THE TRANSACTIONS OF THE FUEL CONFERENCE
TABLE 1 1 THE DIFFERENT TYPES OF FUEL CELLS PT ON CARBON MILITARY ENERGY STORAGE COMBINE HEAT AND POWER DECENTRALIZED SYSTEMS AND START UP TIME AMONG ALL KINDS OF FUEL CELLS PROTON EXCHANGE MEMBRANE PEM FUEL CELLS ARE COMPACT AND LIGHTWEIGHT WORK AT LOW TEMPERATURES WITH A HIGH OUTPUT POWER DENSITY AND OFFER SUPERIOR SYSTEM START UP AND SHUTDOWN PERFORMANCE 6 THESE ADVANTAGES HAVE SPARKED DEVELOPMENT EFFORTS IN VARIOUS QUARTERS OF INDUSTRY TO OPEN UP NEW FIELD OF APPLICATIONS FOR PEM FUEL CELLS INCLUDING TRANSPORTATION POWER SUPPLIES COMPACT COGENERATION STATIONARY POWER SUPPLIES PORTABLE POWER SUPPLIES AND EMERGENCY AND DISASTER BACKUP POWER SUPPLIES 1 THE ADVANTAGES OF FUEL CELLS IMPACT PARTICULARLY STRONGLY ON COMBINED HEAT AND POWER CHP SYSTEMS FOR BOTH LARGE AND SMALL SCALE APPLICATIONS AND ON MOBILE POWER SYSTEMS ESPECIALLY FOR VEHICLES AND ELECTRONIC EQUIPMENT SUCH AS PORTABLE COMPUTERS MOBILE TELEPHONES AND MILITARY COMMUNICATIONS EQUIPMENT THESE AREAS ARE THE MAJOR FIELDS IN WHICH FUEL CELLS ARE BEING USED HOWEVER THERE ARE VARIED ADVANTAGES WHICH FEATURE MORE OR LESS STRONGLY FOR DIFFERENT TYPES AND LEAD TO DIFFERENT APPLICATIONS FIGURE 1 FIGURE 1 1 OPERATING PRINCIPLE OF VARIOUS TYPES OF FUEL CELLS FIGURE 1 2 CHART TO SUMMARIZE THE APPLICATIONS AND MAIN ADVANTAGES OF FUEL CELLS OF DIFFERENT TYPES AND IN DIFFERENT APPLICATIONS THE MOST IMPORTANT ATTRIBUTES OF FUEL CELLS FOR STATIONARY POWER GENERATION ARE THE HIGH EFFICIENCIES AND THE POSSIBILITY FOR DISTRIBUTED POWER GENERATION BOTH LOW TEMPERATURE AND HIGH TEMPERATURE FUEL CELLS COULD IN PRINCIPLE BE UTILISED FOR STATIONARY APPLICATIONS THE LOW TEMPERATURE FUEL CELLS HAVE THE ADVANTAGE THAT USUALLY A FASTER START UP TIME CAN BE ACHIEVED THE HIGH TEMPERATURE SYSTEMS SUCH AS SOFC AND MCFC GENERATE HIGH GRADE HEAT WHICH CAN DIRECTLY BE USED IN A HEAT CYCLE OR INDIRECTLY USED BY INCORPORATING THE FUEL CELL SYSTEM INTO A COMBINED CYCLE SOFCS AND MCFCS ALSO HAVE THE ADVANTAGE THAT THEY CAN OPERATE DIRECTLY ON AVAILABLE FUELS WITHOUT THE NEED FOR EXTERNAL REFORMING FOR A SMALL DISTRIBUTED POWER SYSTEM E G SINGLE HOME OR MULTIPLE HOME POWER GENERATION A PEM SOFC OR PAFC COMBINED WITH A HEAT CYCLE COULD BE USED TO PROVIDE ALL THE NEEDS FOR A HOME THE PAFC START UP TIME IS MUCH LOWER THAN THIS FOR HIGH TEMPERATURE SYSTEMS WHICH MAKES IT MORE ATTRACTIVE FOR SMALL POWER GENERATION THE HEAT GENERATED BY THE FUEL CELL SYSTEM CAN BE EMPLOYED