Unit 6 Test Flashcards
Energy is the capacity to do work
“Doing work” can really be anything- lighting a light bulb, cooling a house, cooking a chicken, jumping up and down, propelling a vehicle forward.
Energy can change forms and be stored- but can neither be created nor destroyed*
As energy changes forms, it usually becomes less useful and more disordered (entropy) - think about heat from a fire dissipating in all directions
Heat is not an organized form of energy, gets messy and gets more entropy
Ability to do work
Which in physics typically means applying a force on an object over a distance.
A force is an object’s mass x acceleration
Energy is applying a force over a distance
For example, to get a parked car to drive forward, a force must act on the vehicle, in essence, accelerating its mass.
ALL UNITS OF ENERGY HAVE COMPONENTS REDUCIBLE TO MASS AND ACCELERATION
Joule = 1 kg of mass and accelerating it over a distance
Can change forms, can be dissipated as heat
As energy changes it becomes less useful (entropy)
Heat is not a useful/organized energy form
calorie def
A calorie is the amount of energy required to raise one gram of water one degree celsius
Renewables vs. Non Renewables
There is a spectrum to renewability → there is a grey area
Renewable - can it be remade at or near consummation rate
Ex. wind, sunlight, water,
Nonrenewable -exists in a fixed about on earth, takes too long to replenish
Replenishable/renewable resources
Can be remade=replenishable, but has to be at the rate of use to be renewable
The renewability of a resource depends, in part, on how we use it. Some resources will never be renewable (eg. fossil fuels) as their formation takes thousands to millions of years.
Others (eg. biofuels) can be renewable, but only if used responsibly.
Others yet are completely renewable (wind, solar) in that there is no realistic future where we would harness more than is theoretically produce-able.
Global Energy Consumption
Global energy use is increasing exponentially- both in terms of per capita energy use in developed countries, and total.
We using more energy than we ever had before
Coal and oil dominate how much energy we are using
Developed vs. Developing Countries
Developed nations use less energy overall, but more energy per capita
Think about Human Demographics- why does this make sense? What happens to nations as they develop? (Demographic Transition)
Industrialized nations have access to better technology, better renewable energy
In an advance society we are using more things that need energy
Canada uses a lot of energy per capita because it is cold → a lot of energy poured into heating houses
Per capita = per person to support their lifestyle
Why might US energy use be so variable by state?
Some states have more factories
Colder areas increase energy
Making things require energy
Making things require energy
Fossil Fuel Reliance: Developing Nations
Globally, fossil fuels dominate
These are easy and cheap- especially for developing nations
This is changing slowly- renewables are taking a larger share of the total, especially nuclear (not your classic ‘clean’ energy) and hydro.
Coal is most often used to generate electricity- and oil for transport. Natural gas is taking an increasing role in heating and electricity generation.
Developing nations are more reliant on fossil fuels
Don’t have the technology to have other ways of creating energy
Our share of natural gas has gone up
Human Development Linked to Increased Energy Use
Less developed nations- subsistence energy use (burning of biomass for heat, cooking, etc.)
More developed nations- oil for vehicles and transport, and coal/nat gas for electricity.
Homes and technology require energy! As does transport, travel, etc.
This is part of the demographic transition…
Stage 3 is fossil fuel
Energy Sources: How Countries Choose
Cost of energy
Costs can have to do with supply and demand- were new reserves discovered? Depleted? New extraction tech? Geopolitics?
Government Regulations
Tax incentives, or taxes? Regulation around procurement? Tariffs?
Availability
Where is it coming from? How is it turned into energy? Does infrastructure allow it to easily travel to those who need it (pipelines, etc.)?
Subsistence Fuels: Wood/charcoal
This is NPP turned into fuel
Wood/Charcoal
Wood burning fires can generate heat for homes or cooking
Cheap, easy access for anyone with a hatchet
Habitat loss and biodiversity loss
Charcoal is wood heated under low oxygen for long periods of time
Coal
Coal is essentially compacted peat- pressure turns peat into rock, which is much more energy dense.
Peat that has been compressed by the earth 3
Deeper burial = more dense = more energy dense
lignite—–> bituminous——> anthracite
Typically, coal is burned to create steam to turn a turbine which generates electricity
Coal mining is horrible for the environment (mountaintop removal)
natural gas
Essentially methane from slowly decomposing plant and animal matter decaying over many thousands to millions of years.
