What is the impact of peak oil and peak coal?
The goal of this post is to explore how peak oil and, yes, peak coal might affect the world’s effort to stabilize CO2 concentrations. Here I present calculations I haven’t seen anywhere else, and since different sources provide different numbers, please view these as a crude estimates. I welcome corrections.
At recent growth rates for oil consumption, we are all but certain to peak in oil production within two decades — and if we follow the recent trend-line for coal use (and for coal reserves), we could hit peak coal within three decades. It looks like it simply isn’t possible for oil and coal use to sustain for decades the trends that led CO2 emissions to rise 3 percent per year since 2000, if the analysis below is roughly correct. That would be a very good piece of news.
Oil: I have already written at length on oil (see "Peak Oil? Bring it on!"). In 2006, the world consumed about 85 million barrels a day (MMBD) of oil. Oil use had been rising about 2 percent per year, though the recent price jump may have slowed things a tad. And, for the first time, not just the “peakists” but the CEOs of major oil companies think we have a big problem.
The CEO of Royal Dutch/Shell emailed his employees, “Shell estimates that after 2015 supplies of easy-to-access oil and gas will no longer keep up with demand.” The CEO of French oil company Total S.A. said that production of even 100 million barrels a day by 2030 will be “difficult.” The CEO of ConocoPhillips said, “I don’t think we are going to see the supply going over 100 million barrels a day.”
Coal: World coal consumption and production in 2006 was about 6 billion metric tons according to the World Coal Institute. World recoverable reserves at the end of 2005 vary by source, but the World Energy Council puts them at 850 billion metric tons, which seems to be a relatively typical figure. Thus, global coal reserves would last some 140 years, at current rates of production and consumption. That said, global coal reserve estimates are of “poor quality” and may be lower than we think, as one recent German study noted [PDF]. The U.S. National Academy of Sciences made a similar point about U.S. reserves last year:
Present estimates of coal reserves are based upon methods that have not been reviewed or revised since their inception in 1974, and much of the input data were compiled in the early 1970s. Recent programs to assess reserves in limited areas using updated methods indicate that only a small fraction of previously estimated reserves are actually minable reserves.
It is worth noting that estimates of world recoverable coal reserves have declined slowly but steadly for two decades by a total of about 15 percent, more than 150 billion tons. Indeed, they have dropped 7 percent from end of 2002 to end of 2005, according to the WEC. As one energy analyst put it, “Reserves figures are dropping far more quickly than actual extraction.” For further analysis suggesting reserves are still very inflated, see the German study and this website by Professor David Rutledge of CalTech.
I’m going to run through two scenarios to explore the impact of fossil fuel resources on carbon emissions trends.
Case 1: The first scenario uses the Princeton assumptions from their wedge analysis that carbon emissions will increase 1.5 percent per year through 2050 (a rate that is based on the pre-2000 trend). For now, I will also assume global carbon emissions in 2006 were 8.4 billion metric tons, the number the Global Carbon Project uses, while acknowledging that the U.S. Energy Information Administration and the International Energy Agency both have lower numbers (if you’re a masochist, see here [PDF] and here [PDF]).
(I’m also going to assume that the fraction of global emissions that coal is responsible for stays the same through 2050. That number is 36 percent, or 3 GtC in 2006. In other words, I’m going to assume that all fossil fuels grow at 1.5 percent per year through 2050 — remember, this is a BAU case, not what we expect to happen at all.)
By 2050, then, everything nearly doubles. Global carbon emissions are 16 GtC — bye-bye, climate — of which 5.8 GtC is coal. We would be consuming over 160 MMBD of oil. That isn’t going to happen. Hard to know exactly what gives, but it doesn’t look like we have the oil (and presumably the natural gas) to get anywhere near that number. Coal use would be 11.5 billion tons a year. Actually, it would have to be more if we peaked in oil by, say 2020, at 106 MMBD. We’d probably start turning a fair amount of coal into oil starting by the 2020s — assuming, again, a BAU case where we don’t care about the climate policies.
Case 2: Now let’s see what happens if global carbon emissions keep rising through 2050 at the rate they have been growing from 2000 to 2006, about 3 percent per year. Global carbon emissions in 2050 would be about 31 GtC — uh, bye-bye, everybody!
(Given that we easily maxed out oil — and presumably gas — in Case 1, I’m going to assume that they both max out again at a 1.5 percent annual rate of growth, and therefore that all the rest of the growth in CO2 beyond Case 1 is from coal. Thus coal generates 5.8 GtC as in Case 1 PLUS all of the difference between 31 GtC and 16 GtC, which is to say about 15 GtC. And so the total coal emissions in 2050 is roughly 21 GtC — seven times the current level.)
In Case 2, coal use in 2050 would be 42 billion tons a year. But, in fact, at that pace of growth, we would have used up all of the current existing recoverable reserves before then. And even if we somehow miraculously doubled global coal reserves during that time, we would only have another 20 years of coal left at this rate of consumption!
Conclusion: I believe peak oil and peak coal will in fact interfere with the path that carbon emissions take in the first half of this century to a very great (but difficult to quantify) extent. That is a terrific piece of news for the planet (though, sadly, we have more than enough coal to destroy the climate if we burn most of it).
It is, however, a so-so piece of news for energy and climate modelers, because we lack solid numbers that are widely agreed upon for …
- how much oil reserves we have
- how much of a role unconventional oil could play in the next few decades (especially if we exclude much coal to liquids because we’re using all the coal up for other uses), and
- how much coal reserves we have now, or might have in a couple of decades.
As I’ve said, Part 4 of this series will look at the politics, policies, market factors, and mindset needed to achieve the 14 to 16 stabilization wedges discussed in Part 2 (here). In that post, I’ll also consider qualitatively how peak oil and peak coal will affect those factors. That should give readers a few days to go over these numbers and find my mistakes!