According to a new study from Cornell University, the greenhouse gas footprint of liquefied natural gas (LNG) is 33% worse than coal when the processing and shipping aspects are considered. The research, titled “The Greenhouse Gas Footprint of Liquefied Natural Gas (LNG) Exported from the United States,” highlights the environmental impact of LNG production and transportation. Author Robert Howarth, a professor of ecology and environmental biology, explains that LNG is made from shale gas and requires supercooling and transportation in large tankers, both of which consume significant amounts of energy.
The study finds that methane and carbon dioxide emissions released during LNG’s extraction, processing, transportation, and storage make up approximately half of its total greenhouse gas footprint. When compared using the measurement of global warming potential over 20 years, the carbon footprint of LNG is one-third larger than coal. Even over a 100-year time scale, LNG’s carbon footprint equals or surpasses that of coal. These findings have implications for LNG production in the United States, the world’s largest exporter, which increased production significantly after lifting an export ban in 2016.
The process of liquefying natural gas, where it is cooled to extremely low temperatures for transportation on tanker ships, comes with its own environmental costs. While ships with two- or four-stroke engines that transport LNG emit lower carbon dioxide than steam-powered ships, methane emissions from the engines can contribute significantly to the greenhouse gas footprint. Methane is over 80 times more harmful to the atmosphere than carbon dioxide, and even small emissions can have a large climate impact. Although modern LNG tankers with more fuel-efficient engines have lower CO2 emissions, methane still escapes into the atmosphere through the exhaust.
The study highlights the significant methane emissions that occur during the natural gas liquefaction process, with emissions ranging from 3.9% to 8.1% on tankers. Most methane emissions occur upstream during shale gas extraction and liquefaction, contributing to the larger climate footprint of LNG compared to natural gas. Howarth emphasizes that LNG will always have a greater climate impact than natural gas, making it substantially worse than coal, despite assumptions that it could be a bridge fuel. The research was supported by a grant from the Park Foundation, shedding light on the environmental consequences of LNG production and transportation.
Overall, the Cornell University study underscores the environmental impacts of LNG production and transportation, with a 33% worse greenhouse gas footprint than coal. The research highlights the methane and carbon dioxide emissions released during LNG’s extraction, processing, transportation, and storage, contributing to its significant climate impact. The process of liquefying natural gas for transportation on tanker ships results in methane emissions and increased greenhouse gas footprint, even with more fuel-efficient engines. These findings have implications for LNG production in the US, the world’s largest exporter, indicating the need for careful consideration of the environmental costs associated with LNG.