Alternative Energy Sources

1
Alternative Energy Sources
2
Background

• Our current primary energy source (fossil fuels)
  is a limited and non-renewable resource.

• The U.S. wastes as much energy as is used by
  two-thirds of the rest of the worlds population!

3
Background

• Simply improving energy efficiency would greatly
  reduce the amount of energy consumed (and
  wasted).

• As consumers, we can make more economical and
  environmentally conscious decisions.

4
Background

• Increasing energy efficiency would have several
  effects, as would the development of renewable
  energy resources
• reduce energy consumption overall
• decrease dependence on foreign oil
• reduce air pollution
• reduce emissions of greenhouse gases
• make nonrenewable resources last longer

5
Background

• Sustainable development is development that meets
  the needs of the present without compromising the
  ability of future generations to meet their own
  needs
• http//timeforchange.org/definition-of-sustainabil
  ity-what-is-sustainable

6
Background

• Our best option in conserving energy immediately
  is by improving energy efficiency, however, we
  must also consider converting to alternative
  sources of energy to satisfy future needs.

7
Background

• Alternative energy sources are resources that are
  constantly replaced and are usually less
  polluting.
• They are not the result of the burning of fossil
  fuels or splitting of atoms.
• The use of renewable energy is contributing to
  our energy supply.
• Some alternative energy sources are biomass,
  geothermal, hydroelectric, solar, wind power, and
  hydrogen fuel cells.

8
Biomass

• biomass energy or "bioenergy"the energy from
  plants and plant-derived materials.
• Biomass is renewable energy that is produced from
  organic matter. Biomass fuels include wood and
  forest and mill residues, animal waste, grains,
  agricultural crops, and aquatic plants.

9
Biomass

• Wood is the largest biomass energy resource today
• Even the fumes from landfills (which are methane,
  a natural gas) can be used as a biomass energy
  source.
• Biomass can be used as a solid fuel, or converted
  into liquid or gaseous forms, for the production
  of electric power, heat, chemicals, or fuels.

10
Biomass
Industrial energy and generation of electricity
use mostly byproducts of paper mills and forestry
residues. This combination of plant material is
fired like fossil fuels to create high pressure
steam, which passes through a turbine to generate
electricity. This process can be used on its own
or can be combined with coal firing to reduce
emissions.
11
Biomass

• The main biomass feedstocks for power are paper
  mill residue, lumber mill scrap, and municipal
  waste.
• For biomass fuels, the feedstocks are corn (for
  ethanol) and soybeans (for biodiesel), both
  surplus crops.
• In the near future, agricultural residues such as
  corn stover (the stalks, leaves, and husks of the
  plant) and wheat straw will also be used.
• Long-term plans include growing and using
  dedicated energy crops, such as fast-growing
  trees and grasses, that can grow sustainably on
  land that will not support intensive food crops.

12
Biomass

• Ethanol and biodiesel are liquid fuels that can
  replace gasoline or can be added to gasoline to
  reduce harmful emissions.
• Generally, agricultural byproducts (e.g. corn or
  other food products for ethanol, animal fat and
  vegetable oil for biodiesel) are used to create
  these energy sources.
• The liquid fuels are produced by degrading plant
  fibers into more simple sugars and starches, then
  fermenting these substances using biocatalysts,
  like yeast, into liquid from.
• Processing this aqueous solution produces fuel
  grade material that can be used directly or can
  be used to create other fuels or electricity.

13
Biomass

• With more use of biomass at lower production
  costs and better technology, the United States
  could generate as much as four-and-a-half times
  more biopower by 2020.
• One source estimates that biomass will have the
  largest increase among renewable energy sources,
  rising by 80 percent and reaching 65.7 billion
  kWh in 2020.
• http//www.pge.com/microsite/PGE_dgz/more/alternat
  ive.html

14
Biomass

• Distribution Biomass provides 4 of total
  energy supply (47 of renewable energy). It
  accounts for 15 of the worlds energy use.
• Cost Because all of the raw materials for
  biomass fuel sources can be found in the US the
  cost of acquiring the unrefined materials is far
  less than for foreign oil. The transportation
  and processing of the raw materials is
  approximately the same for the two types of fuel,
  but biomass energy has far fewer hidden costs to
  human health and environmental health.

