U.S. Northwest Hydro Supplies
by Scott DiSavino and Eileen O'Grady
Surplus of hydroelectric power jams grid
Utilities shut wind, natgas generators
NEW YORK/HOUSTON -- Water supplies in the U.S. Pacific Northwest are near record high levels, forcing the region's power suppliers to shut wind and natural gas-fired generators due to a surplus of cheap hydroelectric power already jamming the grid.
Forecasts call for the April-September water supply at The Dalles Dam on the Columbia River between Oregon and Washington State to be the third highest on record since 1970, Donald Laurine, Development and Operations Hydrologist at the U.S. Northwest River Forecast Center (NWRFC) said Monday.
The NWRFC forecast water supplies at The Dalles for the period to be 137 percent of normal in the 2011 water year, up from 84 percent of normal in 2010.
The all-time record at The Dalles was 143 percent over normal in 1997. The second highest was 139 percent in 1974.
Normal is the average water supply from 1970 to 2000.
The Dalles, the next-to-last dam on the Columbia River, is a key point to measure the volume of water available for power generation in the Northwest, which receives about 65 percent of its power from hydroelectric dams.
Laurine said water supplies this year were higher than usual due to a huge snowfall last winter over much of the Columbia River basin, which covers parts of Washington, Oregon, Idaho, Montana, Wyoming, Utah, Nevada and California in the United States and British Columbia in Canada.
As the snow melted, the Bonneville Power Administration (BPA), the federal agency that markets electricity from the U.S.-owned dams in the Pacific Northwest, started to curtail fossil and wind generators during periods of low energy demand to manage hydro production to protect fish and control for flooding, among other things.
Bonneville replaced that curtailed generation with free or very low-cost hydro generation.
By the end of May, BPA had curtailed a total of 5,810 megawatt-hours (MWh) of fossil generation in its control area. By mid-June, fossil curtailments jumped to 10,366 MWh, according to BPA's website.
Energy analysts say strong water years can lead to a significant reduction in gas use for the region, cutting as much as 1.5 billion cubic feet daily, or about 2.5 percent, from total U.S. gas demand.
WIND HIT HARDEST
The total amount of wind generation BPA curtailed was much higher, totaling 79,119 MWh by mid June.
After a short lull in the overnight cuts, BPA again started curtailing both fossil and wind generation late last week.
Wind generators have complained to federal regulators that Bonneville's curtailing of wind generation without compensation is an unfair use of the federal agency's control of much of the region's power grid.
BPA controls about 75 percent of the high voltage transmission system in the U.S. Northwest.
According to the most recent data available from the Energy Information Administration in its Electric Power Monthly report in June, March was the second wettest on record for the Northwest, resulting in a 52 percent jump in hydro generation from the previous March.
Natural gas-fired generation was 5 percent higher in March than the year-earlier period while coal-fired generation fell nearly 7 percent.
Increased hydro accounted for nearly three-quarters of the overall 2 percent rise in U.S. electric generation for the month, compared to March 2010.
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