Lecture 30 Flashcards
Non-renewable energy sources include:
hydrocarbons (coal, oil, and natural gas), nuclear fuels
non-renewable resources supply well over ___ of the world’s energy
90%
renewable energy sources examples:
hydroelectric, solar, wind, wave, alcohol, wood
North American versus world use of energy
> 10 metric tonnes of coal versus 2.7 metric tones as the world average
Fossil fuels
a class of energy resources that are formed from organic matter that is buried by sedimentary process, and is subsequently altered by heat, pressure, and the activity of microorganisms at depth.
Formation of coal
- Deposition of vegetation (trees, ferns, and other plants) in swamps leads to the formation of peat.
- Burial must be rapid enough to prevent oxidation and erosion of the material
- Peat turns into coal as volatiles such as methane, CO2, and water are lost
Coal Grades
peat, lignite, sub-bituminous, bituminous, anthracite, graphite
Peat use
soil conditioning
Sub-bituminous uses
char production
thermal electric power generation is made by what types of coal
lignite, sub-bituminous, bituminous
Cement production is made by what type of coal
bituminous
Anthracite use
metallurgical coke production
Coalbed methane
Methane that is released suring the coalification of peat may remain trapped in fractures in the coal stream and is held in place by water that saturates the well stream. Water is pumped from the coal seam allowing methane to rise (due to reduced pressure) to the surface.
Formation of oil and gas
Organic matter is trapped in smaller concentrations in other sedimentary rocks, notably in marine environments where phytoplankton settled to the anoxic seafloor which was preserved in black shales.
Black shales
have 8% or more of organic matter, which is referred to as kerogen.
Kerogen
the organic matter inside of black shales, which matures during burial and mild heating, and gives off liquid and gaseous hydrocarbons, including bitumen and tar, oil, light condensates, and natural gas
Petroleum Traps
As oil and gas are less dense, they rise through permeable rock to the surface. Oil and gas get trapped by geologic structures that prevent the escape called petroleum traps.
Potential rock sources for petroleum
black shales and reservoir rocks with high porosity (sandstone or limestone)
_____ are used to identify structures indicative of structural traps
seismic surveys
Hydraulic fracturing
a process that injects mixtures of water and chemicals with a propend (ceramics, sand) into the impermeable rock to fracture it and release oil and gas.
Modern hydraulic fracturing is the combination of the following technologies:
horizontal drilling and hydraulic fracturing
Hydraulic fracturing water cycle
water acquisition, chemical mixing, well injection, produced water handling, and wastewater disposal
Produced water from hydraulic fracturing problems:
inorganic, organic, subsurface reactions, microorganisms (biofueling), suspended solids, toxicity
Tar/oil sands
dense, viscous deposits of asphalt-like oil that cannot be easily pumped. They can be formed in zones where lighter, volatile hydrocarbons have migrated away, leaving heavier material or in areas of lower maturity.
Petroleum refining
Crude oil is sent to refining facilities where a variety of hydrocarbons are produced by the process of cracking.
Products of petroleum refining
gases, gasoline, heavy oils, lubricants, and tars
Crude oil
oil that has risen to the surface
cracking process
breaking down of long carbon chains in crude oil
Nuclear energy produces ___ of the world’s electricity
14%
Ore body types associated with Uranium
- unconformity related ore deposit
2. roll-front ore deposits
unconformity related ore deposit and uranium
convective flow driven by the heat of the basement rocks can drive geofluids from fractures in uranium-containing basement rocks to overlying sedimentary rocks. The drop in temperature and pressure and redox reactions (e.g., with iron and sulfide) leads to the precipitation of uranium minerals such as pitchblende (U3O8) near the unconformity. In addition, depending on the flow regime, fluids containing uranium from the sedimentary rocks can flow into fractures, where uranium is chemically reduced to form insoluble uranium minerals.
Roll-front ore deposits and uranium
an oxic, uranium-containing water flows through a sedimentary rock containing reduced minerals, most often pyrite. As water containing the oxidized uranium moves into the reduced zone, the uranium itself is reduced, immobilized, and thereby concentrated, creating a roll-front ore deposit.
Nuclear fission
Uranium undergoes slow natural radioactive decay which releases geothermal energy. U235 undergoes radioactive decay, where the nucleus splits and releases neutrons and cause other atoms to undergo fission.
Types of renewable sources
solar, hydrogen fuel, wind, biomass (biofuels and biochar), hydroelectric, tidal, and geothermal
Local impacts of extraction
- coal mining requires the removal of a lot of rock that causes toxic mine drainage
- petroleum production causes spills and releases sulfur
- contaminating water
Photochemical smog
produced by emissions of combustion of fossil fuels and agricultural waste produces smog, which is a combination of ozone, nitrous oxides, and particulate matter.
Acid rain and petroleum
The addition of sulfur and nitrogen oxide gases from industrial air pollution can lead to the generation of sulfur, sulfuric, nitric, and nitrous acids that acidify rain to pH 3-5.
The acidification of rain is particularly great in areas of:
downwind of industrial regions and large cities
