title: Energy return on investment for algal biofuel production coupled with wastewater treatment.
abstract: This study presents a second-order energy return on investment analysis to evaluate the mutual benefits of combining an advanced wastewater treatment plant (WWTP) (with biological nutrient removal) with algal biofuel production. With conventional, independently operated systems, algae production requires significant material inputs, which require energy directly and indirectly, and the WWTP requires significant energy inputs for treatment of the waste streams. The second-order energy return on investment values for independent operation of the WWTP and the algal biofuels production facility were determined to be 0.37 and 0.42, respectively. By combining the two, energy inputs can be reduced significantly. Consequently, the integrated system can outperform the isolated system, yielding a second-order energy return on investment of 1.44. Combining these systems transforms two energy sinks to a collective (second-order) energy source. However, these results do not include capital, labor, and other required expenses, suggesting that profitable deployment will be challenging.
authors.affiliation: The Center for Electromechanics, University of Texas at Austin, Austin, 1 University Station R7000, Austin, TX 78712, USA. colinmbeal@gmail.com
authors.forename: Colin M
authors.initials: CM
authors.lastname: Beal
authors.forename: Ashlynn S
authors.initials: AS
authors.lastname: Stillwell
authors.forename: Carey W
authors.initials: CW
authors.lastname: King
authors.forename: Stuart M
authors.initials: SM
authors.lastname: Cohen
authors.forename: Halil
authors.initials: H
authors.lastname: Berberoglu
authors.forename: Rajendra P
authors.initials: RP
authors.lastname: Bhattarai
authors.forename: Rhykka L
authors.initials: RL
authors.lastname: Connelly
authors.forename: Michael E
authors.initials: ME
authors.lastname: Webber
authors.forename: Robert E
authors.initials: RE
authors.lastname: Hebner
mesh_terms: D056804:Biofuels; D018533:Biomass; D002245:Carbon Dioxide / Q000032:analysis; D007449:Investments; D058086:Microalgae / Q000378:metabolism*; D014865:Waste Disposal, Fluid; D018508:Water Purification
chemical_list: D056804:Biofuels; D002245:Carbon Dioxide