Process energy comparison for the production and harvesting of algal biomass as a biofuel feedstock

• Energy demand of 122 microalgae biomass production scenarios were compared.
• Choice of harvesting technology affected energy demand of other phases.
• Raceway ponds, settling, and chamber filter press consumed the least energy.
• Total energy demand for biomass production depends on final concentration.

Harvesting and drying are often described as the most energy intensive stages of microalgal biofuel production. This study analyzes two cultivation and eleven harvest technologies for the production of microalgae biomass with and without the use of drying. These technologies were combined to form 122 different production scenarios. The results of this study present a calculation methodology and optimization of total energy demand for the production of algal biomass for biofuel production.The energetic interaction between unit processes and total process energy demand are compared for each scenario. Energy requirements are shown to be highly dependent on final mass concentration, with thermal drying being the largest energy consumer. Scenarios that omit thermal drying in favor of lipid extraction from wet biomass show the most promise for energy efficient biofuel production. Scenarios which used open ponds for cultivation, followed by settling and membrane filtration were the most energy efficient.