unit 6 Flashcards
1
Q
what defines a renewable energy source
A
they can be replenished naturally at or near the rate or consumption and reused
2
Q
depletable renewable def
A
can run out if overused
ex. biomass (wood, charcoal, ethanol)
3
Q
non-depletable renewable def
A
do run runout if overused
ex. solar, wind, hydroelectric, geothermal
4
Q
what defines a non-renewable energy source
A
exists on earth in fixed amounts and can’t be easily replaced or regenerated
5
Q
examples of non-renewable energy
A
-fossil fuels: millions of years to make
ex. coal, oil, natural
-nuclear energy: energy generated from uranium or other radioactive fuels
6
Q
rate of consumption must be ______ or ______ rate of regeneration for renewables
A
at; below
7
Q
what is the estimate time remaining in each fossil fuel in US.
A
coal: 139
oil: 54
gas: 49
8
Q
Subsistence fuel def
A
biomass fuel sources that are easily accessible (can be found and gathered by hand)
9
Q
where are subsistence fuels often used
A
developing countries as a home heating or cooking fuel
10
Q
what are the three main types of subsistence fuels
A
wood, charcoal, peat
11
Q
how is charcoal formed
A
heating wood at a low temperature for a long time to get rid of the moisture
12
Q
what is peat
A
partially decomposed org. matter often plants, found in wet, acidic, non-aerobic ecosystems
13
Q
how is coal formed
A
pressure from overlying rock and sediment layers compact peat into coal overtime
14
Q
what are the types of coal (in order of density and quality)
A
peat - lignite - bituminous - anthracite
15
Q
why is deeper coal more valuable
A
more pressure from overlaying rock so more energy dense, when it is burned it releases the most energy
16
Q
what is coal mostly used for
A
to make electricity
17
Q
how is natural gas formed
A
decaying remains of mostly marine plants and animals are buried under layers of rock and converted to crude oil and natural gas over time
18
Q
what is natural gas mainly made of
A
methane (CH4)
19
Q
why is natural gas considered the cleanest fossil fuel
A
produces the least air pollutants and least co2 when burned
20
Q
how is crude oil (petroleum) extracted
A
drilling a well through the overlaying rock layers to reach underground deposits and then pumping oil up
21
Q
what are tar sands and how can oils be recovered from them
A
a combination of clay, sand, water, and bitumen
bitumen is a semi-solid form of petroleum, so using a lot of water it can be extracted and used as oil
22
Q
how is crude oil converted to other products
A
using fractional distillation
23
Q
what is fractional distillation
A
-crude oil is burned in a furnace and vapor passes into a column where dif hydrocarbons are separated based on boiling points
-hydrocarbons w/ lower boiling points gather at the top while higher at the bottom
24
Q
what are uses for crude oil once they’ve been boiled (from lowest boiling points to highest)
A
-petroleum gas
-gasoline (fuel for cars)
-naphtha (used to make plastic)
-paraffin (jet fuel, wax)
-diesel fuel
-motor oil
-bitumen (asphalt)
25
cogeneration def
a fuel source is used to generate both usable heat and electricity
ex. heat from a car engine can be used to run cars heater in the winter
26
what is the difference between developing and developed countries when it comes to energy use
developed countries use more energy on a per capita basis (more appliances and travel per person) while developing nations use more energy in total
27
the average us. resident uses __x as much energy as world average
4
28
what is the most used energy source
fossil fuels
29
what are fossil fuels used for that make them the most used energy source
-oil: main fuel for vehicles
-coal: main fuel for electricity gen.
