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Life cycle assessment (LCA) is a valuable tool for determining the environmental impacts associated with different products and has been widely used to assess biofuel production. As a scientific methodology rather than a standardized test, every LCA may be thought of as unique in terms of the selection of functional units or determination of system boundaries. Researchers generally tailor the method to meet the specific goals of their own investigations. This review examines a number of LCAs used to evaluate microalgae-to-energy systems, and evaluates their contributions in terms of their ability to support commercialization efforts in this sector. To this end, a new scoring system for LCAs is proposed based on input/output flows, data origin, production technologies and system boundaries, selection of assumptions and variables, as well as the ability to track environmental, economic, and social impacts. The review suggests that, while a wide variety of new technological pathways for microalgae-to-energy systems are being assessed, the majority of studies reported employ relatively limited system boundaries that may not capture the full impacts of the processes. The number of environmental impact factors being tracked is limited, and many studies do not consider important impacts such as water or land use. Most studies do not incorporate critical information about economics related to new process configurations, which will be essential to support commercialization efforts in this area. © 2016 Society of Chemical Industry and John Wiley & Sons, Lt

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In recent years there has been growing interest in the use of microalgae as a feedstock for biofuels, particularly for biodiesel. The production process of biodiesel from microalgae generally consists of five different phases: cultivation, harvesting, drying, lipid extraction and transesterification. While existing technologies are available to undertake each of these phases, the process would benefit from enhanced sustainability achieved by reducing environmental impact and costs. One process innovation currently under consideration is the use of waste products as inputs to the process, including CO2 captured from industrial flue gas, or nutrients from wastewater. These could be employed in algae cultivation. The co-location of an algae cultivation plant with other industrial facilities, such as a cement plant or a wastewater treatment facility, could result in significantly reduced atmospheric emissions and improve wastewater effluent discharges. A comparative life cycle assessment approach is used to examine two different, realistic alternatives for the co-location of an algae cultivation plant with an existing cement plant or wastewater treatment facility near Kingston, Ontario, Canada. The study seeks to identify a preferred siting option from the perspective of minimizing environmental impacts. The first alternative involves the co-location with the Lafarge Cement plant, on the north shore of Lake Ontario, near Bath Ontario. The second alternative consists in the co-location with the Ravensview wastewater treatment facility east of the city of Kingston on the St. Lawrence River. The algae production plant is based on an open pond technology and is assumed to have a production capacity of about 120 tons of dry microalgal biomass per year. © 2016 The Authors