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Title: Review and evaluation of immobilized algae systems for the production of fuels from microalgae. Final subcontract report

Abstract

The purpose of this paper is to review and evaluate the use of immobilized algae systems. It was the finding that commercial immobilized algae systems are not in operation at this time but, with research, could certainly become so. The use of immobilized algae will depend on, as in all commercial systems, the economic value of the product. This paper reviews the technical feasibility of immobilization as it applies to algae. Finally, the economics of possible immobilized algal systems that would produce liquid fuels were investigated. It was calculated that an immobilized system would have 8.5 times the capital costs of a conventional microalgae culture system. Operational costs would be about equal, although there would be substantial savings of water with the immobilized system. A major problem with immobilizing algae is the fact that sunlight drives the system. At present, an immobilized algal system to mass produce lipids for use as a liquid fuel does not appear to be economically feasible. The major drawback is developing a low-cost system that obtains the same amount of solar energy as provided to a shallow 3 square mile pond while increasing the culture density by an order of magnitude. R and D tomore » increase light availability and to develop low cost transparent tanks could increase the competitiveness of immobilized algal systems. 44 refs., 2 figs., 7 tabs.« less

Publication Date:
Research Org.:
JAYCOR, Alexandria, VA (USA)
OSTI Identifier:
6062417
Report Number(s):
SERI/STR-231-2798
ON: DE85016890
DOE Contract Number:
AC02-83CH10093
Resource Type:
Technical Report
Resource Relation:
Other Information: Portions of this document are illegible in microfiche products. Original copy available until stock is exhausted
Country of Publication:
United States
Language:
English
Subject:
09 BIOMASS FUELS; ALGAE; IMMOBILIZED CELLS; ETHANOL; YIELDS; BIOREACTORS; COMMERCIALIZATION; ECONOMIC ANALYSIS; ETHANOL FUELS; ALCOHOL FUELS; ALCOHOLS; ECONOMICS; FUELS; HYDROXY COMPOUNDS; ORGANIC COMPOUNDS; PLANTS; SYNTHETIC FUELS; IMMOBILIZED ENZYMES; LIPIDS; 090222* - Alcohol Fuels- Preparation from Wastes or Biomass- (1976-1989)

Citation Formats

Not Available. Review and evaluation of immobilized algae systems for the production of fuels from microalgae. Final subcontract report. United States: N. p., 1985. Web. doi:10.2172/6062417.
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Not Available. Review and evaluation of immobilized algae systems for the production of fuels from microalgae. Final subcontract report. United States. doi:10.2172/6062417.
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Not Available. Fri . "Review and evaluation of immobilized algae systems for the production of fuels from microalgae. Final subcontract report". United States. doi:10.2172/6062417. https://www.osti.gov/servlets/purl/6062417.
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@article{osti_6062417,
title = {Review and evaluation of immobilized algae systems for the production of fuels from microalgae. Final subcontract report},
author = {Not Available},
abstractNote = {The purpose of this paper is to review and evaluate the use of immobilized algae systems. It was the finding that commercial immobilized algae systems are not in operation at this time but, with research, could certainly become so. The use of immobilized algae will depend on, as in all commercial systems, the economic value of the product. This paper reviews the technical feasibility of immobilization as it applies to algae. Finally, the economics of possible immobilized algal systems that would produce liquid fuels were investigated. It was calculated that an immobilized system would have 8.5 times the capital costs of a conventional microalgae culture system. Operational costs would be about equal, although there would be substantial savings of water with the immobilized system. A major problem with immobilizing algae is the fact that sunlight drives the system. At present, an immobilized algal system to mass produce lipids for use as a liquid fuel does not appear to be economically feasible. The major drawback is developing a low-cost system that obtains the same amount of solar energy as provided to a shallow 3 square mile pond while increasing the culture density by an order of magnitude. R and D to increase light availability and to develop low cost transparent tanks could increase the competitiveness of immobilized algal systems. 44 refs., 2 figs., 7 tabs.},
doi = {10.2172/6062417},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Fri Nov 01 00:00:00 EST 1985},
month = {Fri Nov 01 00:00:00 EST 1985}
}
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Technical Report:
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DOI:  10.2172/6062417
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  • ;
    An overall objective of the project was to conceptually determine if simple open pond systems have application for the production of fuels from microalgae. To demonstrate the overall objective, work concentrated on showing the potential microalgal yields that are possible from an open pond system on a sustained basis. Furthermore, problems associated with this experimental system were documented and reported so that future endeavors shall benefit. Finally, operational costs were documented to permit preliminary economic analysis of the system. The major conclusions of this project can be summarized as follows: (1) Using two wildtype species in northern California a yearlymore » average productivity of 15 gm/m/sup 2//day, or 24 tons/acre/yr can be obtained in water with TDS = 4 to 8 ppt. (2) This can probably be increased to 20 to 25 gm/m/sup 2//day or 32 to 40 tons/acre/y in southern California. (3) Productivity can probably be further increased by using competitive strains screened for low respiration rates, tolerances to high levels of dissolved oxygen, broad temperature optima, and resistance to photoinhibition. (4) In systems with randomized, turbulent mixing, productivity is independent of channel velocity at least for productivities up to 25 to 30 gm/m/sup 2//day and velocities from 1 to 30 cm/sec. (5) Storage product induction requires one to three days of growth in batch mode under n-depleted conditions. (6) Critical cost centers include CO/sub 2/ input, harvesting and system capital cost. (7) Media recycling, necessary for water conservation, has no adverse effects, at least in the short term for strains which do not excrete organics, and when the harvesting method is at least moderately effective for all algal forms which may be present. 8 refs., 28 figs., 56 tabs.« less

