GAS IS DIRTY ENERGY: burning methane (CH4) generates carbon dioxide (CO2), CH4 leaks & CH4 is 105 times worse than CO2 as a greenhouse gas (GHG)

Sensible public policy depends upon rational risk management, which successively involves (a) correct data, (b) science-based analysis (science involving the critical testing of potentially falsifiable hypotheses) and (c) informed systemic change to minimize risk. Unfortunately this process is typically perverted by (a) incorrect information from ignorance, lying by omission and commission, censorship, intimidation), (b) anti-science spin-based analysis (the selective use of asserted facts top support a partisan position) and (c) blame and shame that counterproductively inhibits correct reportage and increased risk.

As a 5-decade career scientist who is still teaching science students at a major Australian university, I do my bit for rational risk management in the public interest by making  carefully researched, science-based  submissions to media and to MPs to inform them about reality and to correct misconceptions. I frequently write to media and MPs about the worsening climate emergency  and recently received 2 detailed Australian Government responses from Australian public servants who had been asked to respond, respectively, on behalf of  Greg Combet MP, Minister for Climate Change and Energy Efficiency (to whom PM Julia Gillard had forwarded my letter) and Mark Dreyfus MP, Parliamentary Secretary for Climate Change and Energy Efficiency.

Both of these detailed letters contained the same  utterly incorrect comments  concerning  the Australian Government’s  disastrous Carbon Tax-ETS plan to tackle climate change:  “The Australian Government [has] a comprehensive plan to move to a clean energy future. Central to that plan is the introduction of a carbon price that will cut pollution in the cheapest and most effective way and drive investment in clean energy sources such as solar, wind and gas.”

“Tackling climate change” means DECREASING greenhouse gas (GHG) pollution but Treasury modeling, ABARE and US EIA data show that the Australian Government’s plan will result in INCREASING both Domestic and Exported GHG pollution in both 2020 and 2050 in relation to that in 2000. As also shown below, gas is not clean, gas is dirty and a coal to gas transition for power generation will be counterproductive in relation to the urgent, science-demanded need to cease GHG pollution by about 2050.   

(A) Natural gas is not clean – burning gas is dirty GHG-wise

Carbon (C) has an atomic weight of 12, methane (CH4) has a molecular weight of 16 and carbon dioxide (CO2) has a molecular weight of 44.

When you burn CH4 you get CO2: CH4 + 2O2 -> CO2 + 2 H2O.

Accordingly, burning 16 tonnes of CH4 yields 44 tonnes of CO2; burning 100 tonnes of CH4 yields 100 tonnes x 44/16 = 275 tonnes of CO2; and burning 1 tonne CH4 yields 2.75 tonnes CO2.

Burning carbon, C, the major constituent  of coal, you also get CO2: C + O2 -> CO2.

Accordingly, burning  12 tonnes of C yields 44 tonnes of CO2; burning 100 tonnes of C yields 100 tonnes x 44/12 = 367 tonnes of CO2; and burning 1 tonne C yields 3.67 tonnes CO2.

Burning both coal and methane generates the GHG CO2 (as well as other pollutants) i.e. neither coal nor natural gas are not clean GHG-wise, they are both dirty.

(B). Systemic methane leakage increases GHG pollution from burning gas.  

According to the US Environmentlal Protection Agency ( EPA): “The concept of a global warming potential (GWP) was developed to compare the ability of each greenhouse gas to trap heat in the atmosphere relative to another gas. The definition of a GWP for a particular greenhouse gas is the ratio of heat trapped by one unit mass of the greenhouse gas to that of one unit mass of CO2 over a specified time period.” If  there is industrial leakage of CH4 (estimated to be 3.3% in the US  from  US EPA data) [1] then one must consider the GHG effect of the released methane, noting that 1 tonne of CH4 is105 times worse than 1 tonne CO2 as a greenhouse gas on a 20 year time scale with aerosol impacts included [2-5].

Of 100 tonnes of CH4, how much CH4 leakage (y tonnes) gives the same greenhouse effect (in CO2 equivalents or CO2-e) as burning the remaining CH4?

y tonnes CH4 x (105 tonnes CO2-e/tonne CH4) = (100-y) tonnes CH4 x (2.75 tonnes CO2-e/ tonne CH4).

105y tonnes CO2-e = (100-y) 2.75 tonnes CO2-e

105y = 275 – 2.75y

107.75y = 275

y = 275/107.75 = 2.55 i.e. a 2.6 % leakage of CH4 yields the same greenhouse effect as burning the remaining 97.4% CH4.

Check: 2.55  tonnes leaked CH4 corresponds to 2.6 tonnes CH4 x 105 tonnes CO2-e/ tonne CH4 = 268 tonnes CO2-e . Burning the remaining 97.4 tonnes of CH4 corresponds to 97.4 tonnes CH4 x 2.75 tonnes CO2/tonne CH4 = 268 tonnes CO2.

(C). A coal to shale gas transition could double power-based GHG pollution.

