The greenhouse gas emissions' footprint and net energy ratio of utility-scale electro-chemical energy storage systems

Electro-chemical batteries are widely used in portable devices and transportation, but they can also be used in the electricity grid for various applications. The assessment of the environmental impacts of electro-chemical storage systems for stationary use has received little attention. In this study, data-intensive, bottom-up life cycle assessment models were developed to assess the life cycle net energy ratios (NERs) and greenhouse gas (GHG) emissions of utility-scale stationary applications of five electro-chemical energy storage systems: sodium sulfur, lithium-ion, valve-regulated lead-acid, nickel-cadmium, and vanadium redox flow. Four stationary application scenarios were considered: bulk energy storage, transmission and distribution (T&D) investment deferral, frequency regulation, and support of voltage regulation. The Li-ion storage system has the highest NER and lowest GHG emissions in every scenario. The life cycle GHG emissions range from 715 to 784 kg-CO2eq for sodium-sulfur, 625-659 kg-CO2eq for lithium-ion, 749-803 kg-CO2eq for valve-regulated lead-acid, 742-806 kgCO(2eq) for nickel-cadmium, and 800-963 kg-CO2eq for vanadium redox flow per MWh of electricity delivered, depending on the application scenario. The results are highly influenced by the operation phase that involves charging the batteries. Lithium-ion and sodium-sulfur storage systems are the most suitable for all the application scenarios because of their longer cycle lives and higher energy densities.

Automated summary

The study found that the lithium-ion storage system has the highest net energy ratio and lowest greenhouse gas emissions in every scenario. Lithium-ion and sodium-sulfur storage systems are the most suitable choice for all application scenarios due to their longer cycle lives and higher energy densities.