Microalgae biomass production for a biorefinery system: Recent advances and the way towards sustainability
TL;DR: In this paper, the authors reviewed the recently released information regarding the upstream methodologies involved in an algae-based bio-fuels production system, including the better understanding of the conversion of light to biomass, the analysis of the productivities of the most recent culture systems, the use of waste waters as alternative sources of nutrients, and the co-location of the algae biomass production process to an industry.
Abstract: Microalgae are an important source of oils and other molecules that can be used as feedstocks to produce biofuels and high-value products, having the potential of becoming a significant renewable energy source. However, large scale production of microalgal biofuels faces numerous technical challenges, which makes the current growth and development of the microalgae biorefinery industry, still economically unviable. This study reviewed the recently released information regarding the upstream methodologies involved in an algae-based biofuels production system. The better understanding of the conversion of light to biomass, the analysis of the productivities of the most recent culture systems, the use of waste waters as alternative sources of nutrients, and the co-location of the algae biomass production process to an industry are among the approaches that have been proposed to track the challenges in the development of a biorefinery system based on microalgae; these have been analyzed critically in this work.
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TL;DR: This study concludes that sustained research funding, and a shift of microalgae focus from biofuels production to bio-refinery co-products can qualify them as promising feedstocks.
Abstract: The potential of microalgae as an alternative energy source has been adequately studied. However, exclusive use of microalgae as an energy feedstocks cannot warrant their scalability and economical sustainability due to the high cost involved in their biomass processing. The co-processing of microalgae biomass with other related bio-refinery applications can offset their cost and improve their sustainability. Thus, it triggers up the need of exploring the potential of microalgae biomass beyond their typical use. Microalgae offer interesting features to qualify them as alternative feedstocks for various bio-refinery applications. Microalgae have unique abilities to utilize them for industrial and environmental applications. Thus, this review discusses to expand the scope of integrating microalgae with other biotechnological applications to enhance their sustainability. The use of microalgae as a feed for animal and aquaculture, fertilizers, medicine, cosmetic, environmental and other biotechnological applications is thoroughly reviewed. It also highlights the barriers, opportunities, developments, and prospects of extending the scope of microalgae. This study concludes that sustained research funding, and a shift of microalgae focus from biofuels production to bio-refinery co-products can qualify them as promising feedstocks. Moreover, technology integration is inevitable to off-set the cost of microalgae biomass processing. It is expected that this study would be helpful to determine the future role of microalgae in bio-refinery applications.
314 citations
TL;DR: The cultivation conditions for biomass growth and lipid productivity improvement, the available harvesting and lipid extraction technologies, as well as the key challenges and future prospect of microalgae biodiesel production are illustrated.
Abstract: Microalgae has been identified as a potential feedstock for biodiesel production since its cultivation requires less cropland compared to conventional oil crops and the high growth rate of microalgae. Research on microalgae oils often are focused on microalgae oil extraction and biomass harvesting techniques. However, energy intensive and costly lipid extraction methods are the major obstacles hampering microalgae biodiesel commercialisation. Direct biodiesel synthesis avoids such problems as it combines lipid extraction techniques and transesterification into a single step. In this review, the potential of direct biodiesel synthesis from microalgae biomass was comprehensively analysed. The various species of microalgae commonly used as biodiesel feedstock was critically assessed, particularly on high lipid content species. The production of microalgae biodiesel via direct conversion from biomass was systematically discussed, covering major enhancements such as heterogeneous catalysts, the use of ultrasonic and microwave- techniques and supercritical alcohols that focus on the overall improvement of biodiesel production. In addition, this review illustrates the cultivation conditions for biomass growth and lipid productivity improvement, the available harvesting and lipid extraction technologies, as well as the key challenges and future prospect of microalgae biodiesel production. This review serves as a basis for future research on direct biodiesel synthesis from modified microalgae biomass to improve profitability of microalgae biodiesel.
252 citations
TL;DR: In this paper, a review of the literature on exergetic analysis of the lignocellulose pretreatment process has been presented, focusing on the thermodynamic, economic, and environmental features of the resulting biofuels.
217 citations
TL;DR: There is an urgent need for turning current single task-orientated bioprocess to an integrated biological process with multiple tasks of concurrent recovery of water, resource and energy together with zero-solid discharge.
201 citations
TL;DR: In this paper, a review of methods developed for microalgae-based wastewater treatment is described, where conventional and novel technologies used for producing biochar from microalgal biomass, such as pyrolysis and hydrothermal approaches, are presented.
137 citations
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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
TL;DR: About five decades ago, the mass production of certain protein-rich micro-algae was considered as a possibility to close the predicted so called "protein gap".
1,685 citations
01 Jan 2013
TL;DR: In this article, the authors examined three aspects of micro-algae production that will ultimately determine the future economic viability and environmental sustainability: the energy and carbon balance, envi-ronmental impacts and production cost.
Abstract: Micro-algae have received considerable interest as a potential feedstock for producingsustainable transport fuels (biofuels). The perceived benefits provide the underpinningrationale for much of the public support directed towards micro-algae research. Here weexamine three aspects of micro-algae production that will ultimately determine the futureeconomic viability and environmental sustainability: the energy and carbon balance, envi-ronmental impacts and production cost. This analysis combines systematic review and meta-analysis with insights gained from expert workshops.We find that achieving a positive energy balance will require technological advancesand highly optimised production systems. Aspects that will need to be addressed in aviable commercial system include: energy required for pumping, the embodied energyrequired for construction, the embodied energy in fertilizer, and the energy required fordrying and de-watering. The conceptual and often incomplete nature of algae productionsystems investigated within the existing literature, together with limited sources of pri-mary data for process and scale-up assumptions, highlights future uncertainties aroundmicro-algae biofuel production. Environmental impacts from water management, carbondioxide handling, and nutrient supply could constrain system design and implementationoptions. Cost estimates need to be improved and this will require empirical data on theperformance of systems designed specifically to produce biofuels. Significant (>50%) costreductions may be achieved if CO
739 citations
TL;DR: In this paper, the authors examined three aspects of micro-algae production that will ultimately determine the future economic viability and environmental sustainability: the energy and carbon balance, environmental impacts and production cost.
Abstract: Micro-algae have received considerable interest as a potential feedstock for producing sustainable transport fuels (biofuels). The perceived benefits provide the underpinning rationale for much of the public support directed towards micro-algae research. Here we examine three aspects of micro-algae production that will ultimately determine the future economic viability and environmental sustainability: the energy and carbon balance , environmental impacts and production cost . This analysis combines systematic review and meta-analysis with insights gained from expert workshops. We find that achieving a positive energy balance will require technological advances and highly optimised production systems. Aspects that will need to be addressed in a viable commercial system include: energy required for pumping, the embodied energy required for construction, the embodied energy in fertilizer, and the energy required for drying and de-watering. The conceptual and often incomplete nature of algae production systems investigated within the existing literature, together with limited sources of primary data for process and scale-up assumptions, highlights future uncertainties around micro-algae biofuel production. Environmental impacts from water management, carbon dioxide handling, and nutrient supply could constrain system design and implementation options. Cost estimates need to be improved and this will require empirical data on the performance of systems designed specifically to produce biofuels. Significant (>50%) cost reductions may be achieved if CO 2 , nutrients and water can be obtained at low cost. This is a very demanding requirement, however, and it could dramatically restrict the number of production locations available.
708 citations
TL;DR: To produce a high amount of biomass with high lipid content, a fed-batch cultivation with stepwise increasing light intensity was performed and the lipid production was approximately twice that of conventional batch cultivation.
650 citations