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Renewable
Energy:
Alternative Energy
Energy Part 3
I. Why do we need Alternative Energy?
• As of 2016, the most used energy sources in the US
were fossil fuels
• Below is a list of major energy sources and the total
percentage of electricity they generated in the US in
2016, according to the EIA
o Natural gas = 34%
o Coal = 30%
o Petroleum = 1%
o Nuclear = 20%
• The data shows that in 2016, fossil fuels and nuclear
energy generated 85% of the electricity in the US
Why is this large percentage alarming? Why is it potentially bad
that we rely so heavily on those energy sources?
• Recall, fossil fuels and nuclear energy are examples of
________________energy
o Pros = can be used anywhere, more reliable, produce
large amounts of energy
o Cons = limited supply, not environmentally friendly
They are all nonrenewable energy sources!
Nuclear Fossil Fuels
Pro: creates a lot of energy through
________ and ________________
Con: creates _________________,
hard to store waste, terrorism;
uranium and other atoms are finite
(they will eventually run out)
Pro: creates a lot of energy through
___________________
Con: limited supply, __________
(global warming)
nonrenewable
splitting combining atoms
radioactive waste
burning (combustion)
give off CO2
• With all of this being said, in terms of supply and environmental
friendliness, there is a push for alternative, renewable energy
sources
• Recall, __________ energy can be ___________________and
in our lifetime
o Pros = unlimited supply; “clean” energy
o Cons = dependent on climate/geography; can be costly to set-
up and maintain; hard to control how much energy is
produced at a given time
• There are many different sources of renewable energy; below is
a list of the common types and the percentage of US electricity
they generated in 2016
1. Water Energy = 6.5%
2. Wind Energy = 5.6%
3. Biofuel = 1.5%
4. Solar Energy = 0.9%
5. Geothermal = 0.4%
renewable replenished naturally
II. Water Energy
• Water energy, or ____________, is currently the most
utilized renewable energy source in the US.
• It utilizes the following energy conversions:
______________ ____________ ________________
_______________
How it works
• Hydro-electric plants utilize moving or falling water to do
work or in other words, create energy.
1. Water collects behind a dam in a reservoir; typically
placed on a river that has a large drop in elevation
(_________)
2. Water from the dam flows through the intake and into a
pipe called a penstock (_______)
hydropower
Potential Energy Kinetic Energy Mechanical Energy
Electrical Energy
potential
kinetic
3. The moving water pushes against blades in a turbine,
causing them to turn (____________)
4. The turbine spins a generator to produce electricity
(___________)
5. Power lines are connected to generator, carrying electricity
to the desired destination
• There are not many hydroelectric plants in Kansas or Florida but
there are several in Washington. Why?
http://energyquest.ca.gov/story/chapter12.html
mechanical
electrical
Land is too flat---best to have hydropower where
there is change in elevation (mountainous areas with rivers)
III. Wind Energy
• Wind energy is the second most used renewable energy
source in the U.S.
• It utilizes the following energy conversions:
_____________ _________________ ______________
How it works
• Wind turbines utilize the movement of the wind to create
energy
1. Blowing wind (______) spins the blades on a wind
turbine (___________)
2. The blades are attached to a shaft which spins a
generator to create electricity (________)
Kinetic Energy Mechanical Energy Electrical Energy
mechanical
electrical
kinetic
• Wind turbines are placed on a tower to capture the most energy
(at 100ft or more the wind is faster and less choppy)
• In order for a wind turbine to work efficiently, wind speed must be
above 12-14mph.
• The blades don’t turn the main shaft fast enough to generate
electricity so gears are used to speed up the rotation
• A brake is also built in to prevent the blades from turning too fast
and being damaged
• The Great Plains use wind-powered electric plants the most.
Why?
https://www.youtub
e.com/watch?v=ts
ZITSeQFR0
Consistently windy there
IV. Biomass Energy
• Biomass= ____________ from living or recently living
organisms
o Examples: wood, crops, animal manure, human sewage
• The ________ in biomass comes from the ____
• The main way biomass energy is made use of is through the
following conversions: _________ ________
___________ _________
How it works
1. The organic matter gets burned, undergoing a combustion
reaction that releases heat (_________)
2. The heat from the combustion boils water into steam
(________) which turns turbines (___________)
organic matter
energy sun
chemical
electricalmechanical
thermal
chemical
thermal mechanical
3. The turbines power a generator which generates electricity
(_________)
• Biomass is an alternative to burning fossil fuels
• Burning is only one way to release the energy from biomass
o Can also be converted into useable forms of energy like
methane gas, ethanol, or biodiesel.
