Transcript ENVSCI - Unit 7 Notes

UNIT 7
ENERGY RESOURCES
7.1 ENERGY TERMS
1. Energy is the ability to do work and
transfer heat. It comes in the form of
light, heat, electricity, chemical,
mechanical, and nuclear energy.
2. Energy is classified as: Kinetic or
Potential
KINETIC ENERGY
1. Kinetic energy is matter that has
energy because of its mass and
speed.
2. The electromagnetic spectrum is a
form of kinetic energy as wavelengths
of sound, light and radiation.
3. Heat refers to the total kinetic energy
of all moving atoms, ions, or molecules
in a substance.
4. Temperature is a measure of the
average speed of those particles.
POTENTIAL ENERGY
1. Potential energy is stored
energy that has the potential
to do work.
2. High quality energy is
organized or concentrated to
perform useful work.
3. Low-quality energy is
dispersed and disorganized
and has little ability to do work.
ENTROPY
1. Entropy is a measure of
the disorder of energy.
2. The more disorder the less
useful it is.
3. For example: The
molecules in ice are more
orderly and have lower
entropy than steam that
requires more energy to
obtain a highly dispersed
state.
ENERGY CHANGES
1.Physical Change –
• Results in a change of
shape, size, form, etc.
without alteration
chemically.
• Eggs, milk, butter and flour
are just a mixture.
2.Chemical Change • Chemical reactions have
altered the composition of
mixtures or compounds.
• With the addition of heat,
the batter is changed into a
cake.
3. Nuclear Change –
• Nuclei of certain isotopes
change into one or more
different isotopes.
• Radioactive decay is a type
of nuclear change where
unstable isotopes are emitted
as fast-moving or high-energy
radiation or both.
• Radioisotopes can be used to
estimate the age of carboncontaining matter, as tracers
for pollution detection,
agriculture, industry and
medicine.
7.2 LAWS OF ENERGY
LAW OF CONSERVATION OF ENERGY
1. Law of Conservation of
Energy, also known as
the First Law of
Thermodynamics, says
that energy cannot be
created or destroyed, but it
can be changed in form.
2. This does not apply to
nuclear reactions because
they convert mass into
energy, but the total
amount of matter and
energy remains constant.
THE SECOND LAW OF
THERMODYNAMICS
1. So why do we need to worry
about shortages of
resources? The answer
comes from the Second Law
of Thermodynamics.
2. It says that when energy is
changed from one form to
another some of the useful
energy is always degraded to
lower quality energy.
3. It takes energy to produce
energy.
ENERGY YIELD
1. Net energy yield is the amount
of usable energy remaining after
the production cost is
subtracted.
2. The higher the ratio between
input cost and output cost, the
greater the net energy yield.
3. For example, if it cost $8 to
produce one unit of energy, but
that yields $10 worth of high
quality energy, the net energy
yield is a ratio of 10/8 = 1.2 net
yield.
EFFICIENCY
1. Efficiency is the percentage
of total energy input that
does the useful work.
2. Energy-efficient lighting and
appliances may cost more
to purchase but will save
more money in lower
energy costs.
3. The most inefficient and
expensive way to heat is
with electricity, and yet that
is the most common way in
the U.S.
4. This is how energy usage is broken down by categories:
27% Transportation
16% Commercial
37% Industrial
20% Residential
ENERGY SUSTAINABILITY
1. Use renewable energy
2. Recycle nutrients and other
resources efficiently and return
the resources in good
conditions so they can be
reused.
3. The idea is not to convert a
renewable resource, such as
water, into such a polluted state
that it becomes useless.
SAVING ENERGY
1. Cogeneration uses two useful
forms of energy from the same
fuel source.
2. Negawatt revolution - reduce
the demand on utilities by giving
customers rebates for buying
efficient lights and appliances.
3. Provide low interest loans to
industry and individuals for
repairing and upgrading
equipment.
4. The most important way to save
energy is to increase the fuel
efficiency of motor vehicles.
5. Super-insulated buildings, such as
straw-bale houses, save energy
and money.
6. Look for energy efficient ways to
heat houses and water, plug heat
and AC leaks, and use thermal
pane windows.
7.3 NONRENEWABLE ENERGY
RESOURCES
The U.S. is the world’s largest user of energy,
relying on nonrenewable fossil fuels for 93% of its
energy needs. Sadly, 84% of the energy generated
is wasted.
CRUDE OIL (PETROLEUM)
1. Crude Oil or Petroleum is
the most widely used
source of energy in
developed countries.
2. Oil, like other fossil fuels,
comes from the
decomposition of buried
plant and animal matter
trapped under high
temperature and pressures
for million of years.
3. The refining process separates the various hydrocarbons based on
their boiling points.
4. Listed in order from those with the highest boiling point to the
lowest, some of the products derived from petroleum are:
• asphalt
• grease and waxes
• naptha
• diesel oil
• heating oil
• aviation fuel
• gasoline
• gases
5. By-products of oil distillation
• Called petrochemicals, are used as raw materials for more than
85% of organic chemicals.
• They include pesticide, plastics, synthetic fibers, paints,
medicines, and many others.
