ASI: Dunaliella marine microalgae to drop‐in replacement liquid transportation fuel

Abstract

Microalgae are a promising biofuels feedstock, theoretically yielding concentrations of triacylglycerides (TAGs) per unit area that are far higher than traditional feedstocks due to their rapid growth. Dunaliella is particularly advantageous as a feedstock because it is currently commercially mass cultured, thrives in salt water, and has no cell wall. Fourteen strains of Dunaliella have been investigated for growth rates and lipid production in mass culture and tested for enhanced lipid production under a range of environmental stressors including salinity, pH, nitrogen and phosphorus limitation, and light regime. The nuclear genome has been sequenced for four of these strains, with the objective of increasing carbon flux through genetic engineering. Electroflocculation followed by osmotic membrane rupturing may be a very energy and cost efficient means of harvesting the lipid bodies from Dunaliella. A technically feasible and scalable thermo‐catalytic process to convert the lipids into replacements for liquid transportation fuels has been developed. The lipids were converted into long‐chain alkanes through continuous thermal hydrolysis followed by fed‐batch thermo‐catalytic decarboxylation. These alkanes can be reformed into renewable diesel via conventional catalytic hydrocarbon isomerization reactions to improve cold flow properties, if desired. © 2013 American Institute of Chemical Engineers Environ Prog, 32: 916–925, 2013

Extraction, characterization, purification and catalytic upgrading of algae lipids to fuel-like hydrocarbons

“…Indeed, the few contributions utilizing real algae oil samples are limited by the fact that deoxygenation has been accomplished via hydrogen-intensive HDO [11], and/or using precious metal catalysts [43]. Moreover, most studies have been conducted in batch (or semi-batch) mode [19,20,[43][44][45], these tests providing no information about the stability of the catalyst under the reaction conditions. Therefore, the catalytic upgrading of the algal lipids extracted and purified by the aforementioned methods was performed via hydrogen-efficient deCO x using an inexpensive Ni-based catalyst [16,23], a fixed-bed reactor and relatively mild operating conditions, this approach having afforded promising diesel yields in recent work [22][23][24].…”

Interaction of Temperature and Photoperiod Increases Growth and Oil Content in the Marine Microalgae Dunaliella viridis

“…Dunaliella spp . lack a cell wall [ 4 ], which enables the extraction of oil droplets by osmotic shock in freshwater as one of the most inexpensive and environmental friendly ways to extract oil from algae cultures [ 10 ]. Despite all these useful traits of Dunaliella for bioenergy production, production of algae oil for liquid transportation fuels is commercially not viable.…”

Genetic manipulation of microalgae for the production of bioproducts

“…Lowering the NaCl concentration in selective plates allows for reduced concentration of antibiotics used in selection (81, 83). However, some antibiotics such as streptomycin and kanamycin, cannot be used for selection even in low salt concentrations (112)(113)(114)(115). For Marine microalgae species, selectable markers/ resistance genes (Table 1) are BAR/phosphinothricin, BLE/zeocin, CAT/chloramphenicol, PDS(L504R)/ norflurazon, NAT/nourseothricin (70,74,(116)(117)(118).…”