-natural gas: secondary fuel for electricity and main fuel for heating
30
what is the second most used energy source
hydroelectric
31
what is hydroelectric energy used for
generating electricity
32
what is the third most used energy source
nuclear
33
what is nuclear energy used for
uranium fission generates heat to generate electricity
34
why does development increase FF use
-many residents in less developed countries use subsistence fuels
-economic development- affluence - higher per capita GPD - energy use
35
what are the factors that effect energy source use
-availability: FF use depends on discovered reserves and accessibility
-price: prices fluctuate dramatically with discovery of new reserves or depletion of old ones
-Gov. regulation: gov. can mandate certain energy source mixes (25% renewable by 2025)
36
what can the government can and cannot do when regulating energy source use
CANNOT: directly raise or lower prices of energy sources (ex. gas to 10/gallon)
CAN: taxes increase to discourage companies from building FF power plants
CAN: rebates or tax credits to encourage companies to build renewable energy PP
37
what is combustion
reaction between oxygen and FF (hydrocarbons) that releases energy as heat and produces co2 and h20
38
what is the formula for combustion
CxHy + 02 -> co2 + h2o + energy
39
how do FF generate electricity
heat up water - water to steam - steam turns turbine - turbine powers generator - generator produces electricity
40
what are the environmental effects of using coal
-habitat destruction to clear land for mining
-releases more c02 than any other FF
-releases pm and toxic ash that can get into water
41
what are the environmental consequences of using tar sand
-habitate destruction
-ground/surface water depletion and contamination
-CO2 releases from machinery
42
what are the environmental consequences of using crude oil
-possible spill
-spills in water = crude oil covering sun, suffocating fish
-spills on land =toxic to plants, surface/groundwater contamination
43
what are the environmental consequences of fracking
-fracking fluid can leak out and contaminate water
-depletion of groundwater (drawn for fracking fluid)
-increased earthquakes
44
what is fracking fluid flow-back
the waste water that returns to the surface after fracking
45
what are the components of fracking fluid flow-back
acids, detergents, and salt
46
how many years of coal reserves left
100-150
47
how many years of natural gas reserves left
50-60
48
how many years of oil reserves left
50
49
which 5 states have the highest coal reserves
1. US.
2. Russia
3. Australia
4. China
5. India
50
which 5 states have the highest natural gas reserves
1. Russia
2. Iran
3. Qatar
4. US.
5. Saudi Arabia
51
which 5 states have the highest oil reserves
1. Venezuela
2. Saudi Arabia
3. Iran
4. Canada
5. Iraq
52
what is layer D in formation of oil/natural gas
source rock.
-where dead org. matter were buried under hear and pressure over millions of years; become oil and gas that flows to layer above
53
what is layer C in formation of oil/natural gas
Reservoir rock.
layer of permeable rock where oil, natural gas flow and collect
54
what is layer B in formation of oil/natural gas
Caprock.
layer can be porous but not permeable; does not allow flow of oil/ natural gas to surface
55
what is shale gas
gas trapped in semi-permeable, sedimentary rock layers, such as shale, is released by cracking the rock with pressurized water
56
where is the worlds largest oil sand reserve
Alberta Canada
57
Nuclear fission
-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)
58
what is radioactivity
-refers to the energy given off by the nucleus of a radioactive isotope
-radioactive nuclei decay, or breakdown and give off energy (radiation) even without fission, nuclear fission just releases lots of energy all at once
59
what is a common radioactive isotope
uranium-235
60
what is radioactive half life
the amount of time it takes for 50% of the substance to decay
61
how do you generate electricity with uranium fission
-same as with FF just using uranium fission to heat water
-u-235 stored in fuel rods submerged in water in reaction core; heat from fission turns h20 to steam
62
what are control rods in nuclear fission
-are lowered into reactor core to absorb neutrons and slow down the reaction, preventing meltdown (explosion)
63
what is the water pump in nuclear fission
brings cool water to be turned into steam and also cools reactor core down from overheating
64
what is the cooling tower in nuclear fission
-allows steam from turbine to condense back into liquid and cools down before being reused (this give off h2o vapor often mistaken as toxic chemicals)
65
what are the benefits of nuclear fission
-no air pollutants (pm Sox/Nox) or Co2/CH4 released when electricity is generated; but mining of uranium still releases GHG
66
what are the drawbacks of nuclear fission
-possible meltdown
-possible radioactive contamination
-lots of water needed
-thermal pollution
67
why spent fuels rods bad
-remain radioactive for millions of years and need to be stored in lead containers on site
68
what are mine tailings
leftover rock and soil from mining may be radioactive
69
what is thermal pollution
how water from nuclear PP released back into surface waters can cause thermal shock
70
what are the three nuclear meltdowns
-Three mile island (US.)
