research on biofuel from algae

Sustainable Approaches to Algal Biofuels: Opportunities, Key Challenges and Current Status

• First Online: 25 May 2024

Cite this chapter

• Anuradha Devi 4 ,
• Christina Saran 4 ,
• Luiz Fernando R. Ferreira 5 ,
• Sikandera I. Mulla 6 &
• Ram Naresh Bharagava 4  

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As fossil fuel reserves dwindle and the concerns over pollution, global warming and soaring fuel prices exaggerate, the perseverance for renewable energy sources becomes paramount. Algae-based biofuels emerge as an excellent alternative to conventional fossil fuels, leveraging their inherent photosynthetic efficiency, rapid growth rate, minimal land and water requirements in comparison to conventional crops, and superior quality and quantity of biomass yield rich in carbohydrates and lipids. The produced biomass can be used for producing diverse array of biofuels like bioethanol, biomethane, biohydrogen and biodiesel. However, despite their potential opportunistic limitations and challenges persist, notably in production scalability and research focus limited to selection and lab scale cultivation of algal species. This chapter comprehensively explore the opportunities, challenges and economic viability of algal biofuels. From delving into the generations of biofuels to highlighting algae as a third-generation feedstock, it scrutinizes cultivation and harvesting techniques, elucidates various biofuel production opportunities, and addresses engineering for production scale-up. Also, the chapter seeks to address critical limitations inhibiting widespread adoption by evaluating the economic landscape and challenges. By spotlighting these facets, it aspires to catalyse further research and technological advancements in algal biofuel generation, propelling the field towards a sustainable, impactful future.

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Abbreviations

Acetone-Butanol-Ethanol

Aquatic Microbial Oxygenic Photoautotroph

Aquatic Species Program

Chemical oxygen demand

Environmental and Energy Study Institute

Extracellular polymer substances

Fatty Acid Methyl Ester

Greenhouse gases

Internal Rate of Return

Life cycle assessment

Light emitting diodes

Minimum Fuel Selling Price

Net energy ratio

Net Present Value

National Renewable Energy Laboratory

Photosynthetic active radiation

Photobioreactor

Research Institute of Innovative Technology for the Earth

Sustainable Development Goals

Total capital investment

United States dollar

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Acknowledgments

Ms. Anuradha Devi is highly thankful to the ‘University Grants Commission’ (UGC), New Delhi, India for providing the financial support for her research work.

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Devi, A., Saran, C., Ferreira, L.F.R., Mulla, S.I., Bharagava, R.N. (2024). Sustainable Approaches to Algal Biofuels: Opportunities, Key Challenges and Current Status. In: Arya, S.K., Khatri, M., Singh, G. (eds) Value Added Products From Bioalgae Based Biorefineries: Opportunities and Challenges. Springer, Singapore. https://doi.org/10.1007/978-981-97-1662-3_8

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REVIEW article

Scope of algae as third generation biofuels.

• Biochemical Conversion Division, Sardar Swaran Singh National Institute of Renewable Energy, Kapurthala, Punjab, India

An initiative has been taken to develop different solid, liquid, and gaseous biofuels as the alternative energy resources. The current research and technology based on the third generation biofuels derived from algal biomass have been considered as the best alternative bioresource that avoids the disadvantages of first and second generation biofuels. Algal biomass has been investigated for the implementation of economic conversion processes producing different biofuels such as biodiesel, bioethanol, biogas, biohydrogen, and other valuable co-products. In the present review, the recent findings and advance developments in algal biomass for improved biofuel production have been explored. This review discusses about the importance of the algal cell contents, various strategies for product formation through various conversion technologies, and its future scope as an energy security.

Introduction

The requirement of energy for the mankind is increasing day by day. The major source of energy is based on fossil fuels only. Thus, the scarcity of fossil fuels, rising price of petroleum based fuels, energy protection, and increased global warming resulted in focusing on renewable energy sources such as solar, wind, hydro, tidal, and biomass worldwide ( Goldemberg and Guardabassi, 2009 ; Dragone et al., 2010 ; Rajkumar et al., 2014 ).

Different biomass from various sources like agricultural, forestry, and aquatic have been taken into consideration as the feedstocks for the production of several biofuels such as biodiesel ( Boyce et al., 2008 ; Yanqun et al., 2008 ), bioethanol ( Behera et al., 2014 ), biohydrogen ( Marques et al., 2011 ), bio-oil ( Shuping et al., 2010 ), and biogas ( Hughes et al., 2012 ; Singh et al., 2014 ). However, the environmental impact raised from burning of fuels has a great impact on carbon cycle (carbon balance), which is related to the combustion of fossil fuels. Besides, exhaustion of different existing biomass without appropriate compensation resulted in huge biomass scarcity, emerging environmental problems such as deforestation and loss of biodiversity ( Goldemberg, 2007 ; Li et al., 2008 ; Saqib et al., 2013 ).

Recently, researchers and entrepreneurs have focused their interest, especially on the algal biomass as the alternative feedstock for the production of biofuels. Moreover, algal biomass has no competition with agricultural food and feed production ( Demirbas, 2007 ). The photosynthetic microorganisms like microalgae require mainly light, carbon dioxide, and some nutrients (nitrogen, phosphorus, and potassium) for its growth, and to produce large amount of lipids and carbohydrates, which can be further processed into different biofuels and other valuable co-products ( Brennan and Owende, 2010 ; Nigam and Singh, 2011 ). Interestingly, the low content of hemicelluloses and about zero content of lignin in algal biomass results in an increased hydrolysis and/or fermentation efficiency ( Saqib et al., 2013 ). Other than biofuels, algae have applications in human nutrition, animal feed, pollution control, biofertilizer, and waste water treatment ( Thomas, 2002 ; Tamer et al., 2006 ; Crutzen et al., 2007 ; Hsueh et al., 2007 ; Choi et al., 2012 ). Therefore, the aim of the current review is to explore the scope of algae for the production of different biofuels and evaluation of its potential as an alternative feedstock.

Algae: Source of Biofuels

Generally, algae are a diverse group of prokaryotic and eukaryotic organisms ranging from unicellular genera such as Chlorella and diatoms to multicellular forms such as the giant kelp, a large brown alga that may grow up to 50 m in length ( Li et al., 2008 ). Algae can either be autotrophic or heterotrophic. The autotrophic algae require only inorganic compounds such as CO 2 , salts, and a light energy source for their growth, while the heterotrophs are non-photosynthetic, which require an external source of organic compounds as well as nutrients as energy sources ( Brennan and Owende, 2010 ). Microalgae are very small in sizes usually measured in micrometers, which normally grow in water bodies or ponds. Microalgae contain more lipids than macroalgae and have the faster growth in nature ( Lee et al., 2014a ). There are about more than 50,000 microalgal species out of which only about 30,000 species have been taken for the research study ( Surendhiran and Vijay, 2012 ; Richmond and Qiang, 2013 ; Rajkumar et al., 2014 ). The short harvesting cycle of algae is the key advantage for its importance, which is better than other conventional crops having harvesting cycle of once or twice in a year ( Chisti, 2007 ; Schenk et al., 2008 ). Therefore, the main focus has been carried out on algal biomass for its application in biofuel area.

