Unit 12 Geology & Mineral Resources Chapters 16

Earth is dynamic planet whose surface & interior are constantly changing

3 Main Layers of the Earth

1. Core

2. Mantle

3. Crust

• Layers of the Earth

• Continental crust: under continents. 15–56 mi thick

• Oceanic crust: under oceans. Thinner than continental. 3.6- 6.2 miles thick

• Lithosphere: Outer part of earth. Combination of crust & upper mantle. Rigid layers.

• Asthenosphere: Part of the mantle. Very hot, partially melted rock. Like silly putty. 112 miles thick

• Mesosphere: Part of the mantle. Partially melted rock – very hot. Mesosphere ends ~1,800 mi down

• Outer core: Liquid metals. Extremely hot. ~2260 km (1400 mi) thick

• Inner core: Solid metal. Intense pressure keeps inner core solid. 2270 km (1400 miles) thick

• Internal Processes- 2 kinds of movement occur in mantle’s asthenosphere:

1. Mantle plumes – mantle rock flows slowly upward in a column, When reaches the top, it moves out in radial pattern

2. Convection cells/ currents that move large volumes of rock & heat in loops

• Plate Tectonics

– Flow of energy & heated material in mantle’s convection cells cause 15 tectonic plates to move slowly across earth’s surface

– Move from 1 -18 cm per year

– Plate Tectonics = theory explaining movements of plates & the processes that occur at their boundaries (updated version of continental drift)

• Throughout earth’s history, continents have split & joined as plates have very slowly drifted thousands of km back & forth across the planet’s surface

Plate Tectonics: 3 Types of boundaries

1. Divergent Boundary: 2 plates moving away from each other

2. Convergent Boundary: 2 plates pushed together;

Subduction Zone: when a convergent boundary occurs between a continental plate and oceanic plate continental plate rides up over denser oceanic plat and pushes it down into mantle (process called subduction)

3. Transform Fault: 2 tectonic plates slide & grind past each other horizontally, along a fracture in lithosphere

Geology

• Plate Tectonics

• External Processes- geological changes based on energy

from sun & gravity

• While internal processes build up earth’s surface,

external processes tend to wear it down

– Ex:

• Erosion: material is dissolved, loosened or worn

away from one area & deposited elsewhere

–driven by water & wind; accelerated by human

activities

Geology

• External Processes Include:

• Mechanical weathering: rocks broken down into smaller pieces

– Frost wedging: forcing apart of rocks by expansion of water as it freezes in fractures & pores

• Chemical weathering: rock is decomposed due to influence of water, oxygen, & carbon dioxide

• Biological weathering: breakdown of rock through action of plants & animals

Geology • Geological Hazards

• Earthquake: shaking of ground from fracturing & displacement of rock, creating a fault

– Severity is measured by magnitude – measure of amount of energy released

» Scientists use Richter Scale – each unit represents an amplitude 10 times greater than next smaller unit; 6.0 quake is 100 times greater than 4.0

• Volcano: where magma reaches earth’s surface through a central vent or long crack

– Can release debris, liquid lava, gases (water vapor, carbon dioxide, & sulfur dioxide)

Geology Rocks and Minerals

Crust is source of fossil fuels, metallic minerals, & nonmetallic minerals

Mineral: element or inorganic compound that occurs naturally & is solid w/ regular, crystalline structure

Ex: gold, silver, diamond, sulfur; salts, quartz

Rock: solid combination of one or more minerals that is part of crust

Ex: limestone (CaCO3) and quartzite (silicon dioxide, SiO2)

• Rock Cycle: interaction of physical & chemical

processes that changes rocks from one type to another

3 Types of Rock:

1. Igneous rock: formed by solidification of molten

magma (granite, lava rock)

2. Sedimentary rock: formed from layers of sediments

produced by erosion of existing rock become

compacted (sandstone from sand; limestone from

compacted shells & skeletons; coal from plant

remains)

3. Metamorphic rock: formed when rock is subjected to

high pressure &/or heat (marble, slate)

Video

Mineral Resources NONRENEWABLE

Metallic minerals

Aluminum (Al) – used for packaging, structural

materials

Iron (Fe) – used to make steel

Steel – alloy of iron & other elements: Manganese (Mn),

Cobalt (Co), Chromium (Cr)

Copper (Cu) – wiring

Gold (Au) – electrical equipment, coins, jewelry

NON-Metallic minerals

Sand – used to make glass, bricks, concrete

Gravel – used for roads, to make concrete

Types of Mining:

Surface mining: used to extract ~90% of nonfuel mineral resources & ~60% of coal in U.S.

