PowerPoint Presentation

							Renewable Energy
Solar energy
  – originates with thermonuclear fusion in the Sun
  – All the pollution remains on the sun!
  – The solar constant, which is the amount of radiant
    energy that enters the top of the atmosphere is
    1370 watts per square meter.
     • About half of this reaches Earth’s surface
        – some is reflected and some is absorbed by the atmosphere
     • just 40 minutes of sunlight striking the land surface is
       the equivalent of one year’s expenditure of fossil fuel
     • so…what are the problems with solar energy?
– 40 minutes of sunlight delivers the equivalent
  energy of a year’s expenditure of fossil fuel.
– So iif all this energy is free, why aren’t we
  using it? ….. Good question
– The energy from the sun varies from season to
  season, altitude , atmospheric condition and
  time of day.
   • Also, the sun’s energy has to be
      –   Collected
      –   Converted to a usable energy source
      –   And stored
      –   And all this must be cost effective
Heating water using solar energy is very
  easy.
  – This utilizes a solar collector
     • A thin box with a clear top and a black bottom with
       water tubes embedded within.
                      So why doesn’t everyone have one?
                         The initial cost is 5 to 10 times
                         the cost of a gas or electric
                         heater
                         but over time, the solar system
                         costs less to operate than gas or
                         electric.
Spaces in homes and office buildings can
 be heated too.
  – These can be complicated, expensive or
    homemade.
  – The best efficiency in using solar energy to
    heat spaces comes from good design. Then
    the building acts as its own collector
  – Landscaping can be added to contribute to the
    heating and cooling efficiency
Earth Sheltered Housing
  – These are homes that take advantage of the
    insulation characteristics of soil, the more
    moderate temperature of the air underground
    and a favorable directional orientation with
    windows facing southward.
     • So in the summer the house is kept cool by its
       contact with earth
     • And in the winter the walls are super insulated by
       earth.
     • There are even ways to pump air through ductwork
       that is run underground, cooled naturally, and use
       this as air conditioning.
Solar energy building only adds about 5% -
 10% to construction costs and can easily
 use 40% less energy than standard
 construction methods. This is a large
 saving of electricity, oil and natural gas.
  – Energy star awards are given by the EPA to
    public and corporate buildings.
  – In two years over 1,000 buildings gave been
    given the award, saving over $130 million and
    reducing CO2 emissions by 2.6 billion pounds.
Back-up heating systems are still required
  for periods of inclement weather
  – Good insulation is a feature of all solar homes
    and can keep the use of backup heating
    systems to a minimum.
  – Usually a small gas heater or wood stove can
    serve the purpose of a backup heating system.
  – Even with the use of backup systems, the use
    of solar power represents real energy savings
In the 1980’s the oil industry tried to
  curtain the growth of the solar energy
  industry.
  – Solar tax credits expired in 1985.
  – In the 1990’s energy prices were still low,
    making change to solar power unattractive.
  – However, since 1995, the demand for PV cells
    has experienced exponential growth.
Solar energy can be used to produce
  electrical power.
  – Solar cells, or photovoltaic cells are used to
    create an electrical current.
 PV cells are made of two layers of semiconductor
  material separated by a junction layer
   – The upper layer has atoms lacking electrons in their
     outer orbitals.
   – The lower layer has atoms with single electrons in
     their outer orbital that are easily lost.
   – The kinetic energy of light photons striking the two
     layers dislodges electrons from the lower layer
     creating an electrical potential between the layers.
   – This provides an electrical potential, allowing current
     to flow.
   – The lower layer is connected to a motor or another
     electrical device.
   – Their efficiency is about 20%.
   – The most common material used is silicon. Their cost
     is in their construction.
Most people in the Northeast who purchase
 a solar system will want to choose a utility-
 connected one. In these cases, the
 electricity from the system supplements
 what is available to the building from the
 electric utility. When the solar cells do not
 provide sufficient electricity for the
 building's users, extra electricity is
 supplied by the utility and the building's
 electric meter runs forward to record that
 extra electricity used.
