Upload
nelle-guerra
View
32
Download
0
Tags:
Embed Size (px)
DESCRIPTION
Alternative Energy Sources. Activity 31 Fueling Trade-offs. What is energy?. Energy is the ability to do work. Energy sources are all around us. For example, you are all giving off heat (a form of energy) to the environment. But could this energy be easily or economically harvested? - PowerPoint PPT Presentation
Citation preview
What is energy? Energy is the ability to do work. Energy sources are all around us. For
example, you are all giving off heat (a form of energy) to the environment. But could this energy be easily or economically harvested?
Alternative energy sources are not based on the burning of fossil fuels.
Why bother with alternatives? Fossil fuels cause pollution that result in
environmental pollution and illness. Burning fossil fuels releases carbon
dioxide, a gas tied to global warming. Fossil fuels that can be harvested
economically exist in limited amounts. Most of the world supply of oil is in the
Middle East, a politically unstable region.
Types of alternative energy Solar Nuclear Wind Hydro (water) or hydroelectric power Tidal power Biomass Geothermal Hydrogen – fuel cells
Why are fossil fuels accepted by consumers?
They are abundant. They are low cost. They are safe to use.
What are two drawbacks to using fossil fuels?
Environmental degradation
They will not always be available.
Solar Energy
Solar energy uses energy from the sun.
The main expense is collecting, storing and converting the sun’s rays into useful forms of energy.
Environmental impacts/risks are negligible. Solar power is clean and quiet!
http://www.astronomy.com/asy/objects/images/sun_full_disk_soho_09_14_1997.jpg
Solar Energy This is a roof-top solar
collector used to heat water that heats the air in the house.
Unless new technology is developed, solar energy can not be used for large-scale industry or transportation.
http://www.fsec.ucf.edu/en/publications/html/FSEC-CR-978-97/index.htm
Solar Energy A photovoltaic cell produces energy when it is exposed to
light. Silicon (from sand) is the material from which a PV cell is
made. The light excites the electrons in the silicon and that
produces electricity.
http://www.acmegreen.com/page2/page7/files/page7_2.jpg
Solar Energy
Small PV cells are used to power solar calculators and emergency roadside phones.
To provide electricity for a satellite, space station, or typical home, the PV cell would have to be as large as 10 square meters!
The high cost of solar power prevents its use on a wide-scale.
http://www.abc.net.au
http://media.popularmechanics.com
The CIS Tower, Manchester, England, was clad in PV (photovoltaic) panels at a cost of $11 million. It started feeding electricity to the national grid in November 2005.
Solar Energy … An Application
http://en.wikipedia.org/wiki/Photovoltaics
Nuclear Energy Two ways that nuclear energy can be
produced…
Fission – the breaking apart of atomic nuclei
hyperphysics.phy-astr.gsu.edu/hbase/nucene/im...
Nuclear Energy
Fission reactions are used to supply significant amounts of energy for… Electricity Heating Military use
encarta.msn.com
Nuclear Energy Two advantages of
nuclear energy: It produces huge
amounts of energy from small amounts of nuclear fuel (uranium and plutonium).
Earth contains enough nuclear fuel to meet all present and future needs.
www.pollutionissues.com
Nuclear Energy Nuclear energy
produces wastes in the form of heat and spent (used) fuel – which can remain radioactive for thousands of years.
Disposing of this radioactive spent fuel is a major problem.
One proposed disposal site is Yucca Mountain in Nevada.
www.nrc.gov
Nuclear EnergyFour reasons why nuclear
power is not as widely used as it could be…
High cost Peoples’ fear of exposure to
radiation The threat of a meltdown
(nuclear explosion) The fear that nuclear weapons
could be developed using this technology
Stable, highly centralized governmental control is necessary for the safe operation of nuclear
power.
www.answers.com
Nuclear Energy Two ways that nuclear energy can be
produced are fusion and fission.
Fusion – the combining of atomic nuclei – such as in the stars (and sun!) – generates energy
http://www.aa.washington.edu
Nuclear Energy – Fusion Reactor The power produced by a fusion reactor will
be converted to electric energy or other goods like hydrogen or desalinised water. Neutrons produced in the D-T fusion process carry 4/5 of the energy. They will be slowed in the blanket where the tritium breeding takes place. Power by a’s goes to the divertor and first wall (FW).
One or two fluids circulate in the blanket and in the divertor/FW to extract the energy and to provide stable operational temperature of the components. The fluids must flow at high velocity (often in conditions of turbulent flow) while structural materials, pipes, junctions must withstand neutron bombardment, corrosion/erosion, high operational temperature, high heat flux. The presence of a magnetic field plays an important role in optimising the flow regime in electrically conducting fluids. Therefore the energy conversion system is a process that requires a trade off analysis among the various solutions.
http://www.isfrt-erice.enea.it/Page2.htm
China claims fusion reactor test a success Government hopes fusion
provides clean, limitless energy source …
BEIJING - Scientists on Thursday carried out China's first successful test of an experimental fusion reactor, powered by the process that fuels the sun, a research institute spokeswoman said.
China, the United States and other governments are pursuing fusion research in hopes that it could become a clean, potentially limitless energy source. Fusion produces little radioactive waste, unlike fission, which powers conventional nuclear reactors.
http://www.msnbc.msn.com/id/15043462/
updated 3:22 p.m. ET, Thurs., Sept. 28, 2006
Nuclear Energy Fusion reactions are not currently a
practical alternative energy source because…
Scientists have not yet been able to initiate a controlled, long-lasting fusion reaction suitable for producing heat and electricity.
Fusion reactions produce intense radiation that bombards all the materials in the reactor – making them intensely radioactive.
