Sustainable power density in electricity generation

Purpose: When comparing renewables with fossil fuels, emotional approaches are fuelled by the difficulties in defining a proper metric able to make consistent comparisons among energy sources. In literature several approaches have been proposed, all effective in some way but ineffective in others. Variables like energy density, prices, estimated resources, life time emissions, water use and waste, all come at the same time to form an unmanageable mix. This paper discuss the adoption of a shared metric to clarify the boundary conditions that limit the solutions can be operated and to define which scenarios are sustainable and which are not. Design/methodology/approach: Energy density and power density are the cornerstones of the physical limitations in the exploitation of the energy sources. On this basis, a novel classification of energy sources, volumetric and flowing, has been proposed and discussed in light of three parameters: abundance, power density and sustainability. Eventually, an extended definition of power density based on life-cycle assessment is adopted. Findings: Sustainable power density makes possible compare the different energy options and shows how limitation in land comes to be the root of all resources limitations. Originality/value: A definition of a unique parameter is proposed and pros and cons of all energy options are calculated and put in a single graphic providing new insights into the energy policy. © Emerald Group Publishing Limited.