6. Organization of Petroleum
Exporting Countries (OPEC)
• Saudi Arabia is a leading
partner of the 13 countries
who make up OPEC.
• They control 67% of the
world’s oil reserves.
7. The U.S. has only 2% of the
world’s supply but uses 30 % of
the world’s oil - mostly for
transportation.
8. World reserves may not last
more than 80 years, and
petroleum dependence increases
political vulnerability.
NATURAL GAS
1.Natural Gas is the best of the fossil fuels because it can be
transported easily, has a high net energy yield, produces less
air pollution than other fossil fuels, has less heat-trapping
carbon dioxide, causes less environmental damage, is easy to
process, and can be burned in cogeneration power plants or
used in highly efficient fuel cells.
2.Natural gas is a mixture of methane and heavier gaseous
hydrocarbons such as ethane, propane, butane and toxic
hydrogen sulfide.
3.Russia and Kazakhstan have 40% of the world’s natural gas
reserves. Most of the natural gas used in the U.S. is produced
domestically.
COAL
1.Coal is the world’s most
abundant and dirtiest fossil fuel.
2.Negatives include the
environmental damage caused
from mining, transporting, storing,
and burning it.
3.Coal mining is one of the most
dangerous occupations.
4.However, new technology has
made burning coal much cleaner
than in the past.
5. Coal Development
• The first stage begins with
plant material called peat.
• It is transformed into lignite
coal, then into bituminous
coal.
• The final stage is the most
limited and costly coal,
Anthracite, with its low sulfur
and high heat content.
6. Coal provides about 25% of
world’s commercial energy.
7. Most of reserves are located in
the U.S., the former Soviet
Union and China.
NUCLEAR
1. Nuclear plants have not been built
in U.S. or in Japan since 1979.
2. Although, France gets 80% of its
power by nuclear, but it is heavy
subsidized by the government.
3. Nuclear fission creates deadly
radioactive waste products that
have resulted in 45,000
contaminated sites in the U.S.
4. It creates severe operating and
economic problems.
5. A major accident anywhere is a
nuclear accident everywhere.
7.4 RENEWABLE ENERGY
RESOURCES
1. Renewable energy is potentially
sustainable because it can last
indefinitely without reducing the
original supply.
2. It can be replenished through natural
processes in a manner that is quicker
than depletion.
3. It is NOT reusing or recycling energy.
4. Renewable energy resources are:
• Solar
• Water
• Wind
• Biomass
• Geothermal
SOLAR ENERGY
1. The sun is ultimately the
source of energy for all living
things on Earth.
2. It provides a free, one-way
source of high-quality of
power.
3. Using photovoltaic cells,
solar radiation can be directly
converted into electrical
energy.
4. There are two types of solar
power:
a. Passive solar heating system
• Captures sunlight directly
within a structure and
converts it into low
temperature heat for space
heating.
• Passive solar can provide
70% of residential and 60%
of commercial needs.
b. Active solar heating – absorbs
solar energy and fans or
pumps it into a building’s
space heating.
WATER ENERGY
1.Dams control the flow of
water to turn turbines and
produce electricity.
2.Currently, hydroelectric
power supplies about 20% of
the world’s energy.
3.Norway uses hydroelectric
for 95% of its energy needs,
and Canada uses it for 70% of
its power.
4.Dams are expensive to build
and maintain.
5.Dams alter the environment
and involve some risks of
collapse.
6. Tidal energy facilities, like
those in France and the
Bay of Fundy, Nova Scotia
use the flow of the tides to
produce electricity.
7. This provides only a tiny
contribution to their energy
needs because of the
expense and limited
locations.
8. Fundy Tides are the
greatest in the world
dropping more than 53 feet
every 6 hours.
WIND ENERGY
1.Farms in California, Denmark and
Germany harness the potential of
wind to generate electricity.
2.Wind farms may supply about 10%
of the electricity needs in the future.
India is already expanding its use of
wind power.
3.The land used for wind farms can
also support agriculture, but the
blades may be harmful to migrating
birds.
4.Wind power is competitive with coal
and is much easier on the land. It
could become the world’s cheapest
ways to produce electricity.
BIOMASS ENERGY
1.Biomass is the burning of
organic material - wood,
manure, or plant fibers.
2.Roughly 50% of the world’s
population, especially in
developing countries, is using
biomass for energy.
3.However, Sweden is the
world leader in biomass
consumption.
4. It is renewable as long as trees are not harvested faster than
they are planted.
5. It is destructive to the land because deforestation promotes
soil erosion and wildlife decline.
6. Open fires waste energy.
7. Biomass can be converted by bacteria into gaseous and
liquid fuels called Biogas.
8. Some example of Biogas are mixtures of methane and
carbon dioxide, liquid ethanol, and liquid methanol.
GEOTHERMAL ENERGY
1. Transfers heat from
underground concentrations of
steam to heat space, water and
sometimes produce electricity.
2. The disadvantage is that water
can be depleted if removed
faster than it is renewed.
3. About 20 countries are
extracting energy from
geothermal sites.
4. Geothermal is available
everywhere if you can drill deep
enough, but access is difficult
and expensive.
5. It also causes environmental
degradation.