15
Biomass, advantages

• biomass energy has the potential to greatly
  reduce greenhouse gas emissions.
• Burning biomass releases about the same amount of
  carbon dioxide as burning fossil fuels. However,
  fossil fuels release carbon dioxide captured by
  photosynthesis millions of years agoan
  essentially "new" greenhouse gas. Biomass, on the
  other hand, releases carbon dioxide that is
  largely balanced by the carbon dioxide captured
  in its own growth (depending how much energy was
  used to grow, harvest, and process the fuel).

16
Biomass, advantages

• far less SO2, NO, and NO2 produced than fossil
  fuels
• reduce dependence on foreign oil because biofuels
  are the only renewable liquid transportation
  fuels available.
• supports U.S. agricultural and forest-product
  industries.
• renewable as long as rate of consumption doesnt
  exceed rate of replenishment

17
Biomass, advantages

• can be sustainable if issues of deforestation,
  soil erosion, and inefficiency of burning are
  controlled
• could supply half of the worlds electrical
  energy needs
• biomass plantations can be supported in many
  areas that are undesirable for other uses and can
  restore degraded land (up to 200 million acres in
  the US could support biomass)
• reduces impact on landfills

18
Biomass, disadvantages

• currently the use of biomass is unregulated
  causing the rate of consumption to exceed the
  rate of replenishment
• requires adequate water, pesticide and fertilizer
  sources (which have environmental implications of
  their own)
• can cause deforestation if acres of virgin forest
  are removed to make room for biomasss plantations

19
Biomass, disadvantages

• soil erosion associated with monoculture crops
  and large farm equipment
• loss of wildlife habitats
• inefficient methods of burning can cause air
  pollution
• expensive to transport
• process of converting biomass to electricity has
  only 30 efficiency

20
Solar

• There are a variety of technologies that have
  been developed to take advantage of solar energy.
  These include
• Concentrating solar power systems Using the
  sun's heat to produce electricity.
• Passive solar heating and daylighting Using
  solar energy to heat and light buildings.
• Photovoltaic (solar cell) systems Producing
  electricity directly from sunlight.
• Solar hot water Heating water with solar
  energy.
• Solar process heat and space heating and cooling
  Industrial and commercial uses of the sun's
  heat.

21
Solar

• Passive solar heating systems use no mechanical
  equipment at all but can only be used for heating
  and cooling, not actual electricity. This
  involves the proper design of houses and
  buildings, which allows them to absorb and store
  heat from the same methods as above to acquire
  heat, but then have fans or pumps which evenly
  distribute the sun directly. Some things that
  can help accomplish this are energy-efficient
  windows, greenhouses, and sunspaces facing the
  sun. Also, walls and floors of concrete, adobe,
  brick, stone, salt-treated timber, and water in
  55 gallon drum buckets absorb heat and release it
  slowly.
• Active solar heating systems use the heat but
  then have fans or pumps which evenly distribute
  the heat

22
Solar Power

• Photovoltaic cells produce electricity directly
  from solar energy. They are made of an
  ultra-thin semiconductor, which is energized by
  the sun causing the electrons in it to flow.
  This creates a tiny electrical current, and when
  many of these cells are used together enough
  electricity is produced to power things.

23
Solar

• One source estimates that the domestic
  photovoltaic (PV) industry could provide up to
  15 of new U.S. peak electricity capacity that is
  expected to be required in 2020.
  http//www.pge.com/microsite/PGE_dgz/more/alternat
  ive.html
• Solar energy could supply up to 17 of the
  worlds energy. However, there are parts of the
  world where sunlight is not available for long
  enough durations to make this an efficient energy
  source.

