Continuous algal biodiesel production facility

Abstract

Embodiments of the present invention concern methods, compositions, and apparatus for the continuous conversion of algal lipids into biodiesel. In some embodiments, the biodiesel is formed in a multi-step sequence, the first steps occurring in the presence of water and a strong acid wherein the lipids are released from the algae by means of mechanical and chemical action and are then hydrolyzed to free fatty acids. In a subsequent step, this free fatty acid mixture is reacted with methanol to generate fatty acid methyl esters (also known as biodiesel). Such methods produce biodiesel from algal lipids without the requirement for separate algal cell lysis or lipid extraction or purification prior to the acid catalysis sequence. In other embodiments, the multi-step acid catalysis sequence occurs at 100° C. at two atmospheres of pressure.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application claims the benefit of U.S. Provisional Patent Application Ser. No. 60 / 952,443, filed on Jul. 27, 2007, and entitled, “Continuous Algal Biodiesel Production Facility,” which is incorporated by reference herein in its entirety for all purposes.BACKGROUND[0002]1. Field[0003]Embodiments of the present invention concern methods, compositions and apparatus for continuous algal biodiesel production. In particular, methods are provided for continuous biodiesel production from algal biomass, without the need for extraction or separation of algal lipids for esterification into biodiesel. More particularly, such embodiments concern an in-situ hydrolysis and esterification process for production of fatty acid methyl esters (FAME), commonly referred to as biodiesel.[0004]2. Discussion of Related Art[0005]Reducing the reliance of the United States on imported fossil fuels is of concern for the future. Two-thirds of the oil consumed in ...

AI Technical Summary

Benefits of technology

[0013]Various embodiments concern use of one or more closed system bioreactors for algal culture, to provide starting material for the methods of continuous biodiesel production. Additional details of such closed system bioreactors for algal culture are disclosed in U.S. patent application Ser. Nos. 11 / 510,148 and 11 / 510,442; PCT Patent Application Ser. No. PCT / US2006 / 033252; and provisional U.S. Patent Application Ser. Nos. 60 / 894,082, filed Mar. 9, 2007; 60 / 877,907, filed Dec. 20, 1996, and 60 / 878,506, filed Jan. 3, 2007; the text of each of which is incorporated herein by reference.

Problems solved by technology

At the same time, the long-term supply of oil is limited, and a large percentage of proven oil reserves are in countries with unstable or hostile governments.

Combustion of petroleum based products releases enormous amounts of CO2 into the atmosphere, contributing to global warming.

Although substantial progress has been made, with almost five billion gallons of corn ethanol produced in 2006, the resulting impact on corn and food prices suggests that there are limits to how much further production is feasible.

Present corn ethanol production is only sufficient to provide about 1.5% of U.S. fuel needs and consumes over 20% of total U.S. corn production.

However, it is currently necessary to first separate the triglycerides or other source material from the bulk plant matter before the transesterification reaction can proceed.

In addition, biodiesel production from food crops, such as soybeans, will ultimately encounter the same problems that currently limit corn ethanol production.

However, cellulosic ethanol technology, while promising, has not yet been developed to the point of full commercial scale production and the time required to reach that point remains uncertain.

Such proposals ignore the practical difficulties of obtaining water supplies to grow such crops, requirements for fertilizer input, low productivity of marginal land, etc.

However, the open pond system utilized by NREL was susceptible to invasion by contaminating algae, bacteria or algal-consuming organisms and algal productivity was adversely impacted by fluctuating environmental temperature and solar radiation.

Further, in a pond type of system the light penetration depth into dense algal cultures results in only a limited band of photosynthetic productivity, with the majority of algae being shaded by overlying organisms.

While closed systems represent an improvement over open system alternatives, such designs are often expensive to construct and maintain, poorly scalable, and not optimized for maximal algal lipid production under continuous culture conditions.

As methanol is non-renewable and somewhat expensive, about 98 percent of the feed methanol may be recycled.

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