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					   氫能源


材料系 蔡文達 教授




             Dec 31th 2009
    二十一世紀前五十年 人類將面臨之十大問題


   ENERGY
   WATER
   FOOD
   ENVIRONMENT
   POVERTY
   TERRORISM & WAR
   DISEASE
   EDUCATION
   DEMOCRACY
   POPULATION
Overview

           Greenhouse Effect
Global warming – mean surface temperature 1850-2006
Overview

                   Needs of New Type of Energy --
                             Renewable energy
            Renewable energy is energy generated from natural resources—such
           as sunlight, wind, rain, tides and geothermal heat—which are renewable
           (naturally replenished).
            In 2006, about 18% of global final energy consumption came from
           renewables




Monocrystalline solar cell    wind turbines
Types of Energy
 Biomass                Renewable energy
 Fossil energy              Biomass
 Electricity                Solar energy
                             Batteries
      Hydropower
                             Fuel cells
      Natural gas
                             Wind energy
      Coal
                             Hydrogen energy
      Nuclear energy
                             Wide and tidal power
      Wind
      Geothermal
Efficiency
Hydrogen Storage

                                                                     Why
                                                               Challenge?
                    Gasoline or Hydrogen.

                    On a weight basis, hydrogen has nearly three times the
                    energy content of gasoline. However, on a volume basis
                    the situation is reversed and hydrogen has only about a
                    quarter of the energy content of gasoline.
                   To achieve comparable driving range may require larger amount of H2.

                     For the successful commercialization and market
                     acceptance of hydrogen powered vehicles, the
                     performance targets developed are based on achieving
                     similar performance and cost levels as current gasoline
                     fuel storage systems for light-duty vehicles.
氫能經濟的意義
 由來:
  1970年:「Hydrogen Economy(氫能經濟)」
   首次由美國通用汽車公司提出。
  2000年:美國通用汽車公司在國家石油化學與
   煉製協會的年會上說:「我們的長期遠景是氫
   能經濟」。
 意義:主要為描繪未來氫取代石油成為支撐全
  球經濟之主要能源後,整個氫能源生產、輸送、
  貯存及使用之市場運作體系。
Overview

           Building Hydrogen Economy
Overview
Overview


                          H2 utilization (Fuel cell)
           A fuel cell is an electrochemical conversion device. It produces electricity
           from fuel (on the anode side) and an oxidant (on the cathode side), which
           react in the presence of an electrolyte.




              Fig. Direct-methanol fuel cell             Fig. Scheme of fuel cell
Overview


               H2 on-board vehicle application
            A hydrogen vehicle is a vehicle that uses hydrogen as its on-board
           fuel for motive power. The term may refer to a personal transportation
           vehicle, such as an automobile, or any other vehicle that uses hydrogen
           in a similar fashion, such as an aircraft.




                Fig. Hydrogen station
Hydrogen Storage

                                                                     Why
                                                               Challenge?
                                          Gasoline or Hydrogen.
                    On a weight basis, hydrogen has nearly three times the
                    energy content of gasoline. However, on a volume basis
                    the situation is reversed and hydrogen has only about a
                    quarter of the energy content of gasoline.
                   To achieve comparable driving range may require larger amount of H2.

                     For the successful commercialization and market
                     acceptance of hydrogen powered vehicles, the
                     performance targets developed are based on achieving
                     similar performance and cost levels as current gasoline
                     fuel storage systems for light-duty vehicles.
• Overview of hydrogen energy
Overview


                            Hydrogen Energy
           If the energy used to split the water were obtained from renewable or
           Nuclear power sources, and not from burning carbon-based fossil fuels,
           a hydrogen economy would greatly reduce the emission of carbon
           dioxide and therefore play a major role in tackling global warming.




             →                                                        →
Overview


                        Why hydrogen ?
                Clean , Renewable and Sustainable .
                “ The choice for the future .”
           H2
                Hydrogen is the only chemical energy carrier that
                has the potential to used without generating
                pollutants to the atmosphere.
                Environmentally friendly.
                Hydrogen fueled heat engines can be optimized by
                the manufacturer to operate at much higher thermal
                efficiencies than heat engines powered with
                traditional hydrocarbon fuels.
                Efficient combustion.
Overview

                                 H2 production
            Hydrogen is commonly produced by extraction from hydrocarbon
           fossil fuels via a chemical path. Hydrogen may also be extracted from
           water via biological production in an algae bioreactor, or using
           electricity (by electrolysis), chemicals (by chemical reduction) or heat
           (by thermolysis)

           Biological production : Biohydrogen can be produced in an algae
           bioreactor. In the late 1990s it was discovered that if the algae is
           deprived of sulfur it will switch from the production of oxygen, i.e.
           normal photosynthesis, to the production of hydrogen.




