STORING ENERGY FOR THE POWER GRID
by Andrew Boyd
Today, power. The University of Houstonís College of Engineering presents this series about the machines that make our civilization run, and the people whose ingenuity created them.
The power grid. It sounds a bit ominous. What exactly is it?
The electricity for our TVs and toaster ovens arrives through an outlet in the wall. But it begins by passing through a vast, interconnected collection of wires that make up the so-called power grid. At the end of some wires, like our wall outlets, electricity is taken out of the grid. And at the end of other wires, like power plants, we find electricity coming into the grid. Itís like a vast tank of water, where at any moment thousands of people are pouring water in and thousands are taking water out. But thereís one big difference.
A water tank can inexpensively gather water on a rainy day and save it for a sunny day. Thatís not so easy for the power grid. Storing electrical energy on a large scale can be expensive and inefficient. So for the most part, we havenít used storage. When we need more electricity, we simply generate more.
The price we pay is having to build enough power plant capacity to handle peak demand. That means our power plants spend much of their time sitting idle. We could build fewer plants if we could create energy when thereís low demand and store it for periods of high demand.
So engineers have a renewed interest in ways to store electrical energy. Many ideas have been around for years. Others are new. All are creative.
Flywheels are one idea. An electrical motor sets a large mounted wheel spinning. When needed, the motion of the wheel is converted back into electricity.
Of course, there are batteries galore. Batteries convert electrical energy to chemical energy then back to electrical energy when needed. Batteries arenít usually a good choice for storing large amounts of electrical energy — theyíre just not economical.
But hereís a nifty idea. Itís called vehicle to grid technology, and hereís how it works. Whenever an electric car is plugged in, its battery is hooked into the power grid. Now, we normally think of these batteries as simply drawing power from the grid. But what if they actually fed electricity back into the grid? You arrive home from work and find your car battery still has charge left. Electricityís in high demand after work, so you release your batteryís energy back into the grid. Later that night, when everyoneís asleep, your car recharges itself. Of course, your electricity provider gives you a rebate on your bill. After all, you stored power for the grid and saved the provider money.
Itís hard to say how our interaction with the grid will change in coming years. But change is coming. And the wealth of ideas is both amazing and inspiring.
Iím Andy Boyd at the University of Houston, where weíre interested in the way inventive minds work.
Notes and references:
Energy Storage. From the Wikipedia Website: http://en.wikipedia.org/wiki/Energy_storage#cite_note-23. Accessed May 10, 2011.
Vehicle-to-Grid. From the Wikipedia Website: http://en.wikipedia.org/wiki/Vehicle-to-grid. Accessed May 10, 2011.
The picture of the Prius plug-in is from a Toyota Website. All other pictures are from U. S. government Websites.
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Copyright © 1988-2011 by John H. Lienhard.