 But at times when the solar cells produce more
  than enough electricity for the building's users,
  the additional power is fed back into the utility
  grid and the building's electric meter runs
  backwards, recording the "sale" of the electricity
  to the utility. This arrangement, in which the
  electric meter runs both forward and backward, is
  called net metering. In the Northeast, net
  metering is supported by legislation in all New
  England states, Maryland, New York, and
  Pennsylvania.
Stand alone system
On the grid.
 PV cells have no moving parts so they never
  wear out.
   – However, exposure to weather can cause them to
     deteriorate, so their life span is about 20 years.
   – You are already using these cells in calculators,
     watches, and toys.
   – Additionally, they are used in lighthouses, remote
     homes, off shore drilling platforms….
   – One advantage in some states is “net metering” the
     rooftop output is subtracted from the customer’s use of
     power from the power grid.
To work out the cost of PV power, the cost
  of the cells divided by the amount of power
  they may be expected to produce in their
  lifetime.
  – Your book states that this is $.25 to $1.00 per
    kilowatt. Other sources indicate that solar
    power costs closer to $3.00 per kilowatt.
    Other power alternatives cost between $.08
    and $.10 per kilowatt.
  – The price of electricity produced from solar
    cells is still significantly more expensive than
    it is from fossil fuels like coal and oil,
    especially when environmental costs are not
    considered.
 Of all the renewable energy sources available,
  solar cells have the smallest environmental
  impacts.
   – Electricity produced from photovoltaic cells does not
     result in air or water pollution, deplete natural
     resources, or endanger animal or human health.
   – The only potential negative impacts are associated
     with some toxic chemicals, like cadmium and arsenic,
     that are used in the production process.
   – These environmental impacts are minor and can be
     easily controlled through recycling and proper
     disposal.
Utilities
  – What will utility companies do as PV power
    becomes competitive?
     • There is a PV plant in southern CA that produces
       power solely for the grid. This takes up lots of
       land room
     • The most promising future for PV power would be
       in home sized systems. This would eliminate the
       use of land and transmission costs.
     • In CA there is a program that pays homeowners $4
       a month to maintain a 2-4kw PV system on their
       roofs. These systems feed into the power grid.
       This type of program is being used in Japan.
Million Solar Roofs
  – This is a federal program that encourages the
    installation of PV units on a million residential
    and commercial roofs by 2010.
     • There isn’t much financial incentive
     • This program focuses on partnering with other
       organizations.
     • The main focus is to strengthen grassroots demand
       for solar technology
     • We need more incentives (tax credits, deductions)
       to make this effective.
New PV Technologies
  – The cost of solar cells needs to drop
    dramatically
     • Two new technologies
        – Thin film PV cells using amorphous silicon which can
          beapplied as a coating on roofing tiles or glass. This
          means that the whole roof could be a solar collector.
        – Electrically conductive plastics that are made into solar
          cells.
            • These materials are too sensitive to weather
               conditions at this time, but progress is being made.
 Concentrating Solar
  Power
   – Solar Trough
      • The collectors are long
        U shaped collectors
        with reflectors. This
        array would be tilted
        toward the Sun.
      • Inside the pipes there is
        oil or some other heat
        absorbing liquid that is
        used to boil
        water…turn the
        turbine…make
        electricity.
 Power Tower
  – This is an array of mirrors
    that focuses the sunlight
    falling on a large area of
    land onto a receiver
    mounted on a tower.
  – The receiver transfers the
    heat energy to a molten salt
    liquid which flows to a
    heat exchanger to drive a
    turbine
  – The latest existing example
    is Solar Two which
    generates 10 MW of
    electricity, enough for
    10,000 homes.
Dish Engine System
  – This is an array of parabolic concentrator
    dishes that focuses sunlight onto a receiver.
