Natural Gas, Methane, and Global Warming

Robert HowarthThe David R. Atkinson Professor of Ecology & Environmental Biology

Cornell University, Ithaca, NY USA

January 28, 2014

(Hayhoe et al. 2002)

For just the release of carbon dioxide during combustion…..

Is natural gas a “bridge fuel?”

Natural gas 15

Diesel oil 20

Coal 25

g C of CO2 MJ-1 of energy

Methane emissions – the Achilles’ heel of natural gas

• Natural gas is mostly methane.

• Methane is 2nd most important gas behind human-caused global warming.

• Methane is much more potent greenhouse gas than carbon dioxide, so even small emissions matter.

Carbon Dioxide Methane

Marcellus Well Being “Finished” Marcellus Well Being “Finished” Outside Dimock, PA, June 2011Outside Dimock, PA, June 2011

Photo and FLIR Methane-Tuned Video Courtesy Frank Finan

Video

http://www.loe.org/shows/segments.html?programID=12-P13-00002&segmentID=3

Bruce Gellerman, “Living on Earth,” Jan. 13, 2012, based on work of Nathan Phillips

Pipeline accidents and explosions happen, due to large leaks…. ….. small leaks are ubiquitous.

Flames consume homes during a massive fire in a residential neighborhood September 9, 2010 in San Bruno, California. (Photo by Ezra Shaw/Getty Images)

Pipelines in US are old!

PHMSA 2009 Transmission Annual Data

0

15

30

45

60

75

Low Estimate High Estimate Low Estimate High Estimate Surface-mined Deep-Mined

Shale Gas Conventional Gas Coal Diesel Oil

Gra

ms C

arbo

n pe

r MJ

Methane

Indirect CO2

Direct CO2

20-year time frame

Howarth et al. 2011

highmethane

highmethane

low methane

low methane

surfacedeep

Shale Gas Conventional Natural Gas

Coal Oil

0% 3% 6% 9% 12%

4

3

2

1

0

Percent methane emission from natural gas

Gre

enho

use

gas

emis

sion

s re

lativ

e to

coa

l

Greenhouse gas consequences for natural gas compared to coal(compared over integrated 20-year time frame)

Better than coal

Worse than coal

ElectricityEPA 2011

Howarth et al. 2011

Extrapolated from NOAA studies

Coal-powered plant

Natural gas

electricity

Heat pump

Gas burner

Domestic hot water heating

0% 3% 6% 9% 12%

4

3

2

1

0

Percent methane emission from natural gas

Gre

enho

use

gas

emis

sion

s re

lativ

e to

coa

l

Greenhouse gas consequences for natural gas compared to coal(compared over integrated 20-year time frame)

Better than coal

Worse than coal

Electricity

Hot water

EPA 2011

Howarth et al. 2011

Extrapolated from NOAA studies

Water heated by natural gas has a very large

greenhouse gas footprint

http://news.discovery.com/earth/alaskas-arctic-tundra-feeling-the-heat.html

1.5 oC threshold

2.0 oC threshold

Dangerous tipping points are only 15 to 35 years into the future.

Controlling methane is CRITICAL to the solution!

Shindell et al. 2012

(Howarth et al. 2012, based on EPA (2011)

US National Methane Emissions for 2009

Thanks for the invitation to participate.

Special thanks to Tony Ingraffea, Bongghi Hong, and Drew Shindell.

Funding: Park Foundation Wallace Global Fund Cornell University

Shale gas…. A bridge to nowhere