Study Notes for ENV-474 Energy and Sustainability: Fossil Energy - Coal

ENV-474 Energy and Sustainability

## Lecturer Details

  • Dr. Abdulmonem Fetyan

    Course Material

  • Copyright © W.W. Norton & Company 2012

  • Chapter 5 - P1 Fossil Energy - Coal

    Learning Outcomes

    The following learning outcomes are designed to provide a comprehensive understanding of coal within the context of energy and environmental studies:

  • Compare coal's overall contribution to world energy production with other fuels.

  • Explain the origin and formation of coal.

  • Classify the different types of coal.

  • Estimate the world coal resources and their distribution.

  • Describe the extraction processes and the different uses of coal.

  • Discuss the environmental impacts of coal (from extraction to combustion).

    Fossil Fuels Overview

  • Definition of fossil fuels: Fossil fuels refers to natural substances formed from the remains of prehistoric plants and animals, which have been subjected to heat and pressure over millions of years.

  • Types of fossil fuels recognized:

    • Coal

      • Energy content: 29 MJ/kg

      • Applications include electrical power generation, steel and cement industries, direct heating for buildings, materials (such as carbon fiber and activated carbon), and chemicals & synthetic fuels.

    • Oil

      • Energy content: 43 MJ/kg

      • Typically used for transportation, electrical power generation, plastic production, and more.

    • Natural Gas

      • Energy content: 55 MJ/kg

      • Used for direct heating, electricity generation, and transportation.

    Global Fossil Fuel Consumption and Coal Profile

  • Increasing trend in fossil fuel consumption globally.

  • Environmental Impact of Coal:

    • Produces almost double the CO2 emissions per gigajoule compared to natural gas.

  • Contribution to Global Energy Demand:

    • Coal accounts for approximately one-third of global energy demand.

    General Information about Coal

  • Coal is classified as a brownish-black combustible sedimentary rock.

  • It is mainly constituted of carbon derived from fossilized plants, along with varying quantities of other elements like hydrogen, sulfur, oxygen, and nitrogen.

  • Common applications:

    • Predominantly used for electricity production in coal-fired power plants and heating in heavy industries (e.g., steel and cement industries).

    • Historically used to heat homes and operate steam trains and boats.

    Formation of Coal

  • Carboniferous Period (300-350 million years ago):

    • Coal formation began when giant plants died in swamps before the dinosaurs.

    • The decomposed plant matter was subsequently buried under water and dirt.

    • Over millions of years, heat and pressure transformed the dead plants into coal.

    Types of Coal

  • Classification based on age and carbon content:

    • Lignite (brown coal):

      • Age: 150 million years

      • Carbon Content: 30%

      • Energy Content: Lowest

    • Sub-bituminous coal:

      • Age: 150 million to 300 million years

      • Carbon Content: 40%

      • Energy Content: Higher

    • Bituminous (black/hard coal):

      • Age: 300 million years

      • Carbon Content: 50-80%

      • Energy Content: Higher

    • Anthracite (black/hard coal):

      • Age: 350 million years

      • Carbon Content: >95%

      • Energy Content: Highest

  • Peat: Considered the precursor to coal, indicating the beginning stage of coal formation.

    World Coal Reserves

  • Global distribution and characteristics of coal reserves:

    • Coal is more widely found globally than oil or gas, present in numerous countries around the world.

  • Total World Reserves:

    • Estimated to exceed 850 billion tonnes, with an even distribution between high and low-quality coal.

  • Advantages of coal:

    • Low costs for energy production (if external environmental costs are not considered).

    • Simpler processing and refining compared to oil and gas.

    • Easy transportation methods including by train, boat, and lorry.

  • Major coal-consuming countries:

    • United States, China, Russia, India, Germany, and Australia.

  • Longevity of reserves:

    • Current rates of use suggest the global reserves can last for hundreds of years.

    Coal Extraction Methods

  • Underground Mining Methods:

    • Slope mine, shaft mine, and drift mine methods are typical configurations involving the original land surface, rock spoil, and coal beds.

  • Surface Mining Methods:

    • Examples:

      • Dragline, area mine, contour mine, and mountaintop mine utilize various equipment (e.g., dozers, auger miners) for extraction.

    Underground Mining of Coal

  • Notated as one of the most dangerous occupations in the U.S.

    Surface Mining of Coal - Strip Mining

  • Employs massive machinery such as dragline excavators and large lorries for operation.

    Coal Usage Statistics

  • Electricity Production:

    • 68% of global coal consumption is directed towards electricity production.

  • Transporting Coal:

    • Coal is typically transported in long trains; 100 train-cars, each carrying 100 tons, are standard.

    • To produce 1GW of electricity, a daily supply of approximately 10,000 tons (one full trainload) is required.

  • Types of Coal Burning in Power Plants:

    • Power plants predominantly burn “steam coal,” including lignite and sub-bituminous coal for electricity generation.

  • Environmental Concerns:

    • Considerations include thermal pollution and air pollution, alongside waste pollution from ash and coal washing processes.

    Other Uses of Coal

  • Steel Industry Contribution:

    • Approximately 7% of global coal use is related to steel production.

  • Varieties of “fuel-coal” for heating:

    • Charcoal: Derived from incomplete combustion of wood, not considered a fossil fuel, typically used for BBQ.

    • Coke Coal: Bituminous coal processed at 600°C in the absence of oxygen, yielding pure carbon necessary for melting steel (>2000°C).

    • Coal Types:

      • Standard coal types are derived directly from coal beds.

  • Coke coal Usage in Steelmaking:

    • Approximately 71% of the steel industry utilizes coke coal (metallurgical coal) for the melting of steel.

    Uses of Different Types of Coal

  • Steam Coal:

    • Also referred to as thermal coal, predominantly used to generate steam for electricity.

  • Coking Coal:

    • Utilized in production of coke for steel manufacturing.

  • Distribution of Coal Use:

    • Electricity generation: 68%

    • Metal Production: 7%

    • Cement Production: 4%

    • Direct heating: 3%

    • Other applications: 18%

    Environmental Impacts of Coal

  • Coal Industry Footprint:

    • The coal industry produces a significant environmental footprint, including:

      • Mining:

      • Alterations to landscapes and generation of mine tailings.

      • Processing:

      • Issues related to coal washing, including high water usage and resultant pollution.

      • Waste Generation:

      • Coal waste (toxic ash) and thermal pollution from cooling systems.

      • Burning:

      • Major contributors to air pollution and climate change.

    Summary of Coal

  • Overview Statements:

    • Coal is classified as the “dirtiest” among fossil fuels, characterized primarily by carbon content while also containing impurities like sulfur, hydrogen, and nitrogen.

    • Approximate contribution of coal to global energy: ~33% (~40% attributed to electricity production).

    • It is recognized as a type of sedimentary rock found in coal beds or seams.

    • A clear classification of coal types includes:

      • Lignite (youngest, lowest energy content)

      • Sub-bituminous

      • Bituminous

      • Anthracite (oldest, highest energy content)

    • Reserve Distribution:

      • Identified reserves exceeding 850 billion tons are more broadly distributed globally compared to oil and gas.

    • Extraction Techniques:

      • Utilized through open-pit mining (strip mining) or via underground methods.

    • Primary Uses:

      • Mainly electricity production (68%) and secondary applications in steel (7%), cement (4%), domestic heating, and various materials.

    • Significant Environmental Concerns:

      • Issues include air pollution, climate change, land and water use, and the waste generated from power plants.