Methane (CH4) (about 85% of natural gas) is 105 times
worse than CO2 as a greenhouse gas (GHG) on a 20 year time frame and taking aerosol
impacts into account. Methane leaks (3.3% in the US based on the latest US EPA data
and as high as 7.9% for methane from “fracking” coal seams). Using this information
one can determine that gas burning for electricity can be much dirtier than coal
burning greenhouse gas-wise (GHG-wise). While gas burning for power generates twice as
much electrical energy per tonne of CO2 produced (MWh/tonne CO2) than coal
burning and the health-adverse pollution from gas burning is lower than for
coal burning, gas leakage in the system actually means that gas burning for
powercan be worse GHG-wise than coal burning.
Unfortunately pro-gas politicians and gas producers variously add to the popular misconceptions that “gas is clean energy ” or “gas is cleaner energy than coal”. While pricing any bad item (e.g. coal burning, smoking, drinking) is useful the devil is in the detail as to any desired Carbon Price and Carbon Tax as a market-based GHG pollution mitigation mechanism. Thus the Australian Government has made it clear that a significant intent of its proposed Carbon Tax is to promote a coal to gas transition. However, as set out below, a coal to gas transition will be disastrous, involving huge national investments to achieve an increase in GHG pollution.
The current global Gas Boom, Gas Rush and Gasland perversion is enabled by corporate greed, lobbying and the falsehoods that “gas is clean” or that “gas is cleaner than coal”. Methane (CH4) is a major greenhouse gas (GHG) that on a 100 year time scale has a relative global warming potential (GWP) that is 25 times that of carbon dioxide (CO2). However a re-assessment by US scientists that takes atmospheric aerosol responses to CH4 into account has found that on a 20 year time scale CH4 is 105 times worse than CO2 as a GHG. Recent data from the US EPA indicates that the industrial leakage of CH4 in the US is 3.3%. Using this information it can be estimated that gas burning for power can be much dirtier GHG-wise than coal burning.
Dr Drew Shindell and colleagues (NASA's Goddard Institute for Space Studies) have published a paper in the prestigious scientific journal Science (US) that takes gas-aerosol interactions into account in assessing the GWP effectiveness of various GHGs as summarized in the Abstract of their paper : “Evaluating multicomponent climate change mitigation strategies requires knowledge of the diverse direct and indirect effects of emissions. Methane, ozone, and aerosols are linked through atmospheric chemistry so that emissions of a single pollutant can affect several species. We calculated atmospheric composition changes, historical radiative forcing, and forcing per unit of emission due to aerosol and tropospheric ozone precursor emissions in a coupled composition-climate model. We found that gas-aerosol interactions substantially alter the relative importance of the various emissions. In particular, methane emissions have a larger impact than that used in current carbon-trading schemes or in the Kyoto Protocol. Thus, assessments of multigas mitigation policies, as well as any separate efforts to mitigate warming from short-lived pollutants, should include gas-aerosol interactions.” .
The key technical quote from Shindell et al. (2009) provides an estimate that the GWP of CH4 relative to CO2 on a 20 year time scale is 79 (without aerosol effects) and 105 (with aerosol effects considered): “Fig.2. The 100-year GWPs for methane, CO, and NO x (per Tg N) as given in the [IPCC] AR4 and in this study when including no aerosol response, the direct radiative effect of aerosol responses, and the direct+indirect radiative effects of aerosol responses. The AR4 did not report uncertainties for methane or CO and gave no mean estimate for NO x . The range for the GWP of CO is from the third IPCC assessment and encompasses values reported up through the AR4. Our calculations for the shorter 20-year GWP, including aerosol responses, yield values of 79 and 105 for methane, 11 and 19 for CO, and –335 and –560 for NO x , including direct and direct+indirect radiative effects of aerosols in each case. The 100-yr GWPs for SO 2 (per Tg SO 2 ) and ammonia would be –22 and –19, respectively, including direct aerosol radiative effects only, and –76 and –15 adding indirect aerosol radiative effects. GWPs for very short-lived NO x , SO 2 , and ammonia will vary widely by emission location and timing, and hence global values are of limited use.” [2, 3]
The Nature News part of the prestigious scientific journal Nature (UK) has summarized the key findings of Shindell and colleagues as follows: “Aerosols' complicated influence on our climate just got more threatening: they could make methane a more potent greenhouse gas than previously realized, say climate modellers. Drew Shindell, at NASAGoddard Institute for Space Studies, New York , and colleagues ran a range of computerized models to show that methane's global warming potential is greater when combined with aerosols — atmospheric particles such as dust, sea salt, sulphates and black carbon. The International Panel on Climate Change (IPCC) and treaties such as the Kyoto Protocol assume methane to be, tonne-for-tonne, 25 times more potent than carbon dioxide at warming the planet. But the interaction with aerosols bumps up methane's relative global warming potential (GWP) to about 33, though there is a lot of uncertainty around the exact figure.” .
