The recent rapid rises in the cost of energy has significantly increased interest in alternative energy sources. The author discusses the underlying principles of heat pumps and geothermal energy. Related activities for technology education students are included.

A model of an endoreversible Carnot engine is considered where the piston moves with a constant speed "u." Expressions for the cycle time [tau] for the four branches, as well as output power, P[subscript W], are derived and the optimized root for maximum power is obtained in closed form. Our results are discussed in terms of the isothermal…

Discusses the efficient use of energy. Compares reserves and pollutants generated by natural gas, oil, and coal. Points out some alternative energy sources and ways for improving energy efficiency in buildings, industrial processes, and transportation. Describes some problems in developing and developed countries. (YP)