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Unit 1: Limits and Continuity

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Studied by 4017 people

4.8(9)

Hurricane Paths and Hazards

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Studied by 5 people

5.0(1)

Current and circuit symbols

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Studied by 51 people

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Chapter Ten: Helping Others

Chapter 19: Two Rates Experiments and Finding Rates

APES Unit 6

Renewable vs. Nonrenewable

Can be replenished naturally, at or

near rate of consumption &

reused.

Renewable Energy Sources Nonrenewable

Energy Sources

● Depletable renewables can run

out if overused

○ Ex: Biomas (wood,

charcoal, ethanol)

● Nondepletable renewables do

not run out if overused

○ Ex: Solar, wind,

hydroelectric, geothermal

Exist in fixed amounts on earth & can’t

easily be replaced or regenerated

● Fossil Fuels Fossilized remains

of ancient biomass that take

millions of years to form

○ Coal, Oil, Nat. Gas

● Nuclear: energy generated

from uranium or other

radioactive fuels

Key to Renewable Energy

Rate of Consumption

● Rate of use must be at

or below rate of

regeneration for

renewables

● Fossil fuels will run out

because they take far

longer to regenerate

than the rate we use

them

Developed vs. Developing Countries

● Developed nations use more energy on a

per capita basis, but developing nations

may use more energy in total (higher

pop.)

● Developing nations are still

industrializing & pop. is still growing

rapidly

○ It will also increase on a

per/person basis as their

economies industrialize &

residents achieve higher standards

of living

Fossil Fuels: Most Used Energy Source

● Fossil fuels are by far the most

common fuel source globally

● Hydroelectric energy (dams used to create

electricity) are second largest source

○ Water spins a turbine which

generates electricity

● Oil ⇒ gasoline = main fuel for vehicles

● Coal = main fuel for electricity gen.

● Nat. gas = secondary fuel for electricity

gen. & main fuel for heating

● Nuclear is the third largest source

○ Uranium fission releases heat to turn

water into steam to turn a turbine to

gen. electricity

Development Increases FF Consumption

● Many residents of less developed nations

depend on subsistence fuels - biomass that

they can easily gather/purchase

○ Ex: wood, charcoal, dried animal manure

○ Can drive deforestation

● As developing nations develop, fossil fuel

consumption will increase

○ Oil → Gasoline for vehicles

○ Coal & Nat. gas → electricity

■ Electricity demand for homes &

manufacturing

Factors That Affect Energy Source Use

● Gov. Regulation: gov. can mandate certain

energy source mixes (EX: 25% renewable by

2025)

● Gov. CANNOT directly raise or lower prices of

energy sources (ex: raise gas to $10/gallon)

● Gov. CAN use: ○ Taxes increases to discourage

companies from building FF power

plants

○ Rebates, or tax credits to encourage

companies building renewable energy

power plants

Mining Basics

Ore: commercially

valuable deposits of

concentrated

minerals that can be

harvested and used

as raw materials

Metals: elements

that conduct

electricity, heat, and

have structural

properties for

building (found

within ores)

Reserve: The known

amount of a resource

left that can be mined.

Usually measured in

years left of

extraction.

Overburden: Soil, vegetation, & rocks that

are removed to get to an ore deposit below

Tailings & slag: leftover waste material

separated from the valuable metal or

mineral within ore (often stored in ponds @

mine site)

● Removal of overburden to access ore near

surface

● Different types: open pit, strip,

mountaintop removal, placer

- Removal of vegetation & soil

- Topsoil erosion

- Habitat loss

- Increased stream turb.

- Increase PM in air

● Mnt. top removal = esp.

damaging to landscape &

habitats, streams nearby

● As ore near surface becomes

more scarce, mining moves

deeper underground to

subsurface mining (more

dangerous & expensive)

Subsurface Mining ● More expensive due to higher

insurance & health care costs for

workers

● Risks: poor ventilation leading to toxic gas

exposure, mine shaft collapse, injury from

falling rock, lung cancer, asbestos, fires,

explosions

● Vertical “shaft” drilled down into ground

○ Elevator to carry down workers &

transport out resource

○ Often used for coal

● Increasingly used as surface coal deposits

are depleted

Environmental Impacts of

Mining

Acid mine drainage: rainwater leaks into

abandoned mine tunnels & mixes with pyrite,

forming sulfuric acid

● Methane Release: coal mining releases

methane gas (CH4

) from rock around coal

○ Vented out of mine to prevent

explosion & continues seeping out

after mine closes

○ GHG → climate change

- Topsoil erosion

- Habitat loss

- Increased stream turb.

