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ENERGY from the SUN

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ENERGY from the SUN THE SOLAR CELL How the Solar Cell works pn Junction The Entire Process Energy Futures: Hydrogen and THE FUEL CELL Introduction: From the sun ... – PowerPoint PPT presentation

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Title: ENERGY from the SUN


1
ENERGY from the SUN
  • THE SOLAR CELL

2
How the Solar Cell works pn Junction
3
(No Transcript)
4
The Entire Process
5
Energy Futures Hydrogenand THE FUEL CELL
6
Introduction From the sun to consumable energy
(year 2000).
  • The source of almost all energy on earth is the
    sun.
  • Present energy consumption is dependent on fossil
    fuels.
  • Fossil fuels create environmental problems.

7
Introduction From the sun to consumable energy
(possible future).
  • In the future solar, wind, and hydropower may be
    utilized to electrolyze water to produce
    hydrogen.

8
Where will the hydrogen come from?
  • Fossil fuels
  • Examples Coal / Oil / Methane (CH4)
  • Hydrogen is obtained from fossil fuels by a
    process called reforming.
  • This is currently the cheapest method to obtain
    hydrogen.

9
Where will the hydrogen come from?
  • Plants like corn
  • Used to produce alcohols which have a significant
    amount of hydrogen ethanol (C2H5OH).
  • Hydrogen is again obtained by the reforming
    process.

Ethanol plant, Monroe WI
10
Where will the hydrogen come from?
  • Water
  • Electrolysis (breaking up by electricity) of H2O
  • Conventional An electrical current is induced
    in a water and electrolyte (a substance that
    produces electrical current carrying ions)
    solution. Water is ionized (broken up into
    positive (H2) and negative (OH-) ions) and the
    ions collect at opposite electrodes. (Aswan dam,
    Egypt largest H2 production by electrolysis.)
  • The hydrogen gas is collected and may be used
    later as a fuel.
  • Demonstration Electrolysis using a solar cell as
    an electrical source.
  • Solid electrolyte membranes When electrical
    current is applied to the water in a fuel cell,
    H2 protons move through a Proton Exchange
    Membrane (PEM) and unite with electrons (e- on
    the other side of the membrane to form hydrogen
    gas (H2).
  • Demonstration Electrolysis using a reversible
    PEM fuel cell.

11
How will the hydrogen be used?
  • Use it as any other flammable gas would be
  • Gas grills have been converted to use hydrogen.
  • Internal combustion engines can be retrofitted
    for H2.
  • This may be the quickest way to implement a
    hydrogen economy but may not be the best long
    term solution.
  • Environmental pollutants are few but not zero.

12
How will the hydrogen be used?
  • FUEL CELLS that use hydrogen are currently under
    development to replace internal combustion
    engines and for cogeneration of electricity and
    heat.
  • Fuel cells are 50-60 efficient compared to
    internal combustion engines that are 15-20
    efficient.
  • There are no moving parts and run silently.
  • There is little maintenance.
  • The fuel used is proportionate to the load.
  • There are no environmental pollutants.
  • The only byproducts are water and heat (which is
    why they are perfect for use in spacecraft!).
  • Demonstration Car with PEM running on hydrogen
    gas.

13
How does a fuel cell work?
  • A model of a reversible PEM fuel cell.
  • It changes water to H2 and O2 if electrical
    energy is supplied and H2 and O2 to water (H2O)
    if hydrogen is supplied.

14
Fuel Cell Animation
15
What is a fuel cell system?
16
What is the history of the fuel cell?
  • Sir William Grove (a British lawyer) discovered
    the process by which fuel cells operate in 1839!
  • Groves discovery was called a gas battery but
    had a very low energy capacity.
  • Future development was slow mostly due to the
    rapid corrosion of the electrodes.
  • In the 1950s, Francis Tom Bacon succeeded in
    producing the first practical fuel cell.
  • In the 1960s the first PEM fuel cells were
    developed by General Electric and chosen by NASA
    for the space program. The fuel cell used a
    membrane that had a working lifetime of about 500
    hours.

17
What is the history of the fuel cell?
  • A few months later Dupont finished development on
    an improved membrane that had a lifetime of
    thousands of hours.
  • NASA had already made its choice of the GE fuel
    cell membrane and this decision is thought to
    have held back the development of proton exchange
    membrane (PEM) fuel cells by at least 15 years!
  • Modern emphasis on fuel cell development began
    in the 1980s.

18
What are some of the challenges facing fuel cell
development?
  • How to increase the efficiency of the cells
  • Currently 50 at full power and 60 at half power
    consumption.
  • Cogeneration (making use of the heat and
    electricity) reaches 90.
  • Development of better materials that will
    produce more power from the cells.
  • Decreasing internal resistance when a stack of
    fuel cells is used.

19
What are some of the challenges facing fuel cell
development?
  • How to reduce the capital costs
  • In the stationary power market, fuel cells would
    be competitive at a cost of 1500/Kilowatt
    present cost is 4000!
  • In automobiles the competitive cost is
    60-100/Kilowatt!!!!
  • Possible reductions may be made in the areas of
  • Lower cost materials (platinum 5000/pound and
    rhodium in the range of 9000/pound).
  • Reducing the complexity of an entire system.
  • Minimize temperature restraints.
  • Scaling up and streamlining production.

