Varun Sivaram is the Philip D. Reed fellow for science and technology at the Council on Foreign Relations. He is also an adjunct professor at Georgetown University, an adjunct senior research scholar at Columbia University, and a member of the energy and environment advisory boards at Stanford University. He is the author of the book, Taming the Sun: Innovations to Harness Solar Energy and Power the Planet (MIT University Press, 2018) and the editor of the book, Digital Decarbonization: Promoting Clean Energy Systems Through Digital Innovations (CFR Press, 2018). Forbes named him one of its 30 under 30 in law and policy, and Grist named him one of the top 50 leaders in sustainability. John Dabiri is Professor of Civil & Environmental Engineering and of Mechanical Engineering at Stanford University, senior fellow in the Precourt Institute for Energy, and a MacArthur Fellow. His research focuses on science and technology at the intersection of fluid mechanics, energy and environment, and biology. For his research in bio-inspired wind energy, Bloomberg Businessweek magazine listed him among its Technology Innovators, and MIT Technology Review magazine named him one of its 35 innovators under 35. David M. Hart is professor at the Schar School of Policy and Government at George Mason University, co-chair of the Innovation Policy Forum at the National Academies of Science, Engineering and Medicine, and senior fellow at the Information Technology and Innovation Foundation. He co-authored the April 2018 MIT Energy Innovation working paper Energy Storage for the Grid: Policy Options for Sustaining Innovation with William B. Bonvillian and Nathaniel Austin. Solar energy, wind energy, and battery energy storage are enjoying rapid commercial uptake. However, in each case, a single dominant technological design has emerged: silicon solar photovoltaic panels, horizontal-axis wind turbines, and lithium-ion batteries. Private industry is presently scaling up these dominant designs, while emerging technologies struggle to achieve commercial traction. Such technological lock-in could impede a clean energy transition. Farsighted public policy will be crucial to mitigating lock-in, for example by boosting funding for research, development, and demonstration of next-generation technologies.