Monday, February 11, 2008

The "Coal-Dearth Era".

I don't find the topic of fossil fuel depletion, e.g. Peak oil, and the post-peak period which I have dubbed the "Oil-Dearth Era" anything other than depressing, and yet in my more dejected moods, mulling over the subject, I have tended to think along the lines of, "well, at least there's still plenty of coal. We need to use it cleanly, but at least it's there to dig-up and not about to run-out any time soon." Indeed it is sometimes said there is 10 trillion tonnes of coal lying in the ground for us, which could keep the world going for hundreds of years, even if we fended-off the direst consequences of falling oil-production by turning large quantities of it into fuel by coal-to-liquids (CTL) processes.

I have always acknowledged the difference between a resource and a reserve: that reserve is how much of a material there is within acknowledged holdings of it and that as prices go-up, some of the resource (that's the lot, even theoretically estimated amounts) can pass onto the reserve, but it is generally accepted that there are around one trillion tonnes of coal in accessible reserves, worldwide. The rest of that 10 trillion tonnes, including the huge 3 trillion tonnes of coal under the sea off Norway, will probably not be so readily exhumed. At any rate, we still have that trillion tonnes to rely on ...or do we?

Demand for coal rises relentlessly. China is the world's greatest producer of coal (and also of zeolites, interestingly) but became a net importer in 2007, as its own provision could no longer keep pace with demand. 80% of all energy in China comes from coal and within that overall mix, 80% of its electricity component is derived from burning coal. It is often said that China opens one new coal-fired electricity plant every week, and these are about twice the size of a typical such power station in the U.K. In 2006, China increased its electricity production by 102 gigawatts, which is more than twice that used in total in the UK, and three times enough to power California. There are many examples, but overall, the world is using more and more coal, with the effect that estimates of "how many years worth we have left" have fallen dramatically.

Rather as is the case for oil, it is generally conceded that there are unlikely to be any new major discoveries of coal, and Energy Watch made the forecast that there will be a world peak in coal production in 2025. This is also in accord with the predictions of some analysts in Germany, reported a year or so ago. Thus, if the quantity of the reserve is contained and finite, it is in principle possible to apply a Hubbert Peak analysis as he of the same name did for U.S. oil in 1956, and which when applied to world oil production suggests a peak any time now, and certainly within the next 10 years. This doesn't mean the world is about to run out of oil - far from it - but that the commodity of cheap oil will fall into decline at close to 3% per year, and what remains in the oil-wells will become more difficult to extract and refine so that the price of fuel and all else will soar, while the world stock markets oscillate unpredictably.

To an economist, how much of a particular commodity can be produced is a matter of its price and as prices increase, more reserves will emerge to be costed in the marketplace. Thus coal seams (resources) that are, at present prices, too thin, too far below ground or distant from major consumers, can thence become economic and reclassified as reserves. However, prices of mineable commodities tend to reflect rather more pragmatic aspects, namely how easy or not it is to extract the raw materials themselves and coal is no different in this respect than oil, say, or platinum for that matter. David Rutledge at the California Institute of Technology (CIT) has applied a "Hubbert Linearization" to the matter of world coal reserves.

The original Hubbert peak analysis involves drawing a symmetrical "bell-shaped" (logistic) curve, enclosing production/year plotted as a function of time, and hence the area under the curve requires an estimate of the total amount of oil that will ever be produced from the given resource. Hubbert also applied the method to coal production. The upshot is that the peak is reached when half the resource has been produced while the other half is still in the ground, but to get an accurate forecast, it is necessary to have a good idea of how much of the material there is ultimately recoverable. Now this is the tricky part, since estimates of the latter, particularly for coal, tend to be quite unreliable, but here is where the Hubbert linearization comes in.

In the linearization, rather than plotting the annual production (P) vs the increasing number of years (e.g. from 1930 - 2010, say), (P) is expressed as its ratio (P/Q) to total (cumulative) production to date (Q) on the y-axis, and plotted vs total production (Q) on the x-axis: (y is vertical and x is horizontal). Since the denominator (Q) increases over time, i.e. as the resource is extracted, (P/Q) decreases monotonically and ergo the line has a negative slope. The point at which the straight line ("linearization") crosses the horizontal axis corresponds to the total amount that will ever be recovered, when P = P/Q = 0, i.e. there is no more to be recovered and production has ceased entirely.

