Dr. Universe,
How does electrical power travel through metal?
— Gabriel, Illinois
When you watch the zapping bolts during a lightning storm, you know how powerful electricity is. Humans have only been harnessing electricity to bring light and energy to our towns and homes for about 150 years — and metal is one of the main ways we get this powerful tool fromplace to place.
To learn more, I talked to my friend Bob Olsen, a professor emeritus in the Washington State University School of Electrical Engineering andComputer Science.
Olsen said it’s important to realize that we don’t need metal wires to move the waves that carry electricity, which are called electromagnetic waves. Some technologies, like cell phones, pick up waves that are sent through the air.
But these technologies don’t work as well if you get too far from the station that’s sending out the wave. If you go camping out in the woods, you probably won’t be able to make a call on a cell phone.
To get electricity from power plants to houses, we have to use a system that doesn’t fade out. It also needs to be efficient, which means it can carry power from one place to another without losing verymuch energy.
“In that case, metal wires can be used to ‘guide’ the waves between the two locations,” Olsen said.
Metals are good conductors, which means electricity flows through them easily. Most power lines use aluminum and copper. Copper is a bit better conductor than aluminum, but aluminum is lighter — which is important because we don’t want power lines to sag toward buildings or people.
No metal is a perfect conductor, so power lines still lose a little bit of energy into the wires in the form of heat, Olsen said.
“Nevertheless, even long high-voltage power lines transport 90-95% of the power between the beginning and end of the line,” he said. “We say that they arequite efficient.”
Engineers keep looking for ways to move electrical power even more efficiently. One of the things Olsen studies is how to make very long power lines carry more power.
This is important as we switch to new types of power plants, he said. For example, the windiest places in the United States, which are best for wind farms, are in the middle of the country. But most people live on the coasts, so wires have to move the power an extra-long distance.
More efficient power lines are also important around the world, especially in places where people don’t have much money. Millions of people don’t have electricity in their houses or towns. But if they get electricity, it can help them have better medical care, open businesses, get an education or make their lives better in other ways.
If you keep asking interesting questions about electricity, maybe you’ll find a way to move power even more efficiently — and you’ll help make the world a better place for everyone.
Have a science question? Ask Dr. Wendy Sue Universe, WSU’s resident science cat and writer, by email at Dr.Universe@wsu.edu.