Fusion reactors are very expensive to build.
Hydroelectric Power
Four drawbacks to hydroelectric power… Inability to store energy Covers large
geographic areas Large initial investment
for facilities Contributes to habitat
destruction
These drawbacks also apply to wind power.
www.worldproutassembly.org
Hydroelectric PowerDams have an advantage over other alternative energy sources in that they provide power on demand.
This is the Hoover Dam.
photo.e-khmer.net
Hydroelectric Power Three problems associated
with dams include… Dams can gradually fill
with silt which reduces the water stored in the reservoir.
Dams can disrupt the local ecosystems and prevent the migration of some species of fish.
Dams have the potential to break and cause catastrophic floods. This is what is left of the Hadlock dam in the Adirondacks.
thecommunicator.org
Wind power – old to new
Wind power has been used topump water for centuries A modern wind turbine
generates electricity
Wind Power
Wind mills act as giant turbines that spins with the energy of the wind and generate electricity.
This only happens when the wind blows!
www.eere.energy.gov
Wind Power Wind power has some of the same disadvantages of
hydroelectric power. It must be supplemented with other energy sources because the energy produced cannot be stored.
Wind farms can also be noisy (a giant swooshing sound!), unsightly (modern windmills are HUGE!), and can kill migrating birds.
rochsolartech.itcstore.com
Hydroelectric Power Other forms of
hydroelectric power include: Tidal power – dams or
turbines are constructed to capture the energy of incoming or outgoing tides
Wave power – turbines are situated to catch the power of the rising and falling water.
OTEC – Ocean Thermal Energy Conversion.
home.clara.net
www.logicalscience.com
Biomass Biomass is organic
material that can be “combusted” for energy.
Biomass includes municipal wastes, crop residues, manure, lumber and paper by-products.
www.nrcan.gc.ca
Biomass To be used for energy,
biomass can be… burned directly gasified into methane
and hydrogen (the by-products of which can be used as fertilizer)
fermented into ethanol anaerobically digested
to produce biogas (a mixture containing methane and CO2).
sitemaker.umich.edu
Biomass
This is switchgrass, a hardy, fast growing plant that can be used as biomass
http://en.wikipedia.org/wiki/Image:Panicum_virgatum.jpg
Biomass – A Power Plant that Uses Cow Manure!
http://www.cbc.ca/gfx/pix/cowpoop_energy050505.jpg
greenplanets.blogspot.com
Biomass Two major drawbacks of
biomass energy include… The use of farm and forest
residue prevents the recycling of nutrients back into the ecosystem.
Pollution is generated in the process of converting biomass to energy.
However, once methane is purified from biogas, the nitrogen, phosphorus, and other nutrients can be used as fertilizer. www.ctahr.hawaii.edu
Geothermal EnergyRemember, geo means Earth Geothermal energy is
“Earth heat” which is present everywhere beneath the Earth’s surface
The highest temperature and thus the most desirable resources are concentrated in regions of active or geologically young volcanoes.
This is the Old Faithful geyser – atop the supervolcano of Yellowstone!
zebu.uoregon.edu/2001/ph162/special/oldfaith.gif
Geothermal Energy … Wells can be drilled down to 6 miles to reach Earth’s thermal energy.
www.geothermal.ch/bilder/obp0zjs6.jpg
Geothermal EnergyThree major drawbacks to geothermal power
include… Geographic restrictions The cost of drilling down into hot rocks (as
deep as 6 miles!) is very high The environmental impact of habitat
disturbance and the need to dispose of large quantities of noxious gases and very salty water.
Geothermal The Bjarnarflag Geothermal Station in northeast Iceland Iceland gets most of its energy for heating in the winter
from geothermal sources.
Hydrogen Hydrogen and oxygen chemically combine to
form water and energy in the form of heat. An advantage of using hydrogen as fuel is that
fuel cell reactions produce no pollution. This reaction can be used to generate electricity
using fuel cell technology. A fuel cell is somewhat similar to a battery but
with a fuel cell, chemicals constantly flow into the cell so it never goes dead. As long as there is a flow of chemicals into the cell, the electricity flows out of the cell.
Hydrogen must be in the proper form to be used as a fuel. Most hydrogen used in today’s fuel cells comes from methane
Hydrogen Current disadvantages of using hydrogen as a
fuel… Currently it is expensive. Large-scale production will
reduce its costs Range is limited with current fuel storage options Current small distribution channels - California is making
some progress It is extremely flammable – Remember the Hindenberg!
Many improvements are expected as this technology develops
Hydrogen Fuel Cells … A typical hydrogen
fuel cell works by channeling hydrogen and oxygen into different sides.
The hydrogen atoms split into protons and electrons (which produce the current).
The hydrogen and oxygen combine at the end of the process to form water.
http://en.wikipedia.org/wiki/Image:Fuel_cell_still.gif
Hydrogen Other materials can
also supply the fuel for a fuel cell.
This is a methanol fuel cell
The actual fuel cell stack is the layered cubic structure in the center of the image
http://en.wikipedia.org/wiki/Fuel_cell
Hydrogen- Applications …September 2006 - BMW will lease Hydrogen Cars BMW is going to make a
limited number of Hydrogen Series 7 sedans available for lease starting next year. This is the first fleet of hydrogen powered vehicles.
The cars will have tanks for storing liquid hydrogen and gasoline. The BMW Hydrogen 7 will emit only water vapor when burning hydrogen in the combustion engine.
The vehicle has a 260 hp twelve-cylinder engine and will accelerate from 0-62 mph in 9.5 seconds and tops out at 143 mph, according to BMW