Rutlege attempted to validate the model for coal by applying it to UK coal production since 1855, which actually peaked in 1913. Not only does it seem to work, but there are some alarming conclusions. Potentially the result sets some historical excuses to rights, namely that the fall in coal production happened because of Winston Churchill's decision to switch the British navy to oil instead of coal, the various miners strikes, the switch from town-gas (made by heating coal in giant retorts) to natural "North Sea" gas, etc., and explains that the real cause is a fact of geology. This is highly disconcerting, since it suggests we actually have a lot less cheap and readily recoverable coal under these islands than is often claimed. Indeed, it is reported that the UK reserve of coal amounts to 1.5 billion tonnes in existing mine holdings, but that another 190 billion tonnes lies elsewhere if you include areas under the North Sea within British waters. This may be so but the analysis, as in Hubbert's original case for oil, refers to cheap coal which can be extracted relatively easily.

Obviously, if it is necessary to dig a new and enormous mining infrastructure and to access deep seams of coal (half the coal produced in the UK comes from near-surface mines), the process must inevitably incur higher energy and fiscal costs; hence however much coal we might "own" in the UK, whether we can afford to get to it is another matter, and this begins to make coal-gasification look attractive since actual digging is avoided, that is if the technology can be made to work here. [There was, in fact, a pilot study done in Derbyshire in the 1950's with success but the National Coal Board concluded the process was uneconomic. Now it might prove profitable, after all for the UK].

As applied to world coal production, the result of the Hubbert Linearization is not rosy either, since it predicts that there are around 450 billion tonnes of it in readily accessible locations, or less than half the trillion tonne estimate I was banking on. For sure, more coal will be dug, but at increased costs and the resources (oil and gas and indeed coal itself) to provide the energy to do so must be found. Given that coal production must increase by 70% by 2030 to power predicted economic growth, which is coincidentally when "peak coal" is to be expected (2025 according to the linearization model, and in agreement with other forecasts), the world is on its way to an even bigger energy crunch (gap) than is expected to follow peak oil.

If the "Coal Dearth Era" is to provide another seam of depleting energy resources, running parallel with and compounding the "Oil Dearth Era", then the world simply cannot rely on fossil fuels to underpin human societies, and without some new "energy" technology to match the combined scale of oil and coal, or some form of agriculture that can enhance crop yields above the maximum carrying capacity of the planet at 3 billion, what other scenario is there but a die-off from the existing population of 6.5 billion (let alone an increase to 9 billion by 2050, as growth-enthusiasts predict)? I am even less happy than when I began writing this. The good news is, as I have commented before in "Chemistry World", that the inevitable fall in accessible fossil resources will necessarily result in a decline in the world's CO2 emissions, whether we implement deliberate carbon reduction strategies or not - however, we may not have much of a civilization left by then.

Related Reading.
[1] "The great coal hole", by David Strahan:
[2] Chris Rhodes:


Anonymous said...

This has nothing to do with coal, or any other dearth and certainly I do not expect this to be printed, for it is not a legitimate comment.
Just a rant.
For what it's worth, here it is,
Does anyone ever take into account distribution losses when a power project is conceived?
Consider the following:-
There was a news item today about a projected windfarm in the Isle of Lewis, it would cover “about 30 miles (!)”. I looked up the site ""
which has a helpful interactive map. The map shows 5 projected wind farms in Lewis, one of which, Barvis Moor, is of interest. This will have a projected output of 3,000MW, a Project Capacity of 543,000 MW and an Annual Homes Equivalent of 303,618. I do not fully understand these figures, but it sure seems like a lot of electricity.
What are they going to do with this electricity in Lewis, apart from collecting Government subsidies?
I have read that distribution losses can be as high as 80% (which must give distribution the inefficiency jackpot!), so assuming the electricity is cabled to where? Glasgow(?), that 3000MW (assuming steady state good wind) will be(output) 600 MW, or project capacity) 108600 MW or (annual homes) 60724.
Will the cost of construction, taxes (as subsidies), and all other costs make this project viable?
There will be 181 turbines. How will the power from each turbine be collected? By underground cabling, involving massive trenching?
By overhead cabling, involving an opressive overhead web of cables, and the associated pylons?
My point is, considering distribution losses, shouldn’t there be a debate upon the viability of mega-windfarms, as against little-local-windfarms?
Come to that, considering distribution losses, shouldn’t there be a debate about the practicality of mega powerstations as against little-local-powerstations?
If you are still reading so far, thanks.

Anonymous said...

