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Journal ArticleDOI

A critical review of biochemical conversion, sustainability and life cycle assessment of algal biofuels

01 Oct 2011-Applied Energy (Elsevier)-Vol. 88, Iss: 10, pp 3548-3555
TL;DR: In this article, the life cycle assessment (LCA) of algal biofuels suggests them to be environmentally better than the fossil fuels but economically it is not yet so attractive.
About: This article is published in Applied Energy.The article was published on 2011-10-01. It has received 425 citations till now. The article focuses on the topics: Aviation biofuel & Biomass.
Citations
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Journal ArticleDOI
TL;DR: The present review describes the advantages of microalgae for the production of biofuels and various bioactive compounds and discusses culturing parameters.
Abstract: Microalgae have recently attracted considerable interest worldwide, due to their extensive application potential in the renewable energy, biopharmaceutical, and nutraceutical industries. Microalgae are renewable, sustainable, and economical sources of biofuels, bioactive medicinal products, and food ingredients. Several microalgae species have been investigated for their potential as value-added products with remarkable pharmacological and biological qualities. As biofuels, they are a perfect substitute to liquid fossil fuels with respect to cost, renewability, and environmental concerns. Microalgae have a significant ability to convert atmospheric CO2 to useful products such as carbohydrates, lipids, and other bioactive metabolites. Although microalgae are feasible sources for bioenergy and biopharmaceuticals in general, some limitations and challenges remain, which must be overcome to upgrade the technology from pilot-phase to industrial level. The most challenging and crucial issues are enhancing microalgae growth rate and product synthesis, dewatering algae culture for biomass production, pretreating biomass, and optimizing the fermentation process in case of algal bioethanol production. The present review describes the advantages of microalgae for the production of biofuels and various bioactive compounds and discusses culturing parameters.

1,125 citations

Journal ArticleDOI
TL;DR: In this paper, the authors discuss the technology and production platforms for development and creation of different valuable consumer products from microalgal biomass, including triglycerides which can be converted into biodiesel.
Abstract: Microalgae biotechnology has recently emerged into the lime light owing to numerous consumer products that can be harnessed from microalgae. Product portfolio stretches from straightforward biomass production for food and animal feed to valuable products extracted from microalgal biomass, including triglycerides which can be converted into biodiesel. For most of these applications, the production process is moderately economically viable and the market is developing. Considering the enormous biodiversity of microalgae and recent developments in genetic and metabolic engineering, this group of organisms represents one of the most promising sources for new products and applications. With the development of detailed culture and screening techniques, microalgal biotechnology can meet the high demands of food, energy and pharmaceutical industries. This review article discusses the technology and production platforms for development and creation of different valuable consumer products from microalgal biomass.

852 citations

Journal ArticleDOI
TL;DR: This comprehensive review article spots the light on one of the most interesting microalga Chlorella vulgaris and assembles the history and a thorough description of its ultrastructure and composition according to growth conditions.
Abstract: Economic and technical problems related to the reduction of petroleum resources require the valorisation of renewable raw material Recently, microalgae emerged as promising alternative feedstock that represents an enormous biodiversity with multiple benefits exceeding the potential of conventional agricultural feedstock Thus, this comprehensive review article spots the light on one of the most interesting microalga Chlorella vulgaris It assembles the history and a thorough description of its ultrastructure and composition according to growth conditions The harvesting techniques are presented in relation to the novel algo-refinery concept, with their technological advancements and potential applications in the market

677 citations

Journal ArticleDOI
Yusuf Chisti1
TL;DR: The near term outlook for widespread use of algal fuels appears bleak, but fuels for niche applications such as in aviation may be likely in the medium term.

631 citations


Cites background from "A critical review of biochemical co..."

  • ...The published life-cycle analyses of algal fuels (Lardon et al., 2009; Batan et al., 2010; Clarens et al., 2010; Jorquera et al., 2010; Sander and Murthy, 2010; Stephenson et al., 2010; Brentner et al., 2011; Campbell et al., 2011; Clarens et al., 2011; Khoo et al., 2011; Kucukvar and Tatari, 2011; Pfromm et al., 2011; Shirvani et al., 2011; Singh and Olsen, 2011; Yang et al., 2011a,b; Frank et al., 2012) have been generally inconclusive with respect to their sustainability....