FOR HEATING AND PROVIDING THE HOME WITH HOT WATER THE PAFC PRODUCES ENOUGH STEAM TO OPERATE A STEAM REFORMING SYSTEM WHEREAS THE PEM SYSTEM DUE TO ITS LOWER OPERATION TEMPERATURE IS NOT ABLE TO SUPPLY THE NECESSARY HEAT SMALL POWER PLANTS IN THE RANGE ABOVE 250 KW CAN BE OPERATED BY HIGH TEMPERATURE FUEL CELL SYSTEMS THE HIGH GRADE HEAT OBTAINED FROM THESE SYSTEMS CAN BE EXCHANGED AT A BROAD TEMPERATURE RANGE LEAVING THE POSSIBILITY OF DIRECT HEAT USE OR FURTHER ELECTRICITY GENERATION BY STEAM ENGINES THE START UP TIME OF THESE SYSTEMS ARE LONGER THAN FOR LOW TEMPERATURE SYSTEMS BUT THE ADVANTAGES OF BEING ABLE TO OPERATE THE SYSTEM WITHOUT EXTERNAL REFORMING AND THE HIGHER EFFICIENCIES OF SOFCS AND MCFCS MAKES THESE SYSTEMS MORE SUITABLE FOR LARGE SCALE POWER PLANTS FOR VEHICULAR APPLICATIONS FUEL CELL SYSTEMS NEED TO BE DIFFERENT FROM STATIONARY POWER GENERATION AVAILABLE SPACE IN VEHICLES IS MUCH MORE CRITICAL AND FAST RESPONSE TIMES AND START UP TIMES ARE REQUIRED THE CONTROVERSIAL AFC HAS PROVEN TO BE A SUITABLE SYSTEM FOR HYBRID VEHICLES AS LONG AS A CIRCULATING ELECTROLYTE IS USED AND PURE HYDROGEN IS SUPPLIED TO THE FUEL CELL PURE HYDROGEN DISTRIBUTION CENTRES ARE NOT WIDELY SPREAD OVER THE WORLD AND THUS IT IS TO BE PREDICTED THAT AFC VEHICLES WILL BE LIMITED TO SPECIFIED TYPES E G FLEET BUSES AND OTHER CENTRALISED VEHICLES FOR SPACE VEHICLES AFC TECHNOLOGY IS ESTABLISHED AND ALTHOUGH THE TENDENCY TO CHANGE TO PEM FUEL CELLS IS ALSO PENETRATING THE SPACE INDUSTRY IT IS LIKELY THAT AFC SYSTEMS WILL BE EMPLOYED FOR MANY MORE YEARS IN SPACE PEM SYSTEMS STILL NEED TO BE TESTED CONCERNING THE STRINGENT REQUIREMENTS RELIABILITY OF OPERATION ETC FOR SPACE APPLICATIONS PROTOTYPE FUEL CELL POWERED VEHICLES HAVE RECENTLY BEEN DEMONSTRATED BY SEVERAL CAR MANUFACTURES ALL OF THE VARIOUS DEMONSTRATION VEHICLES ARE BASED ON A BASIC CONCEPTUAL DESIGN COMBINING THE PROTON EXCHANGE MEMBRANE PEM FUEL CELL WITH AN ELECTRIC DRIVE THE PEMFC IS REGARDED AS IDEALLY SUITED FOR TRANSPORTATION APPLICATIONS DUE TO ITS HIGH POWER DENSITY HIGH ENERGY CONVERSION EFFICIENCY COMPACTNESS LIGHTWEIGHT AND LOW OPERATING TEMPERATURE BELOW 100 C THE RECENT PEM DRIVEN ELECTRIC VEHICLES HAVE DEMONSTRATED THE TECHNICAL FEASIBILITY OF THE CONCEPT HOWEVER AMONG ALL APPLICATIONS FOR FUEL CELLS THE TRANSPORTATION APPLICATION INVOLVES THE MOST STRINGENT REQUIREMENTS REGARDING VOLUMETRIC AND GRAVIMETRIC POWER DENSITY RELIABILITY AND COSTS THE HIGHER ENERGY