-Fukushima (japan)
-Chernobyl (Ukraine)
71
what happened at Three mile island
partial meltdown due to testing error, radiation released but no deaths or residual cancer cases
72
what happened at Fukushima
an earthquake and tsunami triggered cooling pump failure that lead to a meltdown and widespread radiation release
73
what happened at Chernobyl
stuck cooling valve during test lead to complete meltdown, several deaths and widespread radiation release
74
where does a meltdown happen
and explosion in the reactor core
75
passive solar
absorbing or blocking heat from the sun w/o use of mechanical/electrical equipment
76
examples of passive solar
-using suns heat to cook in a solar oven
-orienting a building to let in sun in the winter and keep out sun in the summer
-double panned windows, southern facing windows w/ overhang, deciduous shade trees, skylight
77
active solar
use of mechanical/electrical equipment to capture suns heat(solar of water heaters or cst- concentrated solar thermal), or convert light rays directly into electricity (photovoltaic cells)
78
what is the best direction to face photovoltaic cells
southern facing in the US
79
what are photovoltaic cells (PV)
AKA soar panels; contain semiconductors (usually silicon) that emits low voltage electrical current when exposed to sun
80
how do PV cells work
-photons (particles carrying energy from the sun) cause separation of charges between two semiconductor layers (n and p); electrons separate from protons and flow through circuit to load delivering energy
81
what can PV cells do
PV cells on a roof can power a building or send excess electricity back to grid (for money)
82
what are the drawbacks of PV cells
-intermittency (solar energy can only be generated in the day
**could be solved by batteries, but currently not cost effective
83
what is concentrated solar thermal (CST)
-heliostats (mirrors) reflect suns rays onto a central water tower in order to heat water to produce steam to turn a turbine which produces electricity
84
what are the drawbacks of CST
-habitat destruction
-light beams frying birds mid air
85
community (solar farms) VS. rooftop solar
-large scale solar "farms" can generate lots of electricity, but do take up land and cause habitat loss
-rooftop solar doesn't take up land, but produces less electricity
86
solar energy pros
- no air pollutants (PM, SOx, NOx) released
-no CO2 released
-no mining of FF
-renewable
87
solar energy cons
-semiconductor metals (silicon) still need to be mined to produce solar panels
-solar panel farms can displace habitat
-costs a lot
-intermittency
88
hydroelectricity basics
-kinetic energy of moving water spins a turbine- powers generator
-water moves either with natural current of rivers or tides, or by falling vertically through channel in dam
89
what is by far the largest renewable source of electricity
hydroelectricity
90
where are the three biggest hydroelectricity producers
US
China
Brazil
91
where is the largest hydroelectricity dam in the world
Three Gorges Dam in China
92
how do water impoundment (dams) work
-dam build in river creates a large artificial lake behind the dam called a reservoir
-damming rivers allows operators to allow more or less water through the channel, increasing or decreasing electricity
93
what are the main reasons dams are built
-Electricity gen
-prevents flooding downstream
--source of recreation money
94
what are the two big impacts of dams
-flooding of ecosystems behind the dam
-and sedimentation of upstream, and decreased nutrients downstream
95
what is the run of river system
-a dam diverts the natural current of a river through a man made channel beside the river
-the natural current turns a turbine that generates electricity
96
what is the benefit of the run of river systems
less impactful, because it doesn't block the flow of the river completely (no reservoir formed so no flooding)
97
what are the drawbacks of the run of river system
-doesn't generate as much electricity
-may be unavailable in hotter seasons when water is low
98
what is tidal power
energy that comes from tidal ocean flow turning a turbine (coastal areas only)
99
what are the ecological impacts of hydroelectric dams
-reservoir floods habitats behind dam
-prevents upstream migration of fish like salmon
-sedimentation changes upstream and downstream conditions
-downstream wetlands especially suffer, nutrients in sediment doesn't reach them
100
what are the environmental impacts of hydroelectric dams
-FF combustion during dam construction
-increased evap. due to larger surface area of reservoir
-methane release due to anaerobic decomp.
