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Global Ozone Project
Curriculum

Lesson:

Renewable Energy

Rev 10A

Brian Carpenter, Jessa Ellenburg and John Birks

Learning Objectives

At the end of this lesson students
should be able to:


Identify
Non
-
Renewable
Energy
Sources.


Identify the top five
Renewable Energy
Sources.


Identify
Pros and Cons

for each
Renewable Energy
Source.





Global Ozone Project
Curriculum

Part 1:

Introduction to Energy
Use

Energy Introduction


Heat
Engine
:

a device that can
convert heat energy
to
mechanical energy.


Fancy name for a car engine, a power plant,
your
refrigerator
, air conditioner, etc
.



Efficiency
of a heat engine is expressed in terms
of the
temperature difference between the hot
side and
the
cold
side. Efficiency
= (
T
hot



T
cold
)/
T
hot



Cars are only about 20 to 30% efficient. Coal fired
power plants are around 35% efficient.



Electricity Introduction


Generating
Electricity


To get electricity, we
convert
mechanical energy
to
electrical
energy



Converting
mechanical energy to
electricity
is done
by
electromagnetic
induction
discovered by
Michael Faraday

in
1831.

Michael Faraday

Electricity

Generating Electricity


Spinning
conductive wires
inside a
magnetic field causes electrons
to
move
inside
the
wires, and moving
electrons
are electricity.



We can use both renewable and
nonrenewable energy sources
(fossil fuels) to do this.

Energy Sources

Major
Renewable

Sources


Solar


Hydropower


Wind


Biomass


Geothermal




Major
Non
-
Renewable

Sources


Oil


Coal


Natural gas


Nuclear


F
uelwood

From
Energy
Sources
to
Electricity

US vs. Global Energy Use

US Energy Use

Global Energy Use

Energy Production by State

Global Ozone Project
Curriculum

Part 2:

Renewable Energy
Technologies

Renewables


Major
Renewable

Energy Sources


Hydropower


Biomass


Geothermal


Wind


Solar


Active Solar

We utilize two types of Solar Energy:


Active Solar
&

Passive Solar

Active
Solar:

Technologies like
Solar
Panels
(
Photovoltaics
)
are used to convert
solar energy
into
electrical
energy
.




Passive Solar
-

Heating and Cooling

Passive Solar:
D
irect
use of sun’s heat
energy for home
heating.

Passive Solar


Water Heating

Another use of passive solar


to heat water for
household use.

Solar Potential for the US

Costs of Solar Electricity (Active Solar)

Costs of PV electricity:


Industrial system (500 kilowatt system, about $2.5M).


Sunny day: 15
-
20 cents/
k
Whr
, 35
-
55 cents on a cloudy
day.


Home system (2 kilowatt system, about $18,000).


Sunny day: 35 cents/
k
Whr
, 80 cents on a cloudy day.


Compare this with electricity from coal:


Peak cost: 15 cents/kilowatt
-
hour.


Off
-
peak cost: 10 cents/kilowatt
-
hour or less.

Pros and Cons of Active Solar (Solar Panels)

Pros:


Solar
panels give off no pollution, the only pollution produced as a result of solar panels is the
manufacturing of these devices in factories, transportation of the goods, and installation.


Solar
energy produces electricity very quietly.


The ability
to harness electricity in remote locations that are not linked to a national grid.


The
installation of solar panels in remote locations is usually much more cost effective than laying the
required high voltage wires.


Solar
energy can be very efficient in
a large area of the globe, and new technologies allow for a more
efficient energy production on overcast/dull days.


Space is not an issue because solar
panels can be installed on top of many
rooftops.


Solar is cost
-
effective. Although
the initial investment
cost of
solar cells may be high, once installed, they
provide a free source of electricity, which will pay off over the coming years.


Utilizing solar energy decreases dependence on fossil fuels.

