Above-normal March precipitation in the Pacific Northwest drove hydro generation to levels well above last year and put downward pressure on wholesale power prices.
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Hydro generation in the Bonneville Power Administration territory totaled about 8.5 million MWh and made up about 78% of the generation mix in March, compared with 5.1 million MWh and 57% of the fuel mix for March 2013, according to data from BPA.
Thermal generation, which includes coal, gas and nuclear generation in the region, made up about 13% of the fuel mix in March, while wind generation was around 9%.
Total generation from 23 of the major hydro facilities in the Northwest in March was about 76% above March 2013, according to preliminary data from the US Army Corps of Engineers.
Total generation for the dams was about 8.6 million MWh, compared with 4.9 MWh in March 2013.
Grand Coulee on the Columbia River generated 1.9 million MWh in March, about 55% higher than last year.
Dworshak on the Clearwater River produced 320,461 MWh, a 540% increase over last year.
Lower Granite on the Snake River generated about 389,000 MWh, an increase of about 119% compared with March 2013.
Northwest off-peak wholesale power prices felt most of the sting of the low cost hydro generation, with prices dipping into negative territory about the middle of the month.
Mid-Columbia off-peak averaged around $18/MWh in March 2014, about $12 below March 2013, as prices ranged from negative $0.50/MWh to $57/MWh.
Even with the heavy dose of hydro in March, on-peak prices were nearly flat to the same period last year.
Mid-Columbia on-peak prices averaged just over $32/MWh during March 2014, which is about 50 cents lower than March 2013, while prices ranged from $13.50 to about $61/MWh.
Average marginal heat rates were crushed by the dominating hydro generation.
March 2014 Mid-C on-peak marginal heat rates averaged around 6,477 Btu/kWh, compared with 9,825 Btu/kWh in February 2014 and 8,767 Btu/kWh in March 2013.
Off-peak marginal heat rates were pushed lower with March averaging near 3,208 Btu/kWh, versus 8,755 Btu/kWh in February and 8,133 Btu/kWh in March last year.