(Invited) Re-Energizing Waste CO2 to Fuels with the Sun: Efficiency, Scale, Resource Utilization, and Economics

The interconnected challenges posed by the strategic and economic importance of petroleum and the increasing concentration of atmospheric carbon dioxide are now widely recognized. A transition away from the fossil fuel dominated global economy toward a system with ever-lower carbon intensity but commensurate with energy demand is necessary. Addressing these challenges requires thinking differently, beginning with recognizing that from a technological point of view, liquid hydrocarbon fuels remain an ideal transportable energy storage medium, and that CO₂ and H₂O are simply the energy depleted, oxidized form of hydrocarbons. Further, it is instructive to acknowledge that conventional fossil fuels are in fact ‘‘stored sunlight’’. This perspective suggests searching for large-scale options that convert and store modern sunlight via reactions of carbon dioxide and water to more usable and transportable forms as nature did, but do so as efficiently, effectively, affordably, and sustainably as possible – including being able to produce at the same rate as the product is being consumed. Conversion of solar energy to chemically or biologically reduce waste CO₂ into hydrocarbon fuels is an attractive option, but it is not without significant resource, economic, and technical challenges. Herein we present a general examination of resource and economic considerations and conclude that solar-to-fuel efficiency is a key metric that drives not only the potential impact (scalability) of a technology for storing (contemporary) sunlight and sequestering carbon above ground as energy dense fuels, but also the economics. In this presentation, we will talk about a number of comparative metrics of significance and concern to accelerating a transition to a low carbon sustainable transportation future.