The  MWh of energy  produced per tonne of CO2 pollution for a gas-fired power station is on average 2 times that of a coal-fired power station (the current situation in the state of Victoria, Australia). Indeed in terms of toxic pollutants such as carbon particles (soot), carbon monoxide, nitrogen oxides, sulphur dioxide, radioactivity and heavy metals, burning gas is cleaner than  burning coal.   However, given significant systemic methane leakage, what would a coal to gas transition for electricity mean in terms of GHG pollution?

In Victoria, Australia, gas-fired power stations (0.60 – 0.90 tonnes CO2-e/MWh, average 0.75 tonnes CO2-e/MWh) are roughly twice as efficient in producing energy as brown coal-burning power stations (1.21-1.53 tonnes CO2-e/MWh) according to a report by Green Energy Markets commissioned by Environment Victoria (EV) [6]. Accordingly, at a systemic leakage of 2.6% the GHG pollution would roughly double to about 1.5 tonnes CO2-e/MWh, equivalent to that of Hazelwood, the dirtiest coal-fired power station in Victoria.

A more precise set of calculations is given below.

If the systemic leakage rate is zero (0) then burning of 100 tonnes CH4 would be associated with 275 tonnes CO2-e to give 0.75 tonnes CO2-e/MWh.

If the leakage rate is 2.6% then combustion of 97.4 tonnes of CH4 would be associated with 275 tonnes CO2 x 97.4/100 = 268 tonnes CO2 (from burning) + 2.6 tonnes CH4 x 105 tonnes CO2-e/ tonne CH4 = 273 tonnes CO2-e (from leakage) = 541 tonnes CO2-e. Accordingly, burning of 100 tonnes CH4 would be associated with 541 tonnes CO2-e x 100/97.4 = 555 tonnes CO2-e i.e. tonnes CO2-e/MWh would increase by a factor of 555/275 = 2.0 to give 2.0 x 0.75 tonnes CO2-e/MWh = 1.5 tonnes CO2-e/MWh (i.e. as dirty as Hazelwood’s 1.5 tonnes CO2-e/MWh).

If the leakage rate is 3.3% (US average) then the combustion of 96.7 tonnes of CH4 would be associated with 275 tonnes CO2 x 96.7/100 = 266 tonnes CO2 (from burning) + 3.3 tonnes CH4 x 105 tonnes CO2-e/ tonne CH4 = 347 tonnes CO2-e (from leakage) = 613 tonnes CO2-e. Accordingly, burning of 100 tonnes CH4 would be associated with 613 tonnes CO2-e x 100/96.7 = 634 tonnes CO2-e i.e. tonnes CO2-e/MWh would increase by a factor of 634/275 = 2.3  to give 2.3 x 0.75 tonnes CO2-e/MWh = 1.73 tonnes CO2-e/MWh (1.2 times as dirty as Hazelwood).

If the leakage rate is 7.9% (the upper estimate with shale formation-derived  gas) [7]  then the combustion of 92.1 tonnes of CH4 would be associated with 275 tonnes CO2 x 92.1/100 = 253 tonnes CO2 (from burning) + 7.9 tonnes CH4 x 105 tonnes CO2-e/ tonne CH4 = 830 tonnes CO2-e (from leakage) = 1,083 tonnes CO2-e. Accordingly, burning of 100 tonnes CH4 would be associated with 1,083 tonnes CO2-e x 100/92.1 = 1,176 tonnes CO2-e i.e. tonnes CO2-e/MWh would increase by a factor of 1,176/275 = 4.3  to give 4.3 x 0.75 tonnes CO2-e/MWh = 3.2 tonnes CO2-e/MWh (roughly 2.1 times as dirty as Hazelwood).

Methane is 105 times worse than carbon dioxide (CO2) as a GHG on a 20 year time scale and major systemic gas leakage  from the hydraulic fracking of shale formations has led Professor Robert Howarth, Cornell University, Ithaca, New York, to conclude that “The large GHG footprint of shale gas undercuts the logic of its use as a bridging fuel over coming decades, if the goal is to reduce global warming. We do not intend that our study be used to justify the continued use of either oil or coal, but rather to demonstrate that substituting shale gas for these other fossil fuels may not have the desired effect of mitigating climate warming”. [7].

(D). Australian Labor Government’s Carbon Tax-ETS plan will INCREASE Domestic GHG pollution.

Treasury modeling of the Australian Government’s Carbon tax-ETS plan [8], Australian Bureau of Resource and Agricultural  Economics (ABARE) data indicating coal and gas exports increasing at 2.6% pa and 9% pa, respectively,  and US Energy Information Administration (EIA) data on Australian coal and liquid natural gas (LNG) exports show the following Australian Domestic and Exported GHG pollution (in millions of tonnes of CO2-equivalent, Mt CO2-e) for Australia under the Carbon Price [9].

2000: 496 (Domestic) + 505 (coal exports) + 17 (LNG exports) = 1018.

2009: 600 (Domestic) + 784 (coal exports) + 31 (LNG exports) = 1,415.

2010: 578 (Domestic) + 803 (coal exports) + 34 (LNG exports) = 1,415.

2020: 621 (Domestic) + 1,039 (black coal exports) + 80 (LNG exports) + 59 (brown coal exports) = 1,799.

