Monday, November 19, 2012

Maximum CO2 Emissions According to IEA's Updated Estimation of Fossil Fuel Reserves and Resources

According to the IEA's World Energy Outlook 2012, the updated data table for fossil fuel reserves and resources is as below. (Notes: (1) R/P ratio = Reserves-to-production ratio based on 2011 levels of production. (2) Resources are remaining technically recoverable resources.)

Table. Fossil-fuel reserves and resources by region and type, end-2011 (coal = 2010 data)

Coal (billion tonnes) Natural gas (tcm) Oil (billion barrels)

Proven reserves Recoverable resources Proven reserves Recoverable resources Proven reserves Recoverable resources
OECD 427 10,657 28 193 244 2,345
Non-OECD 576 10,551 205 597 1,450 3,526
Share of non-OECD 57% 50% 88% 76% 86% 60%
World 1,004 21,208 232 790 1,694 5,871
R/P ratio (years) 132 2,780 71 241 55 189

WEO 2012 says we have plenty of fossil fuels currently: 132 years' supply of coal, 71 years' supply of natural gas, and 55 years' supply of oil, only from "proven" reserves.
Then, however, how much carbon dioxide can be released to the atmosphere if we consume (combustion) all the fossil fuel reserves or resources? Using the BP's suggested conversion factors, I got the following estimation.

Table. A rough estimation of possible CO2 emissions based on reserves or resources*
(unit: gigatonnes of CO2)

Proven reserves Recoverable resources
Coal 2,304 48,668
Natural gas 491 1,671
Oil 709 2,458
Total 3,504** 52,797
* NOT an official estimation. Errors are mine.
** World Energy Outlook 2012 states the global carbon reserve is 2,860 gigatonnes of CO2 (p. 259). I think I used inaccurate emission factors, especially for coal.

That is, proven reserves alone can emit 3,504 (or 2,860) gigatonnes of carbon dioxide. A study published in Nature (Allen et al., 2009) stated that the total anthropogenic emissions could be 3.67 trillion tonnes of CO2 and about half of them had already been emitted since industrialization began. So at the time of the study's publication, about 1.8 trillion tonnes of CO2 were yet to be emitted. However, the new IEA estimation of reserves asserts there are still 3.5 (or 2.9) trillion tonnes of CO2 to emit.
So, technological advancement has significantly increased the possible future CO2 emissions. Do we have to be complacent because we have enough fossil fuels or is it a really sad news for our children? I hope that the world can somehow reach to an agreement soon and prevent the catastrophic climate change that could be realized if we burn all the fuels.

Emissions factors used in the emissions estimation:
Coal 3.96 ton CO2/toe = 2.294789 ton CO2/ton
Natural gas 2.35 ton CO2/toe = 0.002115 ton CO2/cm
Oil 3.07 ton CO2/toe = 0.418748 ton CO2/bbl

Reserves/resources: IEA. (2012). World Energy Outlook 2012. Paris, France: IEA Publications.
Conversion factors modified from: BP. (2012). BP Statistical Review of World Energy June 2012. London, UK: BP p.l.c.
Cited previous study: Allen et al. (2009). Warming caused by cumulative carbon emissions towards the trillionth tonne. Nature, 458, 1163-1166.

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