Found along with petroleum/oil deposits- usually trapped below rock but above oil
Clean burn- produces half as much carbon dioxide as coal to produce the same amount of electricity
No PM production when burned, unlike coal (this is air pollution)
Burns cleanly, doesn’t leave residue/soot → better as a fossil fuel
Methane
Crude oil/petroleum
Coal that is even more compressed- decaying plant and animal matter
Wells are drilled through overlying rock to reach oil ‘deposits’ (which may be old lakes or shallow marine environments)
Oil spills are risky in terms of environmental catastrophe - spills happen regularly enough and can devastate aquatic ecosystems → oil spills are VERY hard to clean up
Fractional Distillation
Oil can be used to make many different products
Boiled and separated into components- different hydrocarbons separated via boiling point
See types of oil products on figure to right
Gasoline is made from oil based on boiling points
Fossil Fuel Energy Distribution
Most oil/natural gas/fossil fuels are distributed around the world, with concentrations in the following areas:
Saudi Arabia
Russia
Iran
US - produces a lot of oil but uses so much so still has to import it
Texas, Alaska, North Dakota, and Oklahoma largest reserves
US Imports a lot of fossil fuels (canada, saudi arabia)
FF Reserves
Fossil fuels are nonrenewable and will run out.
Longer reserves for coal, shorter for natural gas and oil
100-150 years ish
Some of this is presumed to be in the ground still, some is stored in reserves that countries hold for emergencies.
Fracking: What is it? Benefits and Drawbacks
Shale (and gas) deposits throughout the lower 48 are areas where fracking has become common
Short term profitability drives demand for fracking projects
Democrats are against fracking
Big drill → drills into the ground
Groundwater contamination is a big risk
We will run out of fracking material
Where does US Oil come from?
Most of it comes from home
Middle east is important source of oil in US
Most oil consumed in US that isn’t domestically produced comes from Canada
Important geopolitical implications to fossil fuel production, import, cost
Fracking could be a way to boost domestic production
Tar/Oil Sands
Bitumen deposits where crude oil can be recovered, but a very costly process
High water and energy inputs necessary
Alberta has the largest supply
Requires a lot of water and heat
Crude Oil Drilling
Decaying organic matter compressed and trapped under rock
Extracted by drilling a well and then pumping out oil from the ground (easier extraction than fracking or oil sands)
Most wells have been drilled, so fracking is the fossil fuel trend
Simplest way to get oil → drill a hole and suck it up from the ground
Arctic NWR
Oil reserves in Arctic NWR uncertain at this point- we are pretty sure there is some but don’t know how much
Median estimates suggest it may be enough for about 6 months to a year of fuel for the US, with best case scenarios of a couple years worth of oil
This oil would take 20-30 years or more to extract and as such would account for only a few percent (under 3%) of the oil used in the US each year over that period
Is it worth disrupting sensitive ecosystems and undermining federal land protections for what amounts to a drop in the bucket?
Not really worth it unless you’re using it to buy time to make renewable energy work
Only would reduce gas prices by a few cents
FF Combustion
Type of chemical reaction, combustion means to burn
Start with hydrocarbons, in order to burn them you need heat and oxygen, transforms into carbon dioxide, water, and heat and light
Oxygen and fossil fuels produce heat
Byproducts include carbon dioxide and water vapor
Carbon stored in hydrocarbons is released when it combines with oxygen to form carbon dioxide
All combustion reactions are similar- including burning of woody biomass
How fossil fuels are able to produce heat
Chemical potential energy in bonds
How FF Generate Electricity
Electricity is often fossil fuel produced- coal is still primary driver of electricity production, with natural gas not far behind.
DOES NOT MATTER what you are bruning, electricity is produced when water is heated and steam from that water is used to turn a turbine
Turbine powers generators, which create electricity (a conductor is moved through a magnetic field which creates a flow of electrons- eg. electricity)
MORE EFFICIENT Cogeneration: When heat and electricity are generated together
Burn the fossil fuel from consumption using this heat to heat up water which the stream turns a turbine which attaches to a conductor which goes into the grid
Coal plants are not very efficient because of release of energy as heat
Takes 100 lbs of coal to heat 1 lightbulb for 1 year
Subsistence fuels: Peat
Peat
Slowly decomposing organic matter (plant and animal tissue) under anaerobic conditions
Can be dried and burned
Usually found in wetlands and marshes
Wetlands can preserve for long periods of time
Easily ignites and smolders for long periods of time, releases lots of CO2.
Plant matter that dies and sinks to the bottom of the wetland → tissue doesn’t decompose easily
50-90% organic → peat is slowly decaying, cut into bricks, dried up then burned
Doesn’t burn clean
Used a little bit, primary for alcohol
No oxygen in bogs, so peat can form → no composition
