A critical look at the microalgae biodiesel

Petkov, Georgi V.; Ivanova, Alexandra; Iliev, Ivan; Vaseva, Irina

doi:10.1002/ejlt.201100234

Cited by 52 publications

(26 citation statements)

References 56 publications

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“…, mainly depending on annual productivity [27]. Hence, with oil as the sole product, Azolla cultivation is likely outcompeted by palm oil and microalgae.…”

Section: Implications For Biodiesel Productionmentioning

confidence: 99%

Lipid Yield and Composition of Azolla filiculoides and the Implications for Biodiesel Production

Brouwer

Werf²,

Schluepmann

et al. 2015

Bioenerg. Res.

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The aquatic fern Azolla is one of the fastestgrowing nitrogen-fixing plants on Earth and therefore considered as a potential source of biomass for bioenergy production. The lipid fraction from Azolla filiculoides was analyzed to investigate whether it suited biodiesel production. Since the productivity of Azolla is further increased at higher CO 2 concentrations, A. filiculoides biomass was produced at 800 ppm CO 2 mimicking a cultivation system utilizing CO 2 waste from industry. The harvested biomass contained 7.92±0.14 % dry weight (dw) crude lipids. Drying conditions did not significantly affect lipid composition or yields, indicating that drying conditions may be energetically optimized without the risk of product loss. Total lipid extracts contained 4.2±0.38 % free fatty acids. Of the crude lipid fraction, 41±13 % consisted of fatty acids that were converted into fatty acid methyl esters upon saponification in methanol. Unique mid-chain (di)hydroxy compounds constituted 7.2±2.8 % of the crude lipids. Based on the fatty acid profile, it was estimated that Azolla biodiesel meets requirements set by the EN14214 standard on fuel density, cetane number, and iodine value. The cold filter plugging point (CFPP), however, is expected to be too high due to relatively high concentrations of lignoceric acid and the presence of the mid-chain (di)hydroxy compounds. To produce high-quality biodiesel from Azolla lipids, therefore, a fractionation step will be required removing these compounds. As an advantage, the long-chain alcohols and (di)hydroxy fatty acids obtained after fractionation may provide a valuable secondary product stream with applications to chemical industry and nutrition.

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“…, mainly depending on annual productivity [27]. Hence, with oil as the sole product, Azolla cultivation is likely outcompeted by palm oil and microalgae.…”

Section: Implications For Biodiesel Productionmentioning

confidence: 99%

Lipid Yield and Composition of Azolla filiculoides and the Implications for Biodiesel Production

Brouwer

Werf²,

Schluepmann

et al. 2015

Bioenerg. Res.

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“…The challenge is still to extract the oil from the microalgae biomass due to the content of chlorophyll. The purification of lipids from algae requires additional treatments compared with vegetable oil (Petkov et al 2012). Also, microalgal oils are rich in polyunsaturated fatty acids, which are susceptible to oxidation during storage and this reduces their acceptability for use in biodiesel (Chisti 2007).…”

Section: Fine Chemicals Productionmentioning

confidence: 99%

Dark fermentation biorefinery in the present and future (bio)chemical industry

Bastidas‐Oyanedel

Bonk

Thomsen

et al. 2015

Rev Environ Sci Biotechnol

133

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Dark fermentation, also known as acidogenesis, involves the transformation of a wide range of organic substrates into a mixture of products, e.g. acetic acid, butyric acid and hydrogen. This bioprocess occurs in the absence of oxygen and light. The ability to synthesize hydrogen, by dark fermentation, has raised its scientific attention. Hydrogen is a nonpolluting energy carrier molecule. However, for energy generation, there is a variety of other sustainable alternatives to hydrogen energy, e.g. solar, wind, tide, hydroelectric, biomass incineration, or nuclear fission. Nevertheless, dark fermentation appears as an important sustainable process in another area: the synthesis of valuable chemicals, i.e. an alternative to petrochemical refinery. Currently, acetic acid, butyric acid and hydrogen are mostly produced by petrochemical reforming, and they serve as precursors of ubiquitous petrochemical derived products. Hence, the future of dark fermentation relies as a core bioprocess in the biorefinery concept. The present article aims to present and discuss the current and future status of dark fermentation in the biorefinery concept. The first half of the article presents the metabolic pathways, product yields and its technological importance, microorganisms responsible for mixed dark fermentation, and operational parameters, e.g. substrates, pH, temperature and head-space composition, which affect dark fermentation. The minimal selling price of dark fermentation products is also presented in this section. The second half discusses the perspectives and future of dark fermentation as a core bioprocess. The relationship of dark fermentation with other (bio)processes, e.g. liquid fuels and fine chemicals, algae cultivation, biomethane-biohythane-biosyngas production, and syngas fermentation, is then explored.

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“…However, large scale culturing of microalgae for energy purposes has slowed down recently after a period of high expectations. The yields expected from a simple theoretical analysis of the potential productivity of microalgae have proven to be unrealistic (Petkov et al, 2012). Some authors estimate that it would take 10-15 years for microalgae to be a viable alternative to fossil fuels, and, in any case, only comprehensive exploitation of these organisms, rather than a single use for energy, could ensure this alternative (Wijffels and Barbosa, 2010).…”

Section: Introductionmentioning

confidence: 99%