2050: 527 (Domestic) + 2902 (coal exports) + 1,061 (LNG exports) = 4,490.

Both the Australian Liberal Party –National Party Coalition Opposition and the Australian Labor Government have the same goals involving “5% off 2000 Domestic GHG pollution in 2020” and unlimited coal and gas Exports. “Tackling climate change” means DECREASING greenhouse gas (GHG) pollution. However the above data show  that the Australian Labor Government’s plan will mean INCREASING both Domestic and Exported GHG pollution in both 2020 and 2050 in relation to that in 2000 i.e. the Australian Labor Government has absolutely no intention of “tackling climate change” either in the short term or long term. [9].

Indeed it gets worse.  In 2009 the German Advisory Council on Climate Change (WBGU) determined that for a 75% chance of avoiding a disastrous 2 degree C temperature rise, the World must pollute less than 600 Gt CO2 between 2010 and zero emissions in 2050. Unfortunately by August 2011 Australia had already used up its “share” of this terminal greenhouse gas (GHG) budget through disproportionately huge annual fossil fuel burning and exports. [10].

It must be finally noted that Australia has a population of 22 million and accordingly its 2009 annual per capita GHG pollution was 1,415 Mt CO2-e/22 million = 64.3  tonnes per person per year, 71 times that of Bangladesh (0.9). [11].

Conclusions.

Australia has  an annual per capita GHG pollution 71 times that of Bangladesh and has already used up its “fair share” of the global 600 Gt CO2 pollution budget permitted between 2010 and zero emissions  in 2050. Tackling climate change means a DECREASE in  greenhouse gas (GHG) pollution. However the Australian Labor Government’s Carbon tax-ETS plan means that Australia will INCREASE both its Domestic and  Exported GHG pollution in both 2020 and 2050 relative to that in 2000.  Further, the Australian Government adumbrates a coal to gas transition for power generation as a consequence of its carbon price plan. However gas burning is a dirty energy source and if fracked shale gas is used to generate electricity instead of coal  then power sector GHG pollution can double associated with systemic gas leakage.

The recent written advice I have received from the Australian Government  that “The Australian Government [has] a comprehensive plan to move to a clean energy future. Central to that plan is the introduction of a carbon price that will cut pollution in the cheapest and most effective way and drive investment in clean energy sources such as solar, wind and gas” is comprehensively incorrect: the Australian Labor Government’s plan is effectively for climate change inaction, a dirty energy future and indeed dirtier energy future. Further, gas is not clean energy and can be worse than coal GHG-wise due to systemic gas leakage.

[1]. David Lewis, "EPA confirms natural gas leakage rates", The Energy Collective, 7 December 2010: http://theenergycollective.com/index.php?q=david-lewis/48209/epa-confirms-high-natural-gas-leakage-rates .

[2]. Drew T. Shindell , Greg Faluvegi, Dorothy M. Koch ,   Gavin A. Schmidt ,   Nadine Unger and Susanne E. Bauer , “Improved Attribution of Climate Forcing to Emissions”, Science 30 October 2009:
Vol. 326 no. 5953 pp. 716-718: http://www.sciencemag.org/content/326/5953/716 .

 

[3]. Shindell et al (2009), Fig.2: http://www.sciencemag.org/content/326/5953/716.figures-only .

[4]. Katharine Sanderson, “” Aerosols make methane more potent”, Nature News, 29 October 2009: http://www.nature.com/news/2009/091029/full/news.2009.1049.html#B1 .

[5]. Dr Drew Shindell, quoted in Mark Henderson, “Methane's impact on global warming far higher than previously thought”, The Times, 30 October 2009: http://www.timesonline.co.uk/tol/news/science/earth-environment/article6895907.ece .

 

[6]  Green Energy Markets, “Fast-tracking Victoria's clean energy future to replace Hazelwood”, 2010: http://www.environmentvictoria.org.au/sites/default/files/Fast-tracking%20Victoria%27s%20clean%20energy%20future
%20to%20replace%20Hazelwood.pdf
.

 

[7]. Robert W. Howarth, Renee Santoro and Anthony Ingraffea, “Methane and the greenhouse-gas footprint of natural gas from shale formations”, Climatic Change, 2011: http://www.eeb.cornell.edu/howarth/Howarth%20et%20al%20%202011.pdf .

 

[8]. Australian Treasury, “Strong growth, low pollution. Modelling a carbon proce”, 2011: http://cache.treasury.gov.au/treasury/carbonpricemodelling/content/report/downloads/Modelling_Report_Consolidated.pdf?v=1 .

[9]. Gideon Polya, “Analysis: Australian Labor Government Carbon Price-ETS scheme fails & entrenches climate change inaction”, Bellaciao, 16 July 2011: http://bellaciao.org/en/spip.php?article20957 .

[10]. Gideon Polya, “Shocking analysis by country of years left to zero emissions”, Green Blog,1 August 2011: http://www.green-blog.org/2011/08/01/shocking-analysis-by-country-of-years-left-to-zero-emissions/ .

 

[11]. “Climate Genocide”: https://sites.google.com/site/climategenocide/ .

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