TABLE 2.3 The Comparison of Five Leading Microalgae-Based Biofuel Companies.
Company
Name Founded
Time Location Biofuel Type Technology Cultivation Equipments Market Algenol
Biofuels
2006 Florida, USA Ethanol Algenol’s patented technology (known as Direct to EthanolW Technology) enables the production of ethanol for less than $1.00 per gallon and targets commercial production of 6,000 gallons of ethanol per acre per year.
Algenol selects
cyanobacteria strains and enhances their ability to produce ethanol by overexpressing fermentation pathway enzymes, allowing each cell to channel carbon into ethanol production.
Algenol uses a proprietary photobioreactor system to cultivate cyanobacteria and collect ethanol.
The method involves a marine strain of algae and therefore can use seawater.
It also has the added benefits of consuming carbon dioxide from industrial sources and not using farmland.
Algenol’s proprietary flexible plastic film photobioreactor (PBR).
Capital costs to construct its patented facility will range between $4.00 and
$6.00 per annual gallon of capacity.
A pilot-scale integrated biorefinery in Florida on 36 acres was broken ground in 2011.
Algenol intends to produce 1 billion gallons annually by 2012. The company says its production costs will be less than $1.00 per gallon (sale for $3.00 per gallon).
Algenol’s goal is 20 billion gallons per year of low- cost ethanol by 2030.
Sapphire Energy
2007 Headquarters in San Diego, USA;
green crude farm in New Mexico, USA
A liquid that has the same composition as crude oil
Sapphire produces “green crude,” a liquid that has the same composition as crude oil.
The company has shown that its fuel can be used in
The company uses open ponds, raceway.
The test site in Las Cruces, NM, at 22 acres, has more than 70 active ponds, varying in size from
The first phase of Sapphire’s Green Crude Farm was operational in August 2012. When completed, the facility will produce 1.5 million
Continued
372.5COMMERCIALMICROALGAECULTIVATIONSYSTEMSFORBIOFUELPRODUCTION
TABLE 2.3 The Comparison of Five Leading Microalgae-Based Biofuel Companies—Cont’d Company
Name Founded
Time Location Biofuel Type Technology Cultivation Equipments Market two commercial flights
(Continental and JAL airlines) and a cross- country road trip (Algaeus).
14-foot test ponds to 300- foot, 1-million-liter production ponds.
The green crude farm located in Columbus, NM, will have 300 cultivated acres.
gallons per year of crude oil and consist of approximately 300 acres of algae cultivation ponds and processing facilities.
The plan is to make 1 million gallons of diesel and jet fuel per year by 2011, 100 million gallons by 2018, and 1 billion gallons per year by 2025.
Seambiotic 2003 Israel Biodiesel and
bioethanol
Seambiotic grows microalgal cultures in open ponds using flue gases such as carbon dioxide and nitrogen from a nearby coal plant as feedstocks.
The 1,000-square-meter facility produces roughly 23,000 grams of algae per day. Three tons of algal biomass would yield around 100 to 200 gallons of biofuel.
Open ponds, raceway. Seambiotic’s Algae Plant in China was finished in late 2011 with raceway ponds on approximately 10 hectares.
Seambiotic believes that this plant is able to produce enough algae biomass to convert into fuel at prices competitive with traditional fuel by 2012.
Solazyme 2003 South San
Francisco, USA
Biodiesel Solazyme’s proprietary microalgae are
heterotrophic, grow in the dark in fermenters, and are fed plant sugars.
Standard industrial fermentation equipment.
In 2010, Solazyme delivered over 80,000 liters of algal-derived biodiesel and jet fuel to the U.S.
Navy. Subsequently, Solazyme was awarded another contract with the U.S. Department of Defense for production of up to 550,000 additional
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382.DESIGNOFPHOTOBIOREACTORSFORALGALCULTIVATION
TABLE 2.3 The Comparison of Five Leading Microalgae-Based Biofuel Companies—Cont’d Company
Name Founded
Time Location Biofuel Type Technology Cultivation Equipments Market
liters of naval distillate fuel.
Solazyme went public (IPO) in 2011 at $18 per share and raised $198 million in the process.
In 2012, Solazyme expected to archive a 2-million-liter annual capacity.
Solix BioSystems
2006 Colorado,
USA
Biodiesel Solix uses a proprietary closed photobioreactor system and claims that the system can produce up to seven times as much biomass as open-pond systems.
The algal oil is extracted through the use of chemical solvents such as benzene or ether.