From previous "Anonymous" (power distribution losses).
I do not understand how to get past your defences for posting comments. Normally I use my name (Peter Melia) and email address, (, but whichever way I used these I was rejected, so in the end I became anonymous, which I never, normally am, except for this message. Sorry.

Professor Chris Rhodes said...

You are correct about the need for infrastructure to draw power from wind farms, and probably laying underground (sea) cables would be cheapest.

The aspect of infrastructure attends all putative kinds of energy technology, e.g. hydrogen and is the limiting factor in many cases.

However, this is almost never referred to explicitly, as you rightly point out.

I heard about the Isle of Lewis wind farm project too. Sure when all is accounted for, it will be expensive and renewable energy is a growing business. maybe somewhere to invest any spare cash?


Professor Chris Rhodes said...

Hi Peter!

Your comments are much appreciated and I will look into the "defenses" on this system.

Meanwhile, nice to know you.

I am rarely anonymous either. Anybody can find me on the web by typing "Prof. Chris Rhodes" into google.


Jonathan Maddox said...

Apropos peak coal, you write that the peak is down to geology and not the various economic conditions of strikes and fuel substitution.

I really don't understand this. The 1913 UK coal peak and the 1971 US oil peak both took place in the presence of competing, less expensive, near-identical sources abroad. They were smooth transitions made on the basis of economics alone. *Since* the UK coal peak, with domestic sources already in decline, the UK made dramatic steps to rely on other fuels. This is entirely natural. If there had been no cheap coal available for importation, the domestic coal production peak would have occurred much later (at far higher prices), and the fuel substitution would have taken place sooner.

You draw some kind of distinction between 'cheap' coal and 'economically recoverable' coal. But cheap is of course a relative thing. If non-fossil energy technologies do not fall in cost then the price people are willing to pay for fossil fuels will soar, and the size of the 'economically recoverable reserve' will grow accordingly.

There is no historical precedent at all for a *global* fossil fuel peak and decline. The point and the price at which it happens depends not on some geologically-fixed 'total economically recoverable reserve' which is some fraction of the total resource but on the economics of competition between technically interchangeable energy sources.

Non-fossil energy technologies *are* falling in cost and will continue to do so. Electricity from ambient energy already begins to compete with fossil-fuel electricity; as batteries improve they will come to compete with mobile fossil fuels as well (and there are numerous competing transportation fuel technologies).

Coal and oil will follow reasonable Hubbert peak curves *because* substitution with non-fossil energy is already taking place. We have very little to fear; the worst of it (which we already suffer) is the volatility of fossil fuel prices while they still dominate, making forward planning difficult. As transportation shifts away from oil and renewables (or nuclear power) take an ever-growing share of electricity production, this volatility will subside. The prices we pay for energy will never be as low again as we enjoyed in the last decade of the 20th century, but we knew that at the time. We can cope with far higher prices as long as we can plan for them.

P.S. re electricity transmission losses, the 80% figure is absurdly high. Figure 15% in a typical grid, 30-40% in smaller remote installations (which the Isle of Lewis windfarm probably is), and a mere 10% for modern high-capacity long-distance HVDC interconnectors such as will be required to supply power from reliable Icelandic geothermal and Saharan solar energy supplies to the big markets of northern Europe.

Professor Chris Rhodes said...

Where am I supposed to have said about "80% losses from the grid" or even referred to the grid? What I say is that 80% of China's electricity is made from coal.

The Hubbert analysis refers to production from a particular source, and if more sources are found then oil/coal may be recovered for longer but it is likely to be more costly to extract.

Routledge's analysis for coal has put the cat among the pigeons, and it is some coincidence if the fall in coal production is due to implementation of alternatives.

You say: "Coal and oil will follow reasonable Hubbert peak curves *because* substitution with non-fossil energy is already taking place" but the reason they will follow reasonable curves or straight lines is that the resources of the conventionally recovered material are finite.

There is precious little substitution by non-fossil energy so far, unless you mean nuclear power?

There is undoubtedly pletny of oil and coal left in the ground but in more difficultly extractated locations. Fore example to get at the huge deposits of coal under the UK will require digging a whole new network of mines or wholesale coal gasification so it doesnit need to be dug out.

The relationship between oil prices and the markets is complex and inextricable as I wrote about in a recent posting on "Oil Prices".

I am by nature an optimist but I think these Hubbert analyses give a reasonable estimate of "cheap" resources.

The demand supply gap for oil is more pressing as a threat than the actual peak which will simply make the situation worse.


Chris Rhodes.