24
Solar, advantages

• supply of solar energy is limitless and free
• reduces reliance on foreign oil imports
• pollution is nonexistent creates new jobs and
  industries
• no environmental impact
• can store energy during the day and release it at
  night

25
Solar, disadvantages

• inefficient in areas where sunlight is limited or
  seasonal
• home and centralized systems are expensive
• maintenance costs are high systems deteriorate
  and must be replaced
• visual pollution
• efficiency is only 10 25
• needs backup or storage systems

26
Wind Power

• As wind passes through the blades of a windmill,
  the blades spin. The shaft that is attached to
  the blades turns and powers a pump or turns a
  generator to produce electricity. Electricity is
  then stored in batteries.
• Turbines clustered together create a wind farm.
• The speed of the wind and the size of the blades
  determine how much energy can be produced.

27
Wind Power

• Right now wind only produces about 1 of the
  energy used in the US, but it is the most rapidly
  growing alternative energy source, and is
  expected to contribute to 5 of the US energy
  needs by 2020.
• Currently it costs about 3.5-5 cents per kilowatt
  hour to use wind generated electricity, but
  because of government subsidies the price is
  expected to drop to about 2.5 cents per kilowatt
  hour, making it the countrys cheapest source of
  energy.

28
Wind Power, advantages

• unlimited source
• wind farms can be quickly built
• maintenance is low and is automated
• moderate to high net-energy yield

29
Wind Power, advantages

• no pollution
• production of wind turbines would boost the
  economy
• land underneath turbines can still be used for
  agriculture
• efficient in windier parts of the country. The
  Midwestern US has the greatest potential for wind
  generated power.

30
Wind Power, disadvantages

• steady wind is required to make it economical
• backup systems needed when wind isnt blowing
• visual pollution
• noise pollution
• interferes with flight patterns of birds
• may interfere with radio, TV, and microwave
  communications

31
Geothermal

• Geothermal energy uses heat from within the
  earth.
• In some places this heat is used directly to heat
  homes and greenhouses, or to provide process heat
  for businesses or industries. Reykjavik, Iceland
  is heated by geothermal energy.
• Most geothermal resources are concentrated in the
  western part of the United States.

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Types of Geothermal Energy

• Direct use and district heating systems use hot
  water from springs or reservoirs near the
  surface.
• Electricity generation power plants use high
  temperature (300 to 700F) water or steam to
  turn turbine and generate electricity. Usually
  use geothermal reservoirs found a mile or two
  below the surface.
• Geothermal heat pumps (GHP) use stable ground or
  water temperatures near the Earth's surface to
  control building temperatures above ground.

http//tonto.eia.doe.gov/kids/energy.cfm?pagegeot
hermal_home-basics-k.cfm
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Direct Use of Geothermal Energy

• Cooking
• Bathing
• Heating
• Healing

http//www.bing.com/images/search?qhotspringpic
tureFORMBIFDfocalf433c9cdb1cbf9417 496ea6c952c
ce17furlhttp3A2F2Fwww.usatourist.com2Fslides
hows2Fyellowstone2Fimages2FHot2520Spring.jpg
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Geothermal for Power Generation

• The earths mantle is composed of molten rock,
  which contains a vast amount of heat. The rock
  and groundwater in earths crust is close enough
  to this magma to absorb a lot of heat from it.
  Most of this heat is stored in geothermal
  reservoirs, which are collections of hot water
  trapped in cracks and porous rock. This can form
  hot dry-rock zones, pockets of underground dry
  steam (with no water droplets), wet steam, and
  hot water. When these reservoirs are close
  enough to the surface the steam can be tapped to
  provide electricity directly by powering a
  turbine, then the steam could be cooled and
  pumped back into the ground.

