Oil production may soon 'peak', but what about coal? David Strahan reports on the recent figures that suggest global reserves may not be nearly as plentiful as the industry and governments have led us to believe
For weeks, South Africa has suffered rolling blackouts caused in part by a shortage of coal. Gripped by unusually bitter snowstorms, China recently banned coal exports for the next two months. And at Newcastle, Australia, the world's largest coal export terminal in the world's largest coal exporting country, the queue of carriers waiting to load has been known to stretch almost to Sydney, 150km to the south.
Coal, for so long the Cinderella of fossil fuels, is suddenly not just in demand but in desperately short supply. The world's biggest producers and exporters are struggling, and the price of imports to Europe has doubled to almost $140 (£70.5) per tonne over the past year. "It's a global crunch," says John Howland, managing editor of the international coal industry magazine McCloskey's Coal Report.
The immediate reasons for the price spike are soaring demand, inadequate infrastructure and bad weather. But now there are also gnawing doubts that global coal production may, within the next few decades, face fundamental geological constraints, or "peak coal".
Ask most energy analysts how much coal we have left, and the answer will be a variant on "plenty". The latest "official" statistics from the World Energy Council put global coal reserves at the end of 2006 at a staggering 847bn tonnes. Since world coal production that year was just under 6bn tonnes, the reserves-to-production (R/P) ratio - the theoretical number of years the reserves would last at the current rate of consumption - is well over 100 years.
It is commonly assumed, therefore, that there can be no shortage of coal this century. However, a clutch of recent reports suggest that coal reserves may be hugely inflated - a possibility that has profound implications for global energy supply and climate change.
A report published last year by the EU Institute of Energy pointed out that as demand for coal has soared since the turn of the century - with China famously opening one coal-fired power station per week - the world's reserves have fallen fast. The authors calculated that the R/P ratio had dropped by almost a third, from 277 years in 2000 to just 155 in 2005.
Mysteriously, this fall happened despite a sharp rise in the price of coal, which traditional economic theory suggests should increase the level of reserves by making it possible to exploit more marginal deposits. The report warned that "the world could run out of economically recoverable (at current economic and operating conditions) reserves of coal much earlier than widely anticipated". When the latest data, from 2006, was published last year, the R/P ratio had dropped again to just 144 years.
Energy Watch, a group of scientists led by the German renewable energy consultancy Ludwig Bölkow Systemtechnik, has drawn an even more alarming conclusion. In a report also published last year, the group argues that official coal reserves are likely to be biased on the high side. "As scientists, we were surprised to find that so-called proven reserves were anything but proven," says the report's lead author Werner Zittel. "It is a clear sign that something is seriously wrong."
Energy Watch found that many countries' reserves figures had remained suspiciously unchanged for decades - China's since 1992, despite having mined 20% in the intervening years. But in those countries that had revised their figures, the changes were overwhelmingly negative. For instance Britain, Germany and Botswana had cut their reserves by over 90%, more than could be accounted for by mining alone, suggesting these gloomier updates were based on improved data.
As a result, Energy Watch concluded the current reserves figures are likely to represent the upper limit of available coal, meaning that production will stall far sooner than expected. On the basis of a country-by-country analysis, the group forecasts that although global coal output could rise by about 30% over the next decade, it will peak as early as 2025 and then fall into terminal decline.
Less coal, of course, means less carbon, and a recent analysis by Dave Rutledge, chair of the department of engineering and applied science at the California Institute of Technology, suggests that current forecasts of man-made CO2 emissions may be far too pessimistic. By analysing the coal production trends in individual countries, using an ingenious technique called Hubbert linearisation, Rutledge's estimate of the total amount of coal that remains to be produced is much lower than the official figures.
Using historical examples such as Britain, where coal output peaked in 1913 and mining is now all but finished, he can demonstrate that the approach is far more accurate than traditional explanations. By this method, the predicted future global coal production will amount to around 450bn tonnes before mining stops - little more than half the current official reserves figure.
The effect on the emissions outlook is dramatic, producing a peak atmospheric CO2 concentration in 2070 of just 460ppm (parts per million) - fractionally above the 450ppm that many scientists believe is the threshold for runaway climate change, and lower than even the most optimistic of the 40 climate scenarios by the Intergovernmental Panel on Climate Change (IPCC). "In some sense, this is good news," Rutledge says. "We are likely to hit 450ppm without any policy intervention." Therefore, even if governments did nothing, total CO2 concentration would not surpass the presumed climate change threshold by much.
Neither Energy Watch nor Rutledge could remotely be described as climate-change deniers - quite the opposite - but their findings worry many climate scientists, including Pushker Kharecha, at the Nasa Goddard Institute for Space Studies in New York. He agrees that coal reserves are probably overstated, but insists that curtailment of coal emissions is still essential to combat climate change. "What are the risks if the low-coal people are wrong?" he asks. To pin our hopes on low coal would be dangerously complacent, he argues, because if it is only marginally wrong the additional emissions could ensure catastrophe.
Rutledge agrees that although his analysis suggests that the fossil fuel reserves assumed in the IPCC model are far too high, it does not mean the problem of climate change is solved. Recent evidence suggests that the climate is more sensitive to carbon emissions than previously thought, and the IPCC model does not yet take account of long-term "positive feedback loops", such as the melting Siberian permafrost or shrinking icecaps, which will accelerate global warming. Jim Hansen, director of the Goddard Institute, has warned that the danger threshold for CO2 is probably much lower than 450ppm.
What it does mean, however, is that the world's looming energy crisis could be even more severe than anyone imagines. In the International Energy Agency's latest long-term forecast, global coal consumption needs to rise 60% by 2030 to satisfy economic growth, and coal-fired electricity generating capacity has to double. But if Zittel and Rutledge are right, there is little chance of those predictions being fulfilled. And as global oil production goes into terminal decline within the next decade or so, there is even less chance that synthetic coal-to-liquids fuels can make up the crude deficit.
But the good news is that the imperatives of climate change and peak oil are identical. "In the long run, economies that rely on depletable resources are doomed to fail," Zittel warns. "The coal peak makes it even more urgent to switch to renewable energy without delay."
· David Strahan is the author of The Last Oil Shock, published by John Murray Ltd. Details at lastoilshock.com