Coal’s problem is not climate change: Kemp
US coal companies blame climate campaigners and the Obama administration for waging a war on coal that has cost thousands of jobs and threatened struggling mining communities.
But coal’s long-term problems stem not from politics but from physical properties that make it an inferior source of energy compared with oil, gas and (arguably) renewables. Coal has been losing the “war” for market share since the middle of the 20th century as other sources of energy have become cheaper and more abundant. Rising energy consumption in advanced economies and emerging markets masked coal’s relative decline in the second half of the 20th century and first decade of the 21st. But as energy consumption has reached a plateau in developed countries, coal demand has started to decline in absolute and relative terms in the more modern economies.
Consumption has continued to grow in poorer countries, where coal has played a crucial role in making electricity available for the first time to hundreds of millions of households. But the same problems that ensured coal’s replacement in the advanced economies will gradually lead to its replacement in emerging markets as well.
Coal’s displacement by other sources of energy is part of a “grand energy transition” that has seen the dominant energy source shift successively from wood to charcoal, coal and oil. The precise dates vary slightly from country to country, but coal started to become an important source of energy on a global scale just before 1850 (“Energy transitions: history, requirements, prospects”, Smil, 2010).
Traditional biofuels such as wood and corn stalks continued to dominate the global energy system until 1900, when they were finally overtaken in importance by fast-growing coal consumption.
Coal remained the dominant energy source until the 1960s, when it was overtaken by oil (“Global primary energy consumption, 1800-2015”, Our World in Data, 2017). But in recent years, natural gas consumption has been growing faster, and gas is set to overtake oil as the single largest source of primary energy within the next decade. Predicting transitions beyond natural gas is fraught with uncertainty but climate campaigners hope the global energy system will shift from gas to wind and solar.
A question of physics
Each step in the grand energy transition has seen the dominant fuel displaced by one that is more convenient and useful. The reasons for the original shift from traditional biofuels to charcoal and then coal are still disputed by scholars. Wood was in short supply around major urban areas by the 17th and 18th centuries but it is unclear whether shortages were localised or becoming more general. In any event, transporting larger quantities of wood over lengthening distances from increasingly remote forested areas to consuming cities was becoming a logistical problem.
The solution was to turn wood into charcoal, which was much more compact, and eventually to shift to coal, which was even more compact and easier to transport. Traditional biofuels may have been becoming more scarce, but it was the increasing availability of coal and its decreasing price that drove the transition. Coal was simply more useful as a source of energy than traditional biofuels. Once it became cheap enough, it rapidly replaced wood and agricultural waste in most uses. The same process explains the gradual displacement of coal by oil during the 20th century and now by natural gas in the 21st century. There is far more energy in one kilogram of refined gasoline (46 megajoules) or gas (54 megajoules) than in a kilogram of bituminous coal (24-35 megajoules), let alone wood (18 megajoules). —Reuters