Energy return on investment for algal biofuel production coupled with wastewater treatment

Colin M. Beal, Ashlynn S. Stillwell, Carey W. King, Stuart M. Cohen, Halil Berberoglu, Rajendra P. Bhattarai, Rhykka L. Connelly, Michael E. Webber, Robert E. Hebner

Research output: Contribution to journalArticlepeer-review


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.

Original languageEnglish (US)
Pages (from-to)692-710
Number of pages19
JournalWater Environment Research
Issue number9
StatePublished - Sep 2012
Externally publishedYes


  • Algae
  • Algal biofuel production
  • Biofuel
  • Biological nutrient removal
  • Energy balance
  • Energy return on investment
  • Synergy
  • Wastewater treatment

ASJC Scopus subject areas

  • Environmental Chemistry
  • Ecological Modeling
  • Water Science and Technology
  • Waste Management and Disposal
  • Pollution


Dive into the research topics of 'Energy return on investment for algal biofuel production coupled with wastewater treatment'. Together they form a unique fingerprint.

Cite this