The section then considers the wider equilibrium effects across the economy. In a review of 15 previous studies, Wei, Patadia, and Kammen (2010) find that for the United States, all renewable and low-carbon energy sources generate more jobs per unit of energy delivered than the fossil fuel sector. However, the type of employment differs between the technologies, with a shift from resource extraction to manufacturing for example, and the timing and location of employment within a region may vary.