Ch. 23 - Energy and Mineral Resources

Class: GEOL-101

Notes:

Utah’s Bingham Canyon copper mine
This excavation, one of the largest open-pit mines in the world, is nearly 4 kilometers (2.5 miles) across and 900 meters (3000 feet) deep. Although the amount of copper in the rock is less than 0.5 percent, the huge volume of material removed each day yields enough metal to be profitable. In addition to copper, the mine produces gold, silver, and molybdenum—all nonrewable resources.

23.1 Renewable and Nonrenewable Resources

Distinguish between renewable and nonrenewable resources.

Renewable vs. nonrenewable resources

Presentation content:

• Resources can be divided into renewable and nonrenewable resources.
  • Renewable resources can be replenished over relatively short time spans.
    • Plants and animals for food
    • Fiber for clothing
    • Trees for lumber and paper
    • Energy from the Sun, wind, and flowing water
  • Nonrenewable resources are deposits that take millions of years to form.
    • Fossil fuels
    • Metals
    • Groundwater

Notes from the lecture:

• Self explanatory
• There is a sustainable limit to renewable resources if you over-exploit them
• Is not individual use, it is about how much of these resources are used in a year

23.2 Energy Resources: Fossil Fuels

Compare and contrast fossil-fuel types and describe how each of them contributes to U.S. energy consumption.

Coal, petroleum, and natural gas

Presentation content:

• Coal, petroleum, and natural gas are the primary fossil fuels in society.
  • 81 percent of energy consumed in the U.S. comes from fossil fuels.
  • Fossil fuels use energy from the Sun stored by plants and animals millions of years ago.
  • Reserves are declining and future energy needs will have to be met with alternative energy sources.

Notes from the lecture:

• Showing what the percentage of these different resources are used towards energy

Coal

Presentation content:

• Today, accounts for ~18 percent of the nation’s energy needs
  • The major fuel used in power plants to generate electricity.
• Though the percentage of energy used that is derived from coal is decreasing, the energy demand continues to increase—so this does not mean we are using less coal!
  • Problems with coal use include environmental damage from mining and air pollution from burning it.

Notes from the lecture:

• Anthracite is the highest concentration of coal

Oil and Natural Gas

Presentation content:

• Combined, provide more than 60 percent of the energy consumed in the United States

  • In 2011, natural gas production exceeded coal production for the first time in 30 years

• Petroleum formation

  • Both oil and natural gas consist of hydrocarbon compounds
  • Formation begins with the burial of large quantities of organic material
  • Organic material is transformed to liquid and gaseous hydrocarbons through chemical reactions with increasing burial over millions of years
  • Liquids and gases migrate into permeable beds

• An oil trap is an environment that allows for economically significant amounts of oil and gas to accumulate underground.

  • All traps have two basic conditions: (1) reservoir rock—A porous, permeable unit; (2) cap rock—An impermeable unit.

• We need a source of organic matter and a trap
• By trap we mean a geological container
  • an impermeable seal
• The Aquitard traps the water
• Typically a shale
• Why is it stratified in this matter?
  • Density: gas is less dense
• CO travel mechanism can also be a fault

Notes from the lecture:

• Natural gas is a lot cleaner and easier to extract than coal
• Natural gas power plants are easier to operate
• Coal plants need much more higher maintenance, warm up and down systems, etc. -> takes more time for energy production
• We have to preserve that organic matter, how? drilling in the ocean, it is our sink for organic matter
  • As a result it is preserved

• Primary data set we use today is seismic waves
• Nowadays it is harder to drill
• We used this artificial source of seismic energy (generating waves)
• Seismographs are basically little microphones laid as a two dimensional array which will create a 3 dimensional seismic array
• We use these difference in velocity of seismic waves to basically reconstruct a model of the subsurface
  • Different rocks have different density which affects velocity of waves

Oil Sands

Presentation content:

• Mixtures of clay and sand combined with water and bitumen (a viscous tar)
  • Oil in oil sands is much more viscous and cannot be pumped out
• Several substantial deposits around the world
  • Largest reserve in Alberta, Canada
• Oil from tar sands requires large amounts of energy and has significant environmental drawbacks

Notes from the lecture:

• Oil resources can vary quite a bit

Hydraulic Fracturing

Presentation content:

• In some regions, significant amounts of natural gas are trapped in shale with low permeability.
• Shale is shattered (“fracking”) to release the gas.
• Concerns for groundwater contamination and induced seismicity.
  • Still a controversial practice

Notes from the lecture:

• Sand keeps fractures there
• Widely utilized technique
• You are fracturing the well
• Still a very controversial practice about contamination
  • There are legitimate concerns
  • Another concern is the waste of water which is a whole other topic, we have to put this water somewhere

23.3 Nuclear Energy

Describe the importance of nuclear energy and discuss its pros and cons.

