Algae-Powered Sustainable Community Design Life Cycle Assessment and Techno-Economic Analysis

Abstract

Microalgae as a feedstock source for biofuels have been researched extensively over the last decade as the renewable energy community strives to find an environmentally responsible and economically feasible source of transportation fuel. This study focuses on microalgae not as a source of transportation fuel but as a fundamental pillar of sustainable rural communities seeking to achieve a net-zero energy and waste status. Sources of sustenance, waste streams, energy demands, energy production, and recycle methods are evaluated in this life cycle assessment and techno-economic analysis to determine if a rural community can achieve a state of neutrality and self-sustainability. A functional unit of 20,000 MJ/year corresponding to the energy demand of a 902-person community is modeled after a town in Georgia. The model revealed that the total available land for algae production was 7.45 ha, but only 0.02 ha was required for producing 20,000 MJ/year, our functional unit in this study. At this magnitude of algae cultivation, the energy return on investment (EROI) was 0.54 (net negative energy community) and the profitability index was only 0.04 (community is at financial loss). When the algae cultivation area is increased to 1.8 ha, an EROI of 1 is achieved; however, PI is still <1 (0.07). In order to reach PI = 1 (the break-even community), the algae cultivation area must be increased to 1.55 ha, with a corresponding EROI of 3.87. The greenhouse gas offsets for all communities were determined to be substantially larger than their emissions.