The area around nearby Primm, Nevada, is about to become even more of a hotspot for solar energy. The Obama administration endorsed two big projects yesterday near the existing Ivanpah solar plant that went online in January. One of the new developments would be in San Bernardino County; the other would be east of Interstate 15 in Nevada. The approvals renewed concerns among environmentalists about the potential loss of desert tortoises and concern about bird deaths at solar plants. The Stateline and Silverstate South projects are proposed by Tempe, Ariz.-based First Solar Inc. If both are built, solar energy plants would cover about 13 square miles of public land in the Ivanpah Valley. The Stateline project will cover 2.6 square miles on the California side of the border, near to the existing Ivanpah plant, which uses mirrors to focus energy onto boilers mounted on three, 460-foot towers to make electricity. Silverstate South will use 3.8 square miles just east of Primm, on the Nevada side of the border and next to the existing Silverstate North, which occupies 600 acres. The two new projects are expected to supply 550 megawatts of clean energy, enough to power about 170,000 homes, using photovoltaic panel technology.