electrical
V. Solar Energy
• Solar energy, or __________________, has been used since
the beginning of time and is used daily
• Life would not exist without the energy from the sun
• There are two ways to capture this energy
1. Solar Thermal Electricity
2. Solar Cells or Photovoltaic Energy
1. Solar Thermal Electricity = uses the _________ to
generate electricity
o Utilizes the following energy conversions: ________
____________ ___________
energy from the sun
sun’s heat
mechanical electrical
thermal
How it works
1. Heat from the sun (________) is captured and focused
on a pipe filled with “heat transfer fluid”, typically using
mirrors
2. The fluid transfers its heat to water, causing the water to
eventually boil into steam
3. The steam turns a turbine (___________) which moves
the generator to produce electricity (_________)
mechanicalelectrical
thermal
2. Solar Cells or Photovoltaic Energy = uses the ___________ to
generate electricity
o Utilizes the following energy conversions: ______ _________
How it works
1. Sunlight (_____) strikes solar panels, typically made of the semi-
metal silicon, knocking electrons from the silicon atoms’ loose
2. The ___________ of the free _________ results in the
production of electricity (___________)
• The southwest region of the US utilizes solar power the most. Why?
http://video.natio
nalgeographic.c
om/video/solar-
power
light electrical
sun’s light
Where sun shines the most
light
electricalmovement electrons
VI. Geothermal Energy
• Geothermal energy utilizes _________________
• It undergoes the following energy conversions: _________
___________ _________
How it works
1. Hot water and steam from deep underground get piped up
(________)
2. They travel to a special turbine and turn the blades
(_____________)
3. The turbine’s shaft is attached to a generator which makes
electricity (_________)
heat from the earth
thermal
electricalmechanical
thermal
electrical
mechanical
• Most geothermal plants are located in the western US where
hot water reservoirs are common
o Also common where there is volcanic activity
• Some people use geothermally heated water in swimming
pools or even as their hot water source
• Many geothermal plants “recycle” the hot water or steam
back into the ground to preserve the heat source
VII. Other Energy Sources
• With the increase in technology and decline of fossil fuels,
the search and development of alternative energy sources is
increasing
o Specifically renewable energy
• One of the newer energy sources being explored is the
_______
o Given that the ocean covers 71% of the world’s surface,
much research is being done to try and utilize its energy
• There are 2 basic ways to tap the ocean for its energy:
1. Wave Energy
2. Tidal energy
ocean
• Both ways utilize the same main energy conversions:
_______ ___________ __________
o Same idea as hydroelectric power—energy from the
moving water moves a turbine which powers a generator
mechanical electricalkinetic
• ___________are another alternative electricity source
• Produce electricity by converting ________ __________
o Like a battery
• Most involve combining hydrogen and oxygen = hydrogen
fuel cell
Fuel cells
chemical electrical
Nuclear Energy
Pros Cons
• low greenhouse gas
emissions
• Produces lots of energy
• Reliable energy source
• Low operating costs
(expensive to set up
plant but not to run it)
• Creates radioactive
waste
• Hard to dispose of waste
(_____________)
• Used for terrorism
• Nuclear melt-
downs/accidents
• Uranium is finite material
Fossil Fuel Energy
Pros Cons
• Cheap (for now)
• Reliable (not dependent
on other factors)
• Produce a lot of energy
• Creates a lot of jobs
• Emit greenhouse gases
= _______________
____________
• Limited supply
VIII. Comparing Energy Sources
long half-lives
acid rain, global
warming
Water Energy
Pros Cons
• __________ energy source
(unlimited supply)
• “Green” energy – low pollution
• _____ than nuclear and fossil
fuels
• One of the ___________
renewable energy sources
• Low maintenance cost
• __________ to build dams
(high construction costs)
• Can affect wildlife
• Risk of drought
Wind Energy
Pros Cons
• Renewable
• Clean fuel source
• One of ________________
energy sources
• Can help pre-existing farms
• Creates jobs
• More energy independence
from foreign countries
• Unreliable
• Requires a lot of ______
• _______
• Suitable in certain areas more
than other
Renewable
Safer
more reliable
Expensive
cheapest renewablespace
Noise
Solar Energy
Pros Cons
• Renewable energy source
(unlimited supply)
• Environmentally friendly
• “energy independence” won’t
have to rely on others for
energy
• Reduce electricity costs
• Low maintenance
• Silent
• Inconsistent
• Expensive to make/set up
• Materials used to make
panels are rare in nature
Geothermal Energy
Pros Cons
• Low pollution
• Renewable – __________
• Lots of energy potential
• Smallest “land footprint”
• Not weather dependent -
reliable
• Can cause earthquakes
• High initial costs
• Specific sites are better than
others
lots of supply
Biomass Energy
Pros Cons
• Renewable energy source
• Low pollution
• Widely available
• Helps ___________ by using it
• Not the cleanest renewable energy
source
• Expensive
• Not the most efficient energy source
Ocean Energy
Pros Cons
• No emission of greenhouse gases
• Renewable
• More predictable/reliable than wind
and solar
• Lots of energy potential
• Lots of maintenance (due to
conditions)
• High costs
• Still developing
Fuel Cell Energy
Pros Cons
• Clean
• Can use renewable fuels
• Lots of energy
• High cost
• Still developing
reduce waste