The composition of the solid fossil sediments that combine to form coal vary considerably. Brown coal is a younger (approximately 50 million years) fossil fuel, whereas mineral coal is considerably older (approximately 300 million years), has a correspondingly higher carbon content and thus a higher calorific value.
Coal was once Switzerland's most important energy source. But the evolution of the Swiss coal market is a good example of the effectiveness of the substitution efforts that have been implemented in Switzerland in recent years. Not only is coal cumbersome and requires a great deal of suitable storage space, the ash that results from its combustion also has to be properly disposed of, and in view of these drawbacks it is now only used by a small number of households in Switzerland. However, in rural areas and old houses and apartments it is still used for heating purposes. While in 1920, end consumption of coal totalled 932,000 tonnes (which was equivalent to 70% of Switzerland‘s energy supply), it fell rapidly to just 203,000 tonnes in 2004. Coal is therefore only of secondary importance today as far as Switzerland's energy supply is concerned. The proportion of both gross and end consumption is less than 1% of the country's overall energy consumption.
Coal has always been used in Switzerland, mostly by end-users as a form of primary energy, while the extraction of gas from coal for commercial use was the most important form of secondary energy.
The established global coal reserves as of 2004 amounted to 909,064 million tonnes (source: BP 2005 Statistical Review of World Energy). In 2004, world-wide production amounted to 2,732 million toe (tonnes oil equivalent): North America (606 million), South and Central America (44.1 million), Europe (434 million), Africa (140.3 million), and Asia (1,506.3 million). If annual consumption remains unchanged at around 2,000 million toe, given the established reserves the supply of coal would be secured for the next 230 years.
In Switzerland two industries still rely on coal today, namely foundries and cement factories. In the Swiss cement industry in particular, cheap imported coal (primarily from South Africa) remains a highly suitable form of energy, and it is estimated that approximately 80% of Switzerland's coal imports are destined for this industry.