Abstract
It is known that oil extraction processes may require large amounts of organic solvents, which have adverse effects on the nutritional and functional properties of the extracted compounds as well as on human health. Therefore, it is essential to develop novel approach of lipid extraction, which is an effective eco-friendly process. We utilized SimaPro 7.3 as the life cycle assessment tool with Eco-indicator 99 method to evaluate the environmental impact of various microalgae oil extraction. The extractants taken into account include chloroform and methanol (Scenario A), dichloromethane and methanol (Scenario B), isopropanol and cyclohexane (Scenario C), supercritical-CO2 (Scenario D), CO2-expanded methanol (Scenario E), and CO2-expanded ethanol (Scenario F) respectively. The goal of our LCA calculation is to quantitatively interpret the overall environmental impacts in the end of microalgae oil extraction by different extraction methods when 1 kg microalgae oil is extracted (function unit). To achieve this objective, individual input energy (electricity), raw material (extractant), and process (electricity) are taken into account and converted into the equivalent extractant/power consumption. A linear correlation between usage and power consumption is assumed to convert experimental data into function unit. In this study, environmental impact of extractants in Scenario D, E and F are relative low. Take electricity into considerate, environmental impact of Scenario D is highest and electricity cost of producing one unit of microalgae is the highest over others; environmental impact of Scenario E and F are low and low electricity cost. To achieve the goal of green technology, we assess viability of solar power and wind power for alternative energy. Environmental impact of Scenario D is only one third and one fourth when solar and wind energy is applied. The carbon footprint of Scenario D is only one twelfth and one twenty fourth when solar and wind energy is applied; the carbon footprint of Scenario E and F are both lower than other scenarios. The comparison indicates that both Scenario E and F are the relative appropriate methods for extracting microalgae lipids because their low carbon emission, low cost and eco-friendly. Finally, Penghu of Taiwan has been considered a potential location for developing renewable energy such as wind. Using CO2 emitted from local thermal power plant as carbon source, combining with optimized extraction method proposed in this study, to establish a microalgae oil plant at Penghu of Taiwan.