  • ;
    The dual problems of global fossil fuels supplies and global warming focus attention on the need to develop technologies that can provide large amounts of renewable fuels without contributing to global warming. The capture of power plant flue gas CO 2 using microalgae cultures is one potential technology that could meet this objective. The central R&D issues are the design and operation of low-cost algal mass culture systems and the development of algal strains and cultivation techniques that can achieve very high biomass productivities. The major objective of this project was to develop mass culture techniques that could result inmore » greatly increased biomass productivities, well above the about 50 metric tons per hectare per year (mt/ha/y) currently achievable. In this project, two marine microalgae species, the diatom Cyclotella sp.. and the green alga Tetraselmis sp., were cultivated on seawater in both open ponds and closed photo bioreactors, under a variety of different cultivation conditions. Simultaneous operation of the closed photo bioreactors and open ponds demonstrated similar productivities, under the same operating conditions. Thus the very expensive closed systems do not provide any major or inherent advantages in microalgae production over open ponds. Mutants of Cyclotella sp. were developed that exhibited reduced pigment content, which theoretically would result in greatly increased productivities when grown under full sunlight. However, in open ponds, these mutant strains exhibited similar productivities as the parental strains. The mutant strains all grew relatively slowly, suggesting that additional mutations masked whatever inherent potential for increased productivities may have resulted from the reduced pigment content. Research is still required to develop improved low pigment strains. When open pond cultures were exposed to intermittent sunlight, by partially covering the ponds with slats, solar conversion efficiencies increased dramatically, by over 50%. Although such techniques are not directly applicable to practical processes, the experiments demonstrated the inherent potential of algal mass cultures to achieve very high productivities. Nitrogen limited pond cultures demonstrated that it is possible to produce biomass with a potentially high content of carbohydrates or oils (although these were not directly measured in these experiments), without reducing achievable productivities. This suggested that microalgae biomass suitable for conversion to biofuels (ethanol or biodiesel) could be produced without compromising productivity. Experiments combining both light modulation and nitrogen limitation indicated possibly synergistic effects. The goal of developing practical and economic processes for the sustainable production of renewable fuels with microalgae pond cultures using power plant flue gases as sources of CO 2 was advanced by these studies, but requires more work. Most important is the research, development and demonstration in outdoor pond cultures of algal strains with low pigment content. Such strains are the most likely approach to achieve, in combination with the other mass culture techniques investigated in this study, the very high productivities, above 100 mt/ha/y (45 t/acre/y), that are the goal in this field. The projected economics for such a process suggests that, as for higher plant biofuel production, microalgae biofuels production should be developed as a multiproduct process providing additional higher value co-products.« less

  • ; ;
    Climate, land, and water resource requirements of microalgae production systems (MPS) were examined relative to construction costs, operating costs, and biomass productivity. The objective was the stratification of the southwestern United States into zones of relative suitability for MPS. Maps of climate (insolation, freeze-free period, precipitation, evaporation, thunderstorm days), land (use/cover, ownership, slope), and water (saline groundwater) resource parameters were obtained. These maps were transformed into digital overlays permitting the cell-by-cell compositing of selected resource parameters to form maps representing relative productivity, make-up water, climate suitability, land suitability, water suitability, and overall suitability. The Southwest was selected for this studymore » because of its high levels of insolation, saline water resources, and large areas of relatively low valued land. The stratification maps cannot be used for the selection of specific sites because of their low resolution (12,455-acre cells). They can be used to guide future resource studies and site selection efforts, however, by limiting these efforts to the most suitable regions. Future efforts should concentrate on saline water resources, for which only limited data are currently available. 13 refs., 44 figs., 5 tabs.« less

  • ; ;
    The SERI/DOE Aquatic Species Program is conducting a screening project, to select microalgae species and strains that are acceptable for liquid fuel production in outdoor culture. The emphases are on finding species that grow rapidly at high biomass density, in outdoor culture and produce large quantities of lipids. During 1983 over 100 species were isolated from saline waters at the California and Nevada deserts. Some of these species were characterized for growth response to various nutrients, temperatures, and salinities. Selected species were analyzed for lipid composition. Lipids were characterized into fractions, hydrocarbons, isoprenoids, triglyceride, glycolipids, and phospholipids. The most promisingmore » species were tested for growth and monoculture sustainability in outdoor culture. Each section (microalgae selection, chemical profiles of microalgae, mass culture of macroalgae) was abstracted separately. 51 references, 8 figures, 14 tables.« less

  • ; ; ; ...
    A design concept is described for the production of methane, hydrogen, and ammonia using solar energy. Filamentous, nitrogen-fixing blue-green algae are employed as a source of biomass for methane and ammonia generation by anaerobic digestion and as a biological catalyst for the photoproduction of hydrogen from water. The resources needed, biomass production and harvest, anaerobic digester, the process of biophotolysis, and product separation are discussed. The environmental and genetic modifications possible to increase biomass production are indicated. Preliminary cost estimates are made for methane and hydrogen production. It is concluded that biosynthetic methane is not economically competitive with that derivedmore » from coal gasification, but that hydrogen production offers a viable long-range prospect. (JSR)« less