Large-scale open pond algae biomass yield analysis in India: a case study

Global warming, depletion of fossil fuel and increasing demand for energy have led to the substantial interest in developing alternate energy sources, especially biodiesel. First generation biofuels produced from food crops and oil seeds are limited to achieve targets for biodiesel production. Second generation biofuel produced from non-food feed stock such as microalgae provides various potential advantages for biofuel production when compared with first generation biofuels. This paper investigates the possible use of microalgae for biofuel production on the selected potential sites in the country. Algal biomass and oil yield for the selected sites are predicted using the analytical method.     

Commercialization potential of microalgae for biofuels production

Microalgae feedstocks are gaining interest in the present day energy scenario due to their fast growth potential coupled with relatively high lipid, carbohydrate and nutrients contents. All of these properties render them an excellent source for biofuels such as biodiesel, bioethanol and biomethane; as well as a number of other valuable pharmaceutical and nutraceutical products. The present review is a critical appraisal of the commercialization potential of microalgae biofuels. The available literature on various aspects of microalgae, e.g. its cultivation, life cycle assessment, and conceptualization of an algal biorefinery, has been scanned and a critical analysis has been presented. A critical evaluation of the available information suggests that the economic viability of the process in terms of minimizing the operational and maintenance cost along with maximization of oil-rich microalgae production is the key factor, for successful commercialization of microalgae-based fuels.     

Second generation biofuels: Economics and policies

This study reviews economics of production of second generation biofuels from various feedstocks, including crop and wood/forestry residues, lignocellulosic energy crops, jatropha, and algae. The study indicates that while second generation biofuels could significantly contribute to the future energy supply mix, cost is a major barrier to its commercial production in the near to medium term. Depending upon type of biofuels, feedstock prices and conversion costs, the cost of cellulosic ethanol is found to be two to three times higher than the current price of gasoline on an energy equivalent basis. The median cost (across the studies reviewed) of biodiesel produced from microalgae, a prospective feedstock, is seven times higher than the current price of diesel, although much higher cost estimates have been reported. As compared with the case of first generation biofuels, in which feedstock can account for over two-thirds of the total costs, the share of feedstock in the total costs is relatively lower (30–50%) in the case of second generation biofuels. While significant cost reductions are needed for both types of second generation biofuels, the critical barriers are at different steps of the production process. For cellulosic ethanol, the biomass conversion costs needs to be reduced. On the other hand, feedstock cost is the main issue for biodiesel. At present, policy instruments, such as fiscal incentives and consumption mandates have in general not differentiated between the first and second generation biofuels except in the cases of the US and EU. The policy regime should be revised to account for the relative merits of different types of biofuels.     

Biofuel production: Challenges and opportunities

It is increasing clear that biofuels can be a viable source of renewable energy in contrast to the finite nature, geopolitical instability, and deleterious global effects of fossil fuel energy. Collectively, biofuels include any energy-enriched chemicals generated directly through the biological processes or derived from the chemical conversion from biomass of prior living organisms. Predominantly, biofuels are produced from photosynthetic organisms such as photosynthetic bacteria, micro- and macro-algae and vascular land plants. The primary products of biofuel may be in a gas, liquid, or solid form. These products can be further converted by biochemical, physical, and thermochemical methods. Biofuels can be classified into two categories: primary and secondary biofuels. The primary biofuels are directly produced from burning woody or cellulosic plant material and dry animal waste. The secondary biofuels can be classified into three generations that are each indirectly generated from plant and animal material. The first generation of biofuels is ethanol derived from food crops rich in starch or biodiesel taken from waste animal fats such as cooking grease. The second generation is bioethanol derived from non-food cellulosic biomass and biodiesel taken from oil-rich plant seed such as soybean or jatropha. The third generation is the biofuels generated from cyanobacterial, microalgae and other microbes, which is the most promising approach to meet the global energy demands. In this review, we present the recent progresses including challenges and opportunities in microbial biofuels production as well as the potential applications of microalgae as a platform of biomass production. Future research endeavors in biofuel production should be placed on the search of novel biofuel production species, optimization and improvement of culture conditions, genetic engineering of biofuel-producing species, complete understanding of the biofuel production mechanisms, and effective techniques for mass cultivation of microorganisms.     

