Firing power plants with regasified liquefied natural gas (LNG) is a better bet for the environment than burning coal to generate electricity, even in advanced technology plants, according to a study commissioned by the Washington, DC-based Center for LNG. The findings contradict research released in 2007 by Pittsburgh, PA-based Carnegie Mellon University.
The center hired consulting firm Pace to tally emissions under four technology cases:
"The intent of this analysis was to provide a transparent, consistent and equitable 'apples-to-apples' comparison of the GHG [greenhouse gas] emissions attributable to generation in the U.S. based on assumptions that reflect the typical, average or most common practices, processes, equipment and geographical considerations associated with the selected scenarios," Pace said in the study report.
The winner overall in every case was gas-fired generation powered by regasified LNG. "For all of the coal cases, production and combustion emissions were greater than the LNG case. However, the processing and transportation segment emissions were greater in the LNG case," Pace said. "Existing coal technologies emitted more GHG emissions than advanced coal technologies..."
The Pace findings contradict earlier research done at Carnegie Mellon that found the environmental costs of processing and transporting LNG outweighed the environmental benefits of gas-fired generation over advanced coal-fired technologies. Those findings were later refuted by the Gasification Technologies Council, which blasted the Carnegie Mellon researchers for using "averaged and generic data from a variety of sources and incorrect assumptions" (see NGI, Sept. 10, 2007).
Pace found that existing coal technologies produce about 50% more emissions than advanced coal technologies. The difference between LNG and existing coal technology emissions was 1,687 pounds of carbon dioxide (CO2) equivalent per megawatt hour. In other words, existing coal plants produce 161% more emissions on a life cycle basis than gas-fired plants fueled with regasified LNG. "The analysis indicated that the cleanest coal scenario [integrated gasification combined-cycle] releases 73% more emissions from a life cycle perspective than LNG," the report said.
The processing and transportation of LNG was more polluting than those of coal due to LNG liquefaction and regasification and the resulting fugitive methane emissions, which have a GHG potency 21 times greater than CO2, Pace said.
The consultant also noted the shifting profile of domestic gas supply to greater reliance on unconventional resources, which generally incur higher drilling and other costs. "Over the long term, delivered LNG prices are expected to fall below the costs of incremental North American production, thereby moderating long-term natural gas prices," the report said.
The report is available at www.lngfacts.org.
Intelligence Press Inc. All rights reserved. The preceding news report
may not be republished or redistributed, in whole or in part, in any
form, without prior written consent of Intelligence Press, Inc.