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.