石油需求从升转降、国内石油产量从降转升、对外依存度下降到50%以下、成为石油产品净出口国……2011年,美国石油安全出现了标志性变化。美国是进口量最大的世界能源消费大国。上世纪70年代两次石油危机以来,美国一直将提高能源独立性作为国家能源发展的国策。在过去近40年时间里,美国政府出台了提高能源使用效 Oil demand has risen from rising to falling, domestic oil output has risen from down to below 50% depending on foreign dependency, and has become a net exporter of petroleum products ... In 2011, the U.S. oil security showed a landmark change. The United States is the largest importer of energy in the world. Since the two oil crises in the 1970s, the United States has always been making energy independence its national policy of energy development. In the past 40 years, the U.S. government introduced energy efficiency improvements