Energy and the Environment Flashcards
From the simplest algal scum, to the most complex ecosystem, energy is essential to life
- Convert food into energy everyday to power our bodies
- Use fuels to power our stuff
Throughout history, humans have discovered ways to take various sources of energy and use them to their advantage
- The trend has been towards bigger and better sources of energy, from burning wood to nuclear energy
- Keep seeking out more efficient and economical ways to make life easier
Renewable Energy Resources
- Hydropower
- Solar energy
- Biomass energy
- Wind energy
- Ocean energy
- Geothermal energy
Non-renewable Energy Resources
- Nuclear
- Oil
- Coal
- Gas
Energy Consumption
- Oil, coal, and gas (fossil fuels) are high in consumption, but non-renewable and the demand continues to increase
- Need new energy sources, and it’s a global problem
C makes up less than 0.1% by weight of the Earth’s crust, but the basis of all life
- C is our principal source of energy and the raw material of many manufactured goods
- Combustion is a reaction with O2
- Combustion of carbon-based fuels produces CO2, water, and energy
Coal
- Fossil fuel produced from accumulation, burial, and compaction of plant matter in soils
- Can be fossilized O horizon
- Largest source of energy electricity worldwide (cheap, abundant)
- The quality/rank of coal increases with depth of burial/temperature: peat: lignite, sub-bituminous, bituminous, and anthracite
- Burning coal adds a significant amount of CO2 to the atmosphere every year
- Adds SO2 (an indirect GHG and component of acid rain) to the atmosphere
Anthracite is the most energy dense coal. Where do we expect it to form?
Where mountain building is occurring/occurred
Safest and cleanest sources of energy (least to most):
- Coal, oil, natural gas, biomass, hydropower, nuclear energy, wind, solar
So why do we keep using coal if it is the least safe and clean?
Abundant and cheap!
- Waiting for technology to make solar, wind, nuclear, hydro, more affordable and accessible!
Petroleum: crude oil
- Made of hydrocarbons in liquid form
- Naturally occurring yellow to black liquid that forms in the subsurface
- Used for: energy, plastics, fertilizers, insecticides, synthetic fibres, paints, cosmetics
What would life look like without petroleum products?
Insanely different especially due to plastics, but currently shifting away from it!
How petroleum and natural gas were formed
- Tiny sea plants and animals died and were buried on the ocean floor
- Over time, they were covered by layers of sediment and rock
- Over millions of years, the remains were buried deeper and deeper.
- The enormous heat and pressure turned them into oil and gas
Natural Gas
- Primarily methane (CH4)
- From the same source material as petroleum, but tends to form under higher P and T, so it forms at a greater depth than crude oil
- Gas is less dense than oil, so once it forms, it may migrate upwards until it is above the oil
Four conditions to form and preserve a petroleum deposit:
- Source rock
- Reservoir Rock
- Caprock
- Trap
Source rock
Often organic-rich sedimentary rock with commercial quantities of hydrocarbons (typically rocks formed under anoxic condition)
Reservoir rock
Where petroleum migrates to; porous and permeable
Caprock
Impermeable rock prevents oil from migrating further upward (like a lid)
Traps
Geological structure that “traps” the oil
- Anticline
- Salt dome
- Stratigraphic trap
Anticline
Convex upward fold (can occur with fault trap)
Salt dome
Petroleum gets trapped along sides and near top of dome
- Salt forms from evaporation of sea water in a restricted marine basin
- The addition of freshwater is limited, so the sea water becomes super concentrated in salts, leading to precipitation and deposition of layers of salt
- > 500 salt domes in US and Mexico Gulf Coast
Stratigraphic trap
formed as a result of lateral and vertical variation in the thickness, texture, porosity, or lithology of the reservoir rock
Major salt deposits (potash) also formed in western Canada as a result of
evaporation of a restricted portion of a Devonian inland sea
Carboniferous deposits (and domes) are known from
the Canadian Arctic and the Maritime Provinces. Some of these have produced significant oil and gas.
Coal Mining:
- Extracted by underground mining, mountaintop removal, contour mining, and strip mining
- HIGH costs for extraction
Future coal use:
Converting coal into a synthetic replacement for oil and natural gas = syngas
- Syngas is essentially methane, but has half the energy density of methane
- May still be economically viable because it is cheap to make
- In converting coal to syngas, CO2 and SO2 can be captured and then sequestered (stored) underground
Oil Production: Drilling
Oil is extracted through drilling wells
- Reservoirs are under pressure
- Oil moves from high to low pressure
- Most wells require pumping
- In many cases, oil and gas are produced together
- Pressure of the reservoir decreases over time
- Wells can be vertical, horizontal, extended-reach horizontal, or multilateral
Secondary Recovery
May be used to increase pressure and therefore production
- Gas injection
- Water (or water + chemicals) injection
Enhanced recovery increases the mobility of oil to increase recovery
- Steam injection
- Adding surfactants reduces surface tension between water and oil
Once oil is produced, it needs to be transported to a refinery
- Transported via pipe, rail, truck, cargo ships
- Trucks and rail are safest for humans
- Boats, trucks, and rail are the least safe for the environment
Unconventional Fossil Fuels
- Oil sands -> steam into ground?
- Fracking
As fossil fuels run out/environmental pressures increase,
the race is on to find alternative energy sources
