Coal

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  • Coal
    • Formation
      • Coal formed as dead trees gradually became increasingly pure carbon as other materials such as methane gas were squeezed out. Aerobic conditions prevented decomposition and high heat and pressure caused chemical changes
    • Extraction
      • Features that make extraction difficult
        • The processes are very slow
        • Deep burial
        • Young coal has a low energy density
        • Many deposits are thin and widely dispersed
      • Coal is extracted by deep mining and open cast mining.
      • Open cast mining is more mechanised but is only economic where coal is quite near to the surface.
      • Coal that is too deep to be mined can be burned underground under controlled conditions to produce a mixture of fuel gases including hydrogen, carbon monoxide and methane
    • Principle Uses
      • Electricity generation
      • Iron and steel industry
    • Energy Density
      • When coal is burned it reaches high temperatures that allow the smelting of metal ores
      • The high energy density also allows steam to be generated to drive turbines to create electricity
    • The Future
      • Existing supplies of coal are becoming depleted, environmental damage is becoming unacceptable, existing sources cannot satisfy demand caused by increased affluence and population growth.
      • Gasification of coal underground allows the exploitation of coal seams that are too deep, thin or fractured for traditional methods.
    • Environmental Impacts
      • The mining of coal causes habitat loss, noise, dust and turbid drainage water
      • The burning of coal causes acid rain, global climate change, carbon monoxide, photochemical smogs, smoke and ash.
      • Open cast mining of coal causes...
        • Aesthetic problems
          • Solution: Landscaped embankments or landscape the area after mine closure, plant trees and  grass
        • Dust from mining and vehicle movements
          • Solution: Spray water during dry weather
        • Noise from vehicles
          • Solution: Baffle mounds around mines to absorb/deflectnoise
        • Noise from blasting
          • Solution: Limit blasting to daytime periods
        • Turbid drainage water
          • Solution: Sedimentation lagoons
        • Derelict site left on mine closure
          • Solution: Restoration for appropriate use - agriculture, conservation or recreation. Ground instability makes house construction difficult
    • Economic Issues
      • Cheap natural gas contributed to the closure of deep coal mines in the UK
      • Coal and other fossil fuel use causes economic costs that are not paid for by the energy industry
        • Costs such as pollution damage are paid by other sectors of society, such as agriculture, forestry or the health service.

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