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Technology Stocks : Ballard Power -world leader zero-emission PEM fuel cells
BLDP 2.625+3.6%3:59 PM EST
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To: Bill Jackson who wrote (1525)12/23/1997 11:47:00 AM
From: Michael Winkler  Read Replies (1) of 5827
 
Bill:
You made a mistake in your analogy of hybrid cars to super-insulated houses. In a house or other building very high levels of insulation(vacuum panels being the ultimate) can reduce energy needed for heating to very low levels. The limits are only heat loss needed for air exchange to keep the air healthy(although much of this can be recovered through an air-to-air heat exchanger) and heat loss through people entering and leaving a building.

In a vehicle the efficiency of a heat engine is limited by the difference between the temperature of the heat source(in this case the flame temperature of gasoline) and the temperature of the heat sink(in this case the temperature of the outside air). In thermodynamics theory a heat engine follows what is called a Carnot cycle. For practical reasons the thermal effeciency of a piston internal combustion engine can probably never be higher than about 30%(conversion of energy in fuel into motion). A fuel cell is not a heat engine so it is not limited by Carnot cycle efficiency. Efficiency of existing fuel cells is already as high as 55%. Long term efficiency may be as high as 70%.

Internal combustion, piston engine cars can be made much more efficient as hybrids, but their maximum efficiency will always be lower than fuel cells. The overall car(piston or fuel cell) can be made much more efficient in a variety of ways. The best description of this is the "hypercar" as envisioned by the Rocky Mountain institute

rmi.org

Michael Winkler
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