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Unit 7- Geology and Energy
Transcript of Unit 7- Geology and Energy
Unit 7- Geology and Energy
Where do we get our minerals and fossil fuels?
Ch 14- Geology and Mining
Metallic Minerals are extracted from the earth's crust as
Non-renewable energy sources:
3 Types of Rocks
Replacing fossil fuels as an energy source must be done. There are many alternatives.
From the Earth's crust.
The method of removing resources is based on factors like depth of the resource, amount and stability of the overburden, topography of the area, safety of workers and surrounding community, and economics.
Most Common Mining Techniques:
1. Surface (Strip) Mining- removes deposits that lie in horizontal beds close to the Earth's surface.
1. The land is clearcut.
2. Overburden is removed with explosives and
heavy equipment and set aside.
3. Resource is removed with huge power shovels.
4. Overburden is replaced and land is reclaimed.
Most Common Mining Techniques:
2. Mountaintop Removal- a type of surface mining in which coal seams are exposed by removing the top of a mountain using explosives and heavy equipment
1. Mountaintop is removed.
2. The removed material is dumped into adjacent
valleys, sometimes burying forests, rivers, etc.
3. Coal is then removed with power shovels or
4. The land is reclaimed, however, the topography
is never fully restored and surrounding areas
Most Common Mining Techniques:
3. Open-Pit Mining
1. A huge hole is dug using explosives and heavy
2. The resource is removed.
3. If the pit is abandoned, it often fills with water
it can become acidic with heavy metals from
Most Common Mining Techniques:
4. Subsurface Mining- Deep vertical mine shafts are blasted into the earth to remove deposits that very deep underground
This type of mining is very dangerous because
*the mineshafts can cave in causing the
ground surface to collapse.
*methane and coal dust can cause
explosions or poisoning (like black lung
Most Common Mining Techniques:
5. Drilling- removes liquids and gases like oil, natural gas and steam
-deep shafts are drilled into the earth reaching the desired material
-normally pressure in the earth forces the liquid or gas to the surface, but water, steam, and other fluids can be injected to force material out (fracking!)
Environmental Costs of Mining...
1. Habitat above the deposit is destroyed
2. Even if the overburden is replaced, the soils horizons will not be truly restored.
3. Streams and rivers are clouded or buried by sediments
4. Waterways are contaminated with hazardous chemicals from mining waste.
5. 75% of all waste in the US is created from mining operations
6. Acid Mine Drainage- sulfur compounds in mine waste are exposed to air, oxidize, and dissolve into rainwater creating a sulfuric acid solution
The General Mining Law of 1872
- US law was enacted to encourage the exploration and mining of mineral resources. It enables corporations to acquire large tracts of public land far below market prices.
The Surface Mining Control and Reclamation Act of 1977
- requires that mined land be restored to its pre-mining state. This includes the disposal of all mining waste, re-contouring the land, and replanting natural vegetation.
- significant concentration of desired mineral
Low Grade Ore
- trace amounts of desired mineral and expensive to mine
Metallic Minerals Commonly Mined:
-aluminum, iron, lead, chromium, nickel, silver, gold
Non metal Minerals Commonly Mined:
-sand, gravel, limestone, clay, talc
Interesting Fact: The standard of living in a country is directly related to its ability to access these resources!
The material that makes up the earth's crust is in constant motion and it is covered with an array of thick, massive slabs called
The movement of these tectonic plates forms
and causes environmental hazards like
Tectonic Plates meet at 3 types of boundaries:
Plate Boundary- 2 plates are
and molten rock flows into the empty space creating ridges.
Plate Boundary- two plates
oceanic plate collides with continental plate,
the oceanic plate usually goes under the continental plate
resulting in an oceanic trench.
two continental plates collide
, they can push up mountain ranges.
- tectonic plates
past one another and causes frequent earthquakes
What is a rock?!
a solid combination of one or more minerals found in the earth's crust
- made of sediments like dead plant and animal remains and existing rocks that are weathered and eroded into tiny pieces.
sediments are carried by wind, water, or gravity and deposited in layers that accumulate over time.
