Have you ever wondered how “the grid” works? How electricity is generated or how it gets delivered to your home? As I take a current class called Environmental Stewardship and Resilience in Urban Systems, I realize more and more the importance of understanding how the current electricity grid is set up, how it works, and what its flaws are. While I have gotten a brief overview of how a handful of cities across the world have set up their electricity grids, I would like to hone in a little on the United States, as this is currently what is most applicable to me and most closely tied to my personal interests when it comes to the grid.
From what I have learned, the United States electricity grid is divided up into four major parts. The first being individual generators, the second being transmission lines, third, the distribution system, and fourth, consumer use, also known as “load.”
Before we get into this, it is important to understand the term flexibility within the electricity generation context. A flexible power source is one that can be used at any time. Typically we think of flexible power sources as coal fired power plants, as coal can be burned at any given time to generate the electricity demanded by consumers. However, a coal fired power plant is not flexible in the short term, as it takes a while to begin or terminate the electricity generations, but it does remain a reliable energy producer. Another good example might be hydropower, as, for the most part, where dams are built and where hydroelectric power is generated, the water source is continuous. A dam can open up to let water through to spin a turbine and generate electricity at any time, assuming the flow of water remains constant – which, of course, is an entirely different issue in this changing climate. To iterate, two examples of non flexible options are wind and solar power. When the wind is not blowing, or when the sun is not shining, energy cannot be generated from wind turbines or solar panels! Flexibility of a system as a whole implies that one energy generation strategy will be ready to take on weight if one system drops in energy production, which increases the security of the system.
The individual generators that I speak of are any plant that generates electricity, whether that be traditional coal fired power plants, hydroelectric generation plants, solar farms, wind farms, and the like. These generators are often owned by electricity companies or utilities.
Transmission lines, which either run underground or overhead, carry high voltage electricity, connecting the power generators with consumers like you and me. The lines carry electricity at high voltages because it allows less electricity to be lost in transmission. However, generators generate electricity at low voltages, so a transformer is used to bump up the electricity to high voltage, which is then carried through the power lines, and then bumped back down to low voltage as it approaches the consumer destination. There are three main transmission line networks across the United States, including the Western Interconnection, the Eastern Interconnection, and the Electric Reliability Council of Texas (ERCOT).
Distribution lines are used to connect the electricity from transmission lines post transformers directly to homes and businesses.
All of the electricity that consumers use adds up to the system “load.” Maximum, or peak load, occurs when people begin to return home from work. This is where businesses are still operating lights, AC units, and facilities at the same time people are getting home and increasing their electricity usage. The system needs to be ready at any given time to meet “base load,” which is the average amount of electricity called for by consumers. Without this, there could be widespread danger as people are unable to access electricity.
I hope that this may have given you a little bit of insight into how the grid operates. Breaking it down like this certainly helped me break down such a large, sprawling concept into an easily digestible idea! As I learn more about the grid and how it works, I hope to share more here in some following posts.