overview

press releases

media contacts

in the news

image downloads

media kit

experts guide

Fall/Winter 2007 Newsletter

In this issue:

Watt in the World - Energy 101
AC/DC and the current war

We all use electricity. Each day, we turn on lights, televisions, computers and toasters. But the last time you flipped on that light switch, did you ever think about how the electricity got there in the first place? Your electric utility works hard to make sure that the power you need is there when you need it. And that is no small task to accomplish.

But before we can consider how electricity gets to your home or business, we have to first understand how it is generated. In a previous article entitled “What’s a Watt?” we considered the basics of electricity. But how does a Watt come to be and how does it like to travel. Over the next couple issues, we will explore how electricity is generated and distributed.

The genesis of generation

The journey starts in a power plant, a facility dedicated to generating electricity. Power plants come in different designs and sizes. And there are lots of different resources that can be harnessed to make electricity. The earliest power plants utilized coal and water as sources of generation. Today, modern power plants use not only coal and water, but also nuclear fuel, natural gas, petroleum, methane, sunlight, wind, and other sources.

Whatever the source used to power the plant, nearly all forms of electrical production involve the application of a generator. A generator is a machine that converts the mechanical energy caused by its rotation into electrical energy that can be used to power things. The generator is rotated through the use of steam, water, wind, or combustion heat either directly or indirectly from the resources previously mentioned.

Electricity has been utilized in our world for more than a century. But the concept of an electric utility generating power from a centralized plant did not come about overnight. Initially, electricity was generated either on-site or on a very localized scale.

Electricity gets switched on

Thomas Edison is given credit for developing and marketing the first commercially viable electrical generation technology in 1878. A few years later, he would open the world’s first steam-powered plant in London, lighting homes located near the plant with electricity for the first time. That same year, Edison opened the Pearl Street Power Station in New York City, offering affluent New Yorkers the opportunity to showcase this novelty. It was the beginning of a power surge of sorts, that would soon see more than 100 of Edison’s generating plants nationwide in less than a decade.

In each installation, Edison utilized an electric model based on direct current (DC) voltage. Direct current literally means electrons that flow in one direction. DC power is still used widely today. It is most commonly found in applications involving batteries, which can only produce direct current, and those uses requiring lower voltages.

Computers and other products containing electronic circuits usually require DC power. And applications utilizing solar photovoltaic (PV) cells initially produce electricity in DC format.

While DC voltage provided a useful electrical design for Thomas Edison, the world soon began to realize that it had its disadvantages. Direct current did not transmit well over long distances. In fact, in little more than a mile, DC current began to exhibit significant losses in transmission efficiency. As a result, DC power plants could only serve facilities in a close radius to the generator. But the work of one of Edison’s former employees would provide a solution to this problem, and transform the world of electricity at the same time.

Rivals and revolutions

Nikola Tesla, a Croatian-born immigrant who came to New York to work for Thomas Edison, proposed the idea that alternating current (AC), and not DC, was the superior design for distributed electrical generation. His work came to the attention of another inventor, George Westinghouse, who bought the patents to Tesla’s work and began developing power plants of his own based on the AC method of generation.

A war of currents ensued between Westinghouse and Edison which the former ultimately won. In April 1895, the Niagara Falls Power Company commenced operation of a 3.7 Megawatt (MW) power plant utilizing Tesla AC generators developed by George Westinghouse. It was a turning point in the history of electricity, but by no means the end of a contest that continues even today.

Nikola Tesla

The Niagara Falls Power Company, developed by George Westinghouse and featuring alternating current (AC) power generators created by Nikola Tesla, revolutionized the electrical industry.

A versatile voltage

Part of the appeal of AC voltage, is its ability to be stepped up from lower voltages at the time of generation to higher voltages for transmission over large distances. Electricity is transmitted more efficiently at higher voltage, as resistance drops in a power line as voltage increases. More efficient transmission means one power plant can serve a larger service area at a lower cost per kilowatt hour (kWh).

The stepping-up process is accomplished through the use of transformers that increase or decrease voltage depending on the transformer location on the electric line.  DC voltage can not easily be converted in this way which ultimately limits its usable transmission range. It is these transformers and AC’s ability to be converted for long-distance transmission that makes our modern electric grid possible.

In the next issue, we will look at exactly how electricity travels from the power plant to you.