Natural Gas, Methane, and Global Warming
Robert Howarth
The David R. Atkinson Professor of Ecology & Environmental Biology
Cornell University, Ithaca, NY USA
January 28, 2014
Is natural gas a “bridge fuel?”
For just the release of carbon dioxide during combustion…..
g C of CO2 MJ-1 of energy
Natural gas
15
Diesel oil
20
Coal
25
(Hayhoe et al. 2002)
Methane emissions – the Achilles’ heel of natural gas
• Natural gas is mostly methane.
• Methane is 2nd most important gas behind humancaused global warming.
• Methane is much more potent greenhouse gas
than carbon dioxide, so even small emissions matter.
Carbon Dioxide
Methane
Marcellus Well Being “Finished”
Outside Dimock, PA, June 2011
Video
Photo and FLIR Methane-Tuned Video Courtesy Frank Finan
Bruce Gellerman, “Living on Earth,” Jan. 13,
2012, based on work of Nathan Phillips
http://www.loe.org/shows/segments.html?programID=12-P13-00002&segmentID=3
Pipeline accidents and explosions happen, due to large leaks….
….. small leaks are ubiquitous.
Pipelines in US are old!
PHMSA 2009 Transmission Annual Data
Flames consume homes during a massive fire in a residential neighborhood September 9,
2010 in San Bruno, California. (Photo by Ezra Shaw/Getty Images)
20-year time frame
75
Methane
high
methane
Indirect CO2
Grams Carbon per MJ
60
45
Direct CO2
high
methane
low
methane
low
methane
30
deep
surface
15
0
Low Estimate
High Estimate
Shale Gas
Shale Gas
Low Estimate
High Estimate
Conventional
Natural
Gas
Conventional
Gas
Surface-mined Deep-Mined
Coal
Oil
Coal
Diesel Oil
Howarth et al. 2011
Greenhouse gas consequences for natural gas compared to coal
(compared over integrated 20-year time frame)
Worse
than
coal
Better
than
coal
Greenhouse gas emissions relative to coal
4
3
EPA 2011
Electricity
2
1
Howarth et
al. 2011
0
0%
3%
6%
Extrapolated from
NOAA studies
9%
Percent methane emission from natural gas
12%
Domestic hot water heating
electricity
Coal-powered plant
Heat pump
Natural gas
Gas burner
Greenhouse gas consequences for natural gas compared to coal
(compared over integrated 20-year time frame)
Worse
than
coal
Better
than
coal
Greenhouse gas emissions relative to coal
4
Water heated by natural
gas has a very large
greenhouse gas footprint
3
Hot water
EPA 2011
Electricity
2
1
Howarth et
al. 2011
0
0%
3%
6%
Extrapolated from
NOAA studies
9%
Percent methane emission from natural gas
12%
Dangerous tipping points are only 15 to 35 years into the future.
Controlling methane is CRITICAL to the solution!
http://news.discovery.com/earth/alas
kas-arctic-tundra-feeling-theheat.html
2.0 oC threshold
1.5 oC threshold
Shindell et al. 2012
US National Methane Emissions for 2009
(Howarth et al. 2012, based on EPA (2011)
Thanks for the invitation to participate.
Special thanks to Tony Ingraffea, Bongghi Hong, and Drew Shindell.
Shale gas…. A bridge to nowhere
Funding:
Park Foundation
Wallace Global Fund
Cornell University