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11 The Hydrogen Fuel Infrastructure for Fuel Cell Vehicles Venki Raman, Air Products and Chemicals For hydrogen fuel to be a viable fuel for transportation, an extensive hydrogen fuel infrastructure must first be built. In assessing whether such a network is desirable, the benefits and challenges associated with introducing hydrogen as a fuel must first be addressed. In addition to infrastructure issues, hydrogen production on an industrial scale must be examined, and the changes needed for it to become a mass market fuel must be addressed. There are many positive factors related to hydrogen fuel. Most technologists involved in the development of fuel cell vehicles realize that hydrogen fuel offers lower vehicle costs due to the simpler designs and fewer pieces of equipment onboard the automobiles as opposed to reforming gasoline to make hydrogen on the vehicles. While vehicle fuel storage designs are not optimal, existing systems for compressed (high-pressure) hydrogen are operable. Once hydrogen is on a vehicle, there are no pollutants emitted, only water vapor. Finally, using fossil fuels to produce hydrogen allows maximum energy flexibility the ability to switch from fossil fuels today to renewable starting energy sources in the future, since the infrastructure would exist. Unfortunately, the lack of a hydrogen infrastructure presents one of the main challenges to introducing hydrogen into the mass market as a transportation fuel. The nation has already seen such a scenario with natural gas it is widely avail- able, has adequately developed technology, and is economical but natural gas has not penetrated the market. There is also the perception that hydrogen is explosive and unsafe, which needs to be countered by public education. High-pressure gaseous hydrogen or cryogenic liquid hydrogen are inconvenient for individuals to use, and hence better hydrogen storage solutions are required. One desirable option involves solid-state systems operating at low pressure and ambient tem- 66
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THE HYDROGEN FUEL INFRASTRUCTURE FOR FUEL CELL VEHICLES 67 peratures. Inadequate hydrogen storage options may be the greatest barrier to mass hydrogen use. Fleet applications can certainly lower the hurdles to the entry of hydrogen into the fuel market. Usually, bus fueling is done once a day at a central depot. The market can be readily served in the same fashion as existing industrial hydrogen market applications. In fact, there have already been several projects with fleets that have given us the knowledge to clear some hurdles to pave the way for the introduction of hydrogen into the fuel market. Presently, 40 million tons of hydrogen are produced worldwide each year. Ninety-five percent of the hydrogen produced is used captively. That is, the hydrogen molecule is made and immediately reacted to refine oil or to produce ammonia, methanol, and other chemicals. Another 5 percent of the 40 million tons of hydrogen is produced by the merchant hydrogen market including large industrial gas companies such as Air Liquide, Air Products, BOC, and Praxair for sale to third parties. Eighty percent of the hydrogen produced is made from natural gas steam methane reformation. In addition, there are byproduct streams from which hydrogen can be captured and purified. Hydrogen can be transported as a high-pressure gas or a liquid. The high- pressure gas can be moved economically only approximately 100 miles from the plant because of the weight and size of the metal cylinders needed to contain the gas. Although there are very few applications that require liquid hydrogen, it is the most convenient form for transporting hydrogen over long distances. Liquid
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68 ENERGY AND TRANSPORTATION hydrogen can be moved economically approximately 1,000 miles and is usually revaporized before use. Hydrogen at high pressures can be conveyed from the production plant through a pipeline system to a consumer that can be right across the fence or miles away. Air Products operates several hundred miles of hydrogen pipeline in various parts of the United States and the world through which almost 2,000 tons of hydrogen flow every day. The pipelines are fed through multiple production plants, and numerous customers draw hydrogen from them.) Market projections for fuel cell vehicles in 2015 indicate less than 5 percent penetration of fuel cell vehicles into the worldwide vehicle population. Theoreti- cally, there would be approximately 150,000 buses and between 20 million and 80 million light-duty vehicles, which would consume between 20 million and 90 million tons of hydrogen per year. Worldwide hydrogen merchant capacity is presently 2.5 million tons per year. To meet these future fuel cell vehicle needs, either hydrogen must be produced in large central plants and delivered via one of the three previously mentioned modes (high-pressure gas delivery, liquid delivery, pipeline delivery) or very small on-site hydrogen production plants that use electrolysis or reforming technology must be built. There are many more challenges to overcome. To give a car enough range to operate effectively, the pressure of hydrogen fuel must be between 350 and 700 bar a pressure well in excess of those currently used in industrial practice. The ease and speed of fueling are not at levels sufficient for consumer demand. Because of the intermittent nature of refueling, hydrogen production and storage systems will be required, which are significant cost items in any infrastructure design. Hydrogen flow will need to be metered for payment, but current tech- nologies need to be improved. There have been a number of demonstration programs that have been con- ducted for fuel cell vehicles, all based on delivering liquid hydrogen to the fuel station compression and dispensing it to vehicles. A successful program with the Chicago Transit Authority used a reciprocating liquid pump, which can supply a vehicle at very high pressures. Other demonstration programs at SunLine Transit Agency in Palm Springs and Coast Mountain Transit in Vancouver, Canada, used water electrolysis to produce hydrogen. When fuel cell vehicles begin to be introduced, there will be a very small number that are geographically widespread. This will in turn require small- capacity hydrogen plants, and the sporadic demand will result in inefficient capital utilization and high costs. A new project starting in September 2002 in Las Vegas will test the viability of baseloading the hydrogen plant with a fuel cell power plant and using incremental hydrogen capacity for fueling operations. This ilf this method is to be considered for hydrogen fuel vehicles, the economics and efficiency of liquefying hydrogen must be taken into consideration.
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THE HYDROGEN FUEL INFRASTRUCTURE FOR FUEL CELL VEHICLES 69 "Energy Station" concept will be run for 2 years to understand the economics of this approach. In the early days of the hydrogen transportation market, demonstrations and start-up projects will be fueled by liquid hydrogen or distributed hydrogen gen- erators, like those in development for Las Vegas. This could handle less than a ton of hydrogen per day. As demand grows, there will be larger on-site production plants and perhaps even regional plants that could handle 10 to 100 tons per day. Today, world-scale hydrogen plants are in the size range of 100 to 250 tons a day. As demand for hydrogen as a fuel increases, chemists and chemical engi- neers will be presented with the opportunity to develop low-cost hydrogen production, especially for small-scale plants. Hydrogen demand will grow by orders of magnitude when fuel applications expand. There are many challenges to using hydrogen as a fuel. Some are already being met by adapting existing capabilities for the demonstration programs that have been implemented. There is a logical and stepwise pathway to grow the hydrogen infrastructure by adapting industrial hydrogen production experience to hydrogen fueling demonstrations.