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The Importance Of Electricity Reserves

Recently the North American Electric Reliability Council asked: how reliable is our electric system going to be in the next several years?

The Council spent months sifting through historical data and checking statistics about power plants, then asked engineers and other technical experts to peer into the future.

In October 2006, NERC published the results in a big report with lots of predictions about how much electricity will be generated each year during the next decade. The report also predicts how much electricity people will need (the demand for electricity) throughout those years—and compared the two predictions.

NERC found that current plans to build power plants and transmission lines lag behind the expected increase in how much electricity people will want to use.

NERC’s 2006 Long-term Reliability Assessment Report says, “Demand for electricity is expected to increase over the next 10 years by 19 percent in the United States, but confirmed power capacity will increase by only 6 percent.”

To understand the impact of that statement you have to know three things.

1—Electricity is used immediately. It’s generated, flows through power lines to the point where it’s needed, and does whatever work is required at once, whether that’s powering a light bulb at home, a computer in an office, or a conveyor belt in a factory. The electricity can’t be stored—it must be used immediately and it must flow continuously. When everything is flowing smoothly, that’s called reliability.

2—Not every power plant is working all the time. Lots of things can happen to cause a generating plant to stop producing electricity at its usual capacity. On any given day nationally, several plants could be shut down due to problems with fuel, at a hydroelectric plant water levels at the dam could be too low to run the turbines, or at a coal-fired plant regular shipments of coal might be interrupted while railroad lines are being repaired. Normal scheduled maintenance might close any kind of generating station for days or weeks at a time.

3—The transmission grid of high-voltage lines that carry power from generating stations to the distribution grids always needs regular and emergency maintenance. Sometimes weather events destroy cables and towers, interrupting the flow of electricity. Depending on how widespread the problem is, power might be temporarily rerouted around the trouble spot—or because of geography, customers might just have to do without electricity until repairs are completed.

These three physical properties of the electric utility industry mean that in order for electricity users to be assured of reliable service—the kilowatts they need exactly when they need them—a certain amount of excess capacity should always be available.

NERC believes that capacity margins should be in the 15 percent range. In other words, generating stations in a geographic region should be able to produce, altogether, about 15 percent more electricity than users in that area would want during times of peak demand. It’s sort of a built-in emergency backup plan. If one part of the generating and transmission system in that region is out of service, there is enough extra capacity to make up the difference to satisfy the demand for electricity from customers.

Sometimes the excess local capacity can be helpful for a neighboring region, too. If proper transmission lines and grid connections are available, the wiggle room that excess capacity provides can mean that a generating plant might be able to send power outside its own region to help a neighboring region, yet still have enough power to keep its own customers properly supplied.

NERC’s report predicts that capacity margins will drop below minimum reliability target levels in certain areas of the United States within the next two to three years.

Even if all the power plants under construction now are completed on time and begin generating electricity in the amounts they are supposed to, and new construction is started according to plans now under way, many electricity users could find themselves in a potentially troublesome situation—not enough power when it’s needed.

Regions that are likely to be affected by this coming gap between available supply and immediate demand include Texas, New England, the Mid-Atlantic area, some portions of the Midwest, and the Rocky Mountain area. Other parts of our country could face a reliability gap a few years later. In western Canada, the problem could become apparent to customers as soon as next year.

NERC’s other assessment of the situation is also troubling. NERC’s report says, “Expansion and strengthening of the transmission system continues to lag demand growth and expansion of generating resources in most areas.”

NERC states that total transmission miles are projected to increase by less than 7 percent in the United States—and by only 3.5 percent in Canada in the next eight years.

A sudden surge in weather-caused disruptions or a batch of construction delays could turn any or all of NERC’s predictions into so much waste paper—customers could face immediate and recurring disruptions in their supply of electricity.

All that doesn’t mean Kentuckians won’t have enough electricity in the future, says one Kentucky utility executive.

Mike Core, president and CEO of Big Rivers Electric Co-op based in Henderson, believes the lesson of the NERC study is that planning needs to be done now to meet future energy demand. Without advance planning, he says, we could face expensive crisis energy supply programs in the future.

“Somebody is going to build the generation and transmission we will need to supply everyone with electricity,” says Core. “The issue is how we manage the costs.”

NERC recommends 22 strategies to avoid potential problems. Most are aimed at the big players in the bulk power supply system, but one item is of key interest to the ordinary electricity consumer. Beginning now, start doing everything you can to use electricity wisely. These “demand-side” measures include turning off appliances when not in use, replacing old appliances and equipment with more efficient models, and managing your electricity use carefully.

To read NERC’s report online, visit

Next month: Electricity’s future workforce

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