Life-cycle assessment of flue gas CO2 fixation from coal-fired power plant and coal chemical plant by microalgae

The technology of flue gas CO2 fixation by microalgae is highly attractive in the era of CO2 neutrality. However, CO2 emission along the whole process has yet to be sufficiently evaluated. Here, a life-cycle assessment was performed to evaluate the energy conversion characteristics and environmental impacts of flue gas CO2 fixation from coal-fired power plant (Case 1) and coal chemical plant (Case 2) by microalgae. The results show that total energy consumption and CO2 gas emissions for Case 1 are 27.5–38.0 MJ/kg microalgae power (MP) and 5.7–7.7 kg CO2 equiv/kg MP, respectively, which are lower than that for Case 2 (122.5–181.3 MJ/kg MP and 32.7–48.6 kg CO2 equiv/kg MP). The CO2 gas aeration rate and microalgae growth rate are the two most sensitive parameters for the energy conversion and net CO2 emission. Therefore, increasing the CO2 aeration efficiency and microalgae growth rate are key to advance the technology of flue gas CO2 fixation by microalgae which will contribute to carbon naturality.