Maryland must build three new power plants in the next decade to maintain its energy status quo, according to a forecast by the regional power grid.

The PJM Interconnection warned the Public Service Commission at a planning conference Thursday that to keep up with Maryland's growing demand for power, three new 600-megawatt power plants should be constructed by 2017.

So to avoid building costly plants, state officials are pushing instead for more conservation programs.

Maryland already is a net power importer, purchasing more than a quarter of its electricity from other states. The peak demand is expected to grow by 1.6...