According to a study, it produces about one-third more greenhouse gas than coal over a 20-year period. Greenhouse gases such as carbon dioxide and methane are produced in the atmosphere, while the greenhouse gas footprint refers to their impact on the environment. Natural gas is essentially an odorless gas composed of methane, cooled to a liquid state at about -106 degrees Celsius to form liquefied natural gas or LNG.
Robert Howarth, a professor of ecology and environmental biology at Cornell University in the US, said that LNG is considered a better alternative to coal, but if shipping is taken into account, its greenhouse gas footprint is about one-third that of coal. Howarth, author of the study published in the journal Energy Science and Engineering, said LNG is made with shale gas (a type of natural gas). To make it, it has to be cooled in liquid form and then transported to the market in big tankers. It requires energy.
For the study, the researchers looked at previous studies to estimate emissions from the shale rock manufacturing stage to the end consumer. Carbon dioxide and methane produced during extraction, transport and storage of LNG account for nearly half of total greenhouse gas emissions. Analyzing the 20-year global warming potential, the greenhouse gas footprint for LNG as a fuel source is 33 percent higher than that of coal. Even considering a time frame of 100 years (Global Warming Potential), the negative impact of LNG is equal to or greater than that of coal.