There are several advantages of algal biomass for biofuels production: (a) ability to grow throughout the year, therefore, algal oil productivity is higher in comparison to the conventional oil seed crops; (b) higher tolerance to high carbon dioxide content; (c) the consumption rate of water is very less in algae cultivation; (d) no requirement of herbicides or pesticides in algal cultivation; (e) the growth potential of algal species is very high in comparison to others; (f) different sources of wastewater containing nutrients like nitrogen and phosphorus can be utilized for algal cultivation apart from providing any additional nutrient; and (g) the ability to grow under harsh conditions like saline, brackish water, coastal seawater, which does not affect any conventional agriculture ( Spolaore et al., 2006 ; Dismukes et al., 2008 ; Dragone et al., 2010 ). However, there are several disadvantages of algal biomass as feedstock such as the higher cultivation cost as compared to conventional crops. Similarly, harvesting of algae require high energy input, which is approximately about 20–30% of the total cost of production. Several techniques such as centrifugation, flocculation, floatation, sedimentation, and filtration are usually used for harvesting and concentrating the algal biomass ( Demirbas, 2010 ; Ho et al., 2011 ).

The algae can be converted into various types of renewable biofuels including bioethanol, biodiesel, biogas, photobiologically produced biohydrogen, and further processing for bio-oil and syngas production through liquefaction and gasification, respectively ( Kraan, 2013 ). The conversion technologies for utilizing algal biomass to energy sources can be categorized into three different ways, i.e., biochemical, chemical, and thermochemical conversion and make an algal biorefinery, which has been depicted in Figure 1 . The biofuel products derived from algal biomass using these conversion routes have been explored in detail in the subsequent sections.

Figure 1. Algal biomass conversion process for biofuel production .

Biodiesel Production

Biodiesel is a mixture of monoalkyl esters of long chain fatty acids [fatty acid methyl esters (FAME)], which can be obtained from different renewable lipid feedstocks and biomass. It can be directly used in different diesel engines ( Clark and Deswarte, 2008 ; Demirbas, 2009 ). Studies to explore the microalgae as feedstock for the production of liquid fuels had been started for the mid-1980s. In order to solve the energy crisis, the extraction of lipids from diatoms was attempted by some German scientists during the period of World War-II ( Cohen et al., 1995 ). The higher oil yield in algal biomass as compared to oil seed crops makes the possibility to convert into the biodiesel economically using different technologies. A comparative study between algal biomass and terrestrial plants for the production of biodiesel has been depicted in Table 1 . The oil productivity (mass of oil produced per unit volume of the microalgal broth per day) depends on the algal growth rate and the biomass content of the species. The species of microalgae such as Kirchneriella lunaris , Ankistrodesmus fusiformis , Chlamydocapsa bacillus , and Ankistrodesmus falcatus with high levels of polyunsaturated FAME are generally preferred for the production of biodiesel ( Nascimento et al., 2013 ). They commonly multiply their biomass with doubling time of 24 h during exponential growth. Oil content of microalgae is generally found to be very high, which exceed up to 80% by weight of its dry biomass. About 5,000–15,000 gal of biodiesel can be produced from algal biomass per acre per year, which reflects its potentiality ( Spolaore et al., 2006 ; Chisti, 2007 ).

Table 1 . Comparative study between algal biomass and terrestrial plants for biodiesel production .

However, there are some standards such as International Biodiesel Standard for Vehicles (EN14214) and American Society for Testing and Materials (ASTM), which are required to comply with the algal based biodiesel on the physical and chemical properties for its acceptance as substitute to fossil fuels ( Brennan and Owende, 2010 ). The higher degree of polyunsaturated fatty acids of algal oils as compared to vegetable oils make susceptible for oxidation in the storage and further limits its utilization ( Chisti, 2007 ). Some researchers have reported the different advantages of the algal biomass for the biodiesel production due to its high biomass growth and oil productivity in comparison to best oil crops ( Chisti, 2007 ; Hossain et al., 2008 ; Hu et al., 2008 ; Rosenberg et al., 2008 ; Schenk et al., 2008 ; Rodolfi et al., 2009 ; Mutanda et al., 2011 ).

Algal biodiesel production involves biomass harvesting, drying, oil extraction, and further transesterification of oil, which have been described as below.

Harvesting and Drying of Algal Biomass

Unicellular microalgae produce a cell wall containing lipids and fatty acids, which differ them from higher animals and plants. Harvesting of algal biomass and further drying is important prior to mechanical and solvent extraction for the recovery of oil. Macroalgae can be harvested using nets, which require less energy while microalgae can be harvested by some conventional processes, which include filtration ( Rossignol et al., 1999 ) flocculation ( Liu et al., 2013 ; Prochazkova et al., 2013 ), centrifugation ( Heasman et al., 2008 ), foam fractionation ( Csordas and Wang, 2004 ), sedimentation, froth floatation, and ultrasonic separation ( Bosma et al., 2003 ). Selection of harvesting method depends on the type of algal species.

Drying is an important method to extend shelf-life of algal biomass before storage, which avoids post-harvest spoilage ( Munir et al., 2013 ). Most of the efficient drying methods like spray-drying, drum-drying, freeze drying or lyophilization, and sun-drying have been applied on microalgal biomass ( Leach et al., 1998 ; Richmond, 2004 ; Williams and Laurens, 2010 ). Sun-drying is not considered as a very effective method due to presence of high water content in the biomass ( Mata et al., 2010 ). However, Prakash et al. (2007) used simple solar drying device and succeed in drying Spirulina and Scenedesmus having 90% of moisture content. Widjaja et al. (2009) showed the effectiveness of drying temperature during lipid extraction of algal biomass, which affects both concentration of triglycerides and lipid yield. Further, all these processes possess safety and health issues ( Singh and Gu, 2010 ).

Extraction of Oil from Algal Biomass

Unicellular microalgae produce a cell wall containing lipids and fatty acids, which differ them from higher animals and plants. In the literature, there are different methods of oil extraction from algae, such as mechanical and solvent extraction ( Li et al., 2014 ). However, the extraction of lipids from microalgae is costly and energy intensive process.

Mechanical oil extraction

The oil from nuts and seeds is extracted mechanically using presses or expellers, which can also be used for microalgae. The algal biomass should be dried prior to this process. The cells are just broken down with a press to leach out the oil. About 75% of oil can be recovered through this method and no special skill is required ( Munir et al., 2013 ). Topare et al. (2011) extracted oil through screw expeller by mechanical pressing (by piston) and osmotic shock method and recovered about 75% of oil from the algae. However, more extraction time is required as compared to other methods, which make the process unfavorable and less effective ( Popoola and Yangomodou, 2006 ).

