4. Energy from Fossil Fuels: Digital Mapping of Sources and Environmental Issues

At present fossil fuels are the most important sources of energy. In many countries most of the energy is still generated by nonrenewable sources, which are represented by a limited reserve coal, oil, and gas. They will become scarce and therefore prohibitively expensive after a few decades. The choice can be limited by other criteria such as air pollution and climate change. The pollution due to coal power stations depends on the quality of the coal. A coal power station can emit each year a few million tonnes of carbon dioxide, a million tonnes of ash, half a million tonnes of gypsum, and other pollutants such as nitrous oxide, sulfur dioxide, and smaller amounts of other toxic wastes. Besides that coal mining is dangerous, dirty and many miners contract debilitating diseases such as silicosis. Oil became one of the world’s leading energy sources. It has a higher caloric value than coal and is more easily transported. Transport and industry are more dependent on oil supply than on the availability of coal. Moreover oil is the basis of petrochemical industries such as plastics, drugs, and paints. Similarly to coal, main oil reserves last for a few decades, and then the production becomes increasingly expensive. The changes can be more rapid in individual countries, which do not have their own oilfields. Since a large fraction of the oil is used for transport, it is imperative to discover new ways of driving cars and ships. The energy supply of gas has risen rapidly. As the rate of consumption is rising, it is unlikely to last longer than oil. In comparison with other fossil fuels, gas is now the cheapest and convenient energy source, but its world’s reserve is severely limited.