摘要
By 2030,California plans to obtain 60%of its electrical power from renewable sources[1].The state will be able to produce only about half that amount of power itself,however,and will need to import the rest[2].In contrast,by 2030 the Upper Midwest portion of the United States will be generating more than twice as much renewable energy as it needs-so much that wind farms in the region will have to cut back their output by 61%[2].
