17 - Energy and Carbon Intensities of Stored Solar Photovoltaic Energy

Abstract

This chapter shows how storage affects the energy performance and carbon intensity of solar photovoltaic (PV) generated electricity paired with electrical energy storage technologies. These results show that it is more energetically favorable to store solar PV energy than it is to curtail electricity production. Electrochemically based storage technologies, while higher in energy density, result in lower (worse) energy return ratios than large-scale geologically based storage technologies such as compressed air energy storage and pumped hydroelectric storage. Carbon performance of all PV-storage pairings considered here is better than the average US power grid. The lowest carbon storage technologies are pumped hydro, vanadium redox, and lithium-ion. On an energetic basis, stored-PV electricity is more intensive than the average US power grid. Reducing embodied energy costs, increasing efficiency, and increasing depth of discharge will improve the energetic and carbon performance of batteries. On an energetic and carbon performance basis, solar PV energy paired with storage performs trades greatly reduced carbon intensity for increased energy intensity when compared with the US power grid average.