● Rainwater carrier sulfuric acid into nearby

streams, or infiltrates ground water

● Lowers pH of water, making toxic metals

like mercury & aluminum more soluble in

water sources (killing aquatic org.)

● PM Release: coal mining especially, releases lots of

soot and other particulates that can irritate human &

animal lungs

Mine Reclamation

● Process of restoring land to original state

after mining has finished

● Includes:

2. Restoring original contours

of land

1. Filling of empty mine

shafts/hole

4. Replanting of native plants

to restore community to as

close to original state as

possible

Returning topsoil, with acids,

metals, and tailings removed

Subsistence Fuels

⛰ Wood (and charcoal) are two of the most

common fuel sources in developing nations

⛰ Peat is partially decomposed organic maÒer

(oÑen ferns or other plants) found in wet, acidic

ecosystems like bogs and moors

● Wood is free/cheap to cut down and utilize as

fuel; can cause deforestation & habitat loss

● Biomass fuel sources that are easily accessible

(can be found and gathered by hand); oÑen

used in developing countries as a home heating

or cooking fuel

● Can be dried and used as a biomass fuel

source

Charcoal is made by heating wood under low

oxygen conditions for a long time

Coal Formation

⛰ In order of energy density & quality: lignite → bituminous → anthracite

⛰ Because higher energy density means more energy released when a fuel source is burned,

anthracite is the most valuable form of coal (highest quality)

● The deeper a coal reserve is buried, the more pressure from overlying rock layers & the

more energy dense

● Pressure from overlying rock

& sediment layers compacts

peat into coal over time

● Coal is burned to heat water into steam, to

turn a turbine that generates electricity

● More dense coal = hoÒer/longer fire = more

steam = more electricity

Natural Gas

⛰ Natural gas is mostly methane (CH4

) and is found

on top of trapped oil (petroleum) deposits

⛰ Considered the “cleanest” fossil fuel (produces the fewest air pollutants & least CO2

when burned)

● Forms when oil is trapped in a porous, sedimentary rock, underneath

a harder, impermeable rock layer that doesn’t let the gas escape

● Decaying remains of plants & animals

(mostly marine life) are buried under layers

of rock & converted by pressure into oil

(petroleum) and natural gas over time

● Produces about 1⁄2 as much CO2

as coal when burned to generate electricity

● Produces virtually no PM (ash/soot)

○ Produces far less SOx

, NOx

than coal or oil, and NO MERCURY

Crude Oil (petroleum)

⛰ Extracted by drilling a well through the overlying rock layers to reach the underground deposit

and then pumping liquid oil out under pressure

⛰ Can also be recovered from tar sands (combination of clay, sand, water, and bitumen)

● Decaying organic maÒer

trapped under rock layers is

compressed into oil over time

● Bitumen is a thick, sticky, semi-solid form of petroleum (not liquid)

● Extracting & using oil from tar sands is extremely energy and water intensive

○ Lots of water needs to be heated (requiring energy) to create steam that’s

piped down into the tar sand to melt the bitumen into a liquid that can

flow up a pipe

○ Lots more water is used to separate the oil from all of the impurities

(sand, clay) at the refinery

Fossil Fuel Products

⛰ Crude oil (petroleum) is converted into lots of different products

through the process of fractional distillation

● Crude oil is burned in a furnace and vapor passes into a column

where different hydrocarbons are separated based on their boiling

points

● Hydrocarbons w/lower boiling points gather at the top of the column, higher

boiling points gather at boÒom

● Different hydrocarbons within petroleum are used for different products

○ Petroleum gas

○ Gasoline (fuel for cars)

○ Naphtha (used to make plastic)

○ Jet fuel

○ Diesel fuel

○ Motor oil

○ Bitumen (asphalt for roads)

