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Wednesday, October 26, 2016
- In spite of mounting scientific evidence about its negative aspects, Mexico is getting ready to intensify exploration for shale gas, natural gas found trapped in shale, a sedimentary rock.
The state oil company, Petróleos Mexicanos (PEMEX), is planning to sink wells into 175 shale gas reserves between 2011 and 2015, on a budget of 700 million dollars a year.
Since February, PEMEX has been extracting three million cubic feet of shale gas a day from a well in the northern state of Coahuila, where it has invested 25 million dollars.
“It’s a good thing for Mexico to know what resources it has, but it’s not advisable for the country to pursue this adventure. The technology involved is very controversial. Shale gas is found in areas where there is no water,” Lourdes Melgar, an expert at the private Monterrey Institute of Technology and Higher Education (ITESM), told IPS.
Shale, a common type of sedimentary rock made up largely of compacted silt and clay, is an unconventional source of natural gas. The gas trapped in shale formations is recovered by hydraulic fracturing, or “fracking”.
“Fracking” involves pumping water, chemicals and sand at high pressure into the well, a technique that opens and extends fractures in the shale rock to release the natural gas on a massive scale.
Over the next 50 years, PEMEX expects to operate 6,500 wells, producing eight billion cubic feet a day.
Shale gas extraction involves large amounts of water, and drilling and “fracking” generate large quantities of waste fluids, which contain dissolved chemicals and other contaminants that require treatment before recycling or disposal.
While it spends millions of dollars on fossil fuels, Mexico has sidelined renewable sources like wind, solar and geothermal energy.
In its 2011 study “World shale gas resources: an initial assessment of 14 regions outside the United States”, the U.S. Energy Information Administration (EIA) assessed 48 shale gas deposits in 32 countries, including Mexico, and calculated reserves of 5,760 trillion cubic feet (Tcf) of potentially recoverable gas.
Production of shale gas in the United States was 4.87 Tcf in 2010, compared with 0.39 Tcf in 2000, and by 2035 domestic production could supply 45 percent of the country’s gas consumption, according to the EIA.
But recent scientific work has unearthed some negative environmental effects of shale gas and concerned researchers have raised the alarm.
The paper “Methane and the greenhouse gas footprint of natural gas from shale formations”, by Robert Howarth, Renee Santoro and Anthony Ingraffea of Cornell University in Ithaca, New York, published in April in the journal Climatic Change, concluded that shale gas is more polluting than oil and conventional natural gas.
The carbon footprint, or greenhouse gas footprint, is the total set of greenhouse gas emissions caused by an event, process, product or person.
“The footprint for shale gas is greater than that for conventional gas or oil when viewed on any time horizon, but particularly so over 20 years. Compared to coal, the footprint of shale gas is at least 20 percent greater and perhaps more than twice as great on the 20-year horizon, and is comparable when compared over 100 years,” the study says.
Natural gas is composed largely of methane, and 3.6 to 7.9 percent of the methane from shale gas production leaks into the atmosphere over the lifetime of a well. These methane emissions are at least 30 percent higher, and even twice as high, as those from conventional gas, the report says.
Methane is one of the most polluting of the greenhouse gases that are responsible for global warming.
The research study “Methane contamination of drinking water accompanying gas well drilling and hydraulic fracturing”, published in May in the Proceedings of the National Academy of Sciences, documented the environmental impact of shale gas extraction in the northeastern U.S. states of Pennsylvania and New York.
“In active gas extraction areas (one or more gas wells within 1 km), average and maximum methane concentrations in drinking-water wells increased with proximity to the nearest gas well and were a potential explosion hazard,” says the paper by Stephen Osborn, Avner Vengosh, Nathaniel Warner and Robert Jackson of Duke University, a private research university in Durham, North Carolina.
These results bring into question the energy industry’s reasoning that shale gas could replace coal in electricity generation and lower greenhouse gas emissions, to help mitigate climate change.
“It is too premature and too risky a venture. The projects are too costly in terms of sustainability. There are cheaper, more accessible options,” said ITESM’s Melgar.
Furthermore, its energy balance – the ratio of useful energy supplied when the shale gas is burned, to the total energy used to extract it – is unknown, although the indications are that it may be unfavourable.
“A reassessment of energy policy is needed,” that ought to include new “financial, regulatory, technological, legal and infrastructure aspects,” proposed Gasca of CNH.
In April 2010 the U.S. Department of State set up the Global Shale Gas Initiative (GSGI) to help countries identify and develop their unconventional gas resources safely and economically, with a view to furthering U.S. economic and commercial interests, including those of U.S. multinational corporations.
“We conclude that greater stewardship, data and – possibly – regulation are needed to ensure the sustainable future of shale gas extraction and to improve public confidence in its use,” the Duke University study recommended.