Solvent based oil extraction

Oil extraction using solvent usually recovers almost all the oil leaving only 0.5–0.7% residual oil in the biomass. Therefore, the solvent extraction method has been found to be suitable method rather than the mechanical extraction of oil and fats ( Topare et al., 2011 ). Solvent extraction is another method of lipid extraction from microalgae, which involves two stage solvent extraction systems. The amount of lipid extracted from microalgal biomass and further yield of highest biodiesel depends mainly on the solvent used. Several organic solvents such as chloroform, hexane, cyclo-hexane, acetone, and benzene are used either solely or in mixed form ( Afify et al., 2010 ). The solvent reacts on algal cells releasing oil, which is recovered from the aqueous medium. This occurs due to the nature of higher solubility of oil in organic solvents rather than water. Further, the oil can be separated from the solvent extract. The solvent can be recycled for next extraction. Out of different organic solvents, hexane is found to be most effective due to its low toxicity and cost ( Rajvanshi and Sharma, 2012 ; Ryckebosch et al., 2012 ).

In case of using mixed solvents for oil extraction, a known quantity of the solvent mixture is used, for example, chloroform/methanol in the ratio 2:1 (v/v) for 20 min using a shaker and followed by the addition of mixture, i.e., chloroform/water in the ratio of 1:1 (v/v) for 10 min ( Shalaby, 2011 ). Similarly, Pratoomyot et al. (2005) extracted oil from different algal species using the solvent system chloroform/methanol in the ratio of 2:1 (v/v) and found different fatty acid content. Ryckebosch et al. (2012) optimized an analytical procedure and found chloroform/methanol in the ratio 1:1 as the best solvent mixture for the extraction of total lipids. Similarly, Lee et al. (1998) extracted lipid from the green alga Botryococcus braunii using different solvent system and obtained the maximum lipid content with chloroform/methanol in the ratio of 2:1. Hossain et al., 2008 used hexane/ether in the ratio 1:1 (v/v) for oil extraction and allowed to settle for 24 h. Using a two-step process, Fajardo et al. (2007) reported about 80% of lipid recovery using ethanol and hexane in the two steps for the extraction and purification of lipids. Therefore, a selection of a most suitable solvent system is required for the maximum extraction of oil for an economically viable process.

Lee et al. (2009) compared the performance of various disruption methods, including autoclaving, bead-beating, microwaves, sonication, and using 10% NaCl solution in the extraction of Botryococcus sp., Chlorella vulgaris , and Scenedesmus sp, using a mixture of chloroform and methanol (1:1).

Transesterification

This is a process to convert algal oil to biodiesel, which involves multiple steps of reactions between triglycerides or fatty acids and alcohol. Different alcohols such as ethanol, butanol, methanol, propanol, and amyl alcohol can be used for this reaction. However, ethanol and methanol are used frequently for the commercial development due to its low cost and its physical and chemical advantages ( Bisen et al., 2010 ; Surendhiran and Vijay, 2012 ). The reaction can be performed in the presence of an inorganic catalyst (acids and alkalies) or lipase enzyme. In this method, about 3 mol of alcohol are required for each mole of triglyceride to produce 3 mol of methyl esters (biodiesel) and 1 mol of glycerol (by-product) ( Meher et al., 2006 ; Chisti, 2007 ; Sharma and Singh, 2009 ; Surendhiran and Vijay, 2012 ; Stergiou et al., 2013 ) (Figure 2 ). Glycerol is denser than biodiesel and can be periodically or continuously removed from the reactor in order to drive the equilibrium reaction. The presence of methanol, the co-solvent that keeps glycerol and soap suspended in the oil, is known to cause engine failure ( Munir et al., 2013 ). Thus, the biodiesel is recovered by repeated washing with water to remove glycerol and methanol ( Chisti, 2007 ).

Figure 2. Transesterification of oil to biodiesel . R 1–3 are hydrocarbon groups.

The reaction rate is very slow by using the acid catalysts for the conversion of triglycerides to methyl esters, whereas the alkali-catalyzed transesterification reaction has been reported to be 4000 times faster than the acid-catalyzed reaction ( Mazubert et al., 2013 ). Sodium and potassium hydroxides are the two commercial alkali catalysts used at a concentration of about 1% of oil. However, sodium methoxide has become the better catalyst rather than sodium hydroxide ( Singh et al., 2006 ).

Kim et al. (2014) used Scenedesmus sp. for the biodiesel production through acid and alkali transesterification process. They reported 55.07 ± 2.18%, based on lipid by wt of biodiesel conversion using NaOH as an alkaline catalyst than using H 2 SO 4 as 48.41 ± 0.21% of biodiesel production. In comparison to acid and alkalies, lipases as biocatalyst have different advantages as the catalysts due to its versatility, substrate selectivity, regioselectivity, enantioselectivity, and high catalytic activity at ambient temperature and pressure ( Knezevic et al., 2004 ). It is not possible by some lipases to hydrolyze ester bonds at secondary positions, while some other group of enzymes hydrolyzes both primary and secondary esters. Another group of lipases exhibits fatty acids selectivity, and allow to cleave ester bonds at particular type of fatty acids. Luo et al. (2006) cloned the lipase gene lipB68 and expressed in Escherichia coli BL21 and further used it as a catalyst for biodiesel production. LipB68 could catalyze the transesterification reaction and produce biodiesel with a yield of 92% after 12 h, at a temperature of 20°C. The activity of the lipase enzyme with such a low temperature could provide substantial savings in energy consumption. However, it is rarely used due to its high cost ( Sharma et al., 2001 ).

Extractive transesterification

It involves several steps to produce biodiesel such as drying, cell disruption, oils extraction, transesterification, and biodiesel refining ( Hidalgo et al., 2013 ). The main problems are related with the high water content of the biomass (over 80%), which overall increases the cost of whole process.

In situ transesterification

This method skips the oil extraction step. The alcohol acts as an extraction solvent and an esterification reagent as well, which enhances the porosity of the cell membrane. Yields found are higher than via the conventional route, and waste is also reduced. Industrial biodiesel production involves release of extraction solvent, which contributes to the production of atmospheric smog and to global warming. Thus, simplification of the esterification processes can reduce the disadvantages of this attractive bio-based fuel. The single-step methods can be attractive solutions to reduce chemical and energy consumption in the overall biodiesel production process ( Patil et al., 2012 ). A comparison of direct and extractive transesterification is given in Table 2 .

Table 2 . Comparison of extractive transesterification and in situ methods ( Haas and Wagner, 2011 ) .

Bioethanol Production

Several researchers have been reported bioethanol production from certain species of algae, which produce high levels of carbohydrates as reserve polymers. Owing to the presence of low lignin and hemicelluloses content in algae in comparison to lignocellulosic biomass, the algal biomass have been considered more suitable for the bioethanol production ( Chen et al., 2013 ). Recently, attempts have been made (for the bioethanol production) through the fermentation process using algae as the feedstocks to make it as an alternative to conventional crops such as corn and soyabean ( Singh et al., 2011 ; Nguyen and Vu, 2012 ; Chaudhary et al., 2014 ). A comparative study of algal biomass and terrestrial plants for the production of bioethanol has been given in Table 3 . There are different micro and macroalgae such as Chlorococcum sp., Prymnesium parvum , Gelidium amansii , Gracilaria sp., Laminaria sp., Sargassum sp., and Spirogyra sp., which have been used for the bioethanol production ( Eshaq et al., 2011 ; Rajkumar et al., 2014 ). These algae usually require light, nutrients, and carbon dioxide, to produce high levels of polysaccharides such as starch and cellulose. These polysaccharides can be extracted to fermentable sugars through hydrolysis and further fermentation to bioethanol and separated through distillation as shown in Figure 3 .