  – Fluid (molten sodium) transferred to an engine
    that generates electricity. These systems have
    efficiencies of 30% higher than that of any
    other solar technology. They generate from 5
    to 40KW.
  – They are well suited to provide power to
    remote areas.
  – They are still quite costly as they are still in
    the early stages of commercial development
The Promise of solar energy
  – The technology is still move expensive than
    conventional energy but costs are coming
    down
  – Solar energy only works when the sun is
    shining.
     • This would require a backup or storage battery
       during the night.
     • It is very much climate dependent.
  – These factors should still be matched against
    the fact that these systems do not produce air
    pollution, greenhouse gases and nuclear
    wastes.
Matching Demand
  – 70% of demand occurs during the day
  – Proponents say that solar power can be used
    during the day and conventional sources at
    night.
  – The two biggest electricity users in the home
    are refrigeration and air conditioning.
     • Air conditioners could have their own solar
       systems. We might expect these in the marketplace
       within the next few years.
  – Solar power might be very useful in the
    developing world because centralized power is
    unavailable.
Indirrect Solar Energy
Hydropower’
  – This is currently the power produced with
    hydroelectric dams.
     • The power generated is proportional to the height
       of the water behind the dam and the volume of
       water that flows through.
     • About 6.7% of power in the US comes from
       hydroelectric dams.
     • It is nonpolluting, and renewable but there are
       problems.
The problems with dams.
  – The reservoir drowns farmland, historical
    places, wildlife habitats, and places of
    archaeological and aesthetic value.
  – Dams impede the migration of fish. Salmon
    fishing in the US northwest has been heavily
    affected.
  – Cold flowing rivers are very different from
    warm water reservoirs. The reservoir behind
    the Aswan High Dam has fostered the spread
    of a parasitic worm and higher humidity levels
    are impacting ancient monuments.
– Because water flow is regulated according to
  need, water below the dam may go from flood
  stage to barely a trickle and back to flood in a
  single day.
– Sediments with nutrients settle behind the dam
  in the reservoir so smaller than normal
  amounts reach the rivers mouth.
– There are only a few sites that are conducive
  to hydropower.
   • there are already 75,000 dams 6 feet high or more.
   • Only two percent of the nations rivers remain free
     flowing. Many of these are protected by the Wild
     and Scenic Rivers Act.
– Most new dam proposals are heavily
  questioned as to whether the benefits justify
  the ecological and sociological effects.
   • The proposed Three Gorges Dam on the Yangtze
     River in China will be the largest dam ever built
      – It will displace 1.9 million people in order to generate
        18,200 MW of electricity.
      – It would take more than 12 large coal fired plants to
        produce the same amount of electricity,
      – It will result in destruction of habitat, habitat
        fragmentation, increased humidity, destruction of ancient
        burial grounds and temples, and the elimination of the
        Yangtze river dolphin.
Three Gorges Dam, July 2003
Many people think of dams as clean and
 pollution free.
  – All the plant material that is covered by water
    will rot and produce methane.
  – During drawdown periods, plants will grow on
    the banks of the reservoir. During flood
    periods, these will be covered with water, rot
    and release methane into the atmosphere.
Wind Power
 Wind is the fastest growing energy source in the
  world
   – It has become economically competitive with
     conventional energy sources.
   – In 2006, the average monthly residential electricity
     consumption was 920 kilowatthours (kWh).
   – As of the publication date of your book, only .4% of
     the global electricity demand.
   – In 2007, the Us increased its wind power capacity by
     45%. This will power 1.5 million households.
   – The US Is third at 4,685 MW. Germany has over
     12,000 MW capacity. 1 MW = 1x106 watt
   – The wind turbine is the most efficient design with
     wind farms of several thousand turbines producing
     energy for under 5 cents per kilowatt hour. This rate
     is competitive with other traditional sources.
 Listen to the sound of a
  wind turbine
  – The midwest has great potential for meeting the
    electrical needs for the entire country.
  – The nice thing about this is that the land underneath
    the turbines could still be used for farming.
