2025labskids 600
Line art
Engineering process
Materials
Structures
Machines
Energy
Computing

Power that comes out of our walls comes from the energy grid

We don’t normally think about where the energy comes from when we plug something into a wall socket, but the energy comes from the “electric grid.” When you drive around town, you probably see power lines that deliver that electricity from the grid to businesses, homes, schools, hospitals, and other places. The electric grid is the way that we connect energy sources with places that need energy, like homes and businesses.


The electric grid was built to make the movement of energy around the US more efficient

Power lines
The electric grid was created in the early 1900s to make the movement of energy around the country more efficient. Around this time, demand for energy was increasing. Companies found it easier to work together to connect their systems to provide electricity to people. Lots of electric transmission lines were connected to each other, giving people better access to electricity. Transmission lines carry the electricity for long distances, while distribution lines carry electricity small distances within neighborhoods.

The result of these companies connecting their lines is the five grids that combine to make what today we call the electric grid. The two larger, or major, grids are the Eastern Interconnection and the Western Interconnection. The three smaller, or minor, grids are the Texas Interconnection, the Quebec Interconnection and the Alaska Interconnection. Together, these five grids provide electricity for most of the United States, Canada and parts of Mexico.


Transformers allow electricity to be moved more efficiently

Transformers
When you see large power lines next to roads, they are carrying electricity at an extremely high voltage. Voltage is a measure that relates to how much electric current is moving through a wire or device. The higher the voltage in a wire, the more power you get out of it, and the more efficiently power can be transmitted. This means more of the electricity makes it to the final location. Therefore, when we are moving electricity around the country, we are doing so at a much higher voltage than is safe or possible to use to power our items in our home.

We use transformers to change voltage levels between the levels that our homes use and the levels that transmission lines use. Transformers allow for the voltage to be stepped up (made greater) or stepped down (made lower). Transformers step up the voltage after it is generated at a power plant and step down the voltage before providing the power to homes. These transformers are located at electrical substations, on power poles, and in boxes connected to power lines in every neighborhood across the country.


The energy that the grid provides is alternating current (AC)

There are two types of electric current: alternating current (AC) and direct current (DC). In the late 1880s the widespread use of electricity was just beginning. At that time, there was a controversy about whether it was better to distribute power to homes and businesses using AC or DC current. Thomas Edison had just patented the incandescent light bulb, which runs on electricity. Patents give inventors the exclusive rights to an invention for a limited period of time. In order for people to buy and use these new light bulbs, electricity had to be distributed from where it was created, in power plants, to where people would use the light bulbs, like homes and businesses.

The controversy between AC and DC current is sometimes referred to as the “War of Currents”. It was waged between two of the foremost inventors of the industrial age: Thomas Edison and George Westinghouse. Thomas Edison not only held the patent on the incandescent light bulb, but he also held many important patents for the distribution of DC power. George Westinghouse was a very successful engineer and inventor. He was also interested in the distribution of electricity. He acquired critical patents for the distribution of AC power from an inventor named Nicola Tesla.

Edison tried to show that AC power was dangerous because of the high voltages involved. However, AC power quickly outpaced DC in the race for the distribution of electricity, primarily because it was more cost effective. Transformers allowed AC current to travel at high voltages on smaller, less expensive wires, and then be stepped down to a safe voltage for usage. Because AC could travel farther more efficiently, power users could be further away from power sources, which helped use of electricity to grow quickly.


The grid brings energy to your house through a multi-step process

The overall process that the grid follows to get energy to your home is:

1. A power plant generates the electricity. There are over 7,000 power plants that are currently connected into the US electric grid. See the Energy Sources section to learn how different power plants generate electricity.
2. A transformer prepares the electricity to be transmitted through electrical lines by stepping up the voltage.
3. Over 450,000 miles of transmission lines carry the electricity around the United States to the needed location.
4. Another transformer prepares the electricity for use by houses by stepping down the voltage
5. Distribution lines carry the electricity the final distance to houses and businesses.
6. One last transformer steps down the voltage of the electricity before it enters homes to make it 120 volt AC.
7. Electricity is carried throughout the building and powers all things that are plugged into the walls.

Next time you plug something in at your house, think about the trip the energy had to take to get to you. It could have come hundreds of miles to help power your TV, microwave or MP3 player!


Other parts of the world have electric grids as well

There are electric grids all over the world. The continent of Europe has one that reaches over 400 million customers in 24 countries. Although this grid also uses AC, it uses 220 volt current. This is double the volts of the American grid, which uses 110 volts. If you travel to Europe, you won’t be able to plug your devices into the wall. You will need to plug a converter into the wall first. The converter will act as transformer and step down the voltage to work with your device. You might wonder why different parts of the world use different standards for electricity. The answer is largely for historical reasons. Once a standard is established it can be very expensive to change to a new one.


The electric grid is how we connect power sources with power users

When you plug a device into an outlet on the wall, you are using the electric grid. The electricity you are using may have been generated by wind moving a turbine, by coal being burned to generate steam to turn a turbine, or some other method. However the electricity was generated, the electric grid delivers that electricity to your home in the exact way you need it to power whatever machine or device you are using. The electric grids around the world make many modern conveniences possible.


Energysources Energyconversion Electricgrid Energystorage