Average on-peak, day-ahead wholesale electricity prices rose in every region of the Lower 48 states in first-half 2013 compared to first-half 2012. The most important factor was the rise in the price of natural gas (the marginal fuel for generation in much of the nation) in 2013 compared to 10-year lows in April 2012. However, the increase in power prices was not uniform across electric markets as regional natural gas supply issues drove larger increases in the Northeast and Pacific Northwest.

Prices in New England were the highest in the nation mostly because of pipeline constraints that limited the delivery of natural gas. This factor drove electricity prices in New England and New York above $200 per megawatthour (MWh) for several days this winter.

In the Northwest, a decline in precipitation reduced hydroelectric generation and made the region more dependent on gas-fired power than in the first half of 2012. The combination of more reliance on natural gas and higher natural gas prices drove power prices 82% higher in the Northwest compared to the first half of 2012.

The California power market also experienced a large (59%) increase in wholesale power prices. This increase was largely the result of the continued outage of the San Onofre Nuclear Generating Station (SONGS); this factor also caused a large and unusual separation in power prices between the northern and southern parts of the state’s electric system.

via Wholesale electricity prices rose across the United States – Today in Energy – U.S. Energy Information Administration (EIA).