Unit_6_Energy_Lecture

Energy Resources Overview

Rock Cycle

• Igneous Rock

  • Formed when magma rises, cools, and hardens.

  • Constitutes the bulk of the Earth’s crust.

  • Common types include:

    • Granite

    • Basalt

    • Pumice

    • Lava rock

  • Main source of metal and nonmetal resources.

Sedimentary Rock

• Composed of sediments from remains and existing rock.

• Deposited in layers over time, increasing in weight and pressure.

  • Types include:

    • Sandstone

    • Shale

    • Dolomite

    • Limestone

  • Bituminous Coal derives from compacted plant remains.

Metamorphic Rock

• Formed under high temperature and pressure from igneous or sedimentary rock.

  • Examples include:

    • Anthracite (a form of coal)

    • Slate

    • Marble (derived from limestone)

Mining Nonrenewable Minerals

Overview of Minerals

• Minerals: Elements or inorganic compounds.

• Mineral Resource: A concentration of naturally occurring material in the Earth's crust usable at an affordable cost.

  • Categories include:

    • Fossil Fuels

    • Metallic Minerals: Aluminum, iron, copper.

    • Nonmetallic Minerals: Sand, gravel, limestone, phosphate salts.

Ore and Veins

• Ore is rock containing a large enough concentration of a mineral.

• Veins are concentrations of valuable minerals deposited by water into fractures in rocks.

  • High-Grade Ore vs. Low-Grade Ore

Classification of Nonrenewable Resources

• Identified Resources: Deposits with known location, quantity, and quality.

  • Deposits: Based on direct geological evidence.

  • Reserves: Recoverable quantity of resource profitable at current prices.

• U.S. reliance on imports for nickel, cobalt, manganese, chromium.

• Approximately 2 years of aluminum reserves left.

Mining Methods

• Surface Mining: For shallow deposits, removes unwanted material.

• Open-Pit Mining: Deep holes for minerals like copper.

• Strip Mining: For horizontal deposits near the surface.

• Contour Mining: Terracing for hilly terrain.

• Mountaintop Removal: Explosives used to expose coal seams.

• Subsurface Mining: Accessing deeper deposits through tunnels.

Hydraulic Fracturing (Fracking)

• Uses a 99% mixture of sand and water with a small percentage of chemicals.

• Injected deep into the ground to fracture rock and release natural gas.

• Controversial due to suspected environmental effects on groundwater and geology.

Mining Consequences

Waste Management

• Gangue: Undesirable component of ore.

• Tailings: Unwanted rock removed from ore on-site.

• Acid Mine Drainage: Sulfuric acid contamination from minerals in spoils.

• Use alkaline substances like lime to treat soils.

• Slag: Waste matter from smelting or refining ores.

Environmental Effects of Mining

• Scarring and disruption of land surface.

• Subsidence: Collapse of land above mines.

• Toxic mining waste contamination of groundwater.

• Air pollution from fossil fuel emissions and dust.

• Habitat fragmentation from mining infrastructure.

Environmental Effects of Mineral Processing

• Distillation: Separation process using heat.

• Smelting: Heating and chemical reactions to extract metals from ore.

• Air pollutants like sulfur dioxide.

• Toxic holding ponds can leak and pose risks to wildlife.

Reclamation Efforts

• Recreate original environmental conditions post-mining.

  • Fill in depressions and return topsoil.

  • Ensure stability and absence of contaminants in reclaimed material.

  • Plant native vegetation to restore ecosystem.

• Example: Trapper Mine in Colorado.

Mining Legislation

• General Mining Act (1872): Encourages mining on federal land but lacks environment protections.

• Surface Mining Control and Reclamation Act (1977): Regulates surface coal mining and mandates land reclamation after mining.

Supply and Demand

Mineral Resources Distribution

• Uneven distribution of minerals globally.

• Common minerals: iron, aluminum.

• Scarce minerals: manganese, chromium, platinum.

Economic and Military Strength

• Need for imports due to depletion of domestic reserves.

• Economic depletion occurs when extracting a mineral costs more than its value.

Post-Depletion Strategies

• Options after mineral depletion: recycle, reuse, waste less, find substitutes, or do without.

Future of Mining

Lower-Grade Ores

• Methods to extract economically viable lower-grade ores.

• Limiting factors include costs, water supply, and environmental impacts.

• Biomining: Utilizing bacteria for extraction.

Ocean Mining

• Minerals from seawater are low in concentration, except for magnesium, bromine, and NaCl.

• Hydrothermal deposits rich in minerals but retrieving them can disturb ecosystems.

Energy Resources

Nonrenewable Energy Sources

• Two main categories: fossil fuels and nuclear fuels.

• Fossil Fuels: Coal, oil, natural gas.

Units of Energy

• Joule (J) as a basic unit of energy; gigajoule (GJ) and exajoule (EJ) are used for larger quantities.

• U.S. energy consumption averages 355 GJ per person per year.

Energy Categories

Commercial vs. Subsistence Energy

• Commercial energy sources: Bought and sold (coal, oil, natural gas).

• Subsistence energy sources: Gathered for immediate use (wood, animal waste).

Energy Quality

• Liquid energy resources have a high energy-to-mass ratio.

• Gasoline ideal for speed, coal and wood for building heat.

Net Energy Considerations

• Net energy represents usable energy after accounting for extraction and processing costs.

• Energy Return on Energy Investment (EROEI) quantifies energy efficiency.

Electricity Generation

• Primary sources of energy (fuels) are converted into electricity as a secondary source.

• Processes of generating electricity involve burning fuels to create steam and turn turbines.

Environmental Concerns

• Heavy reliance on fossil fuels generates significant air pollutants.

Oil

• Provides 1/3 of the world’s energy.

• Projected 80% depletion between 2050 and 2100; solutions include conservation and alternative energy sources.

Natural Gas

• Cleaner-burning fossil fuel; challenges include demand and availability.

Coal

• Most abundant fossil fuel with significant pollution issues.

• Innovations in coal conversion can yield cleaner energy.

Nuclear Energy

• Advantages: Low environmental impact, but high costs and waste management issues hinder use.

Sustainable Energy Resources

Overview

• Potentially renewable resources can regenerate rapidly (e.g., biomass).

• Nondepletable resources (e.g., solar, wind) are sustainable without depletion risks.

Biomass Energy

• Biofuels like ethanol and biodiesel have land use implications.

• Environmental issues include soil erosion and habitat loss.

Solar Energy

Active and Passive Solar

• Passive: Use of building design for natural heating.

• Active: Uses technology to capture and convert solar energy (photovoltaic cells).

Hydropower

• Generated from falling water, dams, or manipulated water flow.

Wind Power

• Fast-growing energy source, potential for land and offshore use.

Geothermal Energy

• Uses Earth's internal heat; trade-offs include economic and environmental factors.

Transitioning to Sustainability

Strategies

• Improving energy efficiency holds promise for significant energy savings.

• Emphasizing conservation techniques to mitigate demand peaks and manage energy crises.