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Lecture 7

Environmental Science 1021F/G Lecture Notes - Lecture 7: Thermal Energy, Carboniferous, Surface Mining


Department
Environmental Science
Course Code
ENVSCI 1021F/G
Professor
Christie Stewart
Lecture
7

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ENVIROSCI Lecture 7
Energy, specifically THERMAL energy
Energy I: Traditional sources of energy and their drawbacks
Energy Sectors:
Residential
Industrial
Agriculture
o Surprisingly doesn’t use up a lot of energy
Commercial
Transportation
Canadian Energy use
Hyrdo = 59%
Nuclear = 15%
Gas and others = 10%
Coal =9%
o These 3 make up a chunk of what MOST countries use
o This makes up THERMAL energy
Non hydro =7%
Thermal energy
1st law of thermodynamics
We take stored chemical energy and release it by burning it which produces heat which
then generate electricity
Coal and oil come from biological sources, we are burning ancient biomass
o Coal coming from forests and plant material
o Oil coming from marine organisms
Nuclear energy is from radioactive isotopes
The Carboniferous period
o Talked about degradation rates
Coal purity increases over time
Over hundreds and millions of years
Peat is the intermediary version = organic matter that is half broken down
o Can get peat logs to use in fireplace
After compression of peat, turns into Lignite
And so on, until it turns into rock
Example, “Tollund Man” was found in rock in 1950, farmers who found him thought he
died recently because he did not decompose at all because decomposition rates were low
American has 25% of our coal availability
Oil formation
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Marine animals sink to the bottom where there is low degradation
Gets buried in sediment
Bacteria eats lighter hydrocarbons
What is left is oil
Misconception = in the areas we find oil is not where they are stored now
o We drill down to access these areas
o “Cap rock” stops oil from going places it shouldn’t
Impermeable to oil and gas
“Marine snow” = looks like “dust” in the water but is organic material coming from
higher levels in the water which builds up, layers of this build up at the bottom of the
ocean
High oil capacity areas depend on where oceans were previously
Uranium
Often used in nuclear fission for energy generation
Is naturally formed but breaks down automatically
o Radioactive decay, occurs at different isotopes = changes in neutrons, this means
changing the properties
o Mostly use U^235 which is used by most reactors
Reactors usually enrich to 3-4%
Shoots down some of its material and becomes a different atom
Canada used to be #1 Uranium producer
Extraction - coal
Coal extraction
Under sediment, how can we access it?
Mining is the #1 contributor of solid waste
4 types of mining:
o Strip mining is when we have coal seams near the surface AKA overburden
which is sediment we don’t want in order to directly access the coal seam
Occurs in horizontal deposits
o Subsurface mining is use when materials are concentrated not horizontally
Requires digging into the surface/past it diagonally for example
This is dangerous
Overburden waste created
o Open-pit mining
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