Cons:


The major con of solar energy is the initial cost of solar cells. Currently, prices of highly
efficient solar cells can be above $1000, and some households may need more than one.


Solar
energy is only able to generate electricity during daylight hours.


T
he
weather can affect the efficiency of solar cells.



Pollution
can

affect a solar
cell’s efficiency.

Pros and Cons of Passive Solar Heating/Cooling

Pros:


Renewable. No fuels required.


Non
-
polluting. Carbon free except for
production and
transportation.


Simple
, low
maintenance.


Hot
water
provides
some
storage capacity.


Operating costs are
near
-
zero.


Quiet. Few or no moving parts.


Mature
technology.


Good
return on investment.


High
efficiency.


Can
be combined with
photovoltaics

in
highly efficient cogeneration schemes
.

Cons:


Intermittent.


Low
energy
density.


Does not produce
electricity.


Supplemental energy source or storage
required for long sunless
stretches.


Expensive compared to conventional water
heaters.


Construction/installation costs can be
high.


Hard
to compete against very cheap natural
gas.


Some people find them visually
unattractive.


Manufacturing processes can create
pollution.


Installers not available
everywhere.


Generally not practical to store or sell excess
heat.


Produce low grade energy (heat vs.
electricity
).


Dependent
on home location and
orientation.

Future of Solar Power

Ways
to
improve:

1.
Concentrators: these are mirrors that
concentrate
the sun’s
energy to
improve
efficiency.


2
. Hybrid S
olar Systems: combine
solar
with other
forms of
energy production
to
make cheaper and more reliable.
For
example
, solar
-
wind
, and
solar
-
hydro.


3.
Consider Cost of Pollution: Cost
of
coal
-
based
electricity is cheaper in
part because pollution is not factored
into
the cost
.
Cost of pollution
from
solar
(in manufacturing process)
would be
much
less.


Hydropower

Basics:

• Form of solar energy, as
the sun drives water
evaporation from the
ocean and winds carry the
moisture overland.

• Largest form of alternative
energy used today.

• Industrialized countries
have already tapped
much of their potential.

• Non
-
industrialized
countries have the most
untapped potential.


Hydropower
-

Dams

Dams


Height of dam and
mass of water
determine
useful
energy.



Efficiency is
very
good
to excellent
,
generally
80 to 90
%
efficient in converting
potential energy
to
electrical energy.



Potential Energy =
mass*gravity*height

Hydropower Generation

Hydroelectric
power production costs less than half
of fossil
fuel
derived
electricity
(does not include
construction costs).

Future of Hydropower

Tidal
Power
:
Propeller Systems

Tidal P
ower
:
Wave Systems

Tidal
Power
:

Enclosures

Pros and Cons of
Hydropower

Pros:


Very clean.


Cheap.


Flood
control (primary reason for dams
).


Multiple
crops per year
possible.


Cons
:


P
otential
is limited globally to about 5 to 10% of energy
needs.


Dependability
is an issue; prolonged droughts can cut
electrical production
in half or
more
.


Dams
have drawbacks,
including:


Environmental impacts


Loss
of nutrient flow down
river


Loss
of sediment flow down
river


Sedimentation
behind the dam limits lifetime of the
dam


Flooding
of scenic
areas and archaeological sites


Ecosystem
below the dam is usually changed by having
colder, nutrient
poor
water


Aesthetics


Loss
of wild
rivers

Wind Power

Basics


Use dates back
thousands of years
in the form of
windmills
, sailing
ships,
etc.


Typical efficiency is
about 30%.
Maximum theoretical
efficiency is thought
to be about 60
%.

Windmills

US Wind Power Potential

Midwest
has more
than 90% of
US potential

Wind Power Pros/Cons

Pros

Cost is very competitive, production costs are about
5 cents
per
kilowatt
-
hour
(coal electricity is around 15 cents). This
is down from 7 to 10
cents per
kilowatt
-
hour in 1995
and 15
cents per kilowatt
-
hour
in the
1980's.