101
what are the economic impacts of hydroelectric dams
-human homes and businesses must be relocated due to reservoir flooding
-initial construction is expensive
-sediment must be dredged (removes by crane)
-loss of ecosystem services
102
what are fish ladders
cement "steps" or series of pools that migratory fish like salmon can use to continue migration upstream, around or over dams
103
what is a salmon cannon
-a similar alternative like fish ladders that enables salmon to be catapulted or directed into a tube that carries them over the dam
104
what are the benefits of hydroelectric dams
-no GHG when producing electricity
-tourist attraction
-jobs are created
-reliable electricity source
-no air pollutants released during elec gen
-allow for control of downstream seasonal flooding
105
only ____% of dams are used for hydroelectricity
3
106
EROI formula
energy obtained from fuel/energy invested to obtain fuel = EROI
(the higher EROI number, the more effective)
107
how does wind turbines generate electricity
-kinetic energy of moving air (wind) spins a turbine; generator converts mechanical energy of turbine into electricity
-blades of turbine are connected to gearbox by a shaft that rotates; rotating gears create mechanical energy that the generator transforms into electricity
-only works in wind 8-55 MPH
108
what is the avg. turbine power and cap. factor
-the average turbine can power around 940 homes
-the average wind turbine has 21-52% capacity factors (% of total possible energy it could generate)
109
wind turbine location
-clustered in groups (wind projects or farms) in flat (usually rural), open areas
-located together makes service, repair, and building transmission lines to them easier
-can share land with agricultural use
110
what are offshore winds and what do they intel
-wind farms in ocean or lakes
-capitalizes on faster wind speeds
-requires longer transmission lines to reach them in water
-higher cap. factor, but more expensive to build/maintain
111
what are the benefits of wind energy
-Non-depletable renewable
-no GHG emissions or air pollutants released when generating elec.
-can share land use
-doesn't contaminate soil/water
112
what are the drawbacks of wind energy
-intermittency
-can't replace base-load power
-can kill birds and bats
-can be considered an eyesore or a source of noise pollution
113
what can you do to conserve energy at home
-adjust thermostat to reduce energy of heater/AC
-energy efficient appliances
-passive solar home design
-water conservation
-conservation landscaping
114
large scale energy conservation methods
-improve fuel economy for vehicles (CAFE standards)
-battery electric vehicles (BEV or EV) and hybrid vehicles
-public transportation
-green building design
115
what are some sustainable home designs
-ways to either block or use suns natural heat to decrease energy use
-deciduous shade trees (leaves block sun in summer but let in in winter
-using passive solar design concepts to trap suns heat and decrease energy from heating system
-well insulated walls/attic
116
water conservation techniques
-native plants require less water
-low-flow appliances
-rain barrels
117
what is CAFE standards
-corporate average fuel economy
-regulations set in US. to require auto manufactures to make cars that meat certain MPG standards, or pay penalty
118
sustainable building design
-green roof or walls can decrease runoff and absorb sun's heat
-skylights on roof to reduce electricity needed for lighting
-recycling material to build can reduce energy needed to make new ones
119
what is peak demand
-peak demand is the time of the day or year (often early night hours or when it's hot) that electricity demand is highest
120
what are ways to manage peak demand
-variable price model: users pay more during peak demand hours or events to discourage use
121
what is the smart grid technique
the idea of managing demand and energy sources in more varied ways
122
what is biomass
org. matter (wood/charcoal, dried animal waste, dead leaves/brush, peat)
123
what are the human health effects of burning biomass
-releases CO, NOx, SOx, VC
-especially harmful if burned inside w/no ventilation
solutions: chimneys/ventilation, cook outside
124
what are the environmental effects of burning biomass
-deforestation/habitat destruction (and loss of ecosystem services)
-air pollution
125
why is biomass considered carbon neutral
