APES Unit 6 PPT

Renewable Energy Sources

Can be replenished naturally, at or near rate of consumption and reused (depletable and nondepletable)

Nonrenewable Energy Sources

Exist in fixed amounts on earth and can't easily be replaced or regenerated (fossil fuels, nuclear)

Depletable renewables

can run out if overused

example of depletable renewables

biomass (wood, charcoal, ethanol)

nondepletable renewables

do not run out if overused

examples of nondepletable renewables

solar, wind, hydroelectric, geothermal

fossil fuels

remains of ancient biomass that take millions of years to form

3 types of fossil fuels

coal, oil, natural gas

nuclear

energy generated from uranium or other radioactive fuels

what is the key to renewable energy? How can we keep renewable energy sustainably?

rate of use must be at or below rate of regeneration for renewables

why will fossil fuels run out in contrast to renewables?

FFs take far longer to regenerate than the rate we use them

who uses more energy on a per capita basis (and in total)?

developed nations

how much more does a U.S. resident use on average than the world on average?

5 times as much

As population increases, economics industrialize, and residents achieve higher affluence, what happens to energy use? (increase/decrease)

increase

What is the most common fuel source globally?

FFs (coal followed by natural gas)

what is oil used for?

gasoline- main fuel for vehicles

what is coal used for?

main fuel for electricity generation

what is natural gas used for?

secondary fuel for electricity generation and main fuel for heating

what is the second largest energy source?

hydroelectric energy

what is the third largest energy source?

nuclear power

True of False
Development increases FF consumption

True

residents of less developed nations depend on what?

subsistence fuels

subsistence fuels

biomass that they can easily gather/purchase (often used in developing countries as a home heating or cooking fuel)

examples of subsistence fuels

wood, charcoal, dried animal manure

consequence of use of subsistence fuels (and biomass)?

can drive deforestation and habitat loss

As developing nations develop, energy use increases. What does this mean for fossil fuels?

FF consumption will increase

why does energy use increase in industrializing countries?

they need energy to meet the demand for homes (electricity), manufacturing and fuel for vehicles

what factor affect energy source use?

availability, price, government regulation

how does availability affect FFs?

FF use depends on discovered reserves and accessibility of these reserves (type of FF varies by region)

how does price affect FFs?

FF prices fluctuate dramatically with discovery of new reserves or repletion of existing ones

example of factors that affect energy source use

fracking opens new NG reserves, increasing availability, decreasing price, and increasing use

how does government regulation affect energy source use?

can mandate certain energy source mixes

Can government directly raise/lower prices?

NO!!!

What can the government do to lower/raise prices?

-Taxes to discourage
-rebates/tax credits to encourage

what are the two most common fuel sources in developing nations?

wood (cheat and free to cut down), and charcoal (made by heating wood under low oxygen conditions for a long time)

peat

partially decomposed organic matter (often ferns or other plants) found in wet, acidic ecosystem like bogs

what is the importance of peat (related to subsistence fuels)?

peat can be dried and used as a biomass fuel source

how is coal formed?

pressure from overlying rock and sediment layers compacts peat into coal over time

three types of coal types (in order of energy density and quality)

lignite -\> bituminous -\> anthracite

how does coal become more energy dense?

the deeper a coal reserve is buried, the more pressure from overlying rock layers and the more energy dense

how is energy density and energy?

higher energy density will release more energy when burned

how is coal transferred into energy?

coal is burned to heat water into steam, to turn a turbine that will generate electricity

how is natural gas and oil formed?

decaying remains of plants and animals (mostly marine life) are buried under layers of rock and converted by pressure into oil (petroleum) and natural gas over time

what is natural gas mostly made up of?

methane (CH4)

where is NG found?

on top of trapped oil (petroleum) deposits
-when oil is trapped in a porous, sedimentary rock, underneath a harder, impermeable rock later that doesn't let the gas escape

what is the cleanest FF?

NG (produces the fewest air pollutants and least CO2 when burned)
-1/2 as much CO2 as coal when burned to generate electricity
-produces virtually no PM (ash/soot)
-produces less SOx, NOx, than coal or oil, and NO MERCURY

difference between the formation of coal and natural gas/oil

They are formed by the anaerobic decomposition of buried ancient organisms. Generally, coal forms from land sediments, and natural gas and oil form from marine sediment.

how is crude oil (petroleum extracted)?

drilling a well through the overlying rock layers to reach the underground deposit and then pumping liquid out under pressure
-can also be recovered from tar sands

what are tar sands?

a combination of clay, sand, water, and bitumen

bitumen

thick, sticky, semi-solid form of petroleum (not liquid)

why is extracting oil from tar sands difficult?

it is extremely energy and water intensive
-lots of water needed 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

fractional distillation

crude oil (petroleum) is converted into lots of different products through this process

how is crude oil burned?

on a furnace and vapor passes into a column where different hydrocarbons are separated based on their boiling points

how is hydrocarbons in furnaces separated when burned?

hydrocarbons with lower boiling points gather at the top of the column, higher boiling points gather at the bottom

What are examples of different hydrocarbons that 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)

How long does it take for coal, natural gas, and oil to replenish (in order)?

100-150 years, 50-60 years, and 50 years

Top 4 leaders of coal reserves?

1) US
2) Russia
3) China
4) Australia

Top 5 NG reserves?

1) Russia
2) Iran
3) Qatar
4) US
5) Saudi Arabia

Top 5 oil reserves?