20
What are some of the challenges facing fuel cell
development?
  • How to increase the rate of the chemical
    reactions associated with the hydrogen formation
    and the fuel cell
  • Reaction rates are increased by
  • Higher temperatures.
  • Greater concentrations of reactants.
  • More surface area of any solid reactants.
  • Monitoring the frequency of light striking the
    reaction.
  • Catalysts (most research is being done in this
    area). Platinum is the chief catalyst and still
    is the best so research is directed at using the
    minimum amount possible.

21
What are some of the challenges facing fuel cell
development?
  • Developing safe and convenient hydrogen storage
  • Hydrogen in not commonly thought of as a safe
    fuel in part because of the belief that the
    Hindenburg disaster of 1937 was caused by a
    hydrogen explosion. Recent research however
    supports the theory that the rapid burn was
    caused by the flammable nature of the fabric
    covering!
  • In fact hydrogen is considered to be safer than
    gasoline
  • It quickly escapes upward into the atmosphere vs.
    flowing under a vehicle.
  • It burns quickly and must have the right ratio of
    oxygen.
  • Gasoline vapors are a known carcinogenHydrogen
    nontoxic.
  • Vehicles with hydrogen storage have been tested
    and are safe.

22
But the challenge is.
  • Hydrogen is a very small molecule so storage and
    transport systems must be capable of keeping this
    small molecule containedthink about how a helium
    balloon quickly loses its gashydrogen would be
    even faster.
  • Hydrogen is a gas and and as such requires a very
    large volume of storage capacity. To travel 300
    miles using a PEM fuel cell would require 3600
    liters (36 cubic meters) of hydrogen at normal
    temperature and pressure.
  • Liquifying hydrogen like we do propane (LP) is
    costly and the pressure in the tanks would be
    dangerously high.
  • Recent developments have concentrated on
    absorbing hydrogen into metal hydrides. It may
    be possible that the fuel for a 300 mile trip
    could be stored in a volume of 50 liters.

23
Storage challenges.
Hydrogen tanks fill the trunk of this sports car.
24
And some possible solutions???
25
What are some of the challenges facing fuel cell
development?
  • Development of a hydrogen production and
    distribution infrastructure.
  • Options for production are
  • large central solar stations electrolyzing water
    to hydrogen
  • smaller on site production facilities.
  • There will be massive costs to convert refueling
    stations. Some estimate in the range of 300
    billion in the USA alone!
  • One must remember however that this cost will be
    spread over many yearsthe time frame for our
    last infrastructure change from horses to
    automobiles took 20 years.

26
And just think about the infrastructure job
market
  • Hydrogen fuel production and distribution
    personnel will be in demand.
  • Qualified service and maintenance personnel will
    be needed.
  • Continued research and development will be
    imperative.

27
Where are we now?
  • There are several types of fuel cells in various
    stages of development

28
Where are we now?
  • International cooperation to develop a hydrogen
    economy is strong
  • November 2003 the worlds leading fuel cell
    organizations announced that they have entered
    into a cooperative agreement to advance
    commercialization of fuel cells
    worldwiderepresented are more than 300
    businesses and research institutions!
  • Governments are negotiating multilateral programs
    to promote fuel cells and hydrogen.
  • Automakers from around the worldAsia, Europe,
    America are forming coalitions to develop fuel
    cell cars.

29
Where are we now?
  • Two broad categories of fuel cell technology are
    developing Stationary or on site for homes and
    businesses and mobile, especially in the area of
    transportation.
  • STATIONARY
  • Dow Chemical Company and General Motors have
    agreed to develop the largest fuel cell
    installation (June 2003). This should ultimately
    produce enough electricity to power 25000 homes.
    The benefit of this plan is that GM will move
    from building lab specimens to production fuel
    cells and DOW will acquire clean energy.
  • A few homes have smaller solar/hydrogen fuel cell
    systems for cogeneration of electricity and heat.

30
Where are we now?
  • MOBILE
  • Almost forgotten is that there is a real
    possibility that fuel cells will replace
    batteries in consumer electronicsjust add a few
    milliliters of alcohol when needed!
  • PEM fuel cells are the area of most research and
    development for automobiles. At the November
    2003 Tokyo Motor show Toyota, Nissan, and Suzuki
    concept cars drew the most attention, but
  • Japan carmakers like Mazda were also showing
    hydrogen internal combustion engines at the show.
  • January 2004, California unveils a plan to
    provide an Interstate hydrogen fueling network of
    200 stations within the next decade.

31
Reality and vision
  • A methanol fuel cell could provide power to small
    electronic devices up to 20 times longer than a
    battery. The last problem for this technology is
    to prove that the cells can be mass produced
    cheaper than batteries.
  • Some banks and organizations that cannot afford
    to lose power are using fuel cells to provide
    complete security of supply. More to come?
  • Provided there is a fuel supply, the fuel cell
    can be put in any size needed at a point of use
    and provide 10s of thousands of uninterrupted
    hours of electricity.
  • Our high-voltage national electrical grid is not
    very efficient. A combination of fuel cell,
    photovoltaic, and solar energy technology could
    eventually replace the grid with an efficient,
    low polluting source of energy.
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