Climate Central 22 May 2013.
(Contributor’s note: Although this is a US study, it is relevant to South Africa, particularly with respect to the governance of the future use of natural gas in South Africa – both from fracking and from imported liquefied natural gas. Issues such as collecting baseline methane emission and water quality and availability before fracking starts and how depleted fracking wells will be closed down are important. We don’t want a repeat of the acid mine drainage problem. See the interactive graph – it is excellent!)
Knowing how much methane is leaking from the natural gas system is essential to determining the potential climate benefits of natural gas use. Our extensive review of the publicly available studies finds that a pervasive lack of measurements makes it nearly impossible to know with confidence what the average methane leak rate is for the U.S. as a whole. More measurements, more reliable data, and better understanding of industry practices are needed.
It has been widely reported that shifting from coal to gas in electricity generation will provide a 50 percent reduction in greenhouse gas emissions. In reality, the extent of reduced global warming impact depends largely on three factors:
- The methane leak rate from the natural gas system;
- How much time has passed after switching from coal to gas, because the potency of methane as a greenhouse gas is 102 times that of carbon dioxide (on a pound-for-pound basis) when first released into the atmosphere and decays to 72 times CO2 over 20 years and to 25 times CO2 over 100 years, and;
- The rate at which coal electricity is replaced by gas electricity.