To promote the development of renewables, this article evaluates the life cycle greenhouse gas (GHG) emissions from hybrid energy storage systems (HESSs) in 100% renewable power systems. The consequential life cycle assessment (CLCA) approach is applied to evaluate and forecast the environmental implications of HESSs. Based on the power system of Sweden, different HESS combinations, which include energy storage (ES) technologies: pumped hydro ES, hydrogen ES, lithium-ion (Li-ion) batteries, lead-acid (PbA) batteries, vanadium redox (VR) batteries, supercapacitors (SCs), and flywheels, are discussed. The results show that for Sweden and similar large-scale utility applications, the cradle-to-gate GHG emissions from the HESS contribute to a major share of the life cycle GHG emissions due to the under-utilization of the cycle life. Among the HESSs compared in this study, the Pumped hydro+Li-ion+Flywheel combination exhibits the least life cycle GHG emissions. Moreover, the phasing out of nuclear power brings a severe challenge to the carbon reduction target. However, the introduced HESS manages to reduce GHG emissions from a 100% renewable power system.