chapter 15 geologic resources: nonrenewable mineral and energy resources
Post on 04-Jan-2016
224 Views
Preview:
TRANSCRIPT
Chapter 15Chapter 15
Geologic Resources: Geologic Resources: Nonrenewable Mineral and Nonrenewable Mineral and
Energy ResourcesEnergy Resources
Key QuestionKey Question What are nonrenewable mineral resources What are nonrenewable mineral resources
and how are they formed?and how are they formed? How do we find and extract nonrenewable How do we find and extract nonrenewable
mineral and energy resources from the mineral and energy resources from the earth’s crust?earth’s crust?
How fast are mineral supplies being used How fast are mineral supplies being used up?up?
How should we evaluate energy How should we evaluate energy alternatives?alternatives?
What are advantages and disadvantages What are advantages and disadvantages of natural gas?of natural gas?
What are Mineral Resources?What are Mineral Resources?
Concentration of naturally occurring Concentration of naturally occurring material in or on the earth’s crust material in or on the earth’s crust that can be extracted and processed that can be extracted and processed into useful materialsinto useful materials
Classified as Classified as nonrenewable resourcesnonrenewable resources because they take so long to producebecause they take so long to produce
We know how to find and extract We know how to find and extract 100+ nonrenewable minerals from 100+ nonrenewable minerals from the earth’s crustthe earth’s crust
We can extract…We can extract…
Metallic mineral resourcesMetallic mineral resources (iron, (iron, copper, aluminum)copper, aluminum)
Nonmetallic mineral resourcesNonmetallic mineral resources (salt, (salt, clay, sand, phosphates, soil)clay, sand, phosphates, soil)
Energy resourcesEnergy resources (coal, oil, natural (coal, oil, natural gas, uranium)gas, uranium)
OreOre
Rock containing enough of 1+ Rock containing enough of 1+ metallic minerals to be mined for metallic minerals to be mined for profitprofit
We convert 40 metals extracted from We convert 40 metals extracted from ores into everyday items that are ores into everyday items that are either 1) used and thrown away OR either 1) used and thrown away OR 2) reused or recycled2) reused or recycled
Categories of nonrenewable Categories of nonrenewable mineral resourcesmineral resources
US Geological Survey divides nonrenewable US Geological Survey divides nonrenewable mineral resource into categories:mineral resource into categories:
1.1. Identified resourcesIdentified resources: deposits of nonrenewable : deposits of nonrenewable mineral resource with a known location and mineral resource with a known location and quantityquantity
2.2. Undiscovered resourcesUndiscovered resources: potential supplies : potential supplies assumed to exist in theoryassumed to exist in theory
3.3. ReservesReserves: identified resources from which : identified resources from which resource can be extracted for profitresource can be extracted for profit
4.4. Other resourcesOther resources: identified and discovered but : identified and discovered but not classified as reserves not classified as reserves
How do ores form from magma?How do ores form from magma?
Ores form as a result of internal and Ores form as a result of internal and external geologic processesexternal geologic processes
Plate tectonics shape the earth’s Plate tectonics shape the earth’s crust and determine where the crust and determine where the richest mineral deposits are foundrichest mineral deposits are found
As magma cools, it crystallizes into mineral-containing igneous rocks
Ore deposits form through hydrothermal processes
Upwelling magma solidifies into black smokers
Shoots out mineral-rich hot water on the seafloor
Minerals accumulate as hot and cold water contact
Form ore deposits rich in copper, lead, zinc, silver, and gold
Finding nonrenewable resourcesFinding nonrenewable resources
Aerial photos and satellite imagesAerial photos and satellite images Planes that detect deposits of radioactive Planes that detect deposits of radioactive
metalsmetals Gravimeter to measure differences in Gravimeter to measure differences in
density (ore differs from surrounding rock)density (ore differs from surrounding rock) Drilling deep well and extracting core Drilling deep well and extracting core
samplessamples Seismic surveys by explosions and Seismic surveys by explosions and
analyzing shock wavesanalyzing shock waves Chemical analysis of water and plants Chemical analysis of water and plants
(absorb minerals)(absorb minerals)
Mining techniques (once resources Mining techniques (once resources have been found)have been found)
Surface miningSurface mining: equipment strips outer layer of : equipment strips outer layer of soil and rock; in US, used to extract 90% nonfuel soil and rock; in US, used to extract 90% nonfuel resources and 60% coalresources and 60% coal
Open-pit miningOpen-pit mining: machines dig holes and remove : machines dig holes and remove oresores
DredgingDredging: chains scrape underwater mineral : chains scrape underwater mineral depositsdeposits
Area strip miningArea strip mining: parallel strips made in flat land; : parallel strips made in flat land; power shovels usedpower shovels used
Contour strip miningContour strip mining: terraces cut into side of hill; : terraces cut into side of hill; power shovels usedpower shovels used
