Sen. Amy Klobuchar has asked the U.S. Department of Energy to investigate the steep increase in Minnesota gas prices over the past few weeks. Gasoline industry officials say regional gas prices have jumped 80 cents in the past month and 30 cents in the past week because of both unexpected and planned shutdowns at gasoline refineries. But Klobuchar said the impact of temporary closures shouldn't have so much impact on the price consumers have to pay. In a letter to Energy Secretary Steven Chu, the Democratic senator called on the Department of Energy to thoroughly examine the closures and timing...