Referred to as “the largest machine on the planet,” and certainly the most utilized, the U.S. power grid is complex, massive and constantly in motion, serving the 125 million homes in the U.S. While it’s often discussed on the national level, in reality the “grid” is comprised of 3 main regional grids- the Western Interconnection; the Eastern Interconnection; the Electric Reliability Council of Texas (ERCOT). Yes, Texas has its own. The Western extends from the Pacific coast to the Rocky Mountains; the Eastern covers the area east of the Rockies to the Atlantic coast and part of Texas; ERCOT includes most of Texas. See image 1 below.
So how does it get to you? There are three main parts to the grid- generation, transmission, and distribution. Power plants produce the power. Transformers then “step up” the power to 250-550,000 volts for it move on the power highways- the large transmission towers and lines that you see cutting across meadows, highways, and cities. See image 2 below.
Once it arrives at the area of demand, local substations “step down” power and distribute it to homes via local electrical wires. Along the way about 5% of the power is lost during transmission and distribution.
While countries like Denmark and Germany share borders and balance electricity loads and natural resources between them, importing and exporting electricity as needed, in the United States, we trade mostly with our friendly neighboring states. To do this, there are over 450,000 miles of high-voltage transmission lines in the U.S, and millions of low voltage power lines in our neighborhoods. Your neighboring state, and even the one 10 hours away, if it’s in your Interconnect, is relevant to your power supply. One in two states are net electricity importers. California imports 33% of its electricity supply from neighboring states. With about half of states importing electricity, and regional transmission infrastructure and governing bodies, clean, reliable affordable power becomes an interstate issue.