As various companies release their financial information for the second quarter of 2011, the Energy Information Administration released its data on the wholesale electricity market for the first half of 2011.

According to the EIA, average on-peak spot electricity prices varied widely throughout the US from January – June 2011, much more so than in the same period in 2010. Western prices fell 14 – 26%, Midwest and Southeast prices fell by about 4%; and Texas and Northeast prices were up 4 – 13%.

“Key drivers of wholesale electric prices during the first half of 2011 were temperatures, natural gas prices, hydroelectric resource availability, and the disposition of nuclear power plants,” the government agency said.

As shown in the graph above, hydroelectric generation was up and weighed significantly on prices in the West.

This map shows prices nationally: