Development and Economic Analysis of Blue Batteries Using Seawater

It is essential to secure large-capacity ultra-long cycle ESS technology suitable for the facility capacity level of large wind and solar power plants in order to effectively respond to Korea's national agenda of spreading the supply of new and renewable energy for the transition to a carbon-neutral society.

This research team developed a large-capacity long-period energy storage device called "blue battery" using seawater. Blue battery is an ESS technology that stores renewable energy by separating salt in seawater into cations (e.g., Na+) and anions (Cl-). When the salt of seawater is ion-separated, the catholyte becomes a basic solution with a pH of 10-11, and the anolyte becomes an acidic solution with a pH of 3-4. When energy is stored with an acid-base, the theoretical energy storage density is about 10 Wh/L (57.6 kJ/mol), which is relatively low compared to the existing energy storage technology. This research team started the evaluation of the original technology performance of the blue battery on a '2×2 cm2' laboratory scale and succeeded in commissioning a 1 kW/10 kWh blue battery pilot system for the first time in Korea. The 10 kW blue battery system was designed for the purpose of controlling the variability of sunlight, which is pointed out as the main cause of Jeju's renewable energy output control, and the enterprise management system was designed by assuming that it accommodates the expected excess power (1 kW, up to 30% of the power generated) generated from 3 kW solar power generation (about 10 kW)

The economic feasibility of blue batteries was analyzed in two ways: the life cycle analysis of blue batteries themselves and the analysis of carbon reduction when using blue batteries.

First, the economic feasibility of the battery itself was analyzed. As a representative electrochemical long-term energy storage technology, there is a vanadium redox flow battery (VRFB). As a result of conducting the life cycle economic analysis (LCA) of VRFB and blue batteries, it was analyzed that the LCOS of VRFB was 6.05 euros/kWh, while the blue battery was 3.07 euros/kWh, which was nearly 50% cheaper.

Second, the economic feasibility and carbon emission reduction effects were analyzed when solar power generation and blue batteries were introduced into the electricity supply structure of this Jeju farm. The higher the power unit price and the higher the CF, the higher the economic feasibility of installing blue batteries. It can be seen that the introduction of blue batteries significantly increases the effect of reducing carbon emissions by utilizing surplus power. In particular, when solar power generation facilities and blue batteries are installed together, they not only secure power supply safety by compensating for the shortcomings of solar power generation, which is greatly affected by the amount of sunlight, but also significantly reduce carbon costs, indicating economic advantages in the long run.

Blue battery technology using seawater has long-term advantages even when analyzing economic feasibility, is an eco-friendly energy storage technology that does not emit environmental pollutants during energy storage (charging) and power generation (discharging).