Table 3 . Comparative study between algal biomass and terrestrial plants for bioethanol production .

Figure 3. Process for bioethanol production from microalgae .

Pre-Treatment and Saccharification

It has been reported that, the cell wall of some species of green algae like Spirogyra and Chlorococcum contain high level of polysaccharides. Microalgae such as C. vulgaris contains about 37% of starch on dry weight basis, which is the best source for bioethanol with 65% conversion efficiency ( Eshaq et al., 2010 ; Lam and Lee, 2012 ). Such polysaccharide based biomass requires additional processing like pre-treatment and saccharification before fermentation ( Harun et al., 2010 ). Saccharification and fermentation can also be carried out simultaneously using an amylase enzyme producing strain for the production of ethanol in a single step. Bioethanol from microalgae can be produced through the process, which is similar to the first generation technologies involving corn based feedstocks. However, there is limited literature available on the fermentation process of microalgae biomass for the production of bioethanol ( Schenk et al., 2008 ; John et al., 2011 ).

The pre-treatment is an important process, which facilitates accessibility of biomass to enzymes to release the monosaccharides. Acid pre-treatment is widely used for the conversion of polymers present in the cell wall to simple forms. The energy consumption in the pre-treatment is very low and also it is an efficient process ( Harun and Danquah, 2011a , b ). Yazdani et al. (2011) found 7% (w/w) H 2 SO 4 as the promising concentration for the pre-treatment of the brown macroalgae Nizimuddinia zanardini to obtain high yield of sugars without formation of any inhibitors. Candra and Sarinah (2011) studied the bioethanol production using red seaweed Eucheuma cottonii through acid hydrolysis. In this study, 5% H 2 SO 4 concentration was used for 2 h at 100°C, which yielded 15.8 g/L of sugars. However, there are other alternatives to chemical hydrolysis such as enzymatic digestion and gamma radiation to make it more sustainable ( Chen et al., 2012 ; Yoon et al., 2012 ; Schneider et al., 2013 ).

Similar to starch, there are certain polymers such as alginate, mannitol, and fucoidan present in the cell wall of various algae, which requires additional processing like pre-treatment and saccharification before fermentation. Another form of storage carbohydrate found in various brown seaweeds and microalgae is laminarin, which can be hydrolyzed by β-1,3-glucanases or laminarinases ( Kumagai and Ojima, 2010 ). Laminarinases can be categorized into two groups such as exo- and endo-glucanases based on the mode of hydrolysis, which usually produces glucose and smaller oligosaccharides as the end product. Both the enzymes are necessary for the complete digestion of laminarin polymer ( Lee et al., 2014b ).

Markou et al. (2013) saccharified the biomass of Spirulina ( Arthrospira platensis ), fermented the hydrolyzate and obtained the maximum ethanol yield of 16.32 and 16.27% (g ethanol /g biomass ) produced after pre-treatment with 0.5 N HNO 3 and H 2 SO 4 , respectively. Yanagisawa et al. (2011) investigated the content of polysaccharide materials present in three types of seaweeds such as sea lettuce ( Ulva pertusa ), chigaiso ( Alaria crassifolia ), and agar weed ( Gelidium elegans ). These seaweeds contain no lignin, which is a positive signal for the hydrolysis of polysaccharides without any pre-treatment. Singh and Trivedi (2013) used Spirogyra biomass for the production of bioethanol using Saccharomyces cerevisiae and Zymomonas mobilis . In a method, they followed acid pre-treatment of algal biomass and further saccharified using α-amylase producing Aspergillus niger . In another method, they directly saccharified the biomass without any pre-treatment. The direct saccharification process resulted in 2% (w/w) more alcohol in comparison to pretreated and saccharified algal biomass. This study revealed that the pre-treatment with different chemicals are not required in case of Spyrogyra , which reflects its economic importance for the production of ethanol. Also, cellulase enzyme has been used for the saccharification of algal biomass containing cellulose. However, this enzyme system is more expensive than amylases and glucoamylases, and doses required for effective cellulose saccharification are usually very high. Trivedi et al. (2013) applied different cellulases on green alga Ulva for saccharification and found highest conversion efficiency of biomass into reducing sugars by using cellulase 22119 rather than viscozyme L, cellulase 22086 and 22128. In this experiment, they found a maximum yield of sugar 206.82 ± 14.96 mg/g with 2% (v/v) enzyme loading for 36 h at a temperature of 45°C.

Fermentation

There are different groups of microorganisms like yeast, bacteria, and fungi, which can be used for the fermentation of the pretreated and saccharified algal biomass under anaerobic process for the production of bioethanol ( Nguyen and Vu, 2012 ). Nowadays, S. cerevisiae and Z. mobilis have been considered as the bioethanol fermenting microorganisms. However, fermentation of mannitol, a polymer present in certain algae is not possible in anaerobic condition using these well known microorganisms and requires supply of oxygen during fermentation, which is possible only by Zymobacter palmae ( Horn et al., 2000 ).

Certain marine red algae contain agar, a polymer of galactose and galactopyranose, which can be used for the production of bioethanol ( Yoon et al., 2010 ). The biomass of red algae can be depolymerized into different monomeric sugars like glucose and galactose. In addition to mannitol and glucose, brown seaweeds contain about 14% of extra carbohydrates in the form of alginate ( Wargacki et al., 2012 ). Horn et al. (2000) reported the presence of alginate, laminaran, mannitol, fucoidan, and cellulose in some brown seaweeds, which are good source of sugars. They fermented brown seaweed extract having mannitol using bacteria Z. palmae and obtained an ethanol yield of about 0.38 g ethanol/g mannitol.

In the literature, there are many advantages supporting microalgae as the promising substrate for bioethanol production. Hon-Nami (2006) used Chlamydomonas perigranulata algal culture and obtained different by-products such as ethanol and butanediol. Similarly, Yanagisawa et al. (2011) obtained glucose and galactose through the saccharification of agar weed (red seaweed) containing glucan and galactan and obtained 5.5% of ethanol concentration through fermentation using S. cerevisiae IAM 4178. Harun et al. (2010) obtained 60% more ethanol in case of lipid extracted microalgal biomass rather than intact algal biomass of Chlorococcum sp. This shows the importance of algal biomass for the production of both biodiesel and bioethanol.

Biogas Production

Recently, biogas production from algae through anaerobic digestion has received a remarkable attention due to the presence of high polysaccharides (agar, alginate, carrageenan, laminaran, and mannitol) with zero lignin and low cellulose content. Mostly, seaweeds are considered as the excellent feedstock for the production of biogas. Several workers have demonstrated the fermentation of various species of algae like Scenedesmus , Spirulina , Euglena , and Ulva for biogas production ( Samson and Leduy, 1986 ; Yen and Brune, 2007 ; Ras et al., 2011 ; Zhong et al., 2012 ; Saqib et al., 2013 ). The production of biogas using algal biomass in comparison to some terrestrial plants is shown in Table 4 .