Nuclear Energy role

Presentation content:

• Nuclear energy is an important part of U.S. energy needs
  • Fuel comes from energy released by nuclear fission (splitting atoms)
    • Resulting controlled chain reaction releases heat used to drive steam turbines
    • U235 is the only naturally occurring isotope that is readily fissionable
      • Primarily fuel used in nuclear power plants
      • Rare element in Earth’s crust
• Obstacles to Development
  • Plant safety
    • Skyrocketing costs for safety features
      • Plants cannot explode like bombs, however the escape of radioactive debris during a meltdown is a major hazard.
    • Example: Fukushima nuclear power plant, 2011.

Notes from the lecture:

• Energy being produced today is not sufficient for most companies
• Solution: Nuclear Energy
• Fission = splitting
• Fusion = combining
• The last nuclear accident was the Fukushima nuclear power plant incident caused by a tsunami

23.4 Renewable Energy

List and discuss the major sources of renewable energy. Describe the contribution of renewable energy to the overall U.S. energy supply.

Renewable energy sources

Presentation content:

• Renewable energy sources regenerate and can be sustained indefinitely
  • The use of renewable energy is not new
    • 150 years ago, wood supplied most of our energy needs.
    • 13 percent of U.S. electricity is generated from renewable resources.

Notes from the lecture:

• Renewable energy is ramping up, it will continue to grow, with the exception of natural gas

Solar Energy

Presentation content:

• Direct use of the Sun’s rays to supply energy.
  • Passive solar collectors
    • South-facing windows.
  • Active solar collectors
    • Solar hot water.
    • Trough solar collectors.
    • Photovoltaic (solar) cells convert the Sun’s energy directly to electricity.
    • Stirling dish converts thermal energy to electricity.

Notes from the lecture:

• You need to have consistent amount of days with direct sunlight to actually generate electricity
• A challenge is that we can only collect energy when the sun is shinning
• Sun is most efficient during the day but energy demand in the day is not as high as after evening
  • This creates a challenge of energy storage -> a battery system to store energy

Wind Energy

Presentation content:

• Converting the kinetic energy of a moving air mass (wind) into other forms of energy to perform work.

• Increase in the number of wind turbines installed.

  • Wind turbines supply 3 percent of world electricity.

• Wind speed is crucial in determining suitability of installing a wind-energy facility.

  

Notes from the lecture:

• Texas is one of the largest producers of Wind energy
• You can only build wind farms to a certain range, you cannot have two wind farms very close together because then you would have wind interference

Hydroelectric Power

Presentation content:

• Hydroelectric power is power generated by falling water used to drive turbines to produce electricity.
• Most energy is produced at large dams.
  • Dams have finite lifetimes.
  • Limited sites to construct dams.
• Recently a different type of hydro power has come into use: pumped water-storage system.
  • Water is pumped to a higher storage reservoir during periods of low demand.

Notes from the lecture:

• Controversial resource
• Damages ecosystem, causes fish migrations
• Dictated by the amount of water in the reservoir
• A lot less reliable because we experience periods of draughts

Geothermal Energy

Presentation content:

• Geothermal energy is power generated by tapping into underground steam and hot water.
  • Used for heating and to generate electricity
• Three factors determine if a geothermal reservoir has commercial value.
  • A potent source of heat
  • Large and porous reservoirs
  • A cap of low-permeability rocks

Notes from the lecture:

• Systems involve injecting water deep into the earth, steam is circulated up and turns a turbine
• There is a question of what is the rate of when heat balance itself underground
• Areas with thinning of the crust are more efficient generating more energy from heat

Biomass

Presentation content:

• Renewable Energy from Plants and Animals
• Biomass is organic material made from plants and animals.
  • Wood
  • Crops
    • Biofuels
  • Manure
  • Garbage
    • Biogas

Notes from the lecture:

• Using any sort of organic matter that is available
• Waste that we throw out every day will break out in the land fill and we can capture this gas with some drilling system and generate electricity out of this

Tidal Power

Presentation content:

• Ocean’s energy potential remains largely untapped
  • Tidal power is harnessed by constructing a dam across the mouth of a bay or estuary in a coastal area.
  • The narrow opening between the bay and the open ocean magnifies the variations in water level that occur as the tides rise and fall.

Notes from the lecture:

• Tides are dictated by Earth's relationship with the moon
• Very similar to a hydroelectric dam
• There are also environmental implications in terms of fishes and ecosystems
• Michigan has one of these:
  • During certain times of the day they have extra energy which is pumped to an energy reservoir

23.5 Mineral Resources

Distinguish among resources, reserves, and ores.

Minerals

Presentation content:

• Mineral resources are the endowment of useful minerals ultimately available commercially.
• Mineral resources include:
  • Reserves—already identified deposits from which minerals can be extracted profitably.
    • An ore is a useful metallic mineral that can be mined for profit.
• 98 percent of the continental crust is composed of only eight elements
  • A deposit is valuable if the element is concentrated above the level of its average crustal abundance.
  • Known deposits that are not economically or technologically recoverable may become profitable if the demand changes.