                            Fig. An algae bioreactor for hydrogen production.
Overview

                              H2 production
            Electrolysis : Hydrogen can also be produced through a direct
           chemical path using electrolysis. With a renewable electrical energy
           supply, such as hydropower, wind turbines, or photovoltaic cells,
           electrolysis of water allows hydrogen to be made from water without
           pollution.

           Chemical production : By using sodium hydroxide as a catalyst,
           aluminum and its alloys can react with water to generate hydrogen
           gas.
                      Al + 3 H2O + NaOH → NaAl(OH)4 + 1.5 H2
              Solar Energy




                                                 Fig. Photoelectrochemical cell
   Methods for Hydrogen Storage
• Gas form

• Liquid form

• Solid form
                      Hydrogen storage methods

   High pressure gas cylinders (up to 800bar)
   Liquid hydrogen in kryogenic tanks(at 21 K)
   Absorbed hydrogen on materials with a large specific surface
    area(T<100 K)
   Adsorbed on interstial sites in a host metal(at ambient pressure and
    temperature)
   Chemically bond in covalent and ionic compounds (at ambient
    pressure, high activity)
   Oxidation of reactive metals, e.g. Li,Na, with water
Ref: A. Zu¨ttel, P. Wenger, S. Rentsch, P. Sudan,Ph. Mauron, Ch. Emmenegger,Journal of Power Sources 118 (2003) 1–7.
儲氫方法    優點         缺點
壓縮儲氫                        ,
        成本低,應用廣泛。 能量密度低,壓力高 消
        充放氣速度快,且在常 耗較多的壓縮功。
        溫下就可進行運輸和使 氫氣易泄漏和容器爆破
        用方法方便。     等不安全因素,使用和
                   運輸有危險。
液化儲氫    能量密度最大,是一種 能量損失大,成本高。
        輕巧緊湊的儲氫方式。 液氫貯存需要極好的絕
                   熱裝置來隔熱貯存容器
                   龐大。
金屬氫化物   壓力平穩,充氫簡單、 儲氫量小。
儲氫         方便      金屬氫化物易破裂且材
        單位體積的儲氫密度大 料成本高。
        運輸和使用安全。
吸附儲氫    碳奈米管的儲氫能力可 生產奈米碳管的技術尚
        達 10%以上。   不成熟,且價格昂貴。
Overview


                                        H2 storage
           High pressure gas cylinders (up to 800bar)
           Liquid hydrogen in cryogenic tanks(at 21 K)




                                            Fig. Liquid hydrogen tank for a hydrogen car
                   Fig. gas cylinders
Overview


                                   H2 storage
            Adsorbed hydrogen on materials with a large specific surface area
           (T<100 K) : carbon materials or zeolite

            Adsorbed on interstitial sites in a host metal (at ambient pressure and
           temperature) : metal hydride

           Chemically bond in covalent and ionic compounds (at ambient
           pressure, high activity) : complex metal hydride




                   Fig. Carbon nanotube
                                                       Fig. Hydrogen in metal matrix
                                                                  Gasoline
Hydrogen Storage

                   US DOE H2 storage
                   system targets                           or   Hydrogen


                                                  6 wt%          9 wt%




                   The 2015 targets represent what is required based on achieving
                   similar performance to today’s gasoline vehicles (greater than 300
                   mile driving range) and complete market penetration.
                                                      Hydrogen
Hydrogen Storage


                                                       Storage
                                                       Methods




Current approaches include:
Conventional      1. High pressure H2 cylinders (Gas)
Storage           2. Cryogenic and liquid hydrogen (Liquid)
                      Increasing H2 density by Pressure and Temp. control.

Advanced Solid      3. High surface area sorbents (Solid)
Materials Storage   4. Metal hydrides (Solid)
                      Using little additional material to reach high H2 density.
Summary




          The materials science challenge of hydrogen storage is
          to understand the interaction of hydrogen with other
          elements better, especially metals.
          Hydrogen production, storage, conversion has reached a
          technological level, although plenty of improvements
          and new discoveries are still possible.
END




      Thank you for your kind attention.




                  Department of Materials Science and Engineering
                                  National Cheng Kung University
                     Corrosion Prevention Laboratory

				
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