EX: Sandstone, limestone, shale, bituminous coal
- forms when magma wells up from the earth's mantle, then cools and hardens
EX: Granite and lava rock
-igneous rock makes up most of the earth's crust
- forms when pre-existing rock is subjected to high temperatures, high pressures, or chemically active agents
These forces transform the rock by changing its crystalline structure and physical properties.
Ex: Marble (when limestone is exposed to heat and pressure)
Ex: slate (when shale and mudstone are heated)
Crude oil is formed from the
of ancient marine organisms that were buried beneath sediments and subjected to
high heat and pressure
What is Oil?
-mixture of many different
liquids and gases that
provide a variety of energy uses
like fuel oil and gasoline are used to heat homes and transportation
such as propane and butane are used for cooking and heating
include grease, wax, petroleum jelly, and asphalt
Most of the oil reserves are in the Middle East and are controlled by OPEC.
The US has an intense dependence on oil.
There is concern over the reliance on politically unstable governments for such an important energy resource.
led to the call for renewed oil exploration and drilling in environmentally sensitive areas like
offshore and in the Arctic National Wildlife Refuge (ANWR)
Because crude oil is a mixture of liquids, it requires
separation and purification
after it has been extracted.
This happens at an
and uses the process of
that separates liquids at different boiling points.
This refining of oil produces many different products like the ones listed previously and also
that can be made into synthetic fibers, plastics, pesticides, paint, etc..
Oil Shale and Tar Sands are both oily deposits than can yield oil when processed.
although there are large reserves of these energy sources (especially in Canada) it still requires the same destructive techniques that we've seen from mining.
is the most abundant fossil fuel, and is used to produce most of the world's
1. Once coal is extracted from the earth it is pulverized into small pellets and
to produce steam.
2. The steam is directed across blades of a
to rotate it and a generator that makes electricity.
Environmental Costs of Mining Coal:
1. large quantities of air pollution that include heavy metals, particulates, and sulfur dioxide
2. large quantities of water pollution that include heavy metals, mercury, and sediments from overburden
3. produces more CO2 than any other fossil fuel
Coal Formation Process
1. Coal formation starts with
, which forms from partially decomposed plant debris in waterlogged anaerobic conditions.
2. After being
buried by millions of years
of sediments, heat and pressure squeeze the water from the peat and initiates
transformations to coal
Ranks of coal:
Peat (lowest energy content)
Anthracite (highest energy content)
Natural Gas is mostly methane and is formed and found alongside crude oil and coal.
Benefits of Natural Gas over other fossil fuels:
1. Produces less CO2
2. Burns cleaner and emits fewer heavy
metals, particulates, etc.
3. Easy to transport via pipelines
A major disadvantage to extracting natural gas is the use of
hydrolic fracturing or FRACKING
Fracking is when water and other secret chemicals (that are known to be carcinogens) are pumped underground to fracture the rock and create pressure that will pump out the natural gas.
Where do you think these chemicals end up?
Hydrogen Fuel Cells
Ocean Waves/Tidal Energy
Like fossil fuels, nuclear energy is
are associated with extraction, processing, use, and disposal of radioactive fuel.
In the 1950s, nuclear power was thought to be the solution to the world's energy needs!
But... there were many concerns about safety and cost.
However, about 5-10% of electricity in the US comes from nuclear energy. France generates 75% of its electricity from nuclear energy.
Nuclear power plants use the same general method as those fired by fossil fuels-
heat water to produce steam which turns a turbine connected to a generator to make electricity.
Instead of burning (combustion of) coal, nuclear power plants use the process of
The most commonly used nuclear fuel is
, a radioactive element that is mined from the earth.
Nuclear Power Plant Process:
is packed into
that are placed in the
, along with a
that is used to slow down neutrons that are released during nuclear fission.
are interspersed with fuel rods to
the rate of fission and the amount of energy produced.
3. After the used fuel rods are removed they are
in water filled tanks.
*There is no long term disposal site presently available for spent fuel rods and other waste (high level radioactive waste)
A proposal to open the first high-level radioactive waste repository in the world at
Yucca Mountain, Nevada
has been delayed due to safety and security concerns. President Obama does NOT want to use Yucca Mountain for nuclear energy waste storage.