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Journal ArticleDOI
TL;DR: This review aims to collate and present an overview of current harvesting, oil extraction and biofuels production technologies from microalgae, and discusses the various biodiesel production techniques in the later sections.
Abstract: Microalgae are receiving increasing attention worldwide as an alternative and renewable source for energy production. Through various conversion processes, microalgae can be used to produce many different kinds of biofuels, which include biodiesel, bio-syngas, bio-oil, bio-ethanol, and bio-hydrogen. However, large scale production of microalgal biofuels, via many available conversion techniques, faces a number of technical challenges which have made the current growth and development of the algal biofuel industry economically unviable. Therefore, in addition to algae culture and growth, it is also essential to develop cost-effective technologies for efficient biomass harvesting, lipid extraction and biofuels production. This review aims to collate and present an overview of current harvesting, oil extraction and biofuels production technologies from microalgae. Since much of the current studies on oil extraction are focused on biodiesel production from microalga, this study, apart from discussing the various biodiesel production techniques in the later sections, has also done a detailed discussion on the production techniques of other biofuels.

497 citations

References
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Journal ArticleDOI
Yusuf Chisti1
TL;DR: As demonstrated here, microalgae appear to be the only source of renewable biodiesel that is capable of meeting the global demand for transport fuels.

9,030 citations


"A critical review of biochemical co..." refers background in this paper

  • ...For these reasons many believe that microalgae are the only economic route to biodiesel [10,100]....

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Journal ArticleDOI
TL;DR: The various aspects associated with the design of microalgae production units are described, giving an overview of the current state of development of algae cultivation systems (photo-bioreactors and open ponds).
Abstract: Sustainable production of renewable energy is being hotly debated globally since it is increasingly understood that first generation biofuels, primarily produced from food crops and mostly oil seeds are limited in their ability to achieve targets for biofuel production, climate change mitigation and economic growth. These concerns have increased the interest in developing second generation biofuels produced from non-food feedstocks such as microalgae, which potentially offer greatest opportunities in the longer term. This paper reviews the current status of microalgae use for biodiesel production, including their cultivation, harvesting, and processing. The microalgae species most used for biodiesel production are presented and their main advantages described in comparison with other available biodiesel feedstocks. The various aspects associated with the design of microalgae production units are described, giving an overview of the current state of development of algae cultivation systems (photo-bioreactors and open ponds). Other potential applications and products from microalgae are also presented such as for biological sequestration of CO 2 , wastewater treatment, in human health, as food additive, and for aquaculture.

5,158 citations


"A critical review of biochemical co..." refers background in this paper

  • ...Algae represent a vast variety of photosynthetic species dwelling in diverse environments [8,19], they might be autotrophic or heterotrophic in nature [20]....

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Journal ArticleDOI
TL;DR: In this article, the authors reviewed the technologies underpinning microalgae-to-bio-fuels systems, focusing on the biomass production, harvesting, conversion technologies, and the extraction of useful co-products.
Abstract: Sustainability is a key principle in natural resource management, and it involves operational efficiency, minimisation of environmental impact and socio-economic considerations; all of which are interdependent. It has become increasingly obvious that continued reliance on fossil fuel energy resources is unsustainable, owing to both depleting world reserves and the green house gas emissions associated with their use. Therefore, there are vigorous research initiatives aimed at developing alternative renewable and potentially carbon neutral solid, liquid and gaseous biofuels as alternative energy resources. However, alternate energy resources akin to first generation biofuels derived from terrestrial crops such as sugarcane, sugar beet, maize and rapeseed place an enormous strain on world food markets, contribute to water shortages and precipitate the destruction of the world's forests. Second generation biofuels derived from lignocellulosic agriculture and forest residues and from non-food crop feedstocks address some of the above problems; however there is concern over competing land use or required land use changes. Therefore, based on current knowledge and technology projections, third generation biofuels specifically derived from microalgae are considered to be a technically viable alternative energy resource that is devoid of the major drawbacks associated with first and second generation biofuels. Microalgae are photosynthetic microorganisms with simple growing requirements (light, sugars, CO 2 , N, P, and K) that can produce lipids, proteins and carbohydrates in large amounts over short periods of time. These products can be processed into both biofuels and valuable co-products. This study reviewed the technologies underpinning microalgae-to-biofuels systems, focusing on the biomass production, harvesting, conversion technologies, and the extraction of useful co-products. It also reviewed the synergistic coupling of microalgae propagation with carbon sequestration and wastewater treatment potential for mitigation of environmental impacts associated with energy conversion and utilisation. It was found that, whereas there are outstanding issues related to photosynthetic efficiencies and biomass output, microalgae-derived biofuels could progressively substitute a significant proportion of the fossil fuels required to meet the growing energy demand.