Strategies for 2nd generation biofuels in EU – Co-firing to stimulate feedstock supply development and process integration to improve energy efficiency and economic competitiveness

The present biofuel policies in the European Union primarily stimulate 1st generation biofuels that are produced based on conventional food crops. They may be a distraction from lignocellulose based 2nd generation biofuels – and also from biomass use for heat and electricity – by keeping farmers' attention and significant investments focusing on first generation biofuels and the cultivation of conventional food crops as feedstocks. This article presents two strategies that can contribute to the development of 2nd generation biofuels based on lignocellulosic feedstocks. The integration of gasification-based biofuel plants in district heating systems is one option for increasing the energy efficiency and improving the economic competitiveness of such biofuels. Another option, biomass co-firing with coal, generates high-efficiency biomass electricity and reduces CO₂ emissions by replacing coal. It also offers a near-term market for lignocellulosic biomass, which can stimulate development of supply systems for biomass also suitable as feedstock for 2nd generation biofuels. Regardless of the long-term priorities of biomass use for energy, the stimulation of lignocellulosic biomass production by development of near term and cost-effective markets is judged to be a no-regrets strategy for Europe. Strategies that induce a relevant development and exploit existing energy infrastructures in order to reduce risk and reach lower costs, are proposed an attractive complement the present and prospective biofuel policies.     

Prospects of biodiesel production from microalgae in India

Energy is essential and vital for development, and the global economy literally runs on energy. The use of fossil fuels as energy is now widely accepted as unsustainable due to depleting resources and also due to the accumulation of greenhouse gases in the environment. Renewable and carbon neutral biodiesel are necessary for environmental and economic sustainability. Biodiesel demand is constantly increasing as the reservoir of fossil fuel are depleting. Unfortunately biodiesel produced from oil crop, waste cooking oil and animal fats are not able to replace fossil fuel. The viability of the first generation biofuels production is however questionable because of the conflict with food supply. Production of biodiesel using microalgae biomass appears to be a viable alternative. The oil productivity of many microalgae exceeds the best producing oil crops. Microalgae are photosynthetic microorganisms which convert sunlight, water and CO₂ to sugars, from which macromolecules, such as lipids and triacylglycerols (TAGs) can be obtained. These TAGs are the promising and sustainable feedstock for biodiesel production. Microalgal biorefinery approach can be used to reduce the cost of making microalgal biodiesel. Microalgal-based carbon sequestration technologies cover the cost of carbon capture and sequestration. The present paper is an attempt to review the potential of microalgal biodiesel in comparison to the agricultural crops and its prospects in India.     

Biofuels from microalgae—A review of technologies for production,processing, and extractions of biofuels and co-products

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, CO₂, 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.     

Potential of fat,oil and grease (FOG) for biodiesel production: A critical review on the recent progress and future perspectives

Wastewater discharges from restaurants, kitchens, food processing plants and slaughterhouses contain high proportion of fat, oil, and grease (FOG). Critical overview on the attractive features, current state, and needed advancements are timely essential for FOG-derived biodiesel production. Although FOG conversion into biodiesel does not compete with human food, the high contents of moisture and free fatty acids (FFAs) are the main challenges for FOG efficient utilization. The present review discussed the various methods of high FFAs-lipidic feedstocks pretreatment including acid esterification, steam stripping, nanocatalytic technology, biological conversion, glycerolysis, supercritical esterification, and simultaneous in situ conversion. Comparing to other feedstocks, FOG-derived biodiesel showed better characteristics concerning oxidative stability, flash point, cetane number, and total emissions. In addition, most of the FOG-derived biodiesel fuel met the recommendations of the international standards as well as conventional diesel. Due to its lower price, the economic analysis showed that FOG is a strong competitor to other biodiesel feedstocks. The decrease in feedstocks availability, continuous rise in the crude oil prices, life threatening environmental deterioration, and food-versus-fuel debate support FOG to be a potential biodiesel feedstock in the near future. However, the cost of FOG-biodiesel production is still far away from the acceptable ranges to compete fossil diesel. Lastly, this paper suggested a number of future perspectives in order to enhance the economy and feasibility of FOG-derived biodiesel including developing new methods for efficient conversion of brown grease, integrated approaches for sequential production of biofuels from FOG, and co-esterification of FOG with other lipidic feedstocks.     