Solix is also collaborating with the Los Alamos National Laboratory to use its acoustic-focusing technology to concentrate algal cells into a dense mixture by blasting them with sound waves. Oil can then be extracted from the mixture by squeezing it out; this makes the extraction process much easier and cheaper, obviating the need for chemical solvents.
Photobioreactor system includes Solix’s proprietary Lumian panels, Solix Lumian™ Algae Growth System (AGS™).
Solix’s demonstration plant has three algae cultivation basins totaling 3/4 of an acre (0.3 hectares). The plant has over 150,000 liters of algae under cultivation.
Solix’s demonstration facility performed at over 3,000 gallons of algae oil per acre per year in 2010.
392.5COMMERCIALMICROALGAECULTIVATIONSYSTEMSFORBIOFUELPRODUCTION
media preparation, harvesting, reinjection, and system cleaning. Before 2009, the introduction of the Lumian AGS system especially mentioned the vertical orientation of panels that can provide “extended surface area.” However, according to the pictures on Solix’s Website, the panels now are horizontally arranged. The AGS panels contain tubes that deliver CO2
as a carbon source and deliver air to remove oxygen (a byproduct of photosynthesis).
According to an article of the IOP Conference Series in 2009 (Willson, 2009), the marginal cost of large-scale production using the AGS system was approximately $1/liter ($150/barrel), with a defined path of reducing the production cost by half over the next two to three years.
Sapphire and Seambiotic both choose raceway open ponds to cultivate their algae.
Sapphire releases very little technology information about its process: “We grow the algae in open ponds with only sunlight, CO2, and nonpotable saltwater in deserts” (seeFigure 2.8a).
Seambiotic also grows microalgal cultures in raceway open ponds using flue gases carbon dioxide and nitrogen from a nearby coal plant as the feedstock (seeFigure 2.8b). Seambiotic has carried out an R&D pilot study comprising about a 1,000-meter square of ponds in an Israel power plant to use the flue gas to cultivate algae. Both companies emphasize the low cost of using open ponds and choose marine algae strains to reduce biotic contamination.
Solazyme’s algal cultivation method is much different from those of the previously men- tioned companies. Solazyme uses large fermentation tanks to incubate algae in the dark and feed them plant sugars. This platform makes the feedstock more flexible, and it is able to use
Water Water
Sunlight
Each cell is a tiny ethanol
factory
Nutrients Nutrients
CO2 CO2
O2 O2
Photosynthesis
Calvin cycle
Intracellular
fermentation Ethanol
Blue-green algae (Cyanobacteria)
Pyruvate (Sugar)
FIGURE 2.5 The process of Algenol’s Direct to EthanolWtechnology (www.algenolbiofuels.com/media/media- gallery).
40 2. DESIGN OF PHOTOBIOREACTORS FOR ALGAL CULTIVATION
low-cost sugars, varying from sugarcane to corn stover, woody biomass, switchgrass, and other cellulosic materials. By this heterotrophic incubation, algae can accumulate more oil in cells. According to data shown on Solazyme’s Website, the oil content in the company’s algae cells is in excess of 80% (seeFigure 2.9). Considering that the average wild alga yields only 5–10% oil content, this enhanced yield is very critical to lowering the production cost of biofuels.
Sunlight
Ethanol/Water condenses on photobioreactor wall and flows to collection troughs
Photobioreactor film Outside photobioreactor:
ambient cooler temperature Heat transfer
Inside photobioreactor:
greenhouse effect causes high
temperature relative to ambient Condensed ethanol/Water
Ethanol/Water evaporates
Ethanol/Water vapor
Seawater/Algae/Ethanol to VCSS
A
B
to VCSS
FIGURE 2.6 The flexible plastic film photobioreactors used by Algenol; A) the structural diagram, B) the appear- ance (www.algenolbiofuels.com/media/media-gallery).
41
2.5 COMMERCIAL MICROALGAE CULTIVATION SYSTEMS FOR BIOFUEL PRODUCTION
FIGURE 2.7 The Solix Lumian™AGS4000 system (www.solixbiofuels.com/content/products/lumian-ags4000).
FIGURE 2.8 (a) Sapphire’s green crude farm with raceway open ponds (www.sapphireenergy.com/rendition.
medium/images/multimedia/green%20crude%20farm%20ponds.jpg). (b) Seambiotic’s pilot plant (www.seambiotic.
com/uploads/Seambiotic%20Ltd.%20-%20Algae%20Pilot%20Plant%20white%20paper.pdf).