Environmental Costs of Nuclear Energy:
1. waste, runoff, air pollution, and land damage that result from the mining, processing, and transportation of
2. ecological damage due to
of radioactive materials
in bodies of water used as coolant for nuclear power plants
4. lack of long term
of nuclear waste
5. concerns over how to
old nuclear power plants
6. fear of
near nuclear power plants
Take a sheet of paper and make 3 sections and label each as:
1. Three Mile Island 2. Chernobyl 3. Japan Nuclear Disaster
Questions you will answer will be:
-when and where did it take place
-what caused the disaster
-name several impacts of the disaster
-makes use of potential energy of water stored in an elevated reservoir
from the reservoir is made to flow through
that are connected to
to produce electricity! Sound familiar?!
About 25% of the world's energy comes from hydropower!
1. Reliable Energy Production
2. No CO2 or greenhouse gas emissions
1. flooding of habitats upstream from the dam
2. fragmentation of the river ecosystem preventing migration of salmon, river dolphins, etc.
3. fragmentation also blocks the movement of sediments downstream resulting in a build up of sediments at the dam (aka silting)
1. displacement of human communities in flooded area
2. Potential increase of water-borne infectious diseases
Solar energy isn't a new idea- for thousands of years, people have oriented homes to make use of the sun's energy.
2 Types of Solar Energy
Passive Solar Energy
makes direct use of sunlight to heat a building
since the path of the sun is predictable, a building can be positioned to maximize use of the sun
The use of south facing windows will allow sunlight to enter the home year-round
can block out intense summer sun and a
can block intense summer sun and allow sunlight to heat home in the winter.
Active Solar Energy
makes use of pumps to move water or a fluid like antifreeze through solar collectors, where it is heated by the sun and then pumped through the building to provide heat or hot water
Photovoltaic Cells (PV or solar cells)
convert sunlight directly into electricity by making use of the electrical properties of the element silicon
Solar cells can be used to generate electricity in remote locations far from the electrical grid. Excess electricity can be used to charge batteries that will provide electricity at night or on cloudy days.
Current large solar power plants:
3. South Korea
Solar Power Towers
use an array of mirrors that focus sunlight to a single point where that concentrated solar energy is used to heat water to produce steam to turn a turbine connected to a generator.
How Solar Panels Work
History of Wind Power
Modern windmills of today are used to produce electricity.
Many wind farms are built along mountain ridges.
Offshore wind farms are currently being considered as a way to increase the generation of electricity from wind.
Concerns over Wind Energy:
visual disturbance for some
unreliable wind patterns
-makes use of the Earth's internal temperature by tapping into high temperature, high pressure steam that exists below the earth's surface in some areas.
These conditions usually only exist along tectonic plate boundaries and especially Iceland (sits atop the Mid Atlantic Ridge)
collection of different energy sources that all involve obtaining fuel from plant matter and animal waste
burning wood, dung, crop waste, and other biomass is attractive as an inexpensive source of energy.
However, the smoke from fires contain poisonous and possibly carcinogenic CO, ash, soot, and hydrocarbons
Methane digesters can be used to convert animal waste from feedlots and factory farms into methane.
Landfills and wastewater treatment facilities can collect the methane that is produced during decomposition and can be used to produce electricity, for cooking, etc.
Sugarcane, corn, and other crops can be fermented into ethanol that can be used in cars. There is concern that using food crops will increase the price of food and/or increase world hunger.
An alternative to this would be to use non food crops like Switchgrass.
-made from sources like frying oil, waste products from meat processing, vegetable oil, and oil squeezed from algae
Uses chemical reactions to produce electric current.
The most common fuel cells use hydrogen and oxygen as reactants and produce drinkable water as the only product.
For Hydrogen fuel cells, the oxygen can be used from the air, but the hydrogen must be supplied as a gas or liquid.
Because obtaining and storing hydrogen is energy intensive, a fuel cell is a huge net producer of energy.
The issue with Hydrogen fuel cell cars right now is the very limited availability of H refueling stations.
The cost "per gallon" is essentially the same as gasoline.
is a great website for looking at all kinds of alternatively fueled cars!
basically the motion of the ocean turns turbines connected to a generator. Currently they don't provide a ton of energy, but it holds promise for future research.
There are currently 61 commercially operating nuclear power plants with 99 nuclear reactors in 30 states in the United States.