1) Venezuela
2) Saudi Arabia
3) Iran
4) Canada
5) Iraq

Hydraulic Fracturing (fracking) for NG

a method of natural gas extraction that has extended access to natural gas (trapped in shale)
-released by cracking the rock with pressurized water
(extends the supply of NG)
-vertical well that turns horizontal into rock layer
-perforating gun cracks (fractures) the rock layer around horizontal well to make it more permeable
-fracking fluid (water, salt, detergent, acids) pumped into wells as high pressure to crack rocks and allow NG to flow out
-NG is collected at surface and shipped for processing/use
-flowback water (used for fracking fluid) flows back out and is collected and stored in containers of ponds nearby

shale

semi-permeable sedimentary rock layers

Shale Gas Reserves

FFs are non-renewable, and will eventually be depleted, but short-term economic profit still drives extraction & use

where is the world's largest oil sands reserve?

Canada (Alberta region)

FF combustion

reaction between oxygen (O2) and FF (hydrocarbons) that releases energy as heat and produces CO2 and H2O as products
-step in carbon cycle where hydrocarbons (FFs) are burned to release energy and the carbon stored in them reacts with O2 in the air to form CO2

What FFs are involved in combustion to give off energy?

-methane (NG), gasoline, propane, butane, coal, wood, and biomass

initial steps of electricity generation

heat -\> water into steam -\> steam turns a turbine -\> turbine powers generator -\> generator produces electricity

How efficient is coal as a fuel source?

30% (of energy from bonds in hydrocarbons are converted to electricity)

Much of energy is lost and escapes as what?

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)

close to 90% efficient (better than coal/NG alone)

Environmental consequences of fracking

-possibility of well leaking and contaminating groundwater with fracking fluid (salt, detergents, acids) or hydrocarbons (toxic to plants and animals that rely on water sources)
-Habitat loss/fragment
-CH4 (GHG) release
-repletion of ground or surface waters nearby (as they're drawn from for fracking fluid)
-increased seismic activity (earthquakes) linked with wastewater injection wells (storing fracking fluid deep underground)

Nuclear (uranium) fission

neutron is fired into the nucleus of a radioactive (unstable) element, such as uranium
-nucleus breaks apart and releases lots of energy (heat) and 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, breakdown and give off energy even without nuclear fission, but fission releases tons of energy all at once

Nuclear electricity production

heat -\> water into steam -\> steam turns a turbine -\> turbine powers generator -\> generator produces electricity
(same process as FFs, but uranium fission heats water into steam)

Where is U-235 stored?

in fuel rods submerged in water in the reaction core (heat from fission in rods will turn H20 to 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)

Is Nuclear energy renewable/nonrenewable?

NONRENEWABLE (uranium is limited)

Benefits of Uranium

-no air pollutants (PM, SOx, NOx) or CO2/CH4 released when electricity generated; mining of uranium and plant construction
-only gas released from electric generation is water vapor (technically GHG, but stays in atmosphere briefly)

Drawbacks of Nuclear energy

-possibility of meltdown and radioactive contamination
+spent fuel rods, mine tailings, water use, thermal pollution

Drawback of Nuclear energy:
Spent fuel rods

used fuel rods remain radioactive for millions of years and need to be stored in lead containers on site at Nuclear PPs

Drawback of Nuclear energy:
mine tailings

leftover rock and soil from mining may have radioactive elements that can contaminate water or soil nearby

Drawback of Nuclear energy:
water use

nuclear PPs require lots of water and can deplete local surface or groundwater sources

Drawback of Nuclear energy:
thermal pollution

hot water from PP released back into surface waters can cause thermal shock (decreased O2 and suffocation)

3 most Famous Nuclear Meltdowns

three mile island (US), Fukushima (Japan), Chernobyl (Ukraine)

Three Mile Meltdown (US)

partial meltdown due to testing error, radiation released but no deaths or residual cancer cases

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

environmental consequences of meltdowns

genetic mutations & cancer in surrounding people, animals, and plants due to radiation released from reactor core
-contaminated soil and radiation spread

Meltdown drawbacks:
contaminated soil

radiation can remain in soil and harm plants and animals in the future (genetic mutations)

Meltdown drawbacks:
Radiation spread

radiation can be carried by the wind over long distances, affecting ecosystems far from the meltdown site

biomass

organic matter (wood/charcoal, dried animal waste, dead leaves/brush) burned to release heat - primarily for heating homes/cooking
-can also be burned into PPs to generate electricity (less common than FFs)

biofuels

liquid fuels (ethanol, biodiesel) created from biomass (corn, sugar cane, palm oil)
-used as replacement fuel sources for gasoline primarily in vehicles

how is burning biomass better than FFs?

biomass burning releases CO2, but doesn't increase atmospheric CO2 (modern vs. fossil carbon) considered carbon neutral

modern carbon

CO2 that was recently sequestered or taken out of the atmosphere

fossil carbon

carbon found in fossil fuels which has been buried for millions of years and, when reintroduced into the cycle, increases global C02 concentrations

consequences of burning biomass

releases CO, NOx, PM, and VOCs- all respiratory irritants
\-biomass burn, indoors for heat/cooking worsens effects (pollutants and conc.)- asthma, bronchitis, COPD, emphysema, eye irritation

\
Environmental consequences: deforestation and air pollutants -lack of environmental protection laws and financial resources for other fuels lead to more biomass deforestation in developing nations -habitat loss, soil erosion, loss of CO2 sequestration, air and H20 filtration -NOx, VOCs, and PM all contribute to smog formation

Ethanol

corn and sugar cane are fermented into ethanol which is mixed with gasoline
-corn grain/sugar cane broken down and yeast ferment sugars to ethanol

drawbacks of mixing ethanol and gas?

decreases oil consumption for transport, but is less efficient than pure gasoline (ethanol attracts water and injures engines)