fundamentals of water removal from the product are critical in any discussions about largescale fuel production. Laboratory-scale or pilot-scale techniques that use solar drying are relatively slow, require large land areas, and are not likely to scale up commercially.

3.8 SUMMARY

This chapter describes and contrasts pathways that lead from algae cultivation to fuel production. Many technical options exist for each individual component in the processing pathway (for example, algae can be cultivated in an array of open ponds or closed photobioreactor systems with different designs). This chapter illustrates how particular individual components are linked together to constitute the pathway for algal biofuel production and how categorizing these processes into several distinctive pathways can help with the analysis of the sustainability impacts of algal biofuels. This chapter further discusses the potential fuel products and coproducts from various production pathways. In concert with Chapters 4 and 5, the reference and alternate pathways demonstrate the sustainability issues for the photosynthetic methods of producing fuels from microalgae and highlight potential improvements that might alleviate critical sustainability concerns.

Though this chapter focuses on describing algal biofuel production pathways that are further considered in following chapters, it is the only part of the report that considers the value-added propositions associated with coproducts. The committee believed that coproducing high-value products, such as nutraceutical products, with algal biofuels would be viable only on a small scale. If large quantities of high-value algal products are coproduced with biofuels, the value of coproducts likely decreases with market saturation. Animal feedstuff is the only coproduct that is likely to have a large enough market to absorb the large quantities produced if algal biofuels are produced at commercial scale. The coproduct value depends on the composition of the animal feedstuff and the characteristics of the market in which it would be sold. In general, coproduct volumes swell with the scaling up of algal biofuel production, potentially saturating markets for these products unless a wide variety of coproducts for different markets are produced.

REFERENCES

AlfaLaval. 2010. Multiple choice for fats and oils refining. Available online at http://local.alfalaval.com/en-us/key-industries/food/fatsandoils/Documents/PFT00355EN_Degumming_neutralization.pdf. Accessed December 21, 2011.

Beal, C.M., R.E. Hebner, M.E. Webber, R.S. Ruoff, and A.F. Seibert. 2011. The energy return on investment for algal biocrude: Results for a research production facility. Bioenergy Research: DOI: 10.1007/s12155-011-9128-4.

Benemann, J.R. 2008. Opportunities and challenges in algae biofuel production. Available online at http://www.fao.org/uploads/media/algae_positionpaper.pdf. Accessed October 21, 2011.

BioProcess Algae. 2011. Questionnaire reply from BioProcess Algae. Received by the NRC Committee on the Sustainable Development of Algal Biofuels on September 27.

Boussiba, S. 2011. Questionnaire reply from AlgaTechnologies, Kibbutz Qetura. Received by the NRC Committee on the Sustainable Development of Algal Biofuels on July 6.

Chance, R.R., B. McCool, and J.D. Coleman. 2011. A Cyanobacteria-Based Photosynthetic Process for the Production of Ethanol. Presentation to the NRC Committee on Sustainable Development of Algal Biofuels on June 13.

Davis, R., A. Aden, and P.T. Pienkos. 2011. Techno-economic analysis of autotrophic microalgae for fuel production. Applied Energy 88(10):3524-3531.

Fan, X., R. Burton, and G. Austic. 2010. Conversion of degummed soybean oil to biodiesel: Optimization of degumming methods and evaluation of fuel properties. International Journal of Green Energy 7(6):593-599.

Gouveia, L. 2011. Microalgae as a Feedstock for Biofuels: Springer. Available online at http://www.springer.com/life+sciences/microbiology/book/978-3-642-17996-9. Accessed December 21, 2011.



The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement