The Grid: Electrical Infrastructure for a New Era

by Gretchen Bakke

There is another problem that limits the thermodynamic efficiency of a plant—the fragility of the metals from which boilers and turbines are forged. Technologically, we can now build a steam plant that works at 40 percent efficiency. We had some of these already in the 1960s. Practically speaking, this means superheating water to over 1,000 degrees Fahrenheit while upping the pressure to an awesome 3,200 pounds per square inch to convert this water straight into dry, unsaturated steam without boiling it. The construction of a machine robust enough to perform this task 24/7 for thirty years has turned out to be both fraught and expensive. The closer a steam plant comes to 40 percent efficiency, the more routine maintenance it needs, the more often it breaks down despite the constant upkeep, and the more costly the high-tech alloys necessary to endure this onslaught. Sooner or later even these fancy crafted metals will fatigue and give way. By the mid-1960s it had become clear to utility men that a plant run at just over 30 percent efficiency was both the most reliable and the most cost-effective way to make electricity.