Chemical and Functional Properties of Food Saccharides

© 2004 by CRC Press LLC
Also, 1 mole of CH 4 produces 4 moles of H 2, yielding more primary energy (10 to
12 kWh). At the anode, the hydrogen molecule reacts with the carbonate anion
supplied by the electrolyte as a eutectic mixture melting at 480°C:
H 2 + CO 3 2– → H2O + CO 2 + 2e – (free energy)
The CO 2 of the reforming reaction is channeled to the cathode together with O 2 from
air to restore CO 3 2– :
CO 2 + → O 2 + 2e – (consumed energy) → CO 3 2–
Due to the electrolyte temperature of ca. 650°C, the emerging air of 550°C can
support the reforming reaction and also drive a turbine at 450°C, boosting el beyond
65%. Residual steam can serve for heating and refrigeration systems (NaBr absorption).
5 η
A superior reforming can be achieved by ethanol:
C 2H 5OH + 3H 2O + thermal energy → 2CO 2 + 6H 2
with 1 mole of ethanol providing 6 moles of H2. Furthermore, ethanol is readily
stored like oil, warranting service for longer periods. The lifetime of an MCFC
exceeds 40,000 h (4.5 years) before carbonate corrosion attacks the nickel frames
at total efficiencies beyond 85%. Self-supply of farmers is feasible because traces
of water do not disturb MCFCs. Self-supply holds true for PAFC also (based on
phosphoric acid at 200°C) and even more for the ceramic oxide FC at 950°C with η
el up to 70%. The solid oxide fuel cell (SOFC) electrolyte is ZrO2 doped with 8%
YO2 (yttrium oxide) transporting O 2–
2 from anode to cathode. Again, catalysts of the
Pt group are not required. Their immobility predestines them for installation in house
blocks, etc., feeding their surplus kilowatt-hour-power into the grid. Likewise, battery-driven
cars can be loaded on premises, reserving PEMFC-equipped vehicles
for longer distances.
21.3 CAN BIOMASS REPLACE OIL?
In this context, one should remember that global oil reserves are estimated close to
2 to 3 billion barrels, 6 forecasting the end of the oil age within this century. The
surface of our planet is made up of 28% land (148 × 10 6 km 2 ) and 72% sea (362
×10 6 km 2 ), furnishing the rain to enable photosynthesis on land, primarily on arable
regions (4.8% of 510 × 10 6 km 2 = 24.5 × 10 6 km 2 ) and forested areas with more
than 30 in of rainfall per annum whereas pastures of varying qualities receive 10 to
30 in of rainfall only (4.5%, i.e., 23 × 10 6 km 2 ).
The residual land surface of 100 × 10 6 km 2 is either mountainous or desert, ca.
20% (30 × 10 6 km 2 ), with below 10 in of precipitation. Intensive agriculture requires
20–40 in per annum, but extensive grasslands require only 10–20 in., yielding shorter
blades. For growth of plants, the coincidence of sunshine and rain is of paramount
importance, and also the kind of precipitation, for example, convectional (tropical),