The future of coal

Some countries, those who are signatories to the Kyoto Protocol, have decided to reduce their greenhouse gas emissions. These countries should not increase their consumption of coal but rather reduce it in order to limit their CO₂ discharges. For the others, as a result of oil price increases, it is likely that coal will become a cheaper source of energy, which they will want to use even more. The share of coal in total primary energy consumption (1/3) should remain stable for another one or two decades, and then begin to increase. Certain problems of pollution linked to the use of coal can be solved by treatment of the combustion fumes, but the difficult problem still remains, that of CO₂.

Since 2004, oil prices have increased significantly. And it is by no means certain that they will come back down again to their previous cheap level for a long time. In this context of more expensive energy, decision-makers worldwide have the choice of 3 principal lines of action (none of them mutually exclusive):

• Encouraging energy savings,
• Developing new energy sources, if possible sources which are renewable;
• Reintroducing the use of energy sources already known, but whose use had been reduced or even stopped altogether with the arrival of oil.

Coal is an example of this last type of energy source. Oil is starting to be in short supply? Let’s call on coal, among other possibilities, to take its place!

However coal does have certain disadvantages:

- First of all, technical limitations: coal cannot be used for transport purposes, unless we go back to steam machines or, more seriously, if we move to electric vehicles;

- And then, ecological problems: the burning of coal is very polluting. Like oil, coal contains sulphur that gives off sulphur dioxide when it is burnt. In the atmosphere, this becomes sulphuric acid, by oxidation, an irritant for the lungs and the main component of “acid rain”, so harmful to forests. The burning of coal also gives off oxides of nitrogen (NOx). Several efficient processes exist for sulphur and nitrogen cleaning of gas emissions from the burning of coal. Action can be taken both upstream, before burning, or downstream, by treating the fumes. In the latter case, the proportion of SO2 can be reduced by 90% and that of nitrogen oxides by 80%. These procedures are gradually being put into operation in all fuel oil and coal power plants throughout Europe, in order to respect the new European norms.

But the burning of coal, like that of gas and oil, produces carbon dioxide (CO₂), the main greenhouse gas. And in this instance, there is no current solution. Even if ideas have been put forward (the injection of CO₂ into the subsurface rock formations or into the major oceanic trenches; a major increase in forested areas to fix a part of the carbon dioxide …). The signatories of the Kyoto Protocol, who have undertaken to reduce their greenhouse gas emission to 1990 levels, should certainly not increase their coal consumption. Those countries which refuse to make an effort to reduce greenhouse gases and who continue to produce more and more CO₂ because of their needs for economic growth, are without doubt going to increase their coal consumption in the coming years. The future of coal is therefore strongly linked to the commitment, or lack of it, to reducing emissions of greenhouse gases and to making technical progress on the fixing of carbon monoxide in the rock formations or in the oceans.

Lines for technological research are developing rapidly, particularly in the United States, where research programmes exist on:

- The gasification of coal to produce hydrogen for fuel cells;

- The capture and confinement of CO₂ which, once injected into oil wells, contributes to improvement in the hydrocarbon recovery rate.