  – Farmers are paid nicely for leasing their land to wind
    developers
 The drawbacks…
  – Wind is intermittent
  – Backup energy sources or storage must be considered
  – A landscape covered with windmills could be tiresome
    to look at.
  – Windmills are hazards to birds
  – They are noisy
  – The tower has to be extremely sturdy. Some say to
    spend as much on the tower as on the turbine.
 There is a proposed wind farm for an area off
  Nantucket Sound
   – It is not getting support from people concerned with
     the visible impact of hundreds of wind turbines. This
     is classic NIMBY.
 Biomass energy
   – This term refers to any way of obtaining energy from
     present day photosynthesis.
   – This could include not only burning biomass, but also
     producing alcohol from grain.
   – The newest development of biomass energy
     production is a wood stove that uses wood pellets,
     made from wood waste, that are fed to the fire from a
     hopper controlled by a computer chip that controls the
     heat output from the stove.
Pellet stove
– In developing countries where people forage
  for firewood, people could be encouraged to
  produce trees as a cash crop.
– Waste paper and wood waste could be used to
  produce electricity
– In Spain, waste from olive oil production is
  now being used to provide 32 MW of power.

– Methane can be produced from sewage sludge.
– Biogas can also be produced from pig manure
  and cattle dung. The residue can be used as a
  fertilizer.
Renewable Energy for Transportation
Biofuels
  – Ethanol produced by fermentation is made
    from sugar cane, grain or grape4s.
  – Production costs to make ethanol are almost
    twice as expensive as gasoline
  – Gasohol is a mixture of ethanol and gasoline.
     • This was marketed in the Midwest since the late
       1970’s.
     • In order to stimulate its sugar cane industry, Brazil
       is now using a fuel mix for 24% of fuel.
     • Ethanol also makes gasoline cleaner burning;’
       This improves air quality meeting Clean Air Act
       requirements.
– Biodiesel
   • This is a mixture of soybean oil (20%) and diesel
     fuel. Apparently any oil or fat can be mixed with
     an alcohol (methanol) to make fuel.
      – One source of fat is used vegetable oil from frying lieke
        grease from McDonalds and other fast food restaurants
      – There are instructions on the internet for making
        biodiesel. It’s not that hard, anyone can do it.
Hydrogen
 Conventional cars with internal combustion
  engines can be run on hydrogen gas.
   – The only major byproduct of H2 production is water.
   – Hydrogen can be extracted from water using
     electrolysis but this requires an input o energy
   – A method has been found that uses TiO2 as a catalyst
     to produce H2 at an efficiency rate of 8.4%.
   – Another problem is the storage of H to allow it to
     operate over practical distances;
   – Compressing the H to a liquid form would require
     more energy.
   – Another option is to use solar arrays to produce
     electricity to produce H by electrolysis, transport the
     gas through pipelines to where it will be stored as
     needed.
  – Developing hydrogen burning cars is next.
    Ford introduced the Model U which runs on H
    with a hybrid electric drive.
Fuel Cells
  – These are devices in which H2 or some other
    fuel is chemically recombined with O2 to
    produce an electrical potential rather than
    initiating burning.
  – Emissions are only water and heat and the
    efficiency is between 45-60% versus the 20%
    for current combustion engines.
– GM introduced the Hy-wire, which is a car
  build on a skateboard chassis. The Hy-wire's
  fuel cell propulsion system is housed entirely
  in an 11-inch thick skateboard-like chassis.
  By-wire controls attached to the chassis
  through a single docking port use electrical
  signals instead of mechanical links of
  hydraulics to control steering, acceleration and
  braking. Without an engine, steering column
  or other conventional vehicle components, this
  concept provides unprecedented design
  freedom.
the problems now with fuel cell vehicles
  are the high cost and lack of infrastructure
  to provide hydrogen for refueling.
  – President Bush launched his FreedomCar.
    This is the government’s partnering effort with
    the auto companies to develop fuel cell
    powered vehicles.