Biodiesel from oilgae,biofixation of carbon dioxide by microalgae: A solution to pollution problems

Algae containing 30–75% of lipid by dry basis can be called oilgae. All microalgae species produce lipid however some species can contain up to 70% of their dry weight. Microalgae appear to be the only source of renewable biodiesel that is capable of meeting the global demand for transport fuels. Biodiesel production by using oilgae is an alternative process in contrast to other procedures not only being degradable and non-toxic but also as a solution to global warming via reducing emission gases. Algae-based technologies could provide a key tool for reducing greenhouse gas emissions from coal-fired power plants and other carbon intensive industrial processes. Because algae are rich in oil and can grow in a wide range of conditions, many companies are betting that it can create fuels or other chemicals cheaper than existing feedstocks. The aim of microalgae biofixation of CO₂ is to operate large-scale systems that are able to convert a significant fraction of the CO₂ outputs from a power plant into biofuels.     

Transesterification of marine macroalgae using microwave technology

Biodiesel is renewable and environmental friendly, with calori?c value equivalent to regular fossil fuel. This fuel can be produced from a variety of feedstocks, such as ?rst-generation biodiesel feedstock (corn, peanut, soybean), second generation (jatropha, animal fats, waste cooking oils, macroalgae), and third generation (microalgae). Among these feedstocks, biodiesel production from microalgae has drawn special attention for different reasons: they have high lipid content and high growth rates; they are tolerant to severe environmental conditions; they offer the possibility of sequester carbon dioxide from the ?ue gases; their harvesting and transportation are economical compared to other crops; and they have very high photosynthetic yields compared to other terrestrial plants. The advantage of using macroalgae recollected on the beaches as raw material is that allows to obtained energy from a residue.

Microwave-assisted extraction and transesteri?cation of microalgae is being researched as a solution for biodiesel production by its benefits, such as shorter reaction times and less amount of heat energy to obtain biodiesel. It is due to the fact that microwaves can easily penetrate through the cell wall structure to extract and transesterify the oils into biodiesel.

The aim of this research was to explore the possibility of carrying out the microwave-assisted transesterification of three marine macroalgae (brown and green). Different experimental runs were carried out with different process parameters such as macroalgae-to-methanol ratio, reaction time and catalyst concentrations. Based on the obtained results, the best conditions for microwave-assisted transesteri?cation reaction were macroalgae-to-methanol ratio of 1:15 (wt/vol), sodium hydroxide concentration of 2 wt% and reaction time of 3 min.     

Enhanced biohydrogen production from microalgae by diesel engine hazardous emissions fixation

Microalgae cultivation has gained increased attention from research and industry sectors in recent years, due to the wide variety of applications for the produced biomass, such as biofuels and substances of high economic value. Indirect biophotolysis biohydrogen production from microalgae has been shown recently to be limited by the amount of accumulated biomass during the growth phase. As a result, this study focused on developing a strategy to increase biohydrogen generation via biomass production increase through microalgae cultivation using exhaust gases from diesel engines. In order to achieve that objective, four simultaneous cultures were conducted to compare the growth of microalgae under pure air and emissions injection, in different flow regimes. An indigenous microalgae strain was selected to be robust under different weather conditions and was identified as Acutodesmus obliquus through rDNA sequence analysis. The results indicate an increase in biomass production of about 2.8 times for the best case of cultivation with emissions in comparison to a compressed air condition. Besides the growth analyses, the potential for treating the hazardous emissions injected into the system was investigated and the data demonstrated that the CO₂ and NO_x content was substantially reduced, showing that no damage to the microalgae is caused by the diesel engine emissions. Numerical simulation results for the H₂ production indirect biophotolysis demonstrate that there is an optimal rhythm for maximum time averaged H₂ production rate, and that the stoichiometrically limited total H₂ production is augmented by a similar factor to microalgae biomass production increase.     

