8.2 Energy resources  (Page 2/5)

The uses of coal

Although in South Africa, the main use of coal is to produce electricity, it can also be used for other purposes.

1. Electricity In order to generate electricity, solid coal must be crushed and then burned in a furnace with a boiler. A lot of steam is produced and this is used to spin turbines which then generate electricity.
2. Gasification If coal is broken down and subjected to very high temperatures and pressures, it forms a synthesis gas , which is a mix of carbon dioxide and hydrogen gases. This is very important in the chemical industry (this will be discussed in Grade 12).
3. Liquid fuels Coal can also be changed into liquid fuels like petrol and diesel using the Fischer-Tropsch process . In fact, South Africa is one of the leaders in this technology (refer to Grade 12). The only problem is that producing liquid fuels from coal, rather than refining petroleum that has been drilled, releases much greater amounts of carbon dioxide into the atmosphere, and this contributes further towards global warming.

Coal and the south african economy

In South Africa, the coal industry is second only to the gold industry. More than this, South Africa is one of the world's top coal exporters , and also one of the top producers . Of the coal that is produced, most is used locally to produce electricity and the rest is used in industry and domestically.

The problem with coal however, is that it is a non-renewable resource which means that once all the coal deposits have been mined, there will be none left. Coal takes such a long time to form, and requires such specific environmental conditions, that it would be impossible for coal to re-form at a rate that would keep up with humankind's current consumption. It is therefore very important that South Africa, and other countries that rely on coal, start to look for alternative energy resources.

The environmental impacts of coal mining

There are a number of environmental impacts associated with coal mining.

• Visual impact and landscape scars Coal mining leaves some very visible scars on the landscape, and destroys biodiversity (e.g. plants, animals). During strip mining and open cast mining, the visual impact is particularly bad, although this is partly reduced by rehabilitation in some cases.
• Spontaneous combustion and atmospheric pollution Coal that is left in mine dumps may spontaneously combust, producing large amounts of sulfurous smoke which contributes towards atmospheric pollution.
• Acid formation Waste products from coal mining have a high concentration of sulfur compounds. When these compounds are exposed to water and oxygen, sulfuric acid is formed. If this acid washes into nearby water systems, it can cause a lot of damage to the ecosystem. Acid can also leach into soils and alter its acidity. This in turn affects what will be able to grow there.
• Global warming As was discussed earlier, burning coal to generate electricity produces carbon dioxide and nitrogen oxides which contribute towards global warming (refer to chapter [link] ). Another gas that causes problems is methane . All coal contains methane, and deeper coal contains the most methane. As a greenhouse gas, methane is about twenty times more potent than carbon dioxide.