Biodiesel production using enzymes

Biodiesel can be produced from a wide variety of catalysts including enzymes. An excellent overview of recent research related to enzymatic biodiesel production was performed by Fjerbaek ¹. This references previous works which have researched varying alcohol types (methanol or ethanol) and enzyme types, varying alcohol addition, the use of batch processing? versus continuous processing?, the effect of water, and other factors.

The basic benefits of enzymatic processing are:

• The reaction occurs in at low temperatures and pressures (30C - 50C), atmospheric pressure
• Requires less methanol than the traditional process using sodium? or potassium hydroxide
• Most importantly, forms no soaps.

Soap formation in the traditional process causes a variety of problems, including:

• Increasing the use of ion-exchange resins?
• Increasing the use of water washing? , which produces waste water
• Makes product separation more difficult
• Increases yield loss
• Results in salts in the coproduct glycerol

These problems are largely eliminated using enzymes. Enzymatic processing of biodiesel has been widely tested for 15 years. An extensive amount of academic research has been performed, but to date only a single factory is producing significant amounts of biodiesel using enzymes.

Commercialization of the technology is inhibited by the high cost of the enzymes and associated immobilization costs. When enzymes are used in liquid form, they have limited reusability, but lower cost. Conversely, when immobilized on a substrate, it has been shown that enzymes can be reused nearly 100 times without significant deactivation, but the cost of the enzyme increases dramatically² .

Future commercialization will depend on bench-scale method development focused on commercially viable targets for enzyme reusability in addition to enzyme producers bring immobilized enzyme costs down.

Enzymatic facilities and research

In North Carolina, a collaboration between Piedmont Biofuels, Novozymes and the Biofuels Center of North Carolina has resulted in a enzymatic processing unit being built to go beyond bench scale. The official launch of the unit is taking place in July 2010. A picture of the unit can be seen, right.

References

¹ A Review of the Current State of Biodiesel Production Using Enzymatic Transesterification in Biotechnology and Bioengineering, vol. 102, No. 5, April 1, 2009

² Watanabe, Production of FAME from Acid Oil Model Using Immobilized Candida antarctica Lipase, JAOCS, Vol. 82, no.11 (2005)

External Links:

Piedmont Biofuels

Novozymes

Biofuels Center of North Carolina