35
Geothermal Power Generation

• Common near plate boundaries (near volcanoes and
  areas where earthquakes are common fault lines)
• With technological improvements much more power
  could be generated from hydrothermal resources.
  Scientists have been experimenting by pumping
  water into the hot dry rock that is 3-6 miles
  everywhere below the earths surface for use in
  geothermal power plants.

36
Geothermal Power Generation

• Drilling to the site of the geothermal reservoir,
  and constructing the plant used to convert the
  heat energy to electricity are expensive, but not
  much more so than coal fired plants or nuclear
  plants
• Only 22 countries currently extract geothermal
  energy to produce 1 of the worlds total energy
  supply (the US accounts for 38 of this energy
  produced). There are very specific places where
  the geothermal reservoirs are close enough to the
  surface to be tapped

37
Geothermal Power Generation

• Geothermal plants release less than 1 of the
  carbon dioxide emissions of a fossil fuel plant.
• They emit 97 less acid rain-causing sulfur
  compounds than are emitted by fossil fuel plants.
  
• After the steam and water from a geothermal
  reservoir have been used, they are injected back
  into the Earth.

38
Geothermal Powerplants, advantages

• moderate net-energy yield
• limitless and reliable source if managed
• little air pollution
• competitive cost

39
Geothermal Power Plants, disadvantages

• reservoir sites are scarce for geothermal power
  plants
• source can be depleted if not managed well
• noise
• odor

40
Geothermal Power Plants, disadvantages

• may cause land to sink
• local climatic changes
• land damage involved for construction of pipes
  and roads
• can degrade ecosystems due to hot water wastes
  and corrosive or saline water

41
Geothermal Heat Pumps

• Geothermal heat pumps use shallow ground energy
  to heat and cool homes almost anywhere.
• A few feet beneath the Earths surface, the
  ground and groundwater temperature remains
  relatively constant throughout the year. At a
  depth of six feet, the soil temperature in most
  of the world stays between 45 F and 70 F, even
  though the air temperature may fluctuate greatly.
• Geothermal heat pumps are more commonly used in
  this area, as compared to geothermal electrical
  power plants.

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Geothermal Heat Pump

• Heat is absorbed from the ground by a fluid
  circulating through a series of pipes.
• The heat is then concentrated and released inside
  the home.
• The process is reversed in the summer time, so
  heat from the home is expelled into the loop
  (series of pipes) and absorbed by the earth.

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Geothermal Heat Pump

• Thus geothermal heat pumps can be used in place
  of both a furnace and an air conditioner!
• requires little maintenance or attention from
  homeowners.

http//www.matternetwork.com/images/Matter/diagram
heatpump294.jpg
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Geothermal Heat Pump

• 75 more efficient than oil furnaces
• U.S. Is world leader in using geothermal power
  to generate electricity.
• In 2008, U.S. geothermal power plants produced
  14.86 billion kilowatt-hours, or 0.4 of total
  U.S. electricity generation.

45
Geothermal Heat Pumps

• Disadvantages
• Costs more to install than conventional heating
  system
• Older systems contain chlorodifluoromethane,
  which is harmful if leaked depletes the ozone
  layer

• Advantages
• Pays for itself in 3-10 years
• Energy efficient
• Environmentally clean
• Cost-effective

46
Hydropower

• Hydroelectric (hydropower) energy employs the
  force of falling water to drive
  turbine-generators to produce electricity.

47
Hydropower

• In large and small scale hydropower a dam is
  built across a river or stream creating a
  reservoir. This creates stored potential energy.
  The water then passes through the dam in a
  controlled manner turning a turbine, which
  produces energy. The water then continues on its
  path downstream.

48
Hydropower

• In pumped-storage hydropower there are two dams,
  one at a much higher elevation than the other.
  It uses the surplus of energy in times of low
  demand to pump some of the water in the first
  reservoir into the higher reservoir. Then, when
  more electricity is needed water in the upper
  reservoir is released over a generator in that
  dam and then released over the lower generator as
  well. This way the same water produces twice as
  much electricity.