Dr Shindell (NASA Goddard Institute for Spaces Studies, New York ) has given a succinct summary of these findings: “What happens is that as you put more methane into the atmosphere, it competes for oxidants such as hydroxyl with sulphur dioxide. More methane means less sulphate, which is reflective and thus has a cooling effect. Calculations of GWP [Global Warming Potential;] including these gas-aerosol linkages thus substantially increase the value for methane.” .
This re-assessment upwards of the GWP of CH4 to be 105 times that of CO2 on a 20 year time scale must have a big effect on assessment of total annual GHG pollution and the urgency with which this is addressed.
Thus based on a 20 year time scale CH4 GWP relative to CO2 of 72, World Bank analysts have estimated that global livestock production contributes over 51% of total annual global GHG pollution that they have re-assessed upwards from 41.8 billion tonnes CO2-e (CO2 equivalent) to 63.8 billion tonnes CO2-e. .
Further, based on a CH4 GHG contribution 25 times bigger than that of CO2 (on a 100 year time scale), eminent climate scientist Professor Hans Joachim Schellnhuber CBE (Director of the Potsdam Institute for Climate Impact Research [PIK], Germany) has estimated that for a 67% chance of avoiding a catastrophic 2 degree Centigrade temperature rise (the EU target; would you board a plane if it had a 33% chance of crashing?) the World has to cease CO2 emissions by 2050. “All men are created equal” means that all human beings must be allotted equal shares of CO2 pollution until 2050. This in turn means that high annual per capita GHG pollution countries such as the US and Australia must reach zero CO2 emissions by 2020 while low per capita emitters (e.g. India and Burkina Faso) can increase their emissions until finally reaching zero emissions by 2050. .
Similarly, based on CH4 being 25 times worse than CO2 as a GHG, Dr Vicky Pope (Head of Climate Change Advice, UK Met Office Hadley Centre): “Latest climate projections from the Met Office Hadley Centre show the possible range of temperature rises, depending on what action is taken to reduce Greenhouse gas emissions. Even with large and early cuts in emissions, the indications are that temperatures are likely to rise to around 2 °C above pre-industrial levels by the end of the century. If action is delayed or not quick enough, there is a large risk of much bigger increases in temperature, with some severe impacts. In a worst-case scenario, where no action is taken to check the rise in Greenhouse gas emissions, temperatures would most likely rise by more than 5 °C by the end of the century. This would lead to significant risks of severe and irreversible impacts. In the most optimistic scenario, action to reduce emissions would need to start in 2010 and reach a rapid and sustained rate of decline of 3 per cent every year. Even then there would still only be a 50-50 chance of keeping temperature rises below around 2°C. This contrasts sharply with current trends, where the world's overall emissions are currently increasing at 1 per cent every year.” .
On the same CH4 GWP assumptions, Professor Kevin Anderson and Dr Alice Bows (Tyndall Centre for Climate Change Research, University of Manchester, Manchester, UK) concluded: “According to the analysis conducted in this paper, stabilizing at 450 ppmv [carbon dioxide equivalent = CO2 -e, atmospheric concentration measured in parts per million by volume] requires, at least, global energy related emissions to peak by 2015, rapidly decline at 6-8% per year between 2020 and 2040, and for full decarbonization sometime soon after 2050 …Unless economic growth can be reconciled with unprecedented rates of decarbonization (in excess of 6% per year), it is difficult to envisage anything other than a planned economic recession being compatible with stabilization at or below 650 ppmv CO2-e ... Ultimately, the latest scientific understanding of climate change allied with current emissions trends and a commitment to “limiting average global temperature increases to below 4 o C above pre-industrial levels”, demands a radical reframing of both the climate change agenda, and the economic characterization of contemporary society.” .
In short, the re-assessment that CH4 is 105 times worse than CO2 as a GHG on a 20 year time scale means that (a) the annual GHG must be well over 50% greater than hitherto thought and (b) the time for 100% economic decarbonization must be substantially less than the current expert estimate of about 40 years.
A key aspect of economic decarbonization is obviously an urgent shift to non-polluting renewable energy (wind, wave, tide, concentrated solar thermal and solar photovoltaic) and geothermal energy. However this transition has been falsely obfuscated by fossil fuel corporations and their associates in the Western Lobbyocracies who falsely assert that “gas is clean energy” or that “gas is cleaner energy” than coal burning and are hell-bent on a transition from coal burning to gas burning for power. As a result of these false assertions there is currently a major Gas Boom and Gas Rush around the world that is set to become a global Gasland (see the movie “Gasland”).
Professor Robert Howarth (Cornell University) has considered the consequences of a 1.5% industrial methane leakage and a CH4 global warming potential 72 times that of CO2 on a 20 year time scale and has concluded: “A complete consideration of all emissions from using natural gas seems likely to make natural gas far less attractive than oil and not significantly better than coal in terms of the consequences for global warming …Far better would be to rapidly move toward an economy based on renewable fuels. Recent studies indicate the U.S. and the world could rely 100% on such green energy sources within 20 years if we dedicate ourselves to that course. ” .