1. Open-pit mining: Used for iron, copper, gold, sand, gravel, stone

2. Strip mining: Area

strip mining: when

terrain is flat, an

earthmover strips away

overburden & a power

shovel removes mineral

deposit

Contour strip mining:

used to mine coal on hilly

terrain

3. Mountaintop Removal:

explosives, earth movers,

power shovels, etc. are used to

remove top of a mountain and

expose seams of coal

Subsurface Mining involves

underground tunnels & shafts,

Used to remove coal & metal ores

The Damage of Mining:

Scarring & disruption of the land Ex: loss of topsoil slow vegetative growth; high erosion

Wastewater and toxic sludge produced when coal is processed can

release toxins into water (sulfuric acid, mercury, arsenic)

When rainwater seeps through a mine or spoil piles (ore waste) &

carries sulfuric acid into streams and groundwater

Smelting: heating ores to extract metals

Causes air pollution (sulfur dioxide, particles, greenhouse

gases), water pollution, liquid & solid waste

Mineral Resources

How long will supplies last?

– 5 countries supply most of world’s nonrenewable

mineral resources:

• US, Canada, Russia, South Africa & Australia

–4 strategic metal resources – manganese,

cobalt, chromium, & platinum – are not

available in US but important for economy &

military

– Depletion time = time it takes to use up a certain

proportion of the reserves of a mineral at a given rate of

use, Depends on: Recycling & reuse of supplies, Technology, Prices, New discoveries

• Usually set at 80% of reserves used

• Solutions…

– Biomining: using genetically-engineered microorganisms that

breakdown rock material and extract minerals

– Substitute materials: plastics, fiber-optic glass cables

– Recycle & Reuse

• Ex: recycling aluminum can produces 95% less air pollution

& uses 95% less energy

– Cleaner Production – pollution & waste prevention by

companies

Ch. 17 & 18 Nonrenewable & Renewable Energy Resources & Concepts

• Laws of Thermodynamics

• The first law of thermodynamics (Law of Conservation of

Energy) states that energy can be transformed (changed from

one form to another), but cannot be created or destroyed

• The second law of thermodynamics is an expression of the

universal principle of entropy, stating that the entropy of an

isolated system which is not in equilibrium will tend to

increase over time.

Energy & Power Units and Use

1 Btu (British thermal unit) = 252 cal = 0.252 kcal

1 Btu = 1055 J (joule) = 1.055 kJ

1 cal = 4.184 J

1 watt (W) = 3.412 Btu / hour

1 horsepower (hp) = 746 W

kilowatt-hour (kW-h) = 1,000 watt-hours (used for electricity)

Energy

Sun provides 99% of the energy that heats earth

Solar energy comes from nuclear fusion of hydrogen atoms

Solar energy produces indirect forms of renewable solar energy: Wind, Flowing water, Biomass

• Commercial Energy – mostly for Industry

• Most comes from nonrenewable energy resources:

– Fossil fuels: oil, coal, gas

– Nuclear power

• 16% comes from renewable energy resources:

– Biomass

– Hydro-power

– Geothermal

– Wind

– Solar

– U.S. has 4.6% of world population; uses 24% of the

world’s energy

– 85% from nonrenewable fossil fuels

– 8% from nuclear power

– 7% from renewable sources

Net Energy (**important concept!) total amount of useful

energy available from an energy resource minus energy need

to make it available

• Calculated by energy available – [ energy used +

energy automatically wasted + energy unnecessarily

wasted]

• The higher the net energy, the better …. Kinda

–Doesn’t really deal with waste & pollution

–Doesn’t account for long-term depletion

Oil- Petroleum (crude oil) is a thick and gooey liquid consisting of hundreds of combustible hydrocarbons along with small amounts of sulfur, oxygen, and nitrogen impurities

Comes from: deposits deep underground; ancient remains of ocean plankton Extraction: via wells dripped beneath ground or sea bottom Refining oil: separating components with different boiling points

Three largest oil consumers: U.S., China, Japan

• Two types of oil reserves:

– Proven: identified deposits

– Unproven: probable reserves

• Geologists project that proven & unproven reserves of conventional crude oil will be 80% depleted between 2050-2100

–About 50-100 year supply left @ current rates

Petrochemicals: products of crude oil distillation

Used in industrial organic chemicals, cleaning fluids, pesticides, plastics, paints, medicines

Organization of Petroleum Exporting Countries (OPEC) -- 13 countries have 60% world reserves

Includes: Algeria, Angola, Ecuador, Indonesia, Iran, Iraq, Kuwait, Libya, Nigeria, Qatar, Saudi Arabia, the United Arab Emirates, and Venezuela

Saudi Arabia has largest portion

Refinin

g o

il

• Problems in the United States:

–Gets ~40% of commercial energy from crude oil

–Produces about 9% of world’s crude oil, but uses 23%

» US Dept. of Energy estimates that if current trends continue, US will import 70% of oil by 2025

– Conflict of Interests

» Terrorism: almost ¼ of world’s crude oil is controlled by states that sponsor/ condone terrorism

» But have low domestic supplies

» What’s the solution??

