the role of shale gas development in the global methane ......methane $2,900 per ton ch 4 (based on...

The Role of Shale Gas Development in the Global

Methane Cycle: New Insights from 13C and 14C data

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

Biogeochemistry Seminar SeriesCornell University

March 1, 2019

• COP21 Paris Accord target: “well below 2o C”

• Clear recognition that warming beyond 1.5o C is dangerous

•Methane reductions are critical; cannot reach COP21 target with CO2 reductions alone

COP21: United Nations Conference of the PartiesLe Bourget, Paris -- December 2015

Photo courtesy of Sharon Wilson

Methane: colorless, odorless gas.

Invisible to the naked eye, but strong absorber of IR.

Courtesy of Drew Shindell, Feb 2019

Comparison of Carbon Dioxide, Methane, and Black Carbon as Agents of Global Warming

http://news.discovery.com/earth/alas

kas-arctic-tundra-feeling-the-

heat.html

1.5 oC threshold

2.0 oC threshold

Shindell et al. 2012, Science

No greenhouse gas reductions

CO2 reduction only

Methane reduction only (+ soot)

Methane + CO2 (+ soot)

Comparison of impacts of CO2 and methane (including non-climate impacts)

Climate Health CropPollutant Damages Damages Damages

CO2 Very large None Small

Methane Large Medium Large

Based on lecture by Drew Shindell, 8 Feb 2019

Each Mt of methane reductions avoids:

220-490 premature deaths yr-1 due to ozone

120,000-330,000 tons of crop yield loss yr-1 due to ozone

0.0016-0.0024 °C warming over 2-4 decades

$90-177 million in damages yr-1 due to reduced forestry yields, agricultural losses via ozone, and human morbidity

West & Fiore, ES&T, 2005; UNEP/WMO, 2011;Shindell et al., Science, 2012;

Shindell, Climatic Change, 2015

From a lecture by Drew Shindell at Cornell, 8 Feb 2019

Social cost of carbon (including health, agricultural, and environmental costs in addition to climate change)

Carbon dioxide $38 per ton CO2

Methane $2,900 per ton CH4

(based on lecture by Drew Shindell at Cornell, Feb 8, 2019; assumes 4% economic discounting for methane)

Methane in the atmosphere for most of the last 10,000 years vs. change since industrial revolution allows estimation of natural fluxes vs. human-caused fluxes:

Begon et al. 2014

Natural = 220 Tg per year

Human-caused = 350 Tg per year

Total 570

Total natural 220Geological seeps 53Biological sources 167

Total anthropogenic 350Fossil fuels 115Animal agriculture 90Rice 60Landfills & sewage 55Biomass burning 30

Begon et al. (2014)

Global methane sources (Tg/yr), as of 1990 - 2000

August 2017

August 2017

Measured 14C in methane in ice laid down in Antarctica 11,500 years ago (1 ton of ice per sample).

Indicates the methane from 11,500 years ago came very largely from biological sources, not geological seeps.

Total 570



Begon et al. (2014)


0

Total 570



Begon et al. (2014)


0

220

Total 570



Begon et al. (2014)


Not 53

14C content of methane in atmosphere in late 20th Century indicates 30% was from fossil/geological sources (168 Tg/yr)

Total 570



Begon et al. (2014)


Not 53

Not 115

14C content of methane in atmosphere in late 20th Century indicates 30% was from fossil/geological sources (168 Tg/yr)

Total 570



Begon et al. (2014)


Not 53

Not 115

If the fossil fuel number is higher, than other anthropogenic sources must be smaller.

Total 570

Total natural 220Geological seeps 0Wetlands & lakes 220


Based on Begon et al. (2014), modified March 28, 2018


If the fossil fuel number is higher, than other anthropogenic sources must be smaller.

