Life-cycle assessment and geospatial analysis of integrating microalgae cultivation into a regional economy

Microalgae have been recognised as promising feedstock for a bioeconomy. Currently, their environmental sustainability is constrained by a high energy-demand for cultivation, as well as by the provision of carbon dioxide and nutrients. This study evaluates the potential of alternative supply chains based on available waste-streams. For this, the microalgae cultivation process is coupled with anaerobic digestion processes. Consequential life-cycle assessment is applied to compare four different substrates (municipal biowaste, sewage sludge, cattle and swine manure) in three different process designs with a reference scenario using conventional supply chains. A geospatial analysis of the substrate availability was performed to identify the potential for integrated microalgal cultivation facilities. The results indicated that sewage sludge, as well as cattle and swine manure, reduce the environmental burden of microalgae cultivation. It was further found, that cattle stock and the capacities of urban wastewater treatment plants are the most important indicators for the possibility of integrating microalgae cultivation into regional economies.