Table 4 . Comparative study between algal biomass and terrestrial plants for biogas production .

Biogas is produced through the anaerobic transformation of organic matter present in the biodegradable feedstock such as marine algae, which releases certain gases like methane, carbon dioxide, and traces of hydrogen sulfide. The anaerobic conversion process involves basically four main steps. In the first step, the insoluble organic material and higher molecular mass compounds such as lipids, carbohydrates, and proteins are hydrolyzed into soluble organic material with the help of enzyme released by some obligate anaerobes such as Clostridia and Streptococci . The second step is called as acidogenesis, which releases volatile fatty acids (VFAs) and alcohols through the conversion of soluble organics with the involvement of enzymes secreted by the acidogenic bacteria. Further, these VFAs and alcohols are converted into acetic acid and hydrogen using acetogenic bacteria through the process of acetogenesis, which finally metabolize to methane and carbon dioxide by the methanogens ( Cantrell et al., 2008 ; Vergara-Fernandez et al., 2008 ; Brennan and Owende, 2010 ; Romagnoli et al., 2011 ).

Sangeetha et al. (2011) reported the anaerobic digestion of green alga Chaetomorpha litorea with generation of 80.5 L of biogas/kg of dry biomass under 299 psi pressure. Vergara-Fernandez et al. (2008) evaluated digestion of the marine algae Macrocystis pyrifera and Durvillaea antarctica marine algae in a two-phase anaerobic digestion system and reported similar biogas productions of 180.4 (±1.5) mL/g dry algae/day with a methane concentration around 65%. However, in case of algae blend, same methane content was observed with low biogas yield. Mussgnug et al. (2010) reported biogas production from some selected green algal species like Chlamydomonas reinhardtii and Scenedesmus obliquus and obtained 587 and 287 mL biogas/g of volatile solids, respectively. Further, there are few studies, which have been conducted with microalgae showing the effect of different pre-treatment like thermal, ultrasound, and microwave for the high production of biogas ( Gonzalez-Fernandez et al., 2012a , b ; Passos et al., 2013 ).

However, there are different factors, which limit the biogas production such as requirement of larger land area, infrastructure, and heat for the digesters ( Collet et al., 2011 ; Jones and Mayfield, 2012 ). The proteins present in algal cells increases the ammonium production resulting in low carbon to nitrogen ratio, which affects biogas production through the inhibition of growth of anaerobic microorganisms. Also, anaerobic microorganisms are inhibited by the sodium ions. Therefore, it is recommended to use the salt tolerating microorganisms for the anaerobic digestion of algal biomass ( Yen and Brune, 2007 ; Brennan and Owende, 2010 ; Jones and Mayfield, 2012 ).

Biohydrogen Production

Recently, algal biohydrogen production has been considered to be a common commodity to be used as the gaseous fuels or electricity generation. Biohydrogen can be produced through different processes like biophotolysis and photo fermentation ( Shaishav et al., 2013 ). Biohydrogen production using algal biomass is comparative to that of terrestrial plants (Table 5 ). Park et al. (2011) found Gelidium amansii (red alga) as the potential source of biomass for the production of biohydrogen through anaerobic fermentation. Nevertheless, they found 53.5 mL of H 2 from 1 g of dry algae with a hydrogen production rate of 0.518 L H 2 /g VSS/day. The authors found an inhibitor, namely, 5-hydroxymethylfurfural (HMF) produced through the acid hydrolysis of G. amansii that decreases about 50% of hydrogen production due to the inhibition. Thus, optimization of the pre-treatment method is an important step to maximize biohydrogen production, which will be useful for the future direction ( Park et al., 2011 ; Shi et al., 2011 ). Saleem et al. (2012) reduced the lag time for hydrogen production using microalgae Chlamydomonas reinhardtii by the use of optical fiber as an internal light source. In this study, the maximum rate of hydrogen production in the presence of exogenic glucose and optical fiber was reported to be 6 mL/L culture/h, which is higher than other reported values.

Table 5 . Comparative study between algal biomass and terrestrial plants for biohydrogen production .

Some of microalgae like blue green algae have glycogen instead of starch in their cells. This is an exception, which involves oxidation of ferrodoxin by the hydrogenase enzyme activity for the production of hydrogen in anaerobic condition. However, another function of this enzyme is to be involved in the detachment of electrons. Therefore, different researchers have focused for the identification of these enzyme activities having interactions with ferrodoxin and the other metabolic functions for microalgal photobiohydrogen production. They are also involved with the change of these interactions genetically to enhance the biohydrogen production ( Gavrilescu and Chisti, 2005 ; Hankamer et al., 2007 ; Wecker et al., 2011 ; Yacoby et al., 2011 ; Rajkumar et al., 2014 ).

Bio-Oil and Syngas Production

Bio-oil is formed in the liquid phase from algal biomass in anaerobic condition at high temperature. The composition of bio-oil varies according to different feedstocks and processing conditions, which is called as pyrolysis ( Iliopoulou et al., 2007 ; Yanqun et al., 2008 ). There are several parameters such as water, ash content, biomass composition, pyrolysis temperature, and vapor residence time, which affect the bio-oil productivity ( Fahmi et al., 2008 ). However, due to the presence of water, oxygen content, unsaturated and phenolic moieties, crude bio-oil cannot be used as fuel. Therefore, certain treatments are required to improve its quality ( Bae et al., 2011 ). Bio-oils can be processed for power generation with the help of external combustion through steam and organic rankine cycles, and stirling engines. However, power can also be generated through internal combustion using diesel and gas-turbine engines ( Chiaramonti et al., 2007 ). In literature, there are limited studies on algae pyrolysis compared to lignocellulosic biomass. Although, high yields of bio-oil occur through fluidized-bed fast pyrolysis processes, there are several other pyrolysis modes, which have been introduced to overcome their inherent disadvantages of a high level of carrier gas flow and excessive energy inputs ( Oyedun et al., 2012 ). Demirbas (2006) investigated suitability of the microalgal biomass for bio-oil production and found the superior quality than the wood. Porphy and Farid (2012) produced bio-oil from pyrolysis of algae ( Nannochloropsis sp.) at 300°C after lipid extraction, which composed of 50 wt% acetone, 30 wt% methyl ethyl ketone, and 19 wt% aromatics such as pyrazine and pyrrole. Similarly, Choi et al. (2014) carried out pyrolysis study on a species of brown algae Saccharina japonica at a temperature of 450°C and obtained about 47% of bio-oil yield.

Gasification is usually performed at high temperatures (800–1000°C), which converts biomass into the combustible gas mixture through partial oxidation process, called syngas or producer gas. Syngas is a mixture of different gases like CO, CO 2 , CH 4 , H 2 , and N 2 , which can also be produced through normal gasification of woody biomass. In this process, biomass reacts with oxygen and water (steam) to generate syngas. It is a low calorific gas, which can be utilized in the gas turbines or used directly as fuel. Different variety of biomass feedstocks can be utilized for the production of energy through the gasification process, which is an added advantage ( Carvalho et al., 2006 ; Prins et al., 2006 ; Lv et al., 2007 ).