     • His objective was to take cars from concept to
       showroom so that a child born today could be
       driving a pollution free car as a young adult.
     • Not only do the vehicles need to be developed en
       mass, but the fueling infrastructure needs to be in
       place.
Additional Renewables
Geothermal energy
  – Natural hot water is available where molten
    rock is close enough to Earth’s surface to heat
    water . This can be used to produce electricity
    or used directly as a heating source.
     • This method is used in Nicaragua, the Phillipines,
       Kenya, Iceland and New Zealand.
Heat pumps
  – Ground temperature 6 feet below the surface
    remains constant. This can be used as a heat
    exchange system that extracts heat I the winter
    and uses the ground as a heat sink in the
    summer.
Heat exchange pipes are run under
the ground to access the heat
absorbing capacity of the earth.
Air is cooled in the summer and
heated in the winter.
 Tidal Power
  – A tidal barrage is a dam built across the mouth of a
    bay. Turbines are mounted in the structure
  – The incoming tide flowing through the turbines would
    generate power.
  – This would work either way the tide flowed.
  – This technology is feasible in about 30 locations in the
    world where tides are high enough for this kind of use.
  – Problems include trapping sediments, impeding fish
    migration, and a barrier to navigation.
 A way of converting the energy of tides into electric power. A
  tidal barrage works in a similar way to that of a hydro-electric
  scheme, except that the dam is much bigger and spans a river
  estuary. When the tide goes in and out, the water flows through
  tunnels in the barrage. The ebb and flow of the tides can be used
  to turn a turbine, or it can be used to push air through a pipe,
  which then turns a turbine. Large lock gates, like the ones used
  on canals, allow ships to pass.
 The Tidal Generator :The Tidal Generator is based on
  free flow hydrodynamics for regions that have flood and
  ebb tides. Strategically attached to bridges, pilings, river,
  channel, or sea bottoms, this multi-directional generator
  contains two sets of turbine blades. As the tide flows
  inward the inward turbine blades opens to maximum rotor
  diameter while the outward turbine closes into the
  outward cone-shaped hub to create a hydro dynamically
  clean surface for water to flow without drag. The center
  diameter is 75% of the diameter of the turbine blades at
  full rotor extension for stability.
 Product Performance: Performance of the Tidal Generator
  is also dependent on the tides, less predictable than the
  ocean because of shifting bottom conditions, lunar cycles,
  depth of water, and varying strength.
                                        As the tide flows inward the
                                         inward turbine blades opens to
                                         maximum rotor diameter while the
                                         outward turbine closes into the
                                         outward cone-shaped hub to create
                                         a hydro dynamically clean surface
                                         for water to flow without drag.
                                         The center diameter is 75% of the
                                         diameter of the turbine blades at
                                         full rotor extension for stability.
                                        Product Performance
The Tidal Generator is based on
free flow hydrodynamics for             Performance of the Tidal
regions that have flood and ebb          Generator is also dependent on the
tides. Strategically attached to         tides, less predictable than the
bridges, pilings, river, channel, or     ocean because of shifting bottom
sea bottoms, this multi-directional      conditions, lunar cycles, depth of
generator contains two sets of           water, and varying strength.
turbine blades.
The advantage of this type of system is that
  the entrance and exit to the bay is not
  blocked to ships or to fish that migrate into
  the bay for food. One of these schemes is
  being looked at for Alaska, India and San
  Francisco.
OTEC - Ocean Thermal Energy
 Conversion -
  – Most ocean water is cooler at depth than at the
    surface where it is heated by the sun. In fact,
    there is a 20 degree C temperature difference
    between surface water and deep water.
  – The difference in temperature can be used to
    create power.
  – Ammonia, which has a low boiling point, is
    vaporized by the warm surface water. The
    gaseous ammonia’s expansion is used to drive
    turbines.
– The ammonia vapor is recondensed by
  pumping it back to depth where cold water
  cools it.