Advantages: Ample supply for decades, high net energy yield , & efficient distribution system

Disadvantages: dependence on foreign oil, running out, water pollution, air pollution/ climate change

Other Oil Resources

Tar sand/ Oil sand: mixture of clay, sand, water & bitumen (tarlike heavy oil)

Potential source, but causes environmental damage (forest removal, air pollution, greenhouse gases)

Has low net energy yield

Mostly found in Canada & Venezuela

Oil shale: dark-brown or black sedimentary rocks, from which kerogen can be produced by distillation to create shale oil

Kerogen: combustible mixture of hydrocarbons

Disadvantages: take more

energy & money to get than fuel is worth

*Keystone XL pipeline

• Energy Resources: Natural Gas

• Natural Gas: A mixture of gases, 50%-90% of which is methane (CH4)

– Also contains: Ethane (C2H6), Propane (C3H8),

Butane (C4H10), Hydrogen sulfide (H2S)

• Versatile fuel – burned to heat, space & water,

produce electricity, propel vehicles

Conventionally found above reservoirs of crude oil, When tapped, propane & butane are removed:

LPG: liquefied petroleum gas (LP); propane & butane are liquefied and removed as liquefied petroleum gas

Rest of the gas (mostly methane) is dried,

cleaned, and pumped into pressurized pipelines

for distribution

Can be converted to LNG: liquefied natural gas; for shipping across oceans

• Energy Resources: Natural Gas

Location (world): Russia has 27%,

Iran has 15%, US has ~3% (uses

~22% of world’s annual production)

Availability projections: At current

consumption rates, known reserves

should last: World: 62-125 years, US:

80-118 years

• Energy Resources: Natural Gas

• Hydraulic fracturing aka “Fracking”

– is the creation of fractures in a rock layer

by a pressurized fluid

– to release petroleum, natural gas or other

substances for extraction.

» This type of fracturing creates fractures from

a wellbore drilled into reservoir rock

formation

– Pros: independence from foreign oil, creates jobs

– Cons: dangerous chemicals get into groundwater, makes

sediment unstable (more earthquakes??)

• Energy Resources: Coal

• Coal: A solid fossil fuel that formed in several stages as buried remains of land plants that lived 300-400 mya.

–Mostly carbon with small amounts of sulfur impurities

• Used to provide heat & electricity

–Burned in power plants to provide ~40% of world’s electricity (46% of US’s electricity)

• Coalification: After plants died they underwent chemical decay to form a product known as peat

• Peat is converted to coal by great pressures and temperatures Lignite Bituminous Anthracite

• The different major types of coal vary in the amounts of heat, CO2, and SO2 released per unit of mass when they are burned.

Coal Types:

Lignite: brownish-black coal of low quality (i.e., low heat content per unit) with high moisture and volatile matter.

Energy content < lower 4000 BTU/lb

Bituminous: most common coal is dense & black.

Moisture content usually is less than 20 %.

Energy content about 10,500 Btu / lb

Anthracite: hard, black coal containing a high percentage of fixed carbon and a low percentage of volatile matter.

Energy content of about 14,000 Btu/lb.

• Energy Resources: Coal

• Three largest coal-burning countries:

1. China

2. US

3. India

• Location: US has 28% of world’s proven reserves;

Russia has 18%, China 14%, etc.

• Availability projections: identified & unidentified

global sources will last us 200 - 1,100 years at current

rate of usage

How We Get Electricity from Coal:

Burn coal to boal water steam., Steam spins blades in a

turbine, Turbine spins electric generator (wires in a magnet –

causes electrons to move), Steam in recondense to water for reuse

Energy Resources: Coal

Advantages:

MOST ABUNDANT FOSSIL FUEL, high energy,

US has large supply

Disadvantages:

DIRTIEST of all fossil fuels (CO2 & SO2 & mercury),

Health concerns, Mining degrades land

Coal Refining Options: Coal gasification: Coverts solid coal

into Synthetic natural gas (SNG), Coal liquefaction: Converts

solid coal to liquid fuels (called synfuels),

Disadvantages: Requires more coal, Less net energy,

Releases more CO2

Energy Resources: Nuclear Energy

• Used a lot in US, France, & Japan

• In a conventional (boiling water) nuclear power plant reactor:

» A controlled nuclear fission chain reaction occurs

» Heats water Produce high-pressure steam turns turbines Generates electricity

• Most common fuel is uranium-235

Reactor Features: • Core: contains fuel rods; each fuel rods has many pellets;

each pellet has energy equivalent of 1 ton of coal

• Control rods: absorb neutrons & slow reaction (generally made of boron)

• Moderator: medium that reduces the velocity of neutrons; can be water, graphite, or deuterium oxide (aka heavy water)