Conclusion and Future Perspectives

Recently, it is a challenge for finding different alternative resources, which can replace fossil fuels. Due to presence of several advantages in algal biofuels like low land requirement for biomass production and high oil content with high productivity, it has been considered as the best resource, which can replace the liquid petroleum fuel. However, one of its bottlenecks is the low biomass production, which is a barrier for industrial production. Also, another disadvantage includes harvesting of biomass, which possesses high energy inputs. For an economic process development in comparison to others, a cost-effective and energy efficient harvesting methods are required with low energy input. Producing low-cost microalgal biofuels requires better biomass harvesting methods, high biomass production with high oil productivity through genetic modification, which will be the future of algal biology. Therefore, use of the standard algal harvesting technique, biorefinery concept, advances in photobioreactor design and other downstream technologies will further reduce the cost of algal biofuel production, which will be a competitive resource in the near future.

Conflict of Interest Statement

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Acknowledgments

The authors are thankful to Prof. Y. K. Yadav, Director, NIRE, Kapurthala for his consistent support to write this review paper. The authors greatly acknowledge the Ministry of New and Renewable Energy, New Delhi, Govt. of India, for providing funds to carry out research work.

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Keywords: algae, microalgae, biofuels, bioethanol, biogas, biodiesel, biohydrogen

Citation: Behera S, Singh R, Arora R, Sharma NK, Shukla M and Kumar S (2015) Scope of algae as third generation biofuels. Front. Bioeng. Biotechnol. 2 :90. doi: 10.3389/fbioe.2014.00090

Received: 31 July 2014; Accepted: 29 December 2014; Published online: 11 February 2015.

Reviewed by:

Copyright: © 2015 Behera, Singh, Arora, Sharma, Shukla and Kumar. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY) . The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

*Correspondence: Sachin Kumar, Biochemical Conversion Division, Sardar Swaran Singh National Institute of Renewable Energy, Jalandhar-Kapurthala Road, Wadala Kalan, Kapurthala 144601, Punjab, India e-mail: sachin.biotech@gmail.com

Disclaimer: All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.

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Algae: Biomass to Biofuel

Affiliations.

• 1 Sustainable Materials and Catalysis Research Laboratory (SMCRL), Department of Chemistry, Indian Institute of Technology Jodhpur, Jodhpur, India.
• 2 Sustainable Materials and Catalysis Research Laboratory (SMCRL), Department of Chemistry, Indian Institute of Technology Jodhpur, Jodhpur, India. [email protected].
• PMID: 34009581
• DOI: 10.1007/978-1-0716-1323-8_3

Worldwide demand for ethanol alternative fuel has been emerging day by day owing to the rapid population growth and industrialization. Culturing microalgae as an alternative feedstock is anticipated to be a potentially significant approach for sustainable bioethanol biofuel production. Microalgae are abundant in nature, which grow at faster rates with a capability of storing high lipid and starch/cellulose contents inside their cells. This process offers several environmental advantages, including the effective utilization of land, good CO2 sequestration without entering into "food against fuel" dispute. This chapter focuses on the methods and processes used for the production of bioethanol biofuels from algae. Thus, it also covers significant achievements in the research and developments on algae bioethanol production, mainly including pretreatment, hydrolysis, and fermentation of algae biomass. The processes of producing biodiesel, biogas, and hydrogen have also been discussed.

Keywords: Bioethanol; Biofuel; Biogas; Biohydrogen; Biomass; Microalgae.

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AgriLife Today

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Artificial intelligence predicts algae potential as alternative energy source

Jet fuel, animal feed among potential products from algae.

March 4, 2022 - by Blair Fannin

Texas A&M AgriLife Research scientists are using artificial intelligence to set a new world record for producing algae as a reliable, economic source for biofuel that can be used as an alternative fuel source for jet aircraft and other transportation needs.

Joshua Yuan, Ph.D., AgriLife Research scientist, professor and chair of Synthetic Biology and Renewable Products in the Texas A&M College of Agriculture and Life Sciences Department of Plant Pathology and Microbiology , is leading the research project.

The team’s findings were published in January in Nature Communications . Ongoing research is funded by the U.S. Department of Energy Fossil Energy Office. The work is also being funded by a gift from Dr. John ’90 and Sally ’92 Hood, who recently met with Yuan to discuss his biofuels research program. The gift is managed by the Texas A&M Foundation .

The project team includes Bin Long, a graduate student from the Department of Plant Pathology and Microbiology; Bart Fischer, Ph.D., co-director of the Texas A&M Agricultural and Food Policy Center and Texas A&M Department of Agricultural Economics ; Henry Bryant, Ph.D., Department of Agricultural Economics; and Yining Zeng, Ph.D., staff scientist with the U.S. Department of Energy National Renewable Energy Laboratory .

Solving the algae limitations as a biofuel

“The commercialization of algal biofuel has been hindered by the relatively low yield and high harvesting cost,” Yuan said. “The limited light penetration and poor cultivation dynamics both contributed to the low yield.”

Overcoming these challenges could enable viable algal biofuels to reduce carbon emissions, mitigate climate change, alleviate petroleum dependency and transform the bioeconomy, Yuan said.

Yuan has previously been successful at finding methods to convert corn stubble, grasses and mesquite into biodegradable, lightweight materials and bioplastics. His latest project utilizes a patented artificial intelligence advanced learning model to predict algae light penetration, growth and optimal density. The prediction model allows for continual harvest of synthetic algae using hydroponics to maintain the rapid growth at the optimal density to allow best light availability.

The method Yuan and team have successfully achieved in an outdoor experiment is 43.3 grams per square meter per day of biomass productivity, which would be a world record. The latest DOE target range is 25 grams per square meter per day.

“Algae can be used as an alternative energy source for many industries, including biofuel and as jet fuel,” Yuan said. “Algae is a good alternative fuel source for this industry. It’s an alternate feedstock for bioethanol refinery without the need for pretreatment. It’s lower cost than coal or natural gas. It also provides for a more efficient way of carbon capture and utilization.”

Yuan said algae can also be used as a source for animal feed. AgriLife Research has previously investigated algae as a source of livestock protein.

Algae as a renewable energy

Algae biofuel is regarded as one of the ultimate solutions for renewable energy, but its commercialization is hindered by growth limitations caused by mutual shading and high harvest costs.

“We overcome these challenges by advancing machine learning to inform the design of a semi-continuous algal cultivation (SAC) to sustain optimal cell growth and minimize mutual shading,” he said.

Yuan said he is using an aggregation-based sedimentation strategy designed to achieve low-cost biomass harvesting and economical SAC.

“The aggregation-based sedimentation is achieved by engineering a fast-growing blue-green algae strain, Synechococcus elongatus UTEX2973, to produce limonene, which increases cyanobacterial cell surface hydrophobicity and enables efficient cell aggregation and sedimentation,” he said.

