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BPA braces for strong spring runoff, excess power and wind power cuts  

Credit:  By Ted Sickinger, The Oregonian, www.oregonlive.com 6 April 2012 ~~

From a hushed control center tucked into a building in Portland’s Pearl District, Kit Blair and dispatchers at Iberdrola Renewables captain a fleet of 3,000 wind turbines spread over 17 states.

Laid out before them on a wall of flat panel displays is the performance of every Iberdrola turbine component in the United States.

A few keystrokes can bring up a real time schematic of an individual turbine’s gear box in Texas, feather every blade at a wind farm in upstate New York, or still Iberdrola’s entire fleet on the Columbia Plateau.

Across the river in Northeast Portland, Blair’s counterpart sits in a control center at the Bonneville Power Administration, juggling the output of 31 hydroelectric dams in The Columbia Basin.

The teams usually work in perfect harmony. Bonneville, in tandem with the Army Corps of Engineers and the Bureau of Reclamation, fine-tunes hydroelectric output minute-by-minute to compensate for Iberdrola’s fluctuating generation. It sends more water through its turbines when wind farms aren’t generating enough electricity, or dials back when a squall sends windmills spinning.

But all bets are off for the next few months. It’s springtime in the Northwest, meaning rain, warmer temperatures, snow melt and blustery wind. Occasionally, it also means more hydro and wind electricity is pulsing into the grid than anyone can use.

That’s a major problem for wind farm owners, for whom spring has become the season of curtailments, when BPA can suddenly shut down their output to prevent “over-generation.” The cutoffs can mean millions of dollars in lost revenue, and put a cloud over further wind development in the Northwest.

The season just started. No one knows what it will bring. Dispatchers are standing by.

When the situation gets critical, “that thing makes a really obnoxious alarm and we have to scramble,” Blair said, pointing to a display on a flat panel. “We get charged $1,000 a megawatt hour if we generate more than they tell us to. They don’t give us any indication, and suddenly they need 500 megawatts” less wind.

While the output of the Columbia hydro system is awe-inspiring, “over-generation” hasn’t been a problem since the federal government built dams and a slew of industrial customers – shipbuilders, aluminum smelters, semiconductor makers – migrated to the Northwest for cheap power. But many of those energy hogs are gone, only partially replaced by the new data centers east of the Cascades.

Meanwhile, a wind farm boom to satisfy state renewable power mandates plugged 4,400 new megawatts of intermittent generation into BPA’s transmission system. When the windmills go full throttle, they generate enough power for 3.5 million homes.

The problem blew up last year, when wind reached a critical mass and the region faced an unusually high snow pack and runoff. BPA responded by instituting “environmental redispatch,” a protocol to cut off wind farms’ transmission during over-generation and substitute free hydropower to satisfy scheduled deliveries to customers.

BPA says it has no choice. During extreme runoff events, it says it can’t reduce hydro generation by shutting off turbines and spilling excess water over the dams. Resulting turbulence would increase dissolved gases in the river beyond mandated levels set to protect migrating fish.

Fish advocates actually say more flow over the dams would be good for salmon. But BPA says it needs to stick to legal limits. Likewise, BPA says it needs to protect the reliability of the grid by ensuring electricity supply is always perfectly in synch with demand. The largely automated process is complicated with the addition of so much variable capacity from wind farms.

Wind developers acknowledge the problem, up to a point. But they say the real issue is too much hydro, and not enough demand. Last year, federal regulators agreed that BPA’s solution – unilaterally cutting off winds farms’ transmission contracts and substituting hydro without full compensation for lost revenues – illegally discriminated against wind farms.

BPA came up with a cost-sharing mechanism this year, agreeing to split lost revenue with wind farms. But renewables advocates say the new transmission tariff BPA was required to file with federal regulators last month didn’t solve the problem. It leaves BPA with discretion to discriminate when conditions dictate and protect its own power sales at wind farms expense, they say.

That argument will play out in coming months. Meanwhile, spring has sprung.

The frequency of curtailments, which BPA now prefers to call displacements, will depend on weather, and the resulting shape of runoff.

Last year’s La Nina snow pack fed the Columbia 130 percent of its normal water supply. And California, which often absorbs as much electricity as the Northwest can send, was overflowing with its own hydro after record snowfalls in the Sierras.

But the shape of last year’s runoff was nearly ideal, with cool spring and early summer temperatures that slowed snow melt and resulting river flows. The gradual release of water turned what might have been a financial migraine for wind farm operators into a mild headache.

This year, there’s less snow. The Northwest water supply forecast from April to July is currently 112 percent of normal. And California’s snow pack currently has 55 percent of its normal water content after a winter drought.

But that’s no guarantee there won’t be problems. Higher temperatures or a pineapple express storm could send a slug of water into the hydro system, forcing BPA to pull the plug on other generators.

BPA’s analysis suggests the value of lost tax and renewable energy credits alone will average $12 million annually, though it could be as high as $50 million in 2012 if there’s high runoff and intense winds. Those credits are generated only when turbines send electricity into the grid. Wind farm owners say they face additional losses, as the absence of the renewable credits can mean their customers aren’t obligated to pay the contract price.

There are myriad complicating factors. Last year, for example, the nuclear plant in Richland, Wash., that feeds BPA was offline for refueling. This year, it’s running at 85 percent of capacity. That’s an extra 900 megawatts of electricity that needs a home, or, more precisely, the equivalent of 720,000 homes to absorb the output.

BPA, meanwhile, has been spending heavily to eke out more capacity on the big transmission lines that run to California, which are often congested. But at present, almost 40 percent of the capacity on the alternating current lines to California are out of commission for maintenance. That’s 1,850 megawatts of power that can’t flow south for the moment.

Meanwhile, the region’s wind fleet keeps growing. Parts of the Shepherd’s Flat wind farm in eastern Oregon came on line in the last four months, adding 550 megawatts of generation. Its output is under contract with Southern California Edison, though it’s unclear if the owners have secured firm transmission capacity to ship all the power. There’s little left for sale, so when lines are congested, power without transmission stays in the Northwest. On top of it, natural gas is at historically low prices, meaning more competition for wholesale electricity.

Six weeks ago, it looked like wind farms would dodge the curtailment bullet with water supplies well below average.

“Now we’ve had quite a bit of snowpack in March,” said Doug Johnson, a spokesman for BPA. “The volume is pushing us into the situation where oversupply is looking more likely.”

Source:  By Ted Sickinger, The Oregonian, www.oregonlive.com 6 April 2012

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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