49
Hydropower

• Hydropower supplies about 6 of the worlds total
  energy (4 in the US) and 20 of the worlds
  electricity (10 in the US). This is a very
  popular from of energy in developing nations
• Hydropower produces more electricity than any
  other alternative energy sources.
• Once the actual dam is built, the cost of
  maintaining a hydroelectric plant is relatively
  small. In the US the cost of this form of energy
  is estimated at 4 cents per kilowatt hour
  (compared to 3.5-6 cents for natural gas, 3.5-5
  cents for wind, 4-7 cents for geothermal, 5-6
  cents for coal, 10-21 cents for nuclear power,
  and 20 cents for solar cells).

50
Hydropower, advantages

• dams control flooding low operating and
  maintenance costs
• no polluting waste products
• long life spans
• moderate to high net useful energy yield

51
Hydropower, disadvantages

• Dams create large flooded areas, destroy wildlife
  habitats, and uproot people
• they are expensive to build
• decrease the natural fertilization of prime
  agricultural land in river valleys below the
  dams, and trap sediment keep fish from migrating

52
Hydropower, disadvantages

• falling water may pick up nitrogen gas and kill
  fish
• destroys the aesthetic value of the river
• It has been estimated that hydroelectric power
  will decline from 389 billion kWh in the U.S. in
  1999 to 298 billion kWh in 2020 because most of
  the best sites for hydropower have already been
  developed and because of concerns about the
  adverse impact that large-scale hydroelectric
  facilities may have on the environment
  http//www.pge.com/microsite/PGE_dgz/more/alternat
  ive.html

53
Other Types of Hydropower

• Ocean Power
• Wave Power
• Tidal Power

54
Ocean Power

• Oceans cover more than 70 of the Earth and
  contain both thermal energy from the suns heat
  and mechanical energy from the tides and waves.

55
Ocean Power

• Ocean thermal energy conversion (OTEC) converts
  solar radiation to electric power. OTEC power
  plants use the difference in temperature between
  warm surface waters heated by the sun and colder
  waters found at ocean depths to generate
  electricity.

56
Wave Power

• Wave energy conversion extracts energy from
  surface waves, from pressure fluctuations below
  the water surface, or from the full wave. Wave
  energy uses the interaction of winds with the
  ocean surface. This technology is still in the
  exploratory phases in the United States.
• Islay Wave Power Station (shown at left) is in
  Scotland first commercial wave power station in
  world!

http//news.bbc.co.uk/2/hi/science/nature/1032148.
stm
57
Wave Power

• Underwater turbines are devices that act like
  underwater windmills, with blades that rotate as
  the tide flows through them
• Another way to harness wave power is shown here

http//www.bing.com/images/search?qwavepowersta
tionFORMBIFDfocal 15721e5058757f2445ed50b559fb
26cdfurlhttp3A2F2Fwww.darvill.clara.net2Falt
energ2Fimages2Fwave.jpg
58
Tidal Power

• The power of tides can be harnessed to produce
  electricity. Tidal energy works from the power of
  changing tides but it needs large tidal
  differences. The tidal process utilizes the
  natural motion of the tides to fill reservoirs,
  which are then slowly discharged through
  electricity-producing turbines.

Rance Tidal Power Station, France First tidal
power station in world!
http//upload.wikimedia.org/wikipedia/commons/6/63
/Rance_tidal_power_plant.JPG
59
Hydrogen Fuel Cells

• Fuel cells are electrochemical devices that
  produce electricity through a chemical reaction.
• Scientists are exploring ways that they could be
  used as a power source for nearly exhaust-free
  automobiles and how they can be used as
  electricity-generating plants.