In this case subsidies helped to create a viable market.


It is estimated that the costs could
be lowered
to 3
-
4 cents per kilowatt
-
hour
as wind
technology improves
. Improvements
in technology may also
open
less
windy areas up for economically
useful and
viable wind power
.


Cons


Reliability is a key issue, as the wind does
not always
blow. Requires a
storage mechanism
that compensates
for
reliability.


Recently, aesthetics has become a
significant issue
.


Killing of birds and
bats from high blade tip speeds.


Disruption of natural wind patterns.

Biomass

Basics


Energy from the sun, via photosynthesis in
plants.


This is the same energy we use as food.


This is the same energy that made fossil
fuels; fossil fuels are concentrated over time
by the heat and pressure within the Earth.


The oldest form of energy used by humans:
wood fire, a form of biomass.

Biomass

What is
biomass?



Any
plant
tissue can be
used for
energy, but
the faster the
plant grows
,
the more
useful it
is.

Biomass

How does it
work? How
do we convert
biomass energy to
useful forms
of energy?

• Direct burning


Gasification


Cofiring

• Fermentation

Future of Biomass


GMO “Energy Crops”
-

like Poplar and
Willow trees which have been
genetically engineered and bred for
rapid growth

• Algae
-

also grows rapidly

• Biodiesel

-

Canola and
Sorghum, etc
.


Cellulosic
Ethanol

Developing ideas

Biomass Pros and Cons

Pros:


Truly
a renewable
fuel


Widely available


Generally
low cost
inputs


Abundant supply


Can
be domestically produced
for energy
independence


Low
carbon, cleaner than
fossil
fuels


Can
convert waste into
energy, helping to deal with
waste


Cons:


Energy
intensive to
produce


Land
utilization can be
considerable


Requires
water to
grow


Not
totally clean when burned (NOx, soot, ash,
CO, CO
2
)


May
compete directly with food production (e.g.
corn, soy
)


Some
fuels are
seasonal


Energy required to transport


Overall
process can be
expensive


Some
methane and CO
2

are emitted during
production


Not
easily
scalable

Geothermal Power

Geothermal
Electricity


Geothermal in the Home

Geothermal Potential in the US

Future of Geothermal

Ocean
Thermal Energy Conversion (
OTEC
):


This is a special case of geothermal energy, as
the source
of the
energy is the sun, warming the
surface waters
of the ocean
.


Uses the temperature difference between cooler deep and warmer
shallow or surface ocean waters to run a heat engine and produce
useful work, usually in the form of electricity.


The
cold water typically comes from about
1000 meters.


Attractions of
OTEC

are
:


Steady source of energy (all day, all year).


Potential large in warm areas (Florida, Hawaii) requiring air
conditioning.


Could use this energy to create hydrogen gas from seawater.


Could be used to desalinize water.


Mariculture

(seafood farming)

Geothermal Pros and Cons

Pros:


Almost
entirely emission
free.


The
process can scrub out sulfur that might
have otherwise been
released.


No
fuel required (no mining or
transportation
).


Not
subject to the same fluctuations as
solar or
wind.


Smallest
land footprint of any major power
source.


Virtually
limitless
supply.


Inherently
simple and
reliable.


Can
provide base load or peak
power.


Already
cost competitive in some
areas.


Could
be built
underground.


New
technologies show promise to utilize
lower
temperatures.

Cons
:


Prime
sites are very
location
-
specific.


Prime
sites are often far from
population
centers.


Losses
due to long distance
transmission of
electricity.


Water usage.


Sulfur
dioxide and silica
emissions.


High
construction
costs.


Drilling
into heated rock is very
difficult.


Minimum
temperature of 350F+
generally
required.

Emerging Technologies

There are many interesting emerging
renewable technologies. A few examples
are:

Soccer Ball Charger

Spray
-
on Solar Panels

Green Gasoline


What will you come up with??