What's wrong with the electric grid?
The warnings were certainly there. In 1998, former utility executive John Casazza predicted that “blackout risks will be increased” if plans for deregulating electric power went ahead. And the warnings continued to be heard from other energy experts and planners.
So it could not have been a great surprise to the electric-power industry when, on August 14, a blackout that covered much of the Northeast United States dramatically confirmed these warnings. Experts widely agree that such failures of the power-transmission system are a nearly unavoidable product of a collision between the physics of the system and the economic rules that now regulate it. To avoid future incidents, the nation must either physically transform the system to accommodate the new rules, or change the rules to better mesh with the power grid’s physical behavior.
Understanding the grid’s problems starts with its physical behavior. The vast system of electricity generation, transmission, and distribution that covers the United States and Canada is essentially a single machine— by many measures, the world’s biggest machine. This single network is physically and administratively subdivided into three “interconnects”— the Eastern, covering the eastern two-thirds of the United States and Canada; the Western, encompassing most of the rest of the two countries; and the Electric Reliability Council of Texas (ERCOT), covering most of Texas (Figure 1). Within each interconnect, power flows through ac lines, so all generators are tightly synchronized to the same 60-Hz cycle. The interconnects are joined to each other by dc links, so the coupling is much looser among the interconnects than within them. (The capacity of the transmission lines between the interconnects is also far less than the capacity of the links within them.)
This limited use of long-distance connections aided system reliability, because the physical complexities of power transmission rise rapidly as distance and the complexity of interconnections grow. Power in an electric network does not travel along a set path, as coal does, for example. When utility A agrees to send electricity to utility B, utility A increases the amount of power generated while utility B decreases production or has an increased demand. The power then flows from the “source” (A) to the “sink” (B) along all the paths that can connect them. This means that changes in generation and transmission at any point in the system will change loads on generators and transmission lines at every other point—often in ways not anticipated or easily controlled (Figure 2).
