Page 67 - MODERN ASPECTS OF ELECTROCHEMISTRY

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Claude Lamy etal.
intermediate-load, pe¸ -load, and dispersed electric utility power genera-
tion; (2) cogeneration (electricity plus heat for chemical industries, apart-
ment buildings, hospitals, shopping centers); (3) transportation and
electric vehicles (cars, motorcycles, buses, trucks, military vehicles, fleet
vehicles, submarines, trains, ships); and (4) portablp power sources (for
remote areas or backpack power sources for soldiers).
Since the advent of the space era in the 1960s there has been an
exponential growth in the number of publications each year on fuel cell
R&D topics.= The energy era, stimulated by the energy crisis of 1973,
further enhanced the growth of such publications. However, in the early
1980s energyeconomists forecast an abundance of oil and natural gas
reserves, and low energyprices (which was confirmed by lower prices of
gasoline, diesel fuel, jet fuel, and heating oil in the 1980s and 1990s than
in the 1940s, t¸ing into consideration the changing value of the U.S.
dollar). The incentive in the late 1980s and early1990s for fuel cell R&D
was environmental pollution, so that there is now an environmental era
for the development of fuel cells. In the United States, emissions (CO,
Nø x , ø 3, particulates, SO 2, etc.) from power plants and transportation
vehicles are at about a similar level and account for over 90% of air
pollutants.

2. Types of Fuel CellsA
This introductory section presents a brief review of the articles on fuel cell
R&D published during the space, energy, and environmental eras. The
reader is referred to selected publications for more details. 1–10 Several
classifications of the types of fuel cells have appeared in the voluminous
literature (boàs, chapters in boàs, reviews and original articles in
journals, and proceedings of conferences and meetings). These classifica-
tions have mainlybeen done according to (1) type of fuel, (2) operating
temperature range and/or electrolyte, or (3) direct or indirect utilization of
o
fuel. For fuel cells operating at low (<100 C) and intermediate tempera-
o
2
2
tures (up to 200 C), H 2 and H -CO (with minimal amounts of CO) are
-CO gas mixture is produced by steam reform-
the ideal fuels; the H 2 2
ing/shift conversion, or partial oxidatiod/shift conversion of the primary
or secondaryorganic fuels. Hydrogen is a secondary fuel, and løp elec -
tricity, is an energy carrier. On a large scale, hydrogen is produced from
the primaryfuels, natural gas, coal, or oil. For high-temperature fuel cell
o
systems (>650 C), a mixture of H 2, CO, and CO 2 produced by steam
reforming can be used in fuel cells quite efficiently(a power plant