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Transitions to Alternative Transportation Technologies — A Focus on Hydrogen
The Hydrogen-powered ICEV
Hydrogen-powered ICEVs (HICEVs) have been demonstrated by several auto companies including Ford and BMW. BMW even offers a model to the public for lease. The hydrogen ICEV has many of the same advantages as an HFCV in that the fuel can be made from various sources and the primary combustion product is water. However since the HICEV still uses an oil-based lubricant, a small amount of this is consumed and very small CO2 releases result. In addition since combustion still takes place at a high temperature, some NOx emissions also result.
An HICEV can be about 25 percent more efficient than a gasoline ICEV, but this is offset by increases in engine cost resulting from the light nature of hydrogen. It is difficult to get enough air and hydrogen into the cylinders at normal pressure. Either much bigger cylinders are needed or boosting the air pressure through turbocharging or supercharging is needed to achieve the power a gasoline engine provides. Either choice increases the cost.
Perhaps the most difficult technical problem to resolve is storing enough hydrogen on board to travel a reasonable distance. Since the efficiency of the HICEV is only about 60 percent that of an HFCV, much more hydrogen is needed to travel the same distance. This probably will limit the number of HICEVs that enter the market.
Because of the ease in converting an existing gasoline ICEV vehicle design to an HICEV it is likely that if a hydrogen infrastructure were built, some number of HICEVs would also be built. Since the cost of this conversion is much lower than the cost of an HFCV the number could be influenced by future carbon policy or other government actions aimed at increasing hydrogen demand in order to reduce hydrogen cost especially at the beginning of the transition.
manufactured and delivered to a site ready for installation. Research and development has focused on small-scale natural gas reforming and water electrolysis.
This distributed approach likely will include adding hydrogen generating and storage to some existing gasoline filling stations as well as building retail stations specifically designed for hydrogen. The size of the stations can also be increased to become commercial scale (1,500 kg/d), reducing the cost of hydrogen further.
Full-size hydrogen stations, however, require much larger footprints than today’s gasoline equivalent. Typical modern gasoline stations are approximately 6,500 square feet, including a mini-mart. Area requirement is a very significant issue because suitable large sites may be difficult to find in urban areas and acquiring the needed permits is also likely to be difficult. DOE analysis estimates that the footprint for an existing gasoline station will have to be increased by about 7,200 square feet for either a full-size natural gas reformer or a water electrolysis system (Gronich, 2007). Even a smaller unit (e.g., 100 kg/d), would require about 2,200 square feet additional area. In any case, these are significant increases that will limit the number of existing sites that could possibly be used for dispensing hydrogen. This opens up the possibility that many of the hydrogen refueling sites will be at nontraditional locations such as shopping malls and big-box retailer parking areas or even auto dealerships. Box 3.2 discusses the latter option.
Distributed natural gas reforming is the lowest-cost method of delivering hydrogen to an HFCV during this period of low but growing demand for hydrogen. Most large urban areas have an existing natural gas infrastructure allowing its use in such places. For locations in which natural gas is not available, the outer reaches of population centers, or areas between cites along highways. other methods are needed. Water electrolysis is a proven, higher-cost, method of hydrogen production. Table 3.1 summarizes hydrogen
Auto Dealers Selling HFCVs and Hydrogen
Auto dealers selling and servicing HFCVs will need hydrogen on-site for initial fills and likely for some types of service. They may be willing to either sell hydrogen to the general public or to provide land to a fuel supplier at their dealer site. It would be a selling point, especially in the early stages of the transition, because dealers could assure customers that hydrogen fuel would be available at least at their facility and neighboring dealerships. Personnel at the dealership would have to be familiar with fueling procedures anyway, so the need for specially trained personnel would be reduced. Many dealerships also would have sufficient land area, unlike most current gasoline stations.
To see if this concept is feasible, the committee examined General Motors dealerships in the Los Angeles Basin. There are 131 GM dealers in the 2,027 square mile basin, or one for every 15.5 square miles. On average, there is one GM dealership within 2.2 miles of every person, which is not a great driving distance to refuel.
Although this is only one example, and indeed a very simplified way of viewing the concept, it appears that dealerships could contribute to hydrogen availability early in the transition. Dealers and customers would have to adapt to a different mode of business, but this should be feasible. Many other types of locations would also be needed because the number of auto dealerships is small compared to the number of gasoline stations.