I have done simple calculations showing that a 3.7% leakage of CH4 and a CH4 GWP 72 times that of CO2 yields that same greenhouse gas effect as burning the 96.3% remaining CH4 i.e. a roughly doubled GHG emissions from gas burning. However assessment of recent US EPA data indicates a methane leakage rate in the US of 3.3% and, as outlined above, the global warming potential of CH4 on a 20 year time scale is 105 relative to CO2 if the impact on global-dimming aerosols is included.
I have accordingly performed a re-calculation of the gas burning greenhouse gas effect based on these updated assessments as outlined below .(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 CH4 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 Environmental 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)  then one must consider the GHG effect of the released methane, noting that 1 tonne of CH4 is 105 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) .
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)  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”. .
Notwithstanding the science, the fossil fuel industry and allied lobbyists, commentators and politicians in the Western Lobbyocracies and Murdochracies continue to promulgate the falsehoods that “gas is clean energy” or that “gas is cleaner energy than coal”, most notoriously so in Australia, a world leader in per capita greenhouse gas pollution, coal exports and liquid natural gas (LNG) exports. [12-19].
Decent people around the world must (a) inform everyone they can that gas is dirty energy, that gas burning for power can be much dirtier greenhouse gas-wise (GHG-wise) than coal burning and (b) resolutely, through voting, sanctions and boycotts, eschew any avoidable dealings with countries, corporations, people and politicians involved in the worsening, terracidal Gas Boom, Gas Rush and Gasland perversion. Please tell everyone you can – a coal to gas transition will cripple timely implementation of 100% renewable energy, stop realization of zero CO2 emissions by 2050 and prevent the return of atmospheric CO2 concentration from the current dangerous and damaging 392 ppm to the 300 ppm required for a safe planet for all peoples and all species. .
. 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:
. Shindell et al (2009), Fig.2: http://www.sciencemag.org/content/326/5953/716.figures-only .
. IPCC AR4, “Synthesis report summary for policy makers”, 2007: http://www.ipcc.ch/publications_and_data/ar4/syr/en/spm.html .
. 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 .
. 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 .
. Robert Goodland and Jeff Anfang, “Livestock and climate change. What if the key actors in climate change are … cows, pigs and chickens?”, World Watch, November/December 2009: http://www.worldwatch.org/files/pdf/Livestock%20and%20Climate%20Change.pdf .
. Professor Hans Joachim Schellnhuber, “Terra quasi-incognita: beyond the 2 degree C line”, < 4 Degrees & Beyond, International Climate Conference, 26-30 September 2009, Oxford University , UK : http://www.eci.ox.ac.uk/4degrees/ppt/1-1schellnhuber.pdf .
. Dr Vicky Pope, “Met Office warn of “catastrophic” rise in temperature”, The Sunday Times, 19 December 2008: http://www.timesonline.co.uk/tol/news/environment/article5371682.ece .
. Kevin Anderson & Alice Bows, “Reframing the climate change challenge in light of post-2000 emission trends”, Proc. Trans. Roy. Soc, A, 2008: http://rsta.royalsocietypublishing.org/content/366/1882/3863.full .
. Mark Z. Jacobson and Mark A. Delucchi, “A path to sustainable energy by 2030”, Scientific American, November 2009, pp 58 – 65: http://www.scientificamerican.com/article.cfm?id=a-path-to-sustainable-energy-by-2030 .
. Robert Howarth, “Preliminary assessment of the greenhouse
gas emissions from natural gas obtained by hydraulic fracturing”, Cornell University , 1 April 2010: http://www.technologyreview.com/blog/energy/files/39646/
. Gideon Polya, “ Gulf oil & gas disaster, lobbyists, Obama & huge threat of natural gas (methane) to Humanity & Biosphere”, Bellaciao, 19 June 2010: http://bellaciao.org/en/spip.php?article19926 .
. 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 .
. Gideon Polya, “ Resource to stop gas-fired power plants, fossil fuel burning, GHG pollution & man-made climate change”, Bellaciao, 27 February 2011: http://bellaciao.org/en/spip.php?article20592 .
. 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
[16 ]. Robert W. Howarth, Renee Santoro, Anthony Ingraffen, “Methane and the greenhouse gas footprint of natural gas from shale formations”, Climatic Change, May 2011: http://www.sustainablefuture.cornell.edu/news/attachments/Howarth-EtAl-2011.pdf
. Countries, US Energy Information Administration: http://www.eia.gov/countries/ .
. “Australia’s electricity (slowly) getting greener”, Energy Matters, 2009: http://www.energymatters.com.au/index.php?main_page=news_article&article_id=988 .
. Gideon Polya, “ Gas is dirty energy & may be dirtier than coal - Oz Labor's "gas is clean energy" means Put Labor Last”, Bellaciao, 10 June 2010: http://bellaciao.org/en/spip.php?article19894 .
[20 ]. 300.org, “300.org – return atmosphere CO2 to 300 ppm”: http://sites.google.com/site/300orgsite/300-org---return-atmosphere-co2-to-300-ppm .