FF Energy Reserves

1. US

2. Russia

3. China

4. Australia

~100-150 Years ~50-60 Years ~50 Years

1. Russia

2. Iran

3. Qatar

4. US

5. Saudi Arabia

1. Venezuela

2. Saudi Arabia

3. Iran

4. Canada

Fracking & Shale Gas ● Hydraulic fracturing (aka fracking) is a

method of natural gas extraction that has

extended access to natural gas ○ Gas trapped in semi-permeable,

sedimentary rock layers, such as shale, is

released by cracking the rock with

pressurized water

Fracking natural gas

from shale rock

increases & extends

supply of natural gas

Shale Gas Reserves ● FFs are non-renewable, and will eventually be depleted, but

short-term economic profit still drives extraction & use ○ Discovered, but unharvested reserves represent

economic benefit to countries

Tar/Oil Sands ● Tar or oil sands are bitumen deposits where crude oil can be

recovered, but with higher water & energy inputs ● Canada (Alberta region) = world’s largest oil sands reserve ● Just like fracking, tar/oil sands extraction extends the

world’s supply of crude oil

Fossil Fuel Combustion🔥⛽

⛰ Remember: Combustion is a step in the CARBON cycle:

hydroCARBONS (FFs) are burned to release energy & the carbon

stored in them reacts with O2

in the air to form CO2 ⛰ Methane (natural gas), gasoline, propane, butane, coal

are all fossil fuels (hydrocarbons) that release energy in the same way Wood and biomass work the same, carbon is burned & reacts with O2

to form CO2

& give off energy ● Reaction between Oxygen (O2

) & fossil fuels

(hydrocarbons)

FF to Generate Electricity 🔌⚡

⛰ These steps of electricity gen. are the same, no maÒer what you’re burning to produce the initial heat Heat →Water into Steam → Steam turns a turbine → Turbine powers generator → Generator produces electricity

🔥 →💧😤 →🌬→⚙ →⚡💡

⛰ Coal, oil, natural gas, biomass, and trash can all be burned to drive this same process and create energy.

Even nuclear energy work similarly, with nuclear fission producing the initial heat ● The #1 source of electricity production globally is coal, followed by natural gas

Environmental Consequences:

Coal

⛰ Habitat destruction to clear land for mining

⛰ Produces pollutants & releases CO2

(GHG → global warming) ● Releases more CO2

than any other FF when burned for electricity gen. ● Releases PM (soot, ash) which can irritate respiratory tracts of humans/animals ● Produces toxic ash contaminated with lead, mercury, and arsenic ○ Taken to landfills or stored in ash ponds;

both can leak into ground/surface waters, or into soil ● Releases SOx

& NOx

(sulfur and nitrogen

oxides) which irritate resp. systems, and

contribute to smog and acid precipitation

Generating Electricity

⛰ Much of the energy “lost” or not converted into electricity escapes as heat

⛰ Cogeneration: when the heat produced from electricity generation is used to provide heat (air & hot water)

to a building; CHP (Combined Heat and Power) systems are close to 90% efficient (much beÒer than coal/NG alone) ● Coal is ~30% efficient as a fuel source for generating electricity (30% of energy from

Environmental Consequences:

Tar Sands

⛰ Habitat destruction to clear land for: roads, drilling equipment, digging

through ground surface to reach deposits (biodiv. loss)

⛰ Ground or nearby surface water depletion (H2O needed for steam & for washing impurities from bitumen at refinery) ● 🚱 Water contamination: tailing ponds (holes dug for storing wastewater)

can overflow & run into nearby surface waters, or leach into groundwater ○ Benzene (carcinogen) salts, acids, hydrocarbons, bitumen ○ All toxic to plant and animals ● CO2

Environmental Consequences:

Crude Oil/Petroleum

⛰ Possibility of spill (either from tanker ships or pipelines breaking

⛰ Habitat loss or fragmentation when land is cleared for roads, drilling

equipment, pipelines ● Spills in water = crude oil covering sun, clogging fish gills, suffocating many

Fracking (Hydraulic Fracturing)