Mountaintop removalMountaintop removal: explosives used to remove : explosives used to remove top of mountain and expose coal underneathtop of mountain and expose coal underneath
Open Pit Mine
Dredging
Area Strip Mining
Contour Strip Mining
Surface Mining Control and Surface Mining Control and Reclamation Act of 1977Reclamation Act of 1977
Requires mining companies to Requires mining companies to restore surface-mined land so that it restore surface-mined land so that it is usable againis usable again
Although surface-mined land can be Although surface-mined land can be restored, it is expensive and not restored, it is expensive and not done in many countriesdone in many countries
Subsurface miningSubsurface mining
Used to remove coal and other metal Used to remove coal and other metal ores that are too deep to be ores that are too deep to be extracted by surface miningextracted by surface mining
Blast tunnels to get to deposit, use Blast tunnels to get to deposit, use machinery to transport ore to the machinery to transport ore to the surfacesurface
Disturbs 1/10 as much land as Disturbs 1/10 as much land as surface mining, produces less wastesurface mining, produces less waste
More dangerous and expensive More dangerous and expensive
Environmental Effects of Extracting Environmental Effects of Extracting Mineral ResourcesMineral Resources
Fig. 15-6 p. 343
Percolation to groundwaterLeaching of toxic metalsand other compoundsfrom mine spoil
Acid drainage fromreaction of mineralor ore with water
Spoil banks
Runoff ofsediment
Surface MineSubsurfaceMine Opening
Leaching may carryacids into soil andgroundwater supplies
Acid mine drainage-pollution and degradationby acid runoff and toxic chemicals from mining-can kill fish and other aquatic life
Surface mining
Metal ore
Separationof ore frommachine
Scattered in environment
Recycling
Discarding of product
Conversion to product
Melting metal
Smelting
Processes involved in extractionProcesses involved in extraction
SmeltingSmelting: used to separate metal : used to separate metal from other elements in the orefrom other elements in the ore
Enormous amount of pollution which Enormous amount of pollution which damages surrounding vegetation and damages surrounding vegetation and soilsoil
Smelters also produce liquid and Smelters also produce liquid and hazardous waste that must be hazardous waste that must be disposed of safely disposed of safely
Are there environmental limits?Are there environmental limits? Resource experts believe that the Resource experts believe that the
greatest danger from increasing greatest danger from increasing consumption of nonrenewable consumption of nonrenewable resources is environmental damage resources is environmental damage caused by extraction and processing.caused by extraction and processing.
More accessible and high-grade ores More accessible and high-grade ores are exploited firstare exploited first
It takes more $ to exploit the deeper It takes more $ to exploit the deeper ores, causing more environmental ores, causing more environmental effectseffects
Will there be enough mineral Will there be enough mineral resources?resources?
Future of nonrenewable minerals depends on: actual supply and rate at which supply is used
Economic depletion: cost more to find, extract, transport and process than it’s worth
Depletion time: time it takes to use up a 80% of nonrenewable resource
Supplies of mineral resources
Reserve-to-production ratio: number of years that reserves of a NM will last
Materials revolution: new materials (ceramics and plastics) are being developed as replacements for metals
Substitutes cannot be found for many mineral resources
Mined coal
Pipeline
Pump
Oil well
Gas well
Oil storage
CoalOil and Natural Gas Geothermal EnergyHot waterstorage
Contourstrip mining
PipelineDrillingtower
Magma
Hot rock
Natural gasOil
Impervious rock
Water Water
Oil drillingplatformon legs
Floating oil drillingplatform
Valves
Undergroundcoal mine
Water is heatedand brought upas dry steam or
wet steam
Waterpenetratesdownthroughtherock
Area stripmining
Geothermalpower plant
Coal seam
Energy usage
99% of the energy used to heat the earth and our buildings comes from the sun
Without this input, earth would be -400 degrees F!
The other 1%?
…is commercial energy: from extracting and burning nonrenewable mineral resources from earth’s crust (mainly, fossil fuels-oil, natural gas, coal)
A typical citizen of the US uses 65-140x as much energy per day as a hunter-gatherer
Primitive
Hunter–gatherer
Earlyagricultural
Advancedagricultural
Earlyindustrial
Modern industrial(other developed
nations)
Modern industrial(United States)
Society Kilocalories per Person per Day
260,000
130,000
60,000
20,000
12,000
5,000
2,000
Oil
Use of oil climbs by 1%/year Projected to peak between 2010 and 2030
and then begin to decline Natural gas is increasing by 2%/year;
cleanest and least disrupting of the 3 fossil fuels
Biomass: main source for heating in developing countries; renewable energy (fuelwood) BUT fuelwood shortage is a problem
What is oil? Petroleum (crude oil): thick liquid with
hundreds of hydrocarbons with sulfur, nitrogen, and oxygen impurities
Called “oil” when it comes out of the ground
Fossil fuel Produced by the decomposition of dead
plant matter that was 1) buried under lake and ocean sediments millions of years ago and 2) subjected to high temp and pressure for millions of years in the carbon cycle.
