Hydrogen on-board

In 1998 a report prepared for the California Air Resources Board (CARB) called Status and Prospects of Fuel Cells as Automotive Engines favored methanol fuel cell stacks in cars over a direct-hydrogen infrastructure. Hydrogen is not as ready for private automobiles because of the difficulties and costs of storing hydrogen on board and the large investments that would be required to make hydrogen more available. 

Methanol has a number of advantages for powering fuel cell vehicles. As the 2001 study for the caFCP noted, these include methanol s immediate availability without new upstream infrastructure, high hydrogen-carrying capacity, and ability to be readily stored, delivered, and carried on-board without pressurization. 22 In short, our transportation system and its infrastructure favor liquid fuels. Fuel cell vehicles with onboard methanol reformers would have very low emissions of urban air pollutants. Daimler-Chrysler has introduced demonstration fuel cell vehicles that convert methanol to hydrogen on board. 

Goals for Hydrogen On-Board Storage to Achieve Minimum Practical Vehicle... 

Gasoline and other higher hydrocarbons may be converted to hydrogen on board cars by the autothermal processes, using suitable catalysts (Ghen-ciu, 2002 Ayabe et ah, 2003 Semelsberger et ah, 2004). Partial oxidation may also be combined with the palladium-catalyst membrane reactors mentioned in section 2.1.1 (Basile et ah, 2001). 

Methanol has received attention as a means to carry hydrogen on board a fuel cell powered vehicle, see e.g.. Refs. [57-59]. Indeed, the reverse of the 2 step mentioned above, the conversion of methanol to synthesis gas, is facile at low... 

Sandia s design thermally actuates an exothermic reaction of metal hydride with water to generate the hydrogen on board the microsystem. The pressure created by this reaction and the low viscosity of the hydrogen enable the high flow rate of the mobile phase, which, in turn, enables the desired 2 -second chromatographic separation. 

The containers are subdivided into four t)tpes, which are depicted in Fig. 4.33. Simple metal containers are suitable for storage of gases at low pressures. In order to withstand higher pressures, the containers are wrapped with fibers. For natural gas (ca. 200-250 bar) glass fibers are used very often. For the pressures of 350-700 bar as used for hydrogen on-board vehicles the only suitable wraps are the ones with carbon fiber, which has the necessary tensile strength. 

Description. "DaimlerChrysler, headquartered in Auburn Hills, Michigan, has been pioneering fuel ceU technology development decisively since 1994, when it began a program to develop methanol fuel cells for its own use. In fact, DaimlerChrysler and Toyota have already built prototype fuel cell vehicles that cleanly and efficiently reform liquid methanol to gaseous hydrogen on board their cars." ... 

An alternative to the use of H2 as fuel is methanol, which is a liquid fuel and easy to handle. This can be directly transformed to electrical current in a DMFC (direct methanol fuel cell). The DMFC allows a simple system design. However, presently achieved performance data of DMFC is not satisfactory and material costs are too high. As another alternative, methanol or hydrocarbons (e.g. natural gas, biogas) can be transformed to hydrogen on board the electric vehicle by a reformation reaction. This allows use of the H2-PEFC cell, which has a higher level of development. The reformate feed gas may contain up to 2.5% carbon monoxide (CO) by volume, which can be reduced to about 50ppm CO using a selective oxidizer (Wilkinson et al. [1997]). 

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