Making algae economical energy

Scaling-up the SAC with an outdoor pond system achieves a biomass yield of 43.3 grams per square meter per day, bringing the minimum biomass selling price down to approximately $281 per ton, according to the journal article. In comparison, the standard low-cost feedstock for biomass in ethanol is corn, which is currently approximately $6 per bushel or $260 per ton. However, Yuan’s process does not call for costly pre-treatment before fermentation. Corn must be ground and the mash must be cooked before fermentation.

“Algae as a renewable fuel source was a hot topic a decade ago,” Fischer said. “As a result, there’s a lot of skepticism. I was even skeptical. However, the work that Joshua is doing is incredibly innovative. We were excited to partner on this project. At the productivity levels they obtain – and given the low-cost harvest that the strain allows – it shows a lot of promise.”

Yuan said despite significant potential and extensive efforts, the commercialization of algal biofuel has been hindered by limited sunlight penetration, poor cultivation dynamics, relatively low yield, and the absence of cost-effective industrial harvest methods.

“This technology is proven to be affordable and help propel algae as a true alternative form of energy,” he said.

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• DOI: 10.32792/utq/utjsci/v11i1.1194
• Corpus ID: 270596547

An experimental study of the production of biofuel from Lyngbyasp algae

• Abbas Mohsin Abbas , R. J. Elkheralla , +4 authors M.R.Jayp
• Published in University of Thi-Qar Journal… 18 June 2024
• Environmental Science

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20 References

Algae as a feedstock for biofuels an assessment of the current status and potential for algal biofuels production, biodiesel from microalgae., algae based biorefinery - how to make sense, biofuels from algae: technology options, energy balance and ghg emissions: insights from a literature review, biorefinery as a promising approach to promote microalgae industry: an innovative framework, towards sustainable production of biofuels from microalgae, biofuels from microalgae—a review of technologies for production, processing, and extractions of biofuels and co-products, the blue water footprint and land use of biofuels from algae, optimal design of microalgae-based biorefinery: economics, opportunities and challenges, biofuels from algae: challenges and potential, related papers.

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How a biocatalyst might boost the growth of microalgae

by Ruhr-Universitaet-Bochum

Living organisms consist to a large extent of carbon (C) and nitrogen (N) compounds. These have to be taken in with food or, in the case of plants, produced through photosynthesis.

A previously mysterious extension of a starch-degrading enzyme in algae could be a kind of sensor to determine how much nitrogen is currently available. If there is plenty of it, the algal cells quickly release many building blocks for their growth.

The research team led by Dr. Anja Hemschemeier and Dr. Lisa Scholtysek from the Photobiotechnology Group at Ruhr University Bochum, Germany, report their new findings in the journal Plant Direct .

A starch-degrading biocatalyst as a nitrogen sensor

The optimal composition of a living cell is made up of a certain ratio of C and N, but the quantities of these elements in our diet and in the environment of plants and algae are usually not that perfectly balanced. Therefore, living organisms must tune their metabolism and chemical composition to the availability of these—and other—chemical building blocks.

In plant-like organisms, C-containing molecules that are not immediately utilized are stored as starch. Various types of biocatalysts—also termed enzymes—release C skeletons from starch when they are needed as building blocks or as energy source. One of these enzymes is alpha-amylase, which Hemschemeier's research team investigated from the microalga Chlamydomonas reinhardtii.

In the process, the team made a surprising discovery. "The enzyme has an extension that is not needed for starch degradation," explains Hemschemeier, who headed the study. "This protein part has already been discovered in a similar form in many different enzymes, where it usually regulates the function of the biocatalyst.

"Commonly, this protein part senses small compounds that play a role in the corresponding metabolic pathway, so that its speed can be adjusted and coordinated with other pathways."

Lisa Scholtysek, lead author of the study, tested the effect of many different substances on the activity of this amylase. Finally, she identified one that noticeably increased the activity of the enzyme, namely the amino acid glutamine.

This N-containing compound is a building block of proteins. In many organisms, glutamine is also the first product of N assimilation and serves both as the primary N source and as a signal for how much N is available for biosynthetic pathways.

An alpha-amylase as growth booster?

To date, this combination of starch-degrading enzyme and glutamine sensor has not been described in literature. Still, based on bioinformatic analyses conducted by the researchers, many microalgae appear to possess this specific combination.

"Our research is still in its infancy," says Hemschemeier. "So far, we have studied this effect only at the level of the isolated biocatalyst from Chlamydomonas. An important next step is to study it in living algae."

However, the researchers have a hypothesis. "It is conceivable that this alpha-amylase registers when a lot of nitrogen is present. Then, it accelerates the release of C scaffolds from starch for the production of N- and C-containing cell components." This could optimize cell growth when the algae encounter optimal conditions.

Provided by Ruhr-Universitaet-Bochum

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Fact Sheet: Biden- ⁠ Harris Administration’s Actions to Advance American Biotechnology and Biomanufacturing

Through his Investing in America Agenda, President Biden is making a once-in-a-generation investment in our clean energy future. His leadership has spurred a revolution in clean electricity, transportation, and efficiency that is cutting costs for American families and creating good-paying jobs across the country. To meet the challenges of decarbonizing the U.S. economy, President Biden is also driving progress to advance domestic biomanufacturing and biotechnology which will provide an alternative to petroleum-based production for chemicals, medicines, fuels, materials, and more. These investments support President Biden’s climate and clean energy goals, build stronger supply chains, and advance American leadership around the globe.

To advance these efforts, President Biden signed an Executive Order on Advancing Biotechnology and Biomanufacturing Innovation for a Sustainable, Safe, and Secure American Bioeconomy that has catalyzed action across the government to set bold goals, develop the biomanufacturing workforce, promote American leadership in biotechnology research and development, and ensure that these technologies are developed and utilized responsibly. The President’s commitment to a clean energy economy has spurred $29 billion in public and private sector biomanufacturing investments for projects across the country since the start of the Biden-Harris Administration.

Today, the White House, members of the National Bioeconomy Board, and the Departments of Energy (DOE), Defense (DOD), and Agriculture convened major biotechnology and biomanufacturing companies, nonprofits, and other stakeholders met to highlight progress to date and discuss critical upcoming milestones to support the long-term success of the nation’s bioeconomy.

