Energy transition towards renewables and metal depletion: an approach through the EROI concept

More and more attention is being paid to renewable technologies because there are seen as a great opportunity to disengage our society from its dependence on fossil fuels. Such flowbased energy resources that rely on solar energy, are supposed to lead us toward a sustainable energy future. However, because of their high capital intensity, renewable technologies require large amounts of matter, among which common and rare metals. These metals require energy for their production, and more specifically for their extraction. The energy cost associated to metal extraction is linked to mineral ore grade, meaning that as depletion progresses, energy cost increases. On the other hand, renewable energy resources deliver less net energy to society compare to fossil fuels, because of their diffuse nature. It is therefore easy to see that a close relationship exists between energy and metals sectors. In this article, we tried to more precisely describe this relationship by investigating how the energy requirement associated to metal extraction could impact the energy-returnoninvestment (EROI) of different renewable technologies. We found that if only copper is considered, because it is the only metal with sufficient data for a deep analysis, the EROI of renewable technologies is not really affected. However, if other metals are considered in an extreme scenario in which they are all extracted from common rocks, the EROI of renewable technologies could be gravely altered.(This abstract was borrowed from another version of this item.)