⛰ Used to extract natural gas from sedimentary rock

⛰ Vertical well is drilled down to sed. rock layer, then turns horizontally into

the rock layer ● Perforating gun cracks (fractures) the rock layer around hor. well, making

it more permeable ● Fracking fluid (water, salt, detergents, acids) is pumped into well @ very high

pressure to crack the rock even more & allow natural gas to flow out ● Nat. gas is collected @ surface & shipped for processing/use ● Flowback water (used fracking

fluid) flows back out

Environmental Consequences:

Fracking

⛰ Possibility of well leaking & contaminating groundwater with fracking fluid

(salt, detergents, acids) or hydrocarbons

⛰ Depletion of ground or surface waters nearby (as they’re drawn from for

fracking fluid) ● Ponds can overflow or leach into ground & contaminate surface or ground

waters with fracking fluid (salt, detergents, acids) ● Can be toxic to plants & animals that rely on these water sources ● Increased seismic activity

(earthquakes) linked with

wastewater injection wells

(storing fracking fluid deep

underground)

Nuclear Fission & Radioactivity☢

⛰ A neutron is fired into the nucleus of a radioactive (unstable) element, such as Uranium

● Nucleus breaks apart and releases lots of energy (heat) + more neutrons

that break more nuclei apart, releasing more energy (chain reaction)

⛰ Radioactivity refers to the energy given off by the nucleus of a radioactive

isotope (Uranium-235) ● Radioactive nuclei decay, or breakdown and give off energy (radiation)

even without fission; nuclear fission just releases tons of energy all at once ● Radioactive Half-Life = the amount of time it takes for 50% of a radioactive substance to decay (breakdown) ○ Ex: 1⁄2 life of Cobalt-60 isotope = 5.27 yrs. ○ In 5.27 yrs, 1⁄2 of a Co-60 sample would be

Gone (decayed)

Generating Electricity⚛→ ⚡🔌

⛰ Same electricity generation process as with FFs, just uranium fission to heat water into steam

● Heat →Water into Steam → Steam turns a turbine → Turbine powers generator → Generator produces electricity

🔥 →💧😤 →🌬→⚙ →⚡💡

⛰ U-235 stored in fuel rods, submerged in water in reaction core; heat from fission turns H2O → steam... ● Control rods are lowered into reactor core to absorb neutrons and slow down the reaction, preventing meltdown (explosion) ● Water pump brings in cool water to be turned into steam and also

cools reactor down from overheating ● Cooling tower allows steam from turbine to condense back into

liquid and cool down before being reused (this gives off H2O vapor)

Nonrenewable, but cleaner than FFs

⛰ Nuclear energy is NONRENEWABLE because radioactive elements like Uranium are limited ● No air pollutants (PM, SOx

/NOx

) or CO2

/CH4

released when electricity is generated; mining of uranium & plant construction still release GHGs ⛰ Other drawbacks of nuclear energy include possibility of meltdown & radioactive contamination ● Spent Fuel Rods: used fuel rods remain radioactive for millions of years & need to be stored in lead containers on site @ Nuclear PPs ● Mine tailings: leftover rock & soil from mining may have radioactive

elements that can contaminate water or soil nearby ● Water use: nuclear PPs require lots of water and can

deplete local surface or groundwater sources ● Only gas released from elec. gen. is water vapor (which is technically a GHG, but stays in atm, very briefly) ● Thermal Pollution: hot water from PP released back

into surface waters

Nuclear Meltdowns🗾 3⃣🏝

⛰ Three Mile Island (US), Fukushima Japan, and Chernobyl Ukraine = 3 most famous nuclear meltdowns ● Three Mile Island (US): partial meltdown due to testing error; radiation released but no deaths or residual cancer cases ⛰ Environmental consequences of meltdowns: genetic mutations & cancer in surrounding people, animals, and plants due to radiation released from reactor core ● Contaminated soil: radiation can remain in soil and harm plants and

animals in the future (genetic mutations) ● Fukushima (Japan): an earthquake and tsunami triggered cooling pump failure that lead to a meltdown (explosion of reactor core) & widespread radiation release ● Chernobyl (Ukraine): stuck cooling valve during test lead to complete meltdown (explosion of reactor core), several deaths, and widespread radiation release ● Radiation spread: radiation can be carried by

the wind over long distances, affecting

ecosystems far from the meltdown site

Biomass vs. Biofuels 🌽⛽

Biomass organic matter (wood/charcoal, dried animal waste, dead

leaves/brush) burned to release heat - primarily for heating homes/cooking ● Can also be burned in Power Plants to generate electricity (not common)