Howarth (in review), based on Schaefer 2016

Global trend in atmospheric methane concentration, 1980 to 2015

Rapid rise in atmospheric methane globally since 2008

Hansen et al. (2007) suggested critical threshold in climate system, to avoid melting of natural methane clathrates, at ~ 1.8o C.

http://www.nature.com/ngeo/journal/v7/n9/full/ngeo2232.html#f1

http://www.washington.edu/news/2014/12/09/warmer-pacific-ocean-could-release-millions-of-tons-of-seafloor-methane/

Sonar image of methane bubbles rising from the seafloor off the Washington coast from sediments 515 m underwater. Note that plume disappears by 180 m, as methane dissolves into the water, where it is then consumed by bacteria.

So far, monitoring and satellite data do not indicate large increase in methane flux to atmosphere from melting methane clathrates (or from melting permafrost)…

Most methane from melting clathrates dissolves in ocean and is consumed by bacteria…. BUT, if melting rate increases, larger bubbles might reach atmosphere.

Perhaps remains high risk as further warming above 2o C ?

Howarth in review, based on Schaefer 2016

Global trend in atmospheric methane concentration, 1980 to 2015

Rapid rise in atmospheric methane globally since 2008 is probably not from tundra or clathrates

High visibility paper published in March 2016 in Science: Increase in atmospheric methane since 2006 is most likely biogenic in large part, probably from cows.

Based largely on stable carbon isotopic composition (13C vs. 12C) in atmospheric methane.

Howarth in review, based on Schaefer 2016

Global trend in atmospheric methane concentration (top) and stable isotopic composition of that methane (bottom), 1980 to 2015

Average atmospheric 13C composition of global methane and major sources that could drive change over recent decade (values from Schietzke et al. 2016).

Howarth (in review)

Fossil fuelsBiogenic sources(cows, wetlands)

Average for atmospheric methane in 2005

Direction of change (highly exaggerated) during last decade

Schaefer et al. (2016): 84% of the global increase in methane since 2005 was due to biogenic sources, with animal agriculture (cows) being the

single most likely source.

They noted their conclusion contradicted many reports of increased emissions from fossil fuel sources over this time, and

stated their conclusion “is unexpected, given the recent boom in unconventional gas production and reported resurgence in coal mining and the Asian economy.”

Turner et al. (2016)

Satellite data: 30% to 60% of global increase in atmospheric methane between 2010 and 2014 due to emissions from US lower 48 states.

Fewer cows and cattle in US in recent decades, so unlikely to be cause of

increased methane

Decrease in biomass burning over time makes atmospheric methane lighter (more negative) – Worden et al. (2017)

Howarth (in review)




Biomass burning

No change Decreasein biomass in biomassburning burning

Bio

gen

ic c

han

ge

Foss

il fu

el c

han

ge

Estimates of global increase in methane emissions between the 2001-2006 period and 2007-2014 (Tgper yr) attributed to fossil fuel changes (top) and biogenic changes (bottom)….

…. assuming no change in biomass burning (left) and with correction for decreased biomass burning (right).

Adapted from Worden et al. (2017).

Shale gas revolution since 2006

(totally a North American phenomenon, largely US,

through 2015)

US natural gas production, 2000 - 2018

Jeremy Legget, Oct 2018: https://jeremyleggett.net/2018/10/16/history-of-oil-and-gas-production-from-shale-in-pictures-and-charts-why-american-shale-is-heading-for-a-crash-and-fracking-in-the-uk-is-doomed-to-costly-failure-2/

Howarth (in review), based on EIA (2016) and IEA (2017)

Global production of natural gas 2000-2017, with projected increase to 2040.

63% of increase in global gas production over past decade has been shale gas in North America.

Howarth (in review)

As it migrates through sandstone over geological time, some of the methane is consumed by iron-reducing and sulfate-reducing bacteria ….

Leads to fractionation! The methane in conventional natural gas is enriched in 13C relative to the source methane in shale gas.