How is oil extracted?
Deposits are trapped under the earth’s crust on land or under the seafloor in rock formations
Well is drilled Oil is pumped out of the rock pores Transported to refinery by pipeline, truck,
or oil tanker (ship) and separated into different types
Drilling always involves: 1) some oil spills 2) use of nonrenewable resource
Diesel oil
Asphalt
Greaseand wax
Heating oil
Aviation fuel
Gasoline
Gases
Furnace
Heatedcrude oil
Who has the world’s oil supplies?
Oil reserves: identified deposits where oil can be extracted
Saudi Arabia has most oil reserves: 26%, then Iraq, Kuwait, Iran (each with about 10%)
3% in U.S.
Oil in U.S.
3% of all oil reserves in U.S. 25% from offshore drilling 17% from Alaska’s North Slope Currently, 93% of offshore drilling
comes from Gulf of Mexico
MEXICO
UNITED STATES
CANADA
PacificOcean
AtlanticOcean
GrandBanks
Gulf ofAlaska
Valdez
ALASKABeaufort
Sea
Prudhoe Bay
ArcticOcean
Coal
Gas
Oil
High potentialareas
Prince WilliamSound
Arctic National Wildlife Refuge
Trans Alaskaoil pipeline
How long will oil supplies last?
We are currently running out of oil Supplies decline when 1) demand
exceeds production and 2) other energy resources become more environmentally acceptable substitutes
Production expected to peak between 2010 and 2030
Continued…
Global reserves will last about 50 years at current usage rate
U.S. reserves will last about 10-20 years at current usage rate
U.S. oil supplies are projected to be 80% depleted within 10-15 years
TEXAS
LOUISIANA
MISSISSIPPI ALABAMA GEORGIA
FLORIDA
GULF OF MEXICO
Active drilling sites
Natural Gas
Mixture of methane, propane, butane, highly toxic hydrogen sulfide
Conventional natural gas: lies above oil reserves, formed from fossils of plants (like oil), buried deep in seafloor
Unconventional natural gas: found by itself in other underground sources (ex. Small bubbles trapped in ice crystals under arctic permafrost)—very expensive to remove, but technology being developed
Who has natural gas supplies?
Russia and Kazakhstan: 42% Other countries with large reserve:
Iran, Saudi Arabia, Algeria, U.S. (3%) Geologists expect to find more
natural gas reserves In U.S. natural gas reserves are
located in same place as crude oil
Advantages Disadvantages
Good fuel forfuel cells andgas turbines
Low land use
Easily transportedby pipeline
Moderate environ-mental impact
Lower CO2 emissions thanother fossil fuels
Less air pollutionthan otherfossil fuels
Low cost (withhuge subsidies)
High net energyyield
Ample supplies(125 years)
Sometimes burned off andwasted at wellsbecause of lowprice
Shipped acrossocean as highlyexplosive
Methane(a greenhouse gas) can leakfrom pipelines
Releases CO2
when burned
Nonrenewableresource
Difficult to transferfrom one countryto another
Requirespipelines
How long will natural gas supplies last?
Globally, 120 years at current consumption rate
In U.S., 60-75 years at current consumption rate
Pros and Cons?
Natural gas systems (combustion turbines bolted to the ground):
1) produce electricity more efficiently than burning oil or nuclear power
2) Produce much less carbon dioxide 3) Provide backup for solar and wind
power
How much do we use natural gas?
Used in 53% of U.S. homes for heat 16% of U.S. electricity By 2020, it will be 32% of U.S.
electricity
FrackingFracking Drill into reservoir rock formations. Drill into reservoir rock formations. The energy from the injection of a highly-The energy from the injection of a highly-
pressurized fracking fluid creates new pressurized fracking fluid creates new channels in the rockchannels in the rock
This increases the extraction rates and This increases the extraction rates and the recovery of fossil fuelsthe recovery of fossil fuels
Can cause leak of natural gas into Can cause leak of natural gas into groundwater—very toxic!groundwater—very toxic!
Requires TONS of water, carcinogenic Requires TONS of water, carcinogenic chemicals, etc.chemicals, etc.
What is COAL?