Biofuels 🌽⛽ liquid fuels (ethanol, biodiesel)

created from biomass (corn, sugar cane, palm oil) ● Used as replacement fuel sources for

gasoline, primarily in vehicles

Modern vs. Fossil Carbon

⛰ Biomass burning releases CO2

, but doesn’t increase atmospheric CO2

levels like FF burning does ● Burning biomass releases modern carbon (CO2

that was recently

sequestered, or taken out of the atmosphere) whereas FF burning releases

fossil carbon that had been stored for millions of years ● Biomass burning is considered “carbon neutral” ● Think of spending a dollar someone just gave you vs. withdrawing

from your long-term savings account to spend

Human health & Env. Consequences of Biomass Burning

⛰ Biomass burning releases CO, NOx

, PM, and VOCs - all respiratory irritants 👁 ● 3 billion people globally cook on open, biomass fires, mostly in developing world ● Lack of environmental protection laws & financial resources for other fuels

lead to more biomass deforestation in developing nations ● Hab. loss, soil erosion, loss of CO2

sequestration, air & H2O filtration ● Biomass burn. indoors for heat/cooking worsens effects (pollutants trapped & conc.) ○ Worsened asthma, bronchitis, COPD, emphysema, eye irritation

⛰ Environmental consequences = deforestation & air pollutants 🌳 🔥🌫

● NOx

, VOCs, and PM

all contribute to smog formation

Biofuels: Ethanol 🌽⛽ & Algae

⛰ Corn & sugar cane are fermented into ethanol which is mixed w/ gasoline ● Corn grain/sugar cane broken down & yeast ferment sugars → ethanol ● Soil erosion, hab. loss, GHG release (ag. soils, tractors, fertilizers) H2O use ● Lots of corn needed, relative to petroleum; can compete w/human cons. of corn ● E85 or flex fuel = 51-83% ethanol + gasoline mix; used in flex-fuel vehicles ○ Decreases oil consumption for transport, but is less eƗcient than pure gasoline

⛰ Environmental consequences = all the neg. consequences of monocrop ag. ● “renewable” only to the extent that the production of corn / sugar cane are sustainable

Biodiesel🌴⛽

⛰ Liquid fuels produced specifically from plant oils (soy, canola, palm) ● Palm oil biodiesel has been found to produce 98% MORE GHGs than FFs, due to

clearing of forest for palm plantations ● Can be more sustainable if already cleared land is used, or if plantations are

continually replanted (however, also causes all the env. impacts of ag.) CO2

release Loss of hab. Soil erosion Loss of air/H2O filtration

6.8

Active vs. Passive Solar Energy

⛰Passive solar: absorbing or blocking heat from the sun, w/out use of mechanical/electrical equip.

● Using sun’s heat to cook food in a solar oven

● Orienting building design to block sunlight in warmer months & allow sunlight in during

colder months

● Double paned windows, southern facing windows w/roof overhang, deciduous

shade trees, skylight to decrease elect. use, dark colored sunlight abs. floor

⛰Active solar: use of mechanical/electrical equip. to capture sun’s heat (solar water heaters or

CST - concentrated solar thermal), or convert light rays directly into electricity (PV cells)

● Solar water heaters capture sun’s heat in water

or circulating fluid & transfer heat to warm water

for home - in place of electric/gas water heater

Photovoltaic Cells (PV)

Concentrated Solar Thermal (CST)

⛰Aka “solar panels”; contain semiconductor (usually silicon) that

emits low voltage electrical current when exposed to sun

● Photons (particles carrying energy from sun) cause separation

of charges between two semiconductor layers (n & p);

electrons separate from protons & flow through circuit to load,

delivering energy (as electricity)

● PV cells on a roof can directly power the building, or send excess

electricity back to the grid for other users (earning you a credit from your

utility company)

⛰A drawback is intermittency (solar energy can only be generated

during the day)

● Could be solved by cheaper, larger batteries that can store

energy generated during the day for use at night

○ Currently these aren’t cost-effective yet

Concentrated Solar Thermal (CST)