4,432 citations


"A critical review of biochemical co..." refers background in this paper

  • ...mixture known as syngas (a mixture of CO, H2, CO2, N, and CH4) which is combustible at high temperatures (800–1000 C) [37]....

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  • ...AD involves the breakdown of organic matter to produce biogas [37]....

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  • ...It is also certain that the dominant algal strains isolated from the local environmental conditions may not be the optimal for production of biofuel under controlled conditions therefore genetic engineering may be required [37]....

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Journal ArticleDOI
TL;DR: This review provides a detailed summary of the research conducted on the inhibition of anaerobic processes and indicates that co-digestion with other waste, adaptation of microorganisms to inhibitory substances, and incorporation of methods to remove or counteract toxicants before an aerobic digestion can significantly improve the waste treatment efficiency.

4,123 citations


"A critical review of biochemical co..." refers background in this paper

  • ...potential toxicity of sodium [54]....

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  • ...High concentrations of ions such as Na, Ca andMg, which increase alkalinity and decrease the fraction of unionized NH3, can lower the inhibition effects [54]....

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Journal ArticleDOI
TL;DR: A brief summary of the current knowledge on oleaginous algae and their fatty acid and TAG biosynthesis, algal model systems and genomic approaches to a better understanding of TAG production, and a historical perspective and path forward for microalgae-based biofuel research and commercialization are provided.
Abstract: Microalgae represent an exceptionally diverse but highly specialized group of micro-organisms adapted to various ecological habitats. Many microalgae have the ability to produce substantial amounts (e.g. 20-50% dry cell weight) of triacylglycerols (TAG) as a storage lipid under photo-oxidative stress or other adverse environmental conditions. Fatty acids, the building blocks for TAGs and all other cellular lipids, are synthesized in the chloroplast using a single set of enzymes, of which acetyl CoA carboxylase (ACCase) is key in regulating fatty acid synthesis rates. However, the expression of genes involved in fatty acid synthesis is poorly understood in microalgae. Synthesis and sequestration of TAG into cytosolic lipid bodies appear to be a protective mechanism by which algal cells cope with stress conditions, but little is known about regulation of TAG formation at the molecular and cellular level. While the concept of using microalgae as an alternative and renewable source of lipid-rich biomass feedstock for biofuels has been explored over the past few decades, a scalable, commercially viable system has yet to emerge. Today, the production of algal oil is primarily confined to high-value specialty oils with nutritional value, rather than commodity oils for biofuel. This review provides a brief summary of the current knowledge on oleaginous algae and their fatty acid and TAG biosynthesis, algal model systems and genomic approaches to a better understanding of TAG production, and a historical perspective and path forward for microalgae-based biofuel research and commercialization.

3,479 citations


"A critical review of biochemical co..." refers background in this paper

  • ...atively low land usage and high carbon dioxide (CO2) absorption and uptake rate [10–15]....

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  • ...Some microalgae respond to certain chemical and physical stimuli through the accumulation of intracellular triglycerides (TGs) [11]....

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  • ...be grown on saline/coastal sea water and on non agricultural lands (desert, arid and semi-arid land) [11,21] and will not create a food–...

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