Method for producing biodiesel using high-cell-density cultivation of microalga Chlorella protothecoides in bioreactor

Abstract

A method is provided to produce biodiesel from algae using a strain of microalga chlorella protothecoids, by screening a specific strain with characteristics of high yield of biomass and high oil content, cultivating the screened strain for high-cell-density growth for up to 108 grams of dry cell weight per liter of the suspension in a bioreactor using solutions containing carbohydrates as feed, harvesting and drying the high density cultivated algal cells to extract oil from the dried algal cells, and producing the biodiesel by reaction of catalyzed transesterification using the extracted oil as feedstock.

Description

CROSS REFERENCE TO RELATED APPLICATION[0001]This application claims the benefit of China Patent Application No. 200810100871.5, filed on Feb. 25, 2008, and entitled “Method for Producing Biodiesel using High-Cell-Density Cultivation Of Microalga Chlorella Protothecoides”, the entire disclosure of which is incorporated herein by reference.FIELD OF THE INVENTION[0002]The present invention relates to area of regenerable biofuel, in particular to a method for producing biodiesel from microalga oil by high-cell-density heterotrophic cultivation of a specific strain of green alga Chlorella protothecoides rich in lipids coupled with biodiesel production by transeterification reaction.BACKGROUND OF THE INVENTION[0003]Renewable carbon-neutral fuels, such as biodiesel, are considered necessary replacement of traditional petroleum fuel for environmental and economic sustainability. Biodiesel is one such fuel composed of monoalkyl esters of long chain fatty acids transesterified from vegetable ...

AI Technical Summary

Benefits of technology

[0013]The present invention comprises a specific strain of microalga C. protothecoides, Chlorella. Protothecoides sp 0710, with characteristics of high growth rate and high yielding oil.

[0022]Yet another preferred embodiment of the present invention further comprises adding a base to reduce acidity and regulate the pH of the culture medium in the first or the second bioreactor, preferably KOH or other bases.

Problems solved by technology

The high cost of biodiesel, which is mainly due to the high cost of oil feedstock, is the main obstacle to its broader commercialization.

Due to their low oil yield potential and high demands on land, water, and fertilizer, which create competition with food / feed industries, the conventional oil / food crop-based biodiesel production system cannot meet the growing demand on sustainable feedstock for biodiesel production.

However, no technology of biodiesel production by microalgae is economically feasible because rapidly growing cells contain low amounts of lipids and algal cells accumulating high lipid content exhibit little growth.

However, both microalgal cell yield and oil content in harvested dry cells are not high enough for its industrial application.

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