Winner of the Excellence in sustainability Steelie Award 2020
POSCO, together with its research arm, the Research Institute of Industrial Science & Technology (RIST), have developed a steel slag-based artificial reef, called Triton®, and has been creating more than 30 sea forests covering a total of 37.8 hectares in coastal regions of South Korea. Since 2007, a total of 7,554 Triton reefs and 29,378 Triton blocks have been used to transform damaged coastal areas into sea forests with abundant marine algae.
Triton®, the artificial reef, is made of 85% slag aggregates, 15% slag cement, as well as water and admixture. The slag is a co-product of steelmaking. The mineral content of the slag, which is mainly calcium and iron, is higher than that of general aggregates and thus is effective in promoting the growth and photosynthesis of marine algae.
The Triton sea forest sequestrates and stores significant amounts of carbon from the atmosphere and ocean. This is known as ‘blue carbon’ capture, which refers to carbon captured and stored by the oceans and coastal ecosystems. Research shows that 1 hectare of the Triton® sea forest captures 15.7 – 16.6 tonnes of CO2 each year. The accumulated area of the Triton sea forests created so far is about 37.8 hectares. This indicates that the yearly amount of CO2 uptake by the Triton sea forests is more than 600 tonnes.
The increased number of algae species and algae biomass from the Triton® sea forest has also increased marine organisms and therefore increased fish catch in the areas. The total economic value of the Triton® sea forests created so far has been estimated at US$1,080,815 per year for the local communities.
POSCO provides steel slag free of charge to a local reef manufacturer, who then produces strong and stable artificial reefs at a reasonable price. As a result, POSCO can process an average of 13,500 tonnes of steel slag every year, saving about US $1,710,000.
Lastly, in 2014 POSCO transferred the production technology of Triton® reefs to a local reef manufacturer. The company has grown in size and hired more people to run the business, contributing to developing a vital local community.
POSCO’s extensive effort to communicate the use of the Triton® reefs and their positive impact on the marine life and local communities via their social media network has also helped to improve the public perception of steel slag and the steel industry.