A new study has found that the life-time greenhouse gas (GHG) emissions of shale gas are half that of coal, irrespective of whether the gas is used as natural gas or to generate electricity.
Shale gas has been touted as a way to curb climate change and reduce the world’s reliance on coal, but many questions remain, such as whether it is in fact cleaner than coal and whether it contaminates ground water reservoirs, among others.
South Africa has an estimated 390-trillion cubic feet in technically recoverable, but not proven, reserves of natural gas in the Karoo basin. The government is eager to exploit this resource.
Energy Minister Tina Joemat-Pettersson on Monday told Parliament: “The development of shale gas [in South Africa] cannot be dismissed or ignored … We should be learning from others on how to best exploit this resource in the least intrusive and environmentally prudent way.”
There has been a public outcry against the push to include shale-based natural gas in South Africa’s energy mix. To liberate the natural gas – which mainly comprises of methane – from shale rock, the rock has to be hydraulically fractured (commonly known as “fracking”) to break the rock apart. This involves a mixture of chemicals being pumped into rock fissures at very high pressures, with a small amount of this liquid remaining in the ground.
However, the issue of total GHG emission is important in South Africa, a country which is dependent on coal-fired power stations and cheap coal reserves. At the 2009 United Nations climate change talks, South Africa committed to reducing its carbon emissions by 34% before 2020, and by 42% before 2025.
This latest research, conducted by researchers at the United States’s National Renewable Energy Laboratory and published in the Proceedings of the National Academy of Sciences, looked at eight previously published peer-reviewed papers on the life cycle emissions of unconventional natural gas operations. These papers came to different conclusions about whether the GHG emissions from shale were better or worse than coal.
For example, Robert Howarth from New York’s Cornell University found that shale gas had a substantially larger carbon footprint (methane comprises carbon) than coal, whereas scientists said that its footprint was smaller.
“Recent literature has come to different conclusions on this point, largely due to different [scientific] assumptions, baseline comparisons and system boundaries,” the researchers write. They “harmonised” the variables used to calculate the life cycle emissions, ensuring – insofar as possible – that the same things were being measured.
They found that per unit of electricity (or electricity equivalent), “GHG emissions from shale gas-generated electricity are similar to those for conventional natural gas, with both approximately half that of coal”.
“These results can inform future analyses about the role [of] natural gas in climate change mitigation, policy decisions regarding air emissions, and the management of energy resources, as well as motivate further research on key issues.”
More research is needed to determine whether it is possible to exploit South Africa’s shale gas (if it exists) without irreparably harming the environment and contaminating the groundwater in the water-scarce Karoo region.
Lack of highly-trained scientists
The newly formed Centre of Excellence for Integrated Mineral and Energy Resource Analysis (Cimera), hosted by the University of Johannesburg and the University of the Witwatersrand, announced on Monday that it would undertake scientific research into the fossil energy resources of Karoo-aged basins in southern Africa.
“South Africa has an almost complete lack of highly-trained scientists in the field of natural gas and petroleum resource analysis and estimation. This led to the development of the Karoo Research Initiative [Karin], under the umbrella of Cimera,” said Cimera director Professor Nic Beukes. Karin aims to explore all aspects of the hydrocarbon cycle within the southern Karoo basin by determining the primary source potential for shale gas, the University of Johannesburg said. About R2-million had been earmarked for research and student funding for the Karin.
“The name Karoo refers to the sedimentary successions that were deposited on the ancient supercontinent of Gondwanaland some 300 to 170-million years ago, in the area now represented by the southern part of the African continent. These Karoo-aged basins contain all of the important coal deposits of southern Africa, extending from Malawi in the north, into Mozambique, Zimbabwe, Namibia and Botswana southwards to the coal fields of South Africa,” the University of Johannesburg said.