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61
Hydrogen Fuel Cell
62
Hydrogen Fuel Cell, advantages

• Fuel cells are rechargeable
• Easy to maintain with no moving parts
• No environmental pollution low/no emissions
• Virtually no noise
• Efficient
• Hydrogen is a safe fuel (disperses easily, only
  explosive if in confined space so needs to be
  regulated properly, not environmentally
  hazardous)

63
Hydrogen Fuel Cell, disadvantages

• The high cost of manufacturing fuel cells has
  prevented the mass use of this valuable energy
  source.
• It costs more to produce the hydrogen than is
  saved by using hydrogen fuel cells
• Prototype fuel cells dont last long enough to be
  cost-effective
• Hydrogen fuel cells for cars are generally too
  big to be practical. They would also need to be
  insulated for safety and to prevent evaporation
  of hydrogen
• There is nowhere, as yet, to fill up when the
  hydrogen evaporates

64
Hydrogen Fuel Cells

• http//www.fueleconomy.gov/feg/fuelcell8.swf
• http//www.h2fc.com/reframe.php?top/global/tech.s
  htmlbot/technology/fuelcells/general.shtml
• http//ezinearticles.com/?3-Great-Disadvantages-Of
  -Hydrogen-Fuel-Cellsid1656525

65
Nuclear Power

• Not truly an alternative energy source as defined
  at the beginning because it involves splitting
  the atom
• Light water reactors have a fuel rod within the
  core of the reactor that is made up of 97 U-238
  and 3 U-235, which sustain a controlled fission
  reaction. Control rods made of materials like
  graphite are moved in and out of the core to
  absorb excess neutrons that would accelerate the
  reaction. The heat generated by this reaction is
  used to heat water. The steam then powers a
  turbine to create electricity.

66
Nuclear Power

• Nuclear Reaction
• 235U 1 neutron 2 neutrons 92Kr 142Ba
  ENERGY
• A single U-235 atom releases approximately 200
  MeV (million electron volts). A pound (0.45 kg)
  of uranium produces power roughly equivalent to a
  million gallons of gasoline.

67
Nuclear Power

• When a U-235 atom splits, it releases an
  incredible amount of heat and gamma radiation
  (made of high-energy photons, capable of
  disrupting your DNA).
• The two products of a fission reaction weigh less
  than the original U-235 atom. The lost mass is
  actually converted into energy, according to the
  equation E mc2.

68
Nuclear Power

• Scroll down to see nuclear reaction in action!
• http//library.thinkquest.org/17940/texts/fission/
  fission.html
• Shows schematic of nuclear power plant.
• http//science.howstuffworks.com/nuclear-power3.ht
  m

69
Nuclear Power

• Uranium-235 isn't the only possible fuel for a
  power plant. Another fissionable material is
  plutonium-239. Plutonium-239 is created by
  bombarding U-238 with neutrons.

70
Nuclear Power

• Breeder reactors perform the same activity, but
  they also create more nuclear fuel than they
  consume by converting the U-238 into Pu-239
  throughout the reaction.
• There was a brief boom in the creation of nuclear
  energy plants when the technology was newer, the
  Price-Anderson Act protected plants from
  liability, and the government was subsidizing
  their construction. However, now concerns over
  accidents like Chernobyl and Three Mile Island
  combined with controversy over where to store
  radioactive nuclear waste have caused the
  popularity of nuclear energy to diminish.

71
Nuclear Power, advantages

• no air pollution
• releases only about one sixth the CO2 of fossil
  fuel plants, thus reducing global warming
• release less radioactivity than coal fired plants
• water pollution low
• disruption of land is low to moderate

72
Nuclear Power, disadvantages

• safety hazard
• nuclear waste products
• lifetime of plants is only 15 to 40 years
• plants are expensive to build and run

73
Nuclear Power, disadvantages

• high malfunction rate
• public fear
• uranium is a limited resource

74
Some Sources

• http//www.nrel.gov/learning
• http//www.pge.com/microsite/PGE_dgz/more/alternat
  ive.html
• http//www1.eere.energy.gov/biomass/biomass_basics
  _faqs.html