-it released carbon that has just been sequestered, unlike fossil fuels, so it doesn't change the amount of carbon in the amt,
126
modern carbon vs. fossil carbon
burning biomass burns modern carbon (CO2 that was just sequestered) whereas FF releases fossil carbon (carbon that has been stored for millions of years
127
what are biofuels
liquid fuels (ethanol, biodiesel) created from biomass
128
what is ethanol and how is it made
corn or sugar cane are fermented into ethanol which is mixed with gasoline
-low EROI
129
what is biodiesel and how is it made
liquid fuels from new and used vegetable oils (soy, canola, palm) or animal fat (cooking grease); used as replacement fro petroleum
130
what is the most common biofuel
ethanol
131
what are the benefits of biofuels
-renewable, but only if sustainably produced
-can use waste biomass (unconsumable plant parts)
132
what are the drawback s of biofuel
-soil erosion, habitat loss, GHG release (agricultural soils, tractors, fertilizers), H2o use, mono cropping lowers biodiversity
-lots of corn needed relative to petroleum
-palm oil is especially harmful, due to clearcutting fo plantation
133
how does geothermal work
-the natural radioactive decay of elements in the earths core release heat, pushing up hot mantel
-water can be pipped down and get heated to generate steam to turn the turbine
-this hot water can also be used to heat homes directly
134
why is geothermal renewable
because the heat from the earths core won't run out in our in our lifetime
135
what is ground source heating pump
-10 feet down, the ground stays a consistent 50-60 degrees due to heat from sun
-heat absorbing fluid is pumped into the ground and either heats up or cools down, depending on the temp of the air outside
-in the summer, heat from home heats the liquid and the ground cools it off, in the winter, the opposite
136
how does geothermal heating work
-true geothermal heating involves piping up water deep into the ground to be heated by magma and then transferring heat from water to buildings
137
how is true geothermal heating different then ground source heating pump
-the well must go down thousands of meters into the ground to reach heated water reservoir
-heated water is piped up to surface and sent to homes or businesses to heat them up
138
what are the pros of geothermal
-renewable energy source
-much less CO2 emissions than FF elec.
-no release of PM/SOx/NOx/COasin case with FF
139
what are the cons of geothermal
-not everywhere on earth has access to geothermal energy reaching close enough to surface to access it
-hydrogen sulfide can be released, which is toxic and can be lethal
-cost of initial drilling is very expensive, so expensive it might not even be worth it
140
where is the best location for geothermal
near tectonic plate boundaries
141
what are hydrogen fuel cells
-use hydrogen as a renewable alternative fuel source to fossil fuels
142
how do hydrogen fuel cells work
-h2 gas enters fuel cell where it is split into protons and electrons by an electrolyte membrane that only lets protons pass
-electrons take an alternative route around the membrane, which generates an electrical current
-o2 molecules enter fuel cells and combine with hydrogen to form h2o
143
what is the byproduct of hydrogen fuel cells
h2 gas and water
144
what is the most common application of fuel cells
in vehicles
145
what are the two main way of getting hydrogen by itself
-steam reforming (most common but less sustainable)
-electrolysis (more sustainable but less common
146
why are hydrogen fuel cells not used that much
-you have to get hydrogen by itself first
147
what is steam reforming
-burning natural gas (Ch4) and using steam to separate the h gas from teh methane (CH4)
-it emits co2 and requires natural gas (FF) input
148
what is electrolysis
-electrical current is applied to water, breaking it into 02 and h2
-no co2 emissions but does require electricity
149
what are the pros of hydrogen as an energy carrier
-as a gasoline replacement it emits no air pollutants, only h20
-can be stored as liquid or gas making it easy to transport
-they are 80% efficient
150
what are the drawbacks of hydrogen as an energy carrier
-95% of h2 production requires methane (ch4)
-if electrolysis is used to produce h2, its only as renewable as the electricity source
-would require building widespread H distribution networks (like gasoline now)
-expensive