• Coolant: removes heat & produces steam to generate electricity

• Energy Resources: Nuclear Energy

• Half life = The time needed for one-half of the nuclei in a

radioisotope to decay and emit their radiation to form a

different isotope

Half-time Emitted

• Uranium 235 710 million yrs alpha particles, gamma rays

• Plutonium 239 24.000 yrs alpha particles, gamma rays

• During operation, nuclear power plants produce radioactive

wastes, including some that remain dangerous for tens of

thousands of years

Advantages: Low environmental impact, Large fuel supply,

Moderate/low pollution

Disadvantages: VERY low net energy yield & high cost (has to

be subsidized by governments), LONG storage of radioactive

waste, Risk of meltdowns

Radioactive Waste:

–High-level radiation (gives off large amount of radiation)

» Is mainly from spent fuel rods from nuclear power plants

» No agreement about a safe method of storage

» Must be stored for 10,000 - 240,000 years

–Storage ideas:

» Bury underground – most agreed upon option

» Shoot to space or sun

» Bury under Antarctic Ice Sheet, Greenland ice cap (prohibited by law)

» Dump into oceanic subduction area (prohibited by law)

» Bury on stable area of ocean floor (prohibited by law)

» Yucca Mountain Desert storage ?

Yucca Mountain - FAIL

Nevada, approx 80 miles northwest of the Las Vegas - proposed site for the Yucca Mountain nuclear waste repository in 1987

By 2008, gov had spent more than $10.4 billion on preliminary development

Problems with area: earthquake zone & likely to result in a huge explosion

Funding ended for project in 2009

Concerns about the safety, cost, and liability have slowed the growth of the nuclear power industry

Accidents showed that a partial or complete meltdown is possible

Three Mile Island, Penn, US in 1979

Chernobyl, USSR in 1986

Fukushima, Japan in 2011

Three Mile Island – worst nuclear accident in USA

• March 29, 1979, a reactor in Middletown, PA lost coolant

water because of mechanical and human errors and suffered a

partial meltdown

• Non-nuclear portion of plant had a pump malfunction. This

caused pressure to build in nuclear part . A valve was opened

to release pressure and was stuck open, allowing coolant to

leak out.

• Reactor core overheated, started meltdown, but did not

breach containment building

– 50,000 people evacuated & another 50,000 fled area

– Unknown amounts of radioactive materials released

– Partial cleanup & damages cost $1.2 billion

– Released radiation increased cancer rates.

Chernobyl – worst nuclear accident in world

• April 26, 1986, reactor explosions (Ukraine)

• A variety of things “went wrong”: Too many control rods

removed from coolant , Slowing turbine reduced water intake,

safety valves had been circumvented because of testing & poor

communication between safety officials, testing officials

• Russian Health ministry reported 3,576 deaths/ Green Peace

estimates32,000 deaths, About 400,000 people were forced to

leave their homes

• ~160,000 sq km (62,00 sq mi) contaminated

• > Half million people exposed to dangerous levels of

radioactivity

• Cost of incident > $358 billion

Renewable Energy Resources

Only ~14% of global energy is from renewable resources

Types:

1. Hydroelectric energy: force of water turns turbine connected to generator creates electricity

Advantages: flood control, little air pollution (** CH4)

Disadvantages: habitat destruction; silting behind dams, prevents migration

Supplies ~3% of energy worldwide

Energy

2. Solar Energy

A. Passive solar energy collection: use of building materials, building placement and design to collect solar energy to keep building cool/ warm

B. Active solar energy collection: use of devices that collect solar energy

»Can heat water & pump throughout building

»Photovoltaic cells (PV cells) = solar panels that covert solar radiation into electricity (stored in battery or put back into grid)

Advantages: no air

pollution, silent

Disadvantages: materials

(silicon) needed for solar

panels require mining &

fossil fuels Not every place gets enough sunlight

3. Wind Energy-Fastest growing alternative energy source

–Wind turns the blades of a turbine, Cogs turns

generator to produce electricity

4. Geothermal Energy

–Energy that’s produced by harnessing

earth’s internal heat

»Wells drilled down for 1,000s of meters to

water that’s 300-700 F steam turns

turbines

»Used in Hawaii, Iceland, Japan,

Mexico, New Zealand, Russia, &

California

»Disadvantages: limited areas

5. Hydrogen

Chemically locked in water and organic compounds. Must be release through electrolysis (hydrogen atoms stripped from water) = net negative energy yield

Expensive fuel cells are the best way to use hydrogen

Best Option for Future: Photovoltaic electricity to run electrolysis!

6. Biomass & Biofuels

Biomass = Plant materials and animal waste we can burn or turn into biofuels

Includes wood, dung, sugar cane

Biofuels:

Ethanol: alcohol from fermented corn or sugar cane

Biodiesel: diesel fuels from vegetable oil or animal fat

Future Source: ALGAE!