaminate soil and groundwater.
Fracking requires a lot of water – in the millions of gallons – which is particularly concerning in arid areas like the Karoo where this additional demand could threaten human water supply and aquatic ecosystems.
What's the fuss about the Karoo?
It is believed there are large natural gas deposits locked in Karoo shale. While proponents of extracting the gas say this could be an economic boost to poor populations in the area, critics point out that mining could have a devastating impact on the Karoo ecosystem, which, as an arid area, is especially vulnerable and has low resilience.
What is the current situation in South Africa?
Cabinet endorsed a moratorium on fracking in April 2011, which it extended by six months in August 2011. However, this was lifted on 7 September 2012.
Now, a period of exploration to assess the country's shale gas reserves has been allowed: this will likely include some drilling to collect samples, but fracking will not be allowed for the time being.
- Olivia Rose-Innes, EnviroHealth Editor, Health24, September 2012
Image of gas flame: Shutterstock