Golding et al. 2013

Shale gas is depleted in 13C relative to conventional natural gas and other fossil fuels (Howarth, in review)

Howarth (in review)




13C signal from shale gas is more negative (less 13C) than from conventional natural gas

Biomass burning

Assumptions in my analysis:

1) Methane emissions from coal and oil have remained proportional to changes in production;

2) Global increase in coal production is surface-mined coal (China);

3) Methane emissions from new oil production have classic fossil-fuel 13C signal;

4) Methane emission rate for shale gas is an equal percentage of production as for conventional natural gas.

Sources of increased methane emissions to the atmosphere in 2014 compared to 2004 (Tg/year), Howarth (in review)

Biological sources 7.3 (+/- 1.0)

Conventional natural gas 6.9 (+/- 0.4)

Shale gas 11.8 (+/- 0.7)

Total for natural gas 18.7(shale plus conventional)

Total for fossil fuels 21.7(gas, oil, and coal)

Total for all sources 29.0

95% confidence limits are indicated in parentheses for biological sources, conventional natural gas, and for shale gas. Note that the total increase shown in the table (29 Tg/year) is greater than the measured increase of 26 Tg/year, since emissions from biomass burning decreased by 3 Tg/year. See text.






If methane emissions are actually a greater percentage of production for shale gas than for conventional gas, then biogenic emissions even less important, and total natural gas emissions increase.






To the extent methane from shale oil has 13C signal like that of shale gas and/or methane emissions from shale oil are greater than from conventional oil, then again biogenic emissions are even less important. Estimate for natural gas emissions would decrease some, but total methane emissions from oil & gas would increase.

Schaefer et al. Schwietzke et al. Worden et al. Howarth 2016 2016 2017 in review

Biological sources 21 16 12.5 7.3

Fossil-fuel sources 4 8 16.5 21.7

-- natural gas 18.7

-- shale gas 11.8

-- conventional gas 6.9

Recent estimates for increased methane emissions globally for the period from ~ 2005 to ~ 2015 based on 13C data (Tg/yr, only means of estimates shown).

Total 570

Total natural 220Geological seeps 0Wetlands & lakes 220

Total anthropogenic 350Natural gas and oil 136Coal 32Animal agriculture 67Rice 44Landfills & sewage 41Biomass burning 30

R. W. Howarth, based on Begon et al. (2014), modified Feb 25, 2019

Global methane sources (Tg/yr), as of 1990 - 20002015 estimate

596

376

33157

74

27

Social cost of carbon (including health, agricultural, and environmental costs in addition to climate change)

Carbon dioxide $38 per ton

Methane $2,900 per ton

(based on lecture by Drew Shindell at Cornell, Feb 8, 2019; assumes 4% economic discounting for methane)

Increased methane flux from oil & gas industry over past decade of 21 Tg/yr has social cost of $600

BILLION ($60 billion/yr).

IPCC – Oct 2018

Sources of increased methane emissions to the atmosphere in 2014 compared to 2004 (Tg/year), Howarth (in review)

Biological sources 7.3 (+/- 1.0)

Conventional natural gas 6.9 (+/- 0.4)

Shale gas 11.8 (+/- 0.7)

Total for natural gas 18.7(shale plus conventional)

Total for fossil fuels 21.7(gas, oil, and coal)

Total for all sources 29.0

95% confidence limits are indicated in parentheses for biological sources, conventional natural gas, and for shale gas. Note that the total increase shown in the table (29 Tg/year) is greater than the measured increase of 26 Tg/year, since emissions from biomass burning decreased by 3 Tg/year. See text.

Normalized to increase in natural gas production over this time period, equivalent

to 4.1% full-lifecycle emission rate.

New estimate based on 13C: 4.1%(3.4% for conventional gas and 5.1% for shale gas, for sensitivity analysis where emissions from shale assumed to be 1.5X those of conventional natural gas)

First peer-reviewed estimate of methane emissions from shale gas, published April 2011

For the time before the shale gas boom:

Miller et al. (2013, PNAS) used nationwide monitoring data on methane in atmosphere (12,694 observations) for 2007-2008, and compared with EPA bottom-up source estimates spatially using inverse model.