A comprehensive review on biodiesel as an alternative energy resource and its characteristics

As the fossil fuels are depleting day by day, there is a need to find out an alternative fuel to fulfill the energy demand of the world. Biodiesel is one of the best available resources that have come to the forefront recently. In this paper, a detailed review has been conducted to highlight different related aspects to biodiesel industry. These aspects include, biodiesel feedstocks, extraction and production methods, properties and qualities of biodiesel, problems and potential solutions of using vegetable oil, advantages and disadvantages of biodiesel, the economical viability and finally the future of biodiesel. The literature reviewed was selective and critical. Highly rated journals in scientific indexes were the preferred choice, although other non-indexed publications, such as Scientific Research and Essays or some internal reports from highly reputed organizations such as International Energy Agency (IEA), Energy Information Administration (EIA) and British Petroleum (BP) have also been cited. Based on the overview presented, it is clear that the search for beneficial biodiesel sources should focus on feedstocks that do not compete with food crops, do not lead to land-clearing and provide greenhouse-gas reductions. These feedstocks include non-edible oils such as Jatropha curcas and Calophyllum inophyllum, and more recently microalgae and genetically engineered plants such as poplar and switchgrass have emerged to be very promising feedstocks for biodiesel production.It has been found that feedstock alone represents more than 75% of the overall biodiesel production cost. Therefore, selecting the best feedstock is vital to ensure low production cost. It has also been found that the continuity in transesterification process is another choice to minimize the production cost. Biodiesel is currently not economically feasible, and more research and technological development are needed. Thus supporting policies are important to promote biodiesel research and make their prices competitive with other conventional sources of energy. Currently, biodiesel can be more effective if used as a complement to other energy sources.     

Biofuels versus food production: Does biofuels production increase food prices?

Rapidly growing fossil energy consumption in the transport sector in the last two centuries caused problems such as increasing greenhouse gas emissions, growing energy dependency and supply insecurity. One approach to solve these problems could be to increase the use of biofuels.Preferred feedstocks for current 1st generation biofuels production are corn, wheat, sugarcane, soybean, rapeseed and sunflowers. The major problem is that these feedstocks are also used for food and feed production.The core objective of this paper is to investigate whether the recent increase of biofuels production had a significant impact on the development of agricultural commodity (feedstock) prices. The most important impact factors like biofuels production, land use, yields, feedstock and crude oil prices are analysed.The major conclusions of this analysis are: In recent years the share of bioenergy-based fuels has increased moderately, but continuously, and so did feedstock production, as well as yields. So far, no significant impact of biofuels production on feedstock prices can be observed. Hence, a co-existence of biofuel and food production seems possible especially for 2nd generation biofuels. However, sustainability criteria should be seriously considered. But even if all crops, forests and grasslands currently not used were used for biofuels production it would be impossible to substitute all fossil fuels used today in transport.     

Biodiesel production by microalgal biotechnology

Biodiesel has received much attention in recent years. Although numerous reports are available on the production of biodiesel from vegetable oils of terraneous oil-plants, such as soybean, sunflower and palm oils, the production of biodiesel from microalgae is a newly emerging field. Microalgal biotechnology appears to possess high potential for biodiesel production because a significant increase in lipid content of microalgae is now possible through heterotrophic cultivation and genetic engineering approaches. This paper provides an overview of the technologies in the production of biodiesel from microalgae, including the various modes of cultivation for the production of oil-rich microalgal biomass, as well as the subsequent downstream processing for biodiesel production. The advances and prospects of using microalgal biotechnology for biodiesel production are discussed.     

