Life Cycle Greenhouse Gas Emissions From U.S. Liquefied Natural Gas Exports: Implications for End Uses

Abstract

This study analyzes how incremental U.S. liquefied natural gas (LNG) exports affect global greenhouse gas (GHG) emissions. We find that exported U.S. LNG has mean precombustion emissions of 37 g CO2-equiv/MJ when regasified in Europe and Asia. Shipping emissions of LNG exported from U.S. ports to Asian and European markets account for only 3.5-5.5% of precombustion life cycle emissions, hence shipping distance is not a major driver of GHGs. A scenario-based analysis addressing how potential end uses (electricity and industrial heating) and displacement of existing fuels (coal and Russian natural gas) affect GHG emissions shows the mean emissions for electricity generation using U.S. exported LNG were 655 g CO2-equiv/kWh (with a 90% confidence interval of 562-770), an 11% increase over U.S. natural gas electricity generation. Mean emissions from industrial heating were 104 g CO2-equiv/MJ (90% CI: 87-123). By displacing coal, LNG saves 550 g CO2-equiv per kWh of electricity and 20 g per MJ of heat. LNG saves GHGs under upstream fugitive emissions rates up to 9% and 5% for electricity and heating, respectively. GHG reductions were found if Russian pipeline natural gas was displaced for electricity and heating use regardless of GWP, as long as U.S. fugitive emission rates remain below the estimated 5-7% rate of Russian gas. However, from a country specific carbon accounting perspective, there is an imbalance in accrued social costs and benefits. Assuming a mean social cost of carbon of $49/metric ton, mean global savings from U.S. LNG displacement of coal for electricity generation are $1.50 per thousand cubic feet (Mcf) of gaseous natural gas exported as LNG ($.028/kWh). Conversely, the U.S. carbon cost of exporting the LNG is $1.80/Mcf ($.013/kWh), or $0.50-$5.50/Mcf across the range of potential discount rates. This spatial shift in embodied carbon emissions is important to consider in national interest estimates for LNG exports.

Net greenhouse gas emissions savings from natural gas substitutions in vehicles, furnaces, and power plants

“…Data are expressed per MJ higher heating value, except where otherwise noted. CO 2 equivalent emissions are computed by scaling methane and nitrous oxide by 36 and 298 (100-year global warming potentials (GWP) from IPCC [IPCC, 2013] 2012], and from Abrahams et al (2015) for LNG (Table 1). …”

“…We Venkatesh et al (2011b) and Abrahams et al (2015). b Change in base estimate under a 40% change in methane GWP (relative to base GWP=36).…”

A Critical Analysis on Influential Factors on Power Energy Resources in China

“…Realizing green shipping is one of the goals of China's green traffic system. To realize green shipping, the alternative fuels in China's shipping industry should include liquefied power ship, alcohol/ether power ship, and fuel cell power ship; LNG power ship develops fastest among these alternative fuels (Abrahams et al, 2015) (Note 26).…”

“…The companies that handle delivery services are Samsung, Daewoo, and Hyundai, which are followed by three Japanese companies, namely, Mitsubishi Nagasaki, Kawasaki Sakaide, and Mitsui, Chiba. LNG carrier construction is a rising industry in China, which ranks ninth; China's Hudong Zhonghua ranks third, next to Daewoo and Samsung, as shown in Table 21 (Abrahams et al, 2015) (Note 27).…”

Whatever happened to the Golden Age of natural gas?

“…For importing countries, the magnitude of emissions associated with the life cycle of natural gas depends on the end use and the efficiency of the end use processes associated with using the natural gas. Specific questions have been raised about the emission impacts and uncertainty around liquefaction plants [16], variability in power plants emissions [7], power plant efficiency [17], and natural gas end use [7,8]. Given the recent and ongoing growth of the global LNG market, it is critical to improve our understanding of these factors and the overall climate implications of the expanding industry.…”