They concluded EPA estimates were at least 2-fold too low for emissions (before the shale gas boom).

Miller et al. (2013), PNAS: > 3.6%

Ren et al. 2019 JGR Atmospheres

Survey of Estimates for Methane Emissions from Oil & Gas “Production Operations”

Ren et al. 2019

Survey of Estimates for Methane Emissions from Oil & Gas Production Operations

Actual range for total emissions = 1.7% to 7.9%For upstream and midstream production, 0.3% to 4.1%

Ren et al. 2019

Survey of Estimates for Methane Emissions from Oil & Gas Production Operations(ie, production, gathering, and processing, and not transportation, storage, and distribution)

2.2% +/- 1.9%

1.9% (1.6% to 2.4% )

9.1% +/- 6.2%

Ren et al. 2019

Survey of Estimates for Methane Emissions from Oil & Gas Production Operations(ie, production, gathering, and processing, and not transportation, storage, and distribution)

2.2% +/- 1.9%

1.9% (1.6% to 2.4% )

9.1% +/- 6.2%

My new 13C estimate, full lifecycle, is 4.1%

If transportation, storage, and distribution are responsible for 2.5% (+/- 1.1%) as in Howarth et al. 2011,

…. then production, gathering, and processing estimated as 1.6% (+/- 1.1%)

From lecture by Howarth & Ingraffea at Cornell April 15, 2014

From lecture by Howarth & Ingraffea at Cornell April 15, 2014

Downstream emissions (transportation, storage, and distribution) remain very understudied, with no synthesis since Howarth et al. (2011) …… but are probably significant.

Photo by Jack Ossont

Routine and emergency “blowdowns” from pipelines at at compressor stations

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

Methane concentrations at ground level across Boston, MA;

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)

March 12, 2014 – 7 killed in explosion in NYC(127-year old gas mains)

Gas explosions across multiple cities in Merrimack Valley of Massachusetts in Sept 2018: only one person killed, but 39 plus buildings destroyed and tens of thousands of households without gas for months.

0.1 Tg methane leaked

(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

From Howarth (2014):

Assumes average US electric efficiencies of 41.8% for natural gas and 32.8% for coal. Assumes average US methane emission rate of 5.3% from Brandt et al. (2013) for natural gas. Vertical bar represents range from 3.6% to 7.1%. GWP of 20 years assumed.

4.1 %

Break-even Methane Emission Factors for Climate-effects Equivalency

• Electricity generation, natural gas instead of coal = 2.7 %

From Alvarez et al. (2012), modified to update radiative forcing for methane from IPCC (2013), based on time zero of “technology warming potential” (TWP).



• Small vehicle transportation, natural gas instead of gasoline = 1.4 %





• Large truck transportation, natural gas instead of diesel = 0.8 %






• Domestic hot water, natural gas instead of air-source heat pump (with electricity from coal) = 0.3 %

From Hong & Howarth (2016), also based on “Technology Warming Potential” approach.





• Domestic hot water, natural gas instead of air-source heat pump (with electricity from coal) = 0.3 %

• Residential space heating, natural gas instead of ground-source heat pump (with electricity from coal) = 0.2%

Source: Alvarez et al. (2012) for electricity and transportation, recalculated by Tony Ingraffea to reflect greater radiative forcing for methane reported by IPCC (2013);Hong & Howarth (2016) for domestic hot water; extrapolation by Howarth from that approach for residential space heating, assuming 85% efficiency for gas furnace and COP of 3.8 for heat pump; see http://www.eeb.cornell.edu/howarth/methane/tool.htm

http://www.eeb.cornell.edu/howarth/methane/tool.htm

Trend in 13C in methane over time provides valuable information on emissions sources.

Global increase in methane over past decade probably driven largely by oil & gas industry.

Natural gas is not a bridge fuel.

We should move away from ALL fossil fuels ASAP.

Funding:

Cornell University Park Foundation

More info:

howarthlab.org

the role of shale gas development in the global methane ......methane $2,900 per ton ch 4 (based on...

Documents