Hydrogen as a Fuel and Its Storage for Mobility and Transport
- PDF / 539,348 Bytes
- 5 Pages / 612 x 792 pts (letter) Page_size
- 101 Downloads / 174 Views
Hydrogen as a Fuel and Its Storage for Mobility and Transport Louis Schlapbach, Guest Editor Abstract This brief article describes the content of this issue of MRS Bulletin on Hydrogen Storage. Hydrogen is a powerful, clean, synthetic fuel with the inconvenient property of being an ideal gas under ambient conditions. In order to use hydrogen efficiently as a fuel, compacting it for mobile storage is a key issue. As an introduction to the following seven contributions on different storage techniques and their potential, we start with a description of the technical and socioeconomic aspects of the mobility and transport issues involved and present an overview of volumetric and gravimetric storage densities for hydrogen. Keywords: fuel cells, energy density, hydrogen storage, liquid hydrogen, metal hydrides.
Introduction In industrialized countries, one-third to one-half of the energy generated annually is used to power buildings and another third is used to move people and goods. As energy is rather inexpensive to produce, the applied energy technologies are often in the low-technology, low-efficiency range. The need to move people and goods continues to increase with increasing globalization, but the sustainability and safety of the energy supply to meet these needs are questionable. In terms of mass and distance, transport by air consumes the most energy, followed by road travel, then rail. Vehicles can be linked to a power line with a continuous supply of energy (electric trains) or they can carry their energy or produce it on board (trucks, cars, bicyclists, airplanes, submarines). Combustion and electricity are the main methods of supplying energy for mobility and transport. Will this change in the future? Many other high-energy-density, reversible, and controllable chemical reactions may be considered when shortages in the energy supply or environmental issues force us to look for alternatives. Thermally or electrochemically driven
MRS BULLETIN/SEPTEMBER 2002
processes forming oxides, halides, nitrides, carbides, or hydrides with elements and compounds of Periods 1, 2, and 3 should be evaluated. But we dream of another solution: hydrogen as a synthetic fuel.
Why Hydrogen? Hydrogen1–3 is the most abundant element in the universe (75 at.%). On Earth, we find it in small quantities in air and, of course, in unlimited amounts but chemically bound in H2O. It is a nontoxic and highly volatile gas. In the area of energy technology, we find hydrogen (1) in gaseous, liquid, or solid hydrocarbons; (2) in nuclear fission and fusion processes; and (3) as synthetic fuel produced by the dissociation of H2O or hydrocarbons using primary energy (coal and other fossil fuels, electricity or heat from nuclear or renewable energy, photons). Hydrogen is the simplest element in the periodic table, with just one electron. As a gas, it exists in the form of molecular H2, which liquefies at 21 K and solidifies at 14 K. Solid hydrogen is a molecular insulator. Under high pressure, it should transform into an atomic solid, the simple
Data Loading...