This month, the Biden-Harris Administration announced a set of actions to accelerate U.S. domestic biomanufacturing capacity and highlighting progress in the two years since the President signed the Executive Order, including:

• DOE’s Loan Programs Office announced a $213.6 million conditional loan guarantee to Solugen Inc’s Bioforge Marshall facility in Marshall, Minnesota. This commitment is the largest single federal investment in bioindustial manufacturing since President Biden signed Executive Order 14081.The new facility, Bioforge Marshall, will house three modular trains manufacturing various organic acids for use in the concrete, cleaning, agricultural, and energy industries​—cutting harmful emissions from hard-to-decarbonize sectors while helping deliver healthier communities across the nation. As part of President Biden’s  Investing in America  agenda to create good-paying, high-quality job opportunities for American workers, this project will create up to 100 jobs during construction and 56 highly skilled full-time manufacturing jobs once fully operational. 
• The Department of Agriculture is making available recommendations for revisions to the North American Industry Classification System and North American Product Classification System codes for the bioeconomy . These classifications provide a systematic organization of both industries (NAICS) and products (NAPCS) and are currently lacking for the bioeconomy. NAICS industries are defined by similarities in production processes. NAPCS products are defined based on use. The recommendations for revisions to the NAICS and NAPCS are guided by the National Institutes of Standards and Technology’s Bioeconomy Lexicon , and a study of the feasibility of measuring the bioeconomy by the Bureau of Economic. These revisions will lay the foundation to organize, sustain, and accelerate the growth of the U.S. bioeconomy through data-driven decision-making.
• The Department of Agriculture is also releasing a request for information from the public as it explores options for reducing the regulatory burden for modified microbes. Engineered organisms have the potential to improve agricultural productivity and address sustainability and climate goals. The information USDA hopes to receive will inform how to ensure proportionate oversight that will allow for both safety and commercialization of beneficial products.
• The National Security Council is announcing the newly formed Biopharma Coalition (Bio-5) to support secure biopharmaceutical supply chains, in partnership with the Office of Pandemic Preparedness and Response. The United States, EU, India, Japan, and the Republic of Korea will work together to strengthen biopharmaceutical supply chain resilience. The Bio-5, which initially met in a track 1.5 format alongside industry representatives from each entity, will focus on building resilient supply chains for active pharmaceutical ingredients (APIs) currently sourced primarily from the People’s Republic of China. The five countries will seek opportunities for their governments and the private sector to deepen coordination on policy, regulations, R&D capabilities, and other tools to enhance the resilience of this vital sector.

These announcements build upon more than $3.5 billion in investments and a wide range of actions the Biden-Harris Administration has already taken to increase U.S. biomanufacturing capacity:

• The Administration established the National Bioeconomy Board to lead actions to achieve a sustainable, safe, and secure American bioeconomy.
• The Department of Defense, which released its Biomanufacturing Strategy in March 2023, announced an over $1 billion investment in domestic biomanufacturing to strengthen defense supply chains. These efforts will accelerate the bio-materials development pipeline with the Air Force, Army, and Navy laboratories; establish a commercial investment program that seeks to industrialize maturing biomaterials; and build supply chain resilience for the Department. This investment prioritizes applications where technologies have both military and commercial applications covering the primary focus areas of: Food, Fuel, Fitness, Fabrication, and Firepower.
• DOE’s Office of Science supported $264 million for 29 projects to address the scientific challenges underlying DOE’s  Energy Earthshots™ Initiative  to advance clean energy technologies within the decade and drive broader innovation for a sustainable bioeconomy.  The funding will support 11 new Energy Earthshot Research Centers led by DOE National Laboratories and 18 university research teams addressing the Energy Earthshots™ that are focused on six different areas, including biologically-driven solutions in carbon-neutral energy, industrial decarbonization, and carbon storage.
• DOE’s Bioenergy Technologies Office (BETO ) is supporting $151 million to scale promising technologies that convert biomass to biofuels and bioproducts, accelerating the growing Bioeconomy. The selected projects include demonstration-scale biomanufacturing facilities that will ramp up to produce millions of gallons of low-carbon fuel annually. By investing in these technologies, the projects will create good-paying jobs in rural and underserved communities in nine states and enhance education and training opportunities regionally to build the bioenergy workforce.
• DOE’s Fossil Energy and Carbon Management Office (FECM) and BETO have also provided $80M to support research, and field trials for biomass and waste feedstocks including CO2 gases, micro- and macro algae and energy crops to fuel the bioeconomy and over $40M to support research in the development of industrially relevant biocatalysts/microorganisms to make more affordable biofuels and bioproducts.
• DOE’s Office of Clean Energy Demonstration (OCED) announced up to $200 million in Federal Cost Share for the Sustainable Ethylene from CO2 Utilization with Renewable Energy (SECURE) project, led by T.EN Stone & Webster Process Technology, Inc. in partnership with LanzaTech, with plans to demonstrate an integrated process to utilize captured carbon dioxide from ethylene production—an important building block for many products—by applying a biotech-based processand green hydrogen to create clean ethanol and ethylene.
• The National Science Foundation (NSF) announced a $30 million investment in the NSF Science and Technology Center for Quantitative Cell Biology. Led by researchers at the University of Illinois Urbana-Champaign, Harvard Medical School, and the J. Craig Venter Institute, this center brings together an interdisciplinary group of experts to develop whole cell models—a full quantitative description of the physical and chemical processes that define the state of a cell. Whole cell models can be used to predict and design new bioengineered systems or compare the function of healthy cells to diseased cells, leading to a better understanding of what goes wrong in diseased cells.
• NSF, in partnership with the Simons Foundation, announced a $50 million investment in an institute tasked with bringing together experts in mathematics and biology to uncover the fundamental principles governing life through theories, data-informed mathematical models, and computational, statistical, and AI tools, critical fundamental research that will fuel innovations across all sectors of the bioeconomy. The National Institute for Theory and Mathematics in Biology (NITMB), led by Northwestern University and the University of Chicago, will create a nationwide collaborative research community that will target promising and challenging areas of exploration that help address some of societies greatest challenges, including those with impacts on the bioeconomy like sustainable agriculture, preventing pandemics, and mitigating the effects of climate change. The NITMB will also train the next generation of researchers to use to power of mathematics and biology to advances in areas as diverse as the environment, biomedicine, and technology development.
• NSF awarded a first in its kind National Synthesis Center for Emergence in Molecular and Cellular Sciences, a center focused on data synthesis, use and reuse in the molecular and cellular biotechnology space. The $20 million center, led by Pennsylvania State University, with partners including the University of Arizona, Claflin University, Alcorn State University, and Fayetteville State University, will tackle many of the data infrastructure and data workforce issues that are critical to enabling a robust U.S. bioeconomy.
• NSF has committed to increasing U.S. investment in bioeconomy-related infrastructure, including biofoundries and centers, and is completing its first competition for its new bioFoundries to Enable Access to Infrastructure and Resources for Advancing Modern Biology and Biotechnology program. With up to $75 million in funds committed towards the first BioFoundries, NSF is investing in and democratizing access to critical infrastructure that will advance all sectors of the bioeconomy, spur tool development, enable user-initiated research provide user facilities, and train and grow the biotechnology workforce across the U.S.  In addition, with the latest Global Centers competition underway, on Use Inspired Research Addressing Global Challenges through the Bioeconomy, with topics that include biofoundries, and partners from Canada, Finland, Japan, Korea, and the United Kingdom, NSF is poised to commit an additional $25 million, a commitment that will be amplified by the international partners.
• USDA’s Rural Development program has invested more than $500 million in several different loan and grant programs to impact the domestic bioeconomy. These programs invested in areas such as advanced biofuels, biofuel infrastructure, renewable fertilizer production, and biogas and biomass projects.  In addition, the RD Biopreferred catalog of biobased products added 1,517 net new products and 559 net new companies offering those products. 
• USDA has invested over $500 million in new research and development to advance the nation’s bioeconomy since the President’s Executive Order. Pioneering work by USDA scientists created