DENSITY OF A LIQUID FUEL GUARANTEES A DRIVING RANGE SIMILAR TO THAT OF INTERNAL COMBUSTION ENGINE VEHICLES THE FUEL FAVOURED BY MANY CAR MANUFACTURERS IS METHANOL FROM WHICH HYDROGEN CAN BE PRODUCED ON BOARD BY STEAM REFORMING THE REFORMING OF THE FUEL HOWEVER LEADS TO SLOWER RESPONSE TIMES AND EXTENSIVE GAS CLEAN UP PROCEDURES NEED TO BE CARRIED OUT TO SUPPLY THE FUEL CELL WITH HIGH GRADE HYDROGEN BECAUSE OF THE DIFFICULT THERMAL INTEGRATION AND THE SIZE OF THE REFORMER AND GAS CLEANING UNIT A DIRECT METHANOL FUEL CELL DMFC WHERE METHANOL IS OXIDIZED DIRECTLY AT THE ANODE WOULD BE MORE DESIRABLE FOR MOBILE SYSTEMS HIGHER SIMPLICITY OF THE SYSTEM THEREFORE IN ADDITION TO THE REFORMER FUEL CELL COMBINATION DMFCS USING METHANOL WATER VAPOUR OR LIQUID METHANOL WATER MIXTURES AS FUEL ARE BEING INVESTIGATED AND DEVELOPED THE DEVELOPMENT OF THE DMFC FOR TRANSPORTATION APPLICATIONS HOWEVER IS LESS ADVANCED AS COMPARED TO THE INDIRECT PEMFC AND HAMPERED BY PROBLEMS OF REDUCED POWER DENSITY CAUSED BY METHANOL PERMEATION THROUGH THE MEMBRANE AND POISONING OF THE ELECTROCATALYSTS RECENT PROGRESS REGARDING POWER DENSITY AND COMPACTNESS OF DMFC STACKS ARE ENCOURAGING AND INDICATE THAT THIS CONCEPT MAY BE COMPETITIVE IN VEHICLES DUE TO THE MULTITUDE OF REALIZED DEMONSTRATION VEHICLES WITH PEMFC TECHNOLOGY IT APPEARS A FORGONE CONCLUSION THAT ONLY FUEL CELLS BASED ON THE PEM TECHNIQUE ARE SUITABLE FOR TRANSPORTATION APPLICATIONS SYSTEM CONSIDERATIONS HOWEVER SHOW BENEFICIAL PROPERTIES OF HIGH TEMPERATURE FUEL CELLS THAT COULD SIMPLIFY THE SYSTEM CONSIDERABLY CERTAINLY PROTON EXCHANGE MEMBRANE FUEL CELLS PEMFCS HAVE THE ADVANTAGE OF THE LOW OPERATING TEMPERATURE AND THE HIGH POWER DENSITY USING ALCOHOLS OR HYDROCARBONS AS FUEL THERMAL INTEGRATION IS COMPLICATED THE MAIN ADVANTAGE OF SOFCS COMPARED TO PEMFCS CONCERNS THE UNPROBLEMATIC USE OF HYDROCARBON FUELS SOFCS DO NOT REQUIRE PURE HYDROGEN AS FUEL BUT CAN BE OPERATED ON PARTIALLY PRE REFORMED HYDROCARBONS E G GASOLINE THEY DO NOT EXHIBIT ANY SIGNIFICANT POISONING PROBLEM SEVERAL STUDIES HAVE INVESTIGATED THE POTENTIAL OF SOFC FOR TRANSPORTATION APPLICATIONS AND HAVE POINTED OUT THIS ADVANTAGE THESE BENEFICIAL FACTORS HAVE BEEN RECOGNIZED RECENTLY LEADING SEVERAL COMPANIES TO DEVELOP SOFCS AS AUXILIARY POWER UNITS APU FOR GASOLINE VEHICLES THE APU REPLACES THE TRADITIONAL BATTERY AND PROVIDES FURTHER ELECTRICAL ENERGY FOR AIR CONDITIONING AND CAR ELECTRONICS FOR PORTABLE APPLICATIONS LIKE