A global electricity crisis with blackouts and curtailed usage will plague the 1990s unless drastic steps are taken to build more power plants, a panel of energy experts warned Saturday. The impending power shortage threatens jobs, public health and economic development, a panel of 31 energy experts from 13 nations concluded after a weeklong meeting at UC Berkeley. "We need strong leadership to address the problem now," said Kenneth Davis, former deputy secretary of the U.S. Department of Energy and now a consultant for Bechtel Corp. "By the time it assumes a crisis proportion . . . it will be too late to do something about it."