Climate change, peak oil, air pollution, green jobs, or energy security: there is a great deal of momentum towards renewable energy these days. Between 2005 and 2010 the clean energy sector experienced investment growth of 230% (Pew Charitable Trusts 2010). The technical complexities of the renewable energy challenge will require more technical expertise. Such technical challenges cross disciplinary and institutional boundaries and often involve matters beyond the realm of technics. In this essay the authors argue that broad training in the social and environmental dimensions of new technologies in the engineering disciplines is essential to a rapid and successful renewable energy transition. There are several discrepancies between what is technically feasible (or infeasible) and what is socially desirable. For example, renewable technologies (defined as continuous energy flows originating mostly from the sun) have captured the political imagination—but they also have low levels of penetration (National Research Council 2010; REN21 2011), and in some cases face considerable local political/citizen opposition. As renewables expand in scale and opposition wanes, will the new energy systems be sustainable or socially just?