Hybrid Renewable Energy System Model Analysis: Pumped Hydrogen Storage Compared to Battery-Bank Storage Systems

The most common application for small-scale stand-alone power generation using hybrid renewable energy sources typically requires a battery bank storage. Nonetheless, batteries are not a competitive solution due to excessive initial and maintenance costs associated and relatively short product life. An alternative energy storage solution that could replace batteries for a hybrid renewable energy system could be a mini hydro-pumped storage system. Both batteries and water reservoirs serve as an energy storage solution. The intent of this project is to analyze the costs of these two energy systems to find the more cost effective energy storage solution. The selected project is a small state-of-art studio office building located at Issaquah, WA, which has been equipped with pumped hydrogen storage system and battery-bank storage system for comparison and cost analysis. The water resource is Lake Sammamish, WA, 150 feet away from the building. The available renewable energy sources include sun, wind, and water. The annual energy consumptions of these two energy storage systems are collected in separate models and compared for their cost-effectiveness analyses on the initial cost, 5-year projected cost, 10-year projected cost, and 15-year projected cost. Based on the size of the systems designed in this project, the pumped hydrogen system serves as the better option in regard to costs. The most frequent cost was the replacement of batteries. The model developed close to 35% cost saving over a 30-year span of the systems for the hydrogen system compared to the battery system. It is also found that grid-tied systems provide more incentives financially than off-grid. The comparison analysis does not have to be just financial. CO2 emissions could be an alternative way to determine the best solution.