WITH dwindling natural gas and oil reserves, the world is increasingly looking for alternative sources of energy. Industry people say shale gas is one promising option. It is the natural gas trapped in shale, a type of flaky sedimentary rock. It already accounts for 22 per cent of USA’s gas supply. By the US energy information administration’s reckoning, shale gas will meet 14 per cent of the world’s gas needs by 2030.
Environmentalists are sceptic of this option, primarily because of its controversial extraction process. Called hydraulic fracturing or fracking, the process involves injecting a mix of water, sand and chemicals deep underground at ferocious pressure. This breaks up shale formations, releasing the gas trapped so it can be pumped to the surface. The technology so far remains almost unregulated as there was no evidence to show its environmental impact. A recent study by geologists at Duke University in the US found that groundwater near shale extraction sites in the country is contaminated with methane.
They collected water samples from 68 wells in five counties in Pennsylvania and New York. The region overlies the Marcellus and Utica shale formation, the largest known gas reserve in the US. Residents have been complaining of well water contamination since drilling started in 2005. Though there has been little research on the health effects of methane in drinking water, the inflammable gas can cause respiratory problems like asphyxia. There are reports of houses near extraction sites being blown up due to methane leak in the basement.
Tests revealed water in wells within one kilometre of the extraction sites had 17 times more methane than those farther off. The samples contained 19.2-64 mg of methane per litre. This is a potential explosion hazard, the scientists noted in the Proceedings of the National Academy of Sciences on May 9.
The team led by Robert Jackson also used carbon and hydrogen isotope tracers to distinguish between thermogenic methane, formed at high temperatures deep underground and captured in gas wells during fracking, and biogenic methane, produced naturally at shallower depths and lower temperatures. Analysis showed water in wells within a kilometre of extraction sites contained the methane released during shale gas extraction. “We do not know the mechanism for methane contamination. It could have leaked through the well casing,” says Avner Venghosh, co-author of the study. The paper mentions that the contamination could also be due to new fractures formed during fracking.
| Gas With Heavy Footprint Robert Howarth, professor at Cornell University in the US, is a well known expert on fracking. He explains Ruhi Kandhari the cautionary approach of various countries towards shale gas What is USA’s view on shale gas? There is still a lot of debate going on in the US. Some say shale formations are so deep that fracking cannot contaminate groundwater. A large body of evidence, on the other hand, suggests that water contamination is occurring. There seems to be a large amount of leakage into the casing of shale wells, and, of course, accidents and spills happen. Greenhouse gas emissions from fracking is so high that this may aggravate global warming. What’s government’s response to the controversy? The Congress in 2005 passed a law that exempted fracking from the federal regulation, leaving it to the individual 50 states. Since the states are not experienced in dealing with large-scale environmental regulation, some are doing a better job than the others. Pennsylvania, for instance, has been overwhelmed in trying to deal with the problems. It underestimated the seriousness when drilling started. The problems have become apparent in the last two years. New York has not allowed fracking. It is still studying the process. What is the status of fracking in other countries? Fracking is a new technology. It has been done in the past 12 years, and mostly in the past three-four years, first in Texas and Colorado, and recently in northeastern US. Our government and industry are eager to export this technology. President Barack Obama recently signed an bilateral agreement with India in this regard. Industry wants to use the technology in South Africa and Australia. Efforts are on to explore reserves in France, Poland, Germany and Russia. How do these countries react to the plan? As far as I know, Canada is the only country outside the US where significant drilling is being done for shale gas. It has started experiencing the same problems as in Pennsylvania. The province of Quebec has put a temporary ban on fracking. In Europe, there were protests in Paris against this technology. Following similar opposition in South Africa, where they are planning to use the technology in arid areas, the government has put a temporary ban. Australia is slowly adopting the technology. What could be the impact of shale gas in India? I would be terribly concerned about the impact of shale gas in India with the large quantities of water needed and the resultant water pollution. The wastewater is contaminated with radioactivity and toxic substances. The US is doing a terrible job of handling it. Officials put it in municipal sewage treatment plants, which are not equipped to handle this kind of waste, and it flows into rivers and streams. |