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Extra water, wind strain Northwest power grid  

Electricity – Dams are producing more than can be sold and spilling excess water, which can harm fish

The Northwest is awash in electric power this spring.

Rivers are swollen. Columbia River dams are running full bore. Wind farm blades are spinning.

That should be good news for the Northwest, where hydropower is cheap and wind is a leader in renewable energy. And it should be good news for California, a huge electricity consumer that often sucks up Oregon’s springtime surplus.

But a doubling of wind-power supplies and an unusually concentrated surge in water levels have challenged this season’s power operations like never before.

“You throw a spiky late runoff into the equation, and a little extra wind, and it definitely gets interesting,” said Kieran Connolly, a power manager for Bonneville Power Administration.

The result: wasted power generation, excessive spill through the dams and a sometimes frenzied juggling of dam and transmission schedules.

High water levels benefit power supplies and migrating fish, but the levels in recent weeks have been too much of a good thing.

Oregon and Washington can’t use all the electricity that’s available. And southbound transmission lines that are at capacity can’t take the extra power California consumers otherwise would eagerly devour.

In some cases, power producers are paying customers to take electricity off their hands.

Operators of the Columbia-Snake River dams say there’s enough give-and-take in the system to handle large fluctuations in water flow and wind generation. But pressures have steadily increased, and they’ll intensify as more and more wind power comes into play.

“I wouldn’t say it’s totally under control,” Connolly said, “but we’re keeping up at this point.”

The limits snapped into focus a month ago, when warm weather arrived and mountain snow melts poured into Northwest rivers.

River levels rise every spring, usually beginning in March or April and lasting until late June. This year, cool weather persisted until a mid-May heat wave.

“Then everything started running,” said Rick Pendergrass, BPA’s manager of power and operations planning.

Only in the past week did the dousing begin to ease. Overall, the region expects a close-to-normal water year.

BPA, the U.S. Army Corps of Engineers and the U.S. Bureau of Reclamation manage 14 major dams on the Columbia and Snake rivers. They face a slew of requirements, from meeting electricity demand to protecting fish to preventing floods.

When water levels jump as quickly as they did this season and are squeezed into a short time, the difficulties close in.

For one thing, reservoir capacity is limited, so system operators can’t store all the extra water that flows downriver. They can’t allow flooding, either, so they turn to the dams’ turbines and spillways to even things out.

Further, they can’t generate power any time they want. They must have a market for the megawatts. Because electricity demand in the region ebbs in the spring – the heat’s turned off, and so are the air conditioners – high water can quickly become a resource without an outlet via the turbines.

That leaves the spillways, which divert flows around the dams’ turbines. The corps manages spills in the spring to help juvenile salmon migrate downriver. If releases are too powerful, dissolved gas in the water can rise to dangerous levels and give fish a potentially lethal condition akin to the bends, a diver’s disease.

Every day since May 16, the corps has spilled water at volumes that exceed state criteria for water quality and salmon protection. That’s an unusually long time. Measurements of total dissolved gas have climbed during those spills but haven’t gone high enough to harm the fish, corps officials said.

Trade-offs between power generation and spill can produce strange arrangements.

The Grant County Public Utility District, which owns Priest Rapids and Wanapum dams on the upper Columbia in Washington, had too much water to safely spill and too little demand for all the power the hydro turbines could produce. So it created a market by giving out, not taking in, revenue.

“You juggle resources as best you can,” said Kevin Nordt, Grant County PUD’s director of power management. “If you have electricity but no one needs it, sometimes you have to pay someone to take it.”

These deals by a number of Northwest utilities meant prices, which reflect the cost to the buyer, sometimes fell into negative territory on the Mid-Columbia trading hub.

Meanwhile, prices in California remained considerably higher, seesawing with the weather and accompanying demand. Northwest utilities might have tapped that market, but high-voltage transmission lines heading south often were full.

Another variable has blown in to challenge the system: the wind.

Wind-turbine capacity in the Columbia Gorge has doubled in the past year, bringing clean energy onto the grid but more stress to dam operations. The thermal winds that whip through the river corridor crank up in the spring – the very time Columbia River flows peak.

BPA is responsible for blending wind power into the grid. Each hour, wind farm operators give the agency their best forecasts of the megawatts to come. BPA uses the schedules to anticipate changes in hydro generation, then deals with last-minute variations as they occur.

Hydro is considered a good complement to wind because its generation is relatively easy to manipulate. Still, with so many demands on the system and wind’s precise velocity impossible to predict, BPA has found itself scrambling to keep the system in balance.

Several weeks ago, when an unexpected wind surge hit, Bart McManus, a BPA power manager, said he came close to telling wind developers he couldn’t take the generation that exceeded the forecast. “So far, we haven’t had to do that.”

McManus is part of an effort to improve the way wind power joins the system. Dramatic changes must be made within several years, he said.

“If normal operations continue, we’ll have a hard time meeting (electricity) reliability standards,” he said. “We’re busting our tails. We don’t have a lot of time.”

Gail Kinsey Hill
The Oregonian Staff


27 June 2008

This article is the work of the source indicated. Any opinions expressed in it are not necessarily those of National Wind Watch.

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