CBC In Depth
Toronto skyline in darkness.  Photo courtesy of Paul Sampson
INDEPTH: POWER OUTAGE
Electricity terms
CBC News Online | August 20, 2003
Updated November 19, 2003


The North American Electric Reliability Council thinks the power blackout that blanketed much of northeastern North America on August 14, 2003, originated from shorted transmission lines in Ohio.


An electricity transmission tower.
Photo courtesy Hydro One.
Until that day, terms like "power grid" and "transmission line" weren't in common usage for many people affected by the blackout. Here's what these terms, along with some others, actually mean. Click below to jump to the section of your choice:

  • Power grid
  • Transmission line
  • Electricity
  • Cross-border connections
  • Flow cell batteries
  • Silicon switches

  • Power grid: A geographical section of transmission lines. Canada has three – the Western grid, the Eastern grid and the Quebec grid (which includes Atlantic Canada). The border between the eastern and western grids is the Alberta-Saskatchewan borde. The two grids are connected in some areas by direct-current lines, but they are largely independent of each other. There are also three U.S. power grids – the Western Interconnection, the Eastern Interconnection and the Texas Interconnection.


    A transformer station near Pickering, Ont.
    Photo courtesy Hydro One.
    Transmission line: Cables that transmit the energy. These are strung along fields of electrical towers to carry electricity across the country. Lines can also be buried underground. Since the transmission lines are shared, there is little incentive for companies to invest heavily in their upkeep. It's simply not a profitable venture, so it isn't done and breakdown is the result. Many of the lines in the North American system have been around for decades. The U.S. Department of Energy estimates that American generating capacity alone will increase by more than 20 per cent by 2010. Transmission line capacity in that same period is expected to increase by a mere four per cent.

    Electricity: A function of voltage and current. Combining high voltage and low current generates the same amount of power as combining low voltage and high current. Current produces heat, which can wear down transmission lines over time. Because of this, power is transmitted across lines with high voltage and low current.


    Sir Adam Beck II generating station near Niagara Falls, Ont.
    Photo courtesy Ontario Power Generation.
    Cross-border connections: Where electrical grids meet. When parts of Canada's grid were connected with the U.S. grid, the intention was to open a new market for surplus electricity and to establish a source of backup power. The shared system enables generators to operate more efficiently, as they could continue to generate electricity even when local demand is low. With open markets (and shared transmission lines) power can be sold across hundreds of kilometres. Every province is connected to its nearest U.S. neighbour.

    Flow cell batteries: Used to store energy when supply exceeds demand. These batteries, although expensive, can each store 24 hours of power for a small community. Each costs twice as much as a new power line and would be at least the size of a low-rise building.

    Silicon switches: Currently in the development stage, these are designed to shift the electricity loads to where there is available capacity. They could allow transmission line production to be a more profitable venture because the switches allow them to be operated like toll roads. This could allow some power generating facilities to be more strategically placed.






    ^TOP
    MENU

    MAIN PAGE
    HOW IT HAPPENED: THE BLACKOUT EXPLAINED TIMELINE HYDRO Q & A FINAL REPORT ELECTRICITY TERMS NEWS STORIES
    BACKGROUND: EMERGENCY ADVICE ENERGY WARNING BLACKOUTS HISTORY BY THE NUMBERS STATE OF EMERGENCY ENERGY: SOURCES CBC ARCHIVES
    PERSPECTIVE: IN THEIR OWN WORDS WHEN THE LIGHTS WENT OUT GETTING IT ON THE WEB BLACKOUT BABY PERSONAL STORIES
    MEDIA & INTERACTIVES: CBC MEDIA PHOTO GALLERY INTERACTIVE MAP

    MORE:
    Print this page

    Send a comment

    Indepth Index