⛰Aka “solar panels”; contain semiconductor (usually silicon) that

emits low voltage electrical current when exposed to sun

● Photons (particles carrying energy from sun) cause separation

of charges between two semiconductor layers (n & p);

electrons separate from protons & flow through circuit to load,

delivering energy (as electricity)

● PV cells on a roof can directly power the building, or send excess

electricity back to the grid for other users (earning you a credit from your

utility company)

⛰A drawback is intermittency (solar energy can only be generated

during the day)

● Could be solved by cheaper, larger batteries that can store

energy generated during the day for use at night

○ Currently these aren’t cost-effective yet

● Heliostats (mirrors) reflect sun’s rays onto a central water tower in

order to heat water to produce steam to turn a turbine → electricity

⛰A drawback is habitat destruction & light beams frying birds in mid air

Community (solar farm) vs. rooftop solar

⛰FRQ tip: don’t just say “solar panels” differentiate between rooftop (individual home/business)

solar and community or large-scale solar farms

Large-scale solar “farms” can generate lots of electricity, but do take

up land and cause habitat loss/fragmentation

Rooftop solar doesn’t take up land,

but only produces a little

electricity

Solar Energy Pros

⛰No air pollutants (PM, SOx, NOx) released to gen. electricity

● No CO2 released when gen. electricity

6.9

● Renewable, unlike FFs which will run out

● No mining of fossil fuels for electricity production

Solar Energy Cons

⛰Semiconductor metals (silicon) still need to be mined to produce PV cells (solar panels)

● This can disrupt habitats & pollute water with mine tailings, air with PM

● Silicon is a limited resource

● Solar panel farms can displace habitats

Hydroelectricity Basics

⛰Kinetic energy of moving water 🌊 → spins a turbine (mechanical energy) ⚙ → turbine powers generator ⚡

● Water moves either with natural current of river or tides, or by falling vertically through channel in a dam

● By far the largest renewable source of electricity globally

● China, Brazil, and US = 3 biggest hydroelectricity producers

Water Impoundment (Dams)

Run of River System & Tidal Energy

⛰Dam built in a river creates a large artificial lake behind the dam (reservoir)

● Damming the river enables operators to allow more or less water through the channel in the dam, increasing or

decreasing electricity production (water flows through channel, turns turbine, turbine powers generator → ⚡)

● Also allows for control of flow downstream, prevention of seasonal flooding due to high rainfall

● Reservoirs are also a source of recreation money (boating fees, tourism, increased property values, fishing, etc.)

● 2 big impacts = flooding of ecosystems behind dam & sedimentation (buildup of sediments behind dam)

⛰A dam diverts the natural current of a river through man-made channel beside the river

● Natural current of the river turns the turbine...powers the generator...⚡

● Less impactful to surrounding ecosystem since no reservoir is formed & ecosystems behind dam aren’t flooded

● Doesn’t stop natural flow of sediments downstream like water impoundment systems do

● Doesn’t generate nearly as much power & may be unavailable in warmer seasons when river water levels are lower

● Tidal power comes from tidal ocean flow turning turbine

(coastal areas only)

Drawbacks of Hydro⚡Dams (Ecol/Env/Econ)

Fish Ladders

⛰Reservoir floods habitats behind dam (forests/wetlands → gone; river becomes a lake)

● Prevents upstream migration of fish like salmon, that need to swim up to spawning grounds to reproduce

● Sedimentation changes upstream & downstream conditions

○ Upstream becomes warmer (less O2) and rocky streambed habitats covered in sediment

○ Downstream loses sediment (important nutrient source), decreased water level, loses streambed hab.

● Downstream wetlands especially suffer since nutrients in sediment doesn’t reach them

⛰Env. Impacts = FF combustion during dam construction, increased evap. due to larger surface area of reservoir, and

methane release due to anaerobic decomp. of organic matter in reservoir

⛰Econ. Impacts = human homes & businesses must be relocated due to reservoir flooding, Initial construction is very

expensive (does create long-term jobs though), sediment buildup must be dredged (removed by crane) eventually

● Loss of ecosystem services from downstream wetlands, potential loss of fishing revenue if salmon breeding is

disrupted