Notes from the lecture:

• We have two different categories, metallic and non metallic mineral resources
• We know that 8 elements consist of 98% of the Earth's crust, most of them are feldspars

• Someof these rare minerals are critical for our electronics

23.6 Igneous and Metamorphic Processes

Explain how different igneous and metamorphic processes produce economically significant mineral deposits.

Magmatic Differentiation

Presentation content:

• Separation of heavy minerals that crystallize early or enrichment of rare elements in the residual melt
  • Especially in the late stages of a melt
• Sometimes crystals form in a fluid-rich environment
  • As fluids don’t solidify, the crystals grow unusually large
  • Pegmatites are rocks with unusually large crystals.
  • Often contain some of the least abundant elements.
  • Some pegmatites include semiprecious gems such as beryl, topaz, and tourmaline.

Notes from the lecture:

• Examples:
  • Quartz
  • Feldspar
    • Incorporating a lot of pegmatite elements

Hydrothermal Solutions

Presentation content:

• Hydrothermal (hot water) solutions are the best known and most important ore deposits.

• Vein deposits

  • Hot, metal-rich fluids migrate through cracks in the rock before eventually depositing the metals.
  • Many of the most productive deposits of gold, silver, and mercury occur as hydrothermal vein deposits.

• Disseminated deposits

  • Instead of being concentrated in narrow veins, disseminated deposits are distributed as small masses throughout the entire rock
    • Example: Copper, Bingham Canyon mine.

• Hydrothermal activity at oceanic ridges

  • Black smokers are a source of metal-rich sulfide deposits.

Notes from the lecture:

• An example is Gold, mobilized by fractures

• Look at ancient ridge systems, this is where a lot of copper has been mine from

Diamonds and Metamorphism

Presentation content:

• Diamonds
  • Best known as gems but commonly used as abrasives
  • Originate at great depths (200 kilometers!)
  • Carried upward through pipe-shaped conduits that increase in diameter toward the surface
  • Crystals are disseminated in ultramafic rock called kimberlite.
• Metamorphic Processes
  • Many important ores are created by contact metamorphism.
    • Most common minerals associated with contact metamorphism
      • Sphalerite (zinc).
      • Galena (lead).
      • Chalcopyrite (copper).
      • Magnetite (iron).
      • Bornite (copper).

Notes from the lecture:

• Diamond formation:
  • Carbon based material is heated and pressurized
  • Most forms of carbon (inorganic/organic) is in the form of hydrocarbons or coal, we can also found something like graphite which requires more work
  • Pipe systems exists to replicate conditions for diamond creation but are very rare
  • Most diamonds are extremely rare and poor quality
• Magma chamber implies contact metamorphism with the near rocks

23.7 Mineral Resources Related to Surface Processes

Discuss ways in which surface processes produce ore deposits.

Weathering

Presentation content:

• Weathering creates deposits by concentrating metals into economically valuable concentrations (secondary enrichment).
• Bauxite
  • Principal ore of aluminum.
  • Forms in rainy tropical climates from chemical weathering and the removal of undesirable elements by leaching.

Notes from the lecture:

• Soils tend to have a low PH
• As those elements are a little bit heavier like aluminum, as they undergo chemical weathering they accumulate in a zone (i.e. under clay) that forms these kind of products

Other Deposits

Presentation content:

• Weathering processes concentrate metals that are deposited through low-grade primary ore.
  • Examples: copper and silver.
  • Typically occurs in deposits containing pyrite.
    • Pyrite is important because when it chemically weathers, sulfuric acid forms.
    • Enables percolating waters to dissolve the ore metals.
    • Metals gradually migrate downward through the primary ore body until they are precipitated.

Notes from the lecture:

• Easily accumulated because everything else is transported away
• Pyrite corrodes everything else and removes everything else from the system

Placer Deposits

Presentation content:

• Placers are deposits formed when heavy metals are mechanically concentrated by currents.

• Involve heavy and durable minerals.

• Examples include:

  • Gold.
  • Diamonds.
  • Tin.

  

Notes from the lecture:

• Crust is around 2.5-6
• Gold is about 3 times more dense than oceanic crust ~9
• Over time, river has eroded sediments
• More dense materials will concentrate in the river because other materials are eroded away easily

23.8 Nonmetallic Mineral Resources

Nonmetallic Minerals

Presentation content:

• Use of the word “mineral” is very broad
  • Materials not used for fuels or processed for metals are called nonmetallic mineral resources.
• Two common groups
  • Building materials.
  • Industrial minerals.

Notes from the lecture:

• A lot of these are used in construction materials

Building Materials

Presentation content:

• Natural aggregate
  • Crushed stone, sand, and gravel.
• Gypsum
  • Plaster and wallboard.
• Clay
  • Tile, bricks, and cement.

Notes from the lecture:

• Example: Limestone is considered both a building material and an industrial mineral. This quarry is near Amsterdam, Indiana.

Industrial Minerals

Presentation content:

• Fertilizers: Nitrate, phosphate, and potassium compounds are important to agriculture.
• Sulfur: Used to produce sulfuric acid.
• Salt: Used to “soften” water, keep streets ice-free, and as a nutrient.