By Deborah Austin While many longtime U.S. mainstream industries are shrinking, the electric power industry faces the opposite scenario: production capability outpaced by demand growth. In fact research by market intelligence firm Industrial Information Resources Inc. (IIR), Houston, suggests power plant construction leads the way in U.S. industrial expansion. In its 2001 Industrial Outlook, IIR forecasts corporations that own, operate or are building new industrial plants in the U.S. will spend $256-billion-plus on capital and maintenance projects. The power industry comprises the largest segment of this expected year-2001 spending, at $48.7 billion. New power generating units planned for the coming 24 months represent a total investment value of $81.1 billion, says IIR -- $65.2 billion at 340 new sites, and $15.9 billion at 167 operational plants. Over the next 20 years U.S. demand for electricity will rise by 45%, requiring 1,300 to 1,900 new electric plants, estimates the National Energy Development Group established by President George W. Bush.