Solid fossil fuel formed in several stages as buried remains of plants (300-400 mill years ago) were subjected to high heat and pressure
Coal contains: sulfur, trace amts of mercury and radioactive materials
Anthracite is the most desirable form of coal because of low sulfur content and high heat
How is it extracted? Some is extracted underground by miners
working in tunnels Area strip mining: when coal lies close to
the earth’s surface on flat terrain Contour strip mining: when coal lies close
to the earth’s surface on hilly terrain Transported to processing plant where it is
broken up, crushed, and washed to remove impurities
Dried and shipped to power plants and industrial plants
Where are the largest coal supplies?
Coal provides 21% of the world’s energy
Burned to generate 62% of the world’s electricity
66% of the world’s coal reserves are in U.S., Russia, China, and India.
Half of the global coal consumption takes place in China and U.S.
How long will coal supplies last?
Coal is the world’s most abundant fossil fuel
Reserves should last at least 220 years
Increasing moisture content
Increasing heat and carbon content
Peat(not a coal)
Lignite(brown coal)
Bituminous Coal(soft coal)
Anthracite(hard coal)
Heat
Pressure Pressure Pressure
Heat Heat
Partially decayedplant matter in swampsand bogs; low heatcontent
Low heat content;low sulfur content;limited supplies inmost areas
Extensively usedas a fuel becauseof its high heat contentand large supplies;normally has ahigh sulfur content
Highly desirable fuelbecause of its highheat content andlow sulfur content;supplies are limitedin most areas
Advantages Disadvantages
Low cost
High net energyyield
Ample supplies(220–895 years)
Releases radioactive particles and mercury into air
High CO2 emissionswhen burned
Severe threat tohuman health
High land use (including mining)
Severe land disturbance, air pollution, andwater pollution
Very high environmentalimpact
Mining andcombustiontechnologywell-developed
Air pollution canbe reduced withimprovedtechnology (butadds to cost)
Nuclear Power
U.S. companies started developing nuclear power plants in the 1950s because:
1. Atomic Energy Commission promised nuclear power would produce electricity at much lower cost
2. Government paid ¼ of the cost of building first group of reactors
3. Price-Anderson Act: protects industry from public liability in case of accidents
Front end Back end
Uranium mines and millsOre and ore concentrate (U3O8)
Geologic disposalof moderate-and high-levelradioactive wastes
High-levelradioactivewasteUranium tailings
(low level but long half-life)
Conversion of U3O8
to UF6
Processeduranium ore
Uranium-235 as UF6
Enrichment UF6
EnrichedUF6
Fuel fabrication
Spent fuelreprocessing
Plutonium-239as PuO2
(conversion of enriched UF6 to UO2
and fabrication of fuel assemblies)
Fuel assemblies Reactor Spent fuel assemblies
Interim storageunder water
Open fuel cycle today
Prospective “closed” end fuel cycle
Decommissioningof reactor
Decommissioningof reactor
Spent fuelassembliesSpent fuelassemblies
Nuclear Fuel Cycle
Figure 15-37Page 368
Operational
Decommissioned
Proposed high levelnuclear waste storage site
Reactors
1
2
Low risk of accidents because of multiple safety systems
Moderate land use
Moderate landdisruption andwater pollution
Emits 1/6 asmuch CO2 as coal
Lowenvironmentalimpact (withoutaccidents)
Large fuelsupply
Spreads knowledge and technology for building nuclear weapons
No acceptable solution for long-term storage of radioactive wastes
Catastrophic accidents can happen
High environmental impact (with major accidents)
Low net energy yield
High cost
Advantages Disadvantages
Nuclear Power
Coal
Ample supply
High net energyyield
Very high airpollution
High CO2
emissions
65,000 to 200,000deaths per yearin U.S.
High land disruption fromsurface mining
High land use
Low cost)
Nuclear
Ample supplyof uranium
Low net energyyield
Low air pollution
Low CO2
emissions
About 6,000deaths per year in U.S.
Much lower landdisruption fromsurface mining
Moderate land use
High cost)
COAL vs. NUCLEAR POWER
What should we do with high-level radioactive waste?
Proposals:1. Bury it deep underground (not sure
about long-term behavior of sites)2. Shoot it into space or into the sun (very
high cost and if accident occurred, waste could be dispersed all over earth)
3. Bury it under ice caps (long-term stability of ice caps is not known)
4. Dump it into deep ocean (waste might be spewed out somewhere else by volcanic activity)
Connection between nuclear reactors and spread of nuclear weapons?
60 countries (1 out of 3) have nuclear weapons or knowledge to build them
Info for this has come mostly from the U.S. which has been selling in international marketplace
Bad news: enough nuclear weapons to kill everyone in the world 30x
“dirty bombs”: dynamite mixed with radioactive material (easy to obtain-stolen from loosely-guarded sources)
Sources: hospitals, research labs, industries, smoke detectors
top related