Comparative Techno-economic Analysis of Large-scale Renewable Energy Storage Technologies

Energy storage is an effective way to address the instability of renewable energy generation modes, such as wind and solar, which are projected to play an important role in the sustainable and low-carbon society. Economics and carbon emissions are important indicators that should be thoroughly considered for evaluating the feasibility of energy storage technologies (ESTs). In this study, we study two promising routes for large-scale renewable energy storage, electrochemical energy storage (EES) and hydrogen energy storage (HES), via technical analysis of the ESTs. The levelized cost of storage (LCOS), carbon emissions and uncertainty assessments for EESs and HESs over the life cycle are conducted with full consideration of the critical links for these routes. In order to reduce the evaluation error, we use the Monte Carlo method to derive a large number of data for estimating the economy and carbon emission level of ESTs based on the collected data. The results show that lithium ion (Li-ion) batteries show the lowest LCOS and carbon emissions, at 0.314 US$ kWh-1 and 72.76 gCO2e kWh-1, compared with other batteries for EES. Different HES routes, meaning different combinations of hydrogen production, delivery and refueling methods, show substantial differences in economics, and the lowest LCOS and carbon emissions, at 0.227 US$ kWh-1 and 61.63 gCO2e kWh-1, are achieved using HES routes that involve hydrogen production by alkaline electrolyzer (AE), delivery by hydrogen pipeline and corresponding refueling. The findings of this study suggest that HES and EES have comparable levels of economics and carbon emissions that should be both considered for large-scale renewable energy storage to achieve future decarbonization goals.