PPT Slide
- Integrating small, light weight, inexpensive, and efficient fuel cell engines into automobiles
- Designing storage tanks for sufficient onboard hydrogen storage capacity
- Developing an appropriate hydrogen refueling infrastructure
- Gaining public acceptance
Notes:
- Integrating small, light weight, inexpensive, and efficient fuel cell engines into automobiles
- Designing storage tanks for sufficient onboard hydrogen storage capacity
- Developing an appropriate hydrogen refueling infrastructure
Many analysts believe that the first two challenges are surmountable, but that the third is much more difficult. Progress toward the first challenge has been greatly successful in the last decade as fuel cell power densities have been improved. Critical thermal and water management barriers have been overcome, and the use of expensive platinum catalysts has been greatly reduced.
Storing hydrogen onboard vehicles arises from the very low energy density of hydrogen gas. A more efficient vehicle can travel farther on a smaller quantity of fuel and would therefore require less space for storing fuel. Reductions in vehicle weight by use of super light vehicle components and reductions in air resistance and rolling resistance are effective methods for reducing hydrogen storage requirements. Another method is to redesign the entire vehicle around the storage tanks. The result is an internal rearrangement of supports and components.
**infrastructure: Eventually, renewable sources of hydrogen, such as the sun, wind, and biomass, will be able to compete economically with Hydrogen produced from natural gas or coal. Preparing for renewable hydrogen in the long-term is perhaps the strongest argument for making wise infrastructure choices today.
The storage and delivery of hydrogen fuel are technically challenging because of the low energy density of H gas. These challenges may be met in several ways, including tanker truck delivery of liquid H, pipeline distribution of gaseous H, and tanker truck delivery of H stored in a medium, such as hydride carbon, or glass microspheres, that increase energy density. The most common method of delivering H today is via tanker trucks carrying liquid H, a dense form of H at temps less than –250 C. Given the existence of major centralized hydrogen production facilities in the petroleum and fertilizer industries, excess H could be liquified and delivered to refuleling sites with minimal initial capital costs. A major drawback is the large amount of electricity needed for liquifiication, which could be as much as 30% of the original fuel energy of the H.
The distribution of hydrogen through a network of underground pipelines would be the most efficient long-term delivery option once major centers of H production are established. These pipelines would be similar to natural gas pipelines, but engineered to account for the lower energy density and higher diffusion rate of H. An extensive distribution system would cost hundreds of billions of dollars and require multiple decades of planning and development. The construction of these pipelines would be an efficient and cost effective delivery solution for a large-scale H economy of the future, but it is not a cost effective, timely, or sufficiently adaptable solution for what is needed today: the delivery of small volumes of H to a large number of dispersed refueling sites.
The most likely manner of delivering H to a national fleet of fuel cell vehicles within the next 5 to 20 years would be to extend the practice of reforming natural gas into H used in the petroleum and fertilizer industry.