March 16, 2006 — Carbon dioxide gas is produced by various natural processes and by burning fossil fuels, and is the major contributor to global warming. But not all carbon dioxide is the same. Some is produced when gasoline is burned by cars and other vehicles, while some other carbon dioxide is emitted by natural gas furnaces that warm many homes.
By analyzing different forms or “isotopes” of carbon in carbon dioxide gas in Salt Lake City’s air, University of Utah researchers were able to tell when the city’s residents turned on or off their natural gas furnaces due to cooler or warmer weather.
During pre-dawn hours when furnaces turned on and warmed Salt Lake City homes, carbon dioxide from furnace emissions made up 60 percent to 70 percent of the newly emitted carbon dioxide in Salt Lake City’s air. That proportion dropped to 30 percent to 40 percent during the evening rush hour, when furnaces were less likely to be in use and when motorists filled the roadways.
The researchers also found carbon dioxide emissions from furnaces dropped during a relatively warm period during their wintertime study, which was conducted from Dec. 15, 2004, to Jan. 20, 2005.
The new study was published recently in the online edition of Geophysical Research Letters, a journal of the American Geophysical Union (AGU). A brief news release from the AGU is below.
The study was conducted by Diane Pataki, a former University of Utah research assistant professor of biology who now works at the University of California, Irvine; and by these scientists at the University of Utah: David Bowling, assistant professor of biology; Jim Ehleringer, distinguished professor of biology; and John Zobitz, a graduate student in mathematics.
Most of the authors are traveling during the current spring break at the University of Utah, but Bowling is on campus this week and may be reached by news media at (801) 581-2130 or bowling@biology.utah.edu
Copies of the full study are availble by contacting Lee Siegel at (801) 581-8993 or leesiegel@ucomm.utah.edu.
Lee Siegel, science news specialist
University of Utah Public Relations
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Monitoring urban carbon dioxide emissions on small spatial and time scales
Monitoring the amounts and patterns of fossil fuel emissions will be critical to estimating future carbon dioxide concentrations in the atmosphere. Seeking to improve fossil fuel emissions monitoring, Pataki et al. used a tunable diode laser absorption spectrometer to measure carbon dioxide mixing ratios and associated carbon isotope compositions in the atmosphere over Salt Lake City, Utah, between 15 December 2004 and 20 January 2005. They found a pronounced diurnal pattern that reflected the contribution of gasoline versus natural gas combustion to atmospheric carbon dioxide , where natural gas combustion varied from 30-40 percent of total manmade carbon dioxide released during evening rush hour and 60-70 percent during pre dawn hours. They also observed that during a brief warming period, the proportional contribution of natural gas combustion decreased as air temperatures rose, indicating changes in residential heating patterns. These data show that for the first time, atmospheric measurements can be used to infer patterns of energy and fuel usage on hourly to daily time scales.
Title: High resolution atmospheric monitoring of urban carbon dioxide sources
Authors:
D. E. Pataki: Department of Earth System Science and Department of Ecology and Evolutionary Biology, University of California Irvine, California, U.S.A.;
D. R. Bowling and J. R. Ehleringer: Department of Biology, University of Utah, Salt Lake City, Utah, U.S.A.;
J. M. Zobitz: Department of Mathematics, University of Utah, Salt Lake City, Utah.
Source: Geophysical Research Letters (GRL) paper 10.1029/2005GL024822, 2006