Utilization of flue gas from a power plant for tank cultivation of the red seaweed Gracilaria cornea

Flue gases containing 12-15% CO₂, mixed with warm seawater disposed by a power plant, were used to cultivate Gracilaria cornea (Rhodophyta) in 1000 L or 40 L tanks at pH 8.0. During the 13-month study, growth rates were similar to those where commercial CO₂ was used (94.1% vs. 91.3% biomass increments per week), with additions of NH₄ and PO ₄ having significant enhancing effects on algal growth. Concentrations of chemical components, including heavy metals, measured in the seawater medium were within the range of those found in the tissue and agar of G. cornea, meeting international standards for marine pollutants. In average, the agar content and agar strength were similar for the different treatments, as were the levels of carbohydrates and total soluble proteins. These results show that flue gas and warm seawater can be used for intensive long-term seaweed tank cultivation presumably at reduced production costs as compared with commercial CO₂.