Mercury News: Against a backdrop of high gas prices and calls for energy independence, two renewable energy measures on the November ballot claim to offer solutions. Both, however, face uncertain support. Even environmental groups are campaigning against them. While supporters say Propositions 7 and 10 will lead to cleaner air and cars, groups like the Sierra Club charge the measures could actually hinder the state’s move toward using more solar, wind and geothermal energy. In addition, critics say …