Assessment of algae biodiesel viability based on the area requirement in the European Union,United States and Brazil

The replacement of diesel by biofuels is considered unrealistic because of the land used to produce their feedstock. One appointed solution is the use of algae which have higher productivity per unit area when compared with other feedstocks. In light of this, the total area, including water and land required for the European Union (EU), the United States (US), and Brazil was determined using international policies and targets, the present and future diesel demand, the current biodiesel production (released by international organizations), and specific data of algae productivity from the literature.GIS software was used to locate possible cities where algae cultivation could occur nearby. Bearings on the availability of area (flat and unoccupied zones), favourable climate, proximity to the process inputs (such as nutrients (preferably from municipal waste water treatment), CO₂ and water sources) and political boundaries were used as assessment criteria. It was possible to identify seven suitable cities with more than 500,000 inhabitants in the EU, two in the USA and thirteen in Brazil.It was also shown that it is possible to attain targets required by current policies and replace diesel with algae-derived diesel based on attainable cultivation areas.     

Comparison of dairy wastewater and synthetic medium for biofuels production by microalgae cultivation

This study is concerned with comparing raw dairy wastewater (DWW) with blue-green medium (BG11 medium) for biofuel production. Three microalgae strains (Chlorella sp., Scenedesmus sp., and Chlorella zofingiensis) were cultured in tubular bubble column photobioreactors with two media separately. After 8 days of cultivation, DWW was demonstrated to be more suitable medium for microalgae biomass and lipid production than BG11 medium. The biomass and lipid produced within wastewater provided suitable feedstocks for anaerobic digestion and biodiesel conversion. Nutrients in wastewater were efficiently removed (>90% total nitrogen removal, approximately 100% ammonia removal, and >85% total phosphorus removal) during this process.     

微藻培养方法研究进展

微藻是一种有前景的生物柴油原料。微藻培养是微藻生物柴油生产过程的重要环节。本文就微藻培养方法的研究进展进行了阐述。对自养、异养及兼养三种培养方法进行了比较,并对微藻培养提出了建议。     

Dual role of microalgae: Phycoremediation of domestic wastewater and biomass production for sustainable biofuels production

Global threats of fuel shortages in the near future and climate change due to green-house gas emissions are posing serious challenges and hence and it is imperative to explore means for sustainable ways of averting the consequences. The dual application of microalgae for phycoremediation and biomass production for sustainable biofuels production is a feasible option. The use of high rate algal ponds (HRAPs) for nutrient removal has been in existence for some decades though the technology has not been fully harnessed for wastewater treatment. Therefore this paper discusses current knowledge regarding wastewater treatment using HRAPs and microalgal biomass production techniques using wastewater streams. The biomass harvesting methods and lipid extraction protocols are discussed in detail. Finally the paper discusses biodiesel production via transesterification of the lipids and other biofuels such as biomethane and bioethanol which are described using the biorefinery approach.     

Transesterification of Prunus armeniaca oil using calcium methoxide as a catalyst: Identification of methyl esters and proposed mechanistic pathways

The utilization of nonedible feedstocks for biodiesel production is getting top priority in the recent years, as they do not interfere with the global food economy. In the present study, calcium methoxide (Ca(OCH₃)₂) catalyst was synthesized for the production of biodiesel from Prunus armeniaca oil via transesterification reaction. Under optimized reaction conditions, the biodiesel yield of 89.93% was achieved and catalyst could be reused for four times with slight loss in activity. The fatty acid methyl esters in the produced biodiesel were detected by gas chromatography/mass spectrometry (GC/MS), and six fragments were identified based on mass-to-charge ratio (m/z) at different retention time. The fuel properties of the biodiesel obtained were in conformity with the ASTM standards.