Algae biofuel makes the third generation of biofuels. Algae are being utilized to produce both bioethanol and biodiesel. In fact, it is also being utilized for making renewable hydrocarbon biofuels.
Many strains of microalgae have the inherent ability to synthesize oil or ethanol. This ability makes them suitable candidate for biofuel production. But the quantity of the synthesized oil and ethanol is very less. To produce the algae biofuel in large scale this inherent ability is enhanced through biotechnological interventions.
In this description the algae biofuel production processes and producer companies are listed.
Biofuel Production Capacity of Algae
In a report published in May 2014 by researchers from University of Utah USA, it is stated that under the optimized conditions algae can produce around 2500 gallons of biofuel/acre of land/year as compared to corn (435 gallon/acre of land /year) and soybean (63 gallon/acre of land /year). The high production capacity is one of the many attributes contributing in making algae favorite of biofuel industries. Algae biofuels can be produced by utilizing algae in different ways leveraging from the diversity of characteristics present in their different species.
Algae Biofuel Production Processes and Producer Companies
Both microalgae and macroalgae are being targetted to get different types of biofuels including drop-in renewable hydrocarbon biofuels.
1. Production of drop-in fuels from microalgae
A drop-in fuel is a liquid hydrocarbon fuel with physicochemical properties very similar to fossil fuels. Drop in fuels are capable of replacing the traditional gasoline, diesel and jet fuels up to any extent which means that they are chemically indistinguishable from traditional petroleum-based fuels. Utilization of microalgae to get drop-in fuels is now being considered as one of the best routes for drop-in fuel production.
Different technologies that lead to the production of drop-in fuels from algae are described here:
(a) Production of drop-in fuels from oil producing autotrophic algae: Photosynthesis in the presence of sun light
Autotrophic algae means the ones that synthesize their own food in the presence of sun light through photosynthesis. When an autotrophic system is selected to produce biofuel as the end product light is used to initiate photosynthesis and the algae produces its own food. When the algae is naturally able to produce oil, the conditions are optimized for maximum oil production. The produced algae oil is extracted and further refined by processes such as hydrocracking and hydrogenation to produce drop-in gasoline or jet fuels.
Sapphire Energy, a biofuel production company follows this line of production and their proprietary commercial technology is known as ‘Green crude’.
(b) Production of drop-in fuels from oil producing heterotrophic algae: fermentation in the absence of sun light
In a heterotrophic system algae are grown in the dark places with no sunlight. Carbon containing rich growth medium is externally supplied to them . The conditions for maximum oil production are optimized.
Solazyme’s propriatory technology for synthesis of drop-in fuels utilizes this approach.
(c) Pyrolysis of algal biomass to get bio oil
The acceleration of natural process of oil generation in the algae is the first step in this process. Full grown algae are separated and subjected to high temperature and pressure to get bio oil which in turn is subjected to refining to get drop-in fuels.
Bio Fuel Systems (BFS) follows this route to produce drop-in fuels.
2. Production of bioethanol from microalgae
The first step towards making bioethanol from microalgae is identification of algal strains able to produce ethanol. Their ethanol production ability can be enhanced by over expression of fermentation pathway enzymes.
Algenol is one of the leading biofuel production companies following this route of algae bioethanol synthesis.
Macroalgae biofuel production
Certain strains of macroalgae are rich in cellulose and starch. Such full grown macroalgae can be used as feedstock. The algae feedstock is converted into simple sugars and the further fermentation of the sugars by yeast result in bioethanol production. Sea6 Energy is the example of bioethanol production using this route.
The above mentioned routes are very promising and have met with some success.