Feeding a Gas Turbine with Aluminum Plant Exhaust for Increased CO₂ Concentration in Capture Plant

Aluminum production contributes to global CO₂ emissions both due to the production process itself and due to the generation of electric power required for aluminum production. A concept is presented for increasing the CO₂ concentration in the aluminum exhaust from ∼1% to ∼5% through the feeding of aluminum plant exhaust gas to a natural gas combined cycle (NGCC). The specific energy demand for CO₂ capture is therewith reduced for both the aluminum plant and the NGCC. An evaluation was made of the impact the aluminum exhaust gas may have on the gas turbine and it is estimated that the most critical issues are corrosion due to SO₂ in the aluminum plant exhaust gas and gas turbine inlet filter saturation, since the exhaust gas is saturated with seawater after the wet scrubber. A gas turbine inlet filter was tested for a period of five weeks, but a longer filter test period would be required for verifying filter integrity over time. In order to proceed, the viability of the concept should be evaluated by a gas turbine manufacturer. An alternative concept to evaluate for concentration of CO₂ emissions could be to feed the aluminum plant exhaust gas to a boiler in a steam power plant.