The high theoretical productivity of microalgae makes it a promising energy crop, but economically viable large-scale production facilities have yet to emerge. Furthermore, life-cycle studies indicate biofuel from algae produced with current technology has a lower net energy ratio (NER) than other biofuels. These drawbacks are due partly to the carbon dioxide and fertilizer input requirements. Therefore, coupling algae cultivation ponds with flue gas emissions from power utilities to provide carbon dioxide and municipal wastewater to provide nutrients has been recommended. This flue-gas and wastewater coutilization (FWC) strategy not only reduces the upstream impacts and costs associated with providing inputs, but also provides a credit for wastewater treatment, a service currently required to reduce production costs to a viable level. This study provides the first national assessment of the potential for producing algal biofuel in the United States in a manner that is cost-competitive with fossil fuel. A spatial-temporal algae growth simulation incorporating solar radiation and temperature data is built to calculate the average annual algae yield for any location, which is used to establish the required pond size, the predominant economic hurdle. The results of this model are then integrated into a geospatial overlay analysis which establishes the economic viability and biofuel production potential of FWC at any location by considering the relative abundance of the input resources as well as their proximity. It was found that less than 200 million gallons of biofuel could be produced annually, less than half of the transport fuel consumed daily, due to the limited amount of nutrients present in wastewater and the unfavorable climatic conditions at most locations. This presentation will also explore strategies for increasing algal biofuel production, including nutrient recycling and utilization of nutrients from livestock waste.
CSS Publication Number:
June 7, 2011
Nolan Orfield, Greg Keoleian and Nancy Love. “A Gis Based National Assessment Of Algal Biofuel Production Potential Through Flue-Gas And Wastewater Coutilization.” 6th International Conference of the International Society for Industrial Ecology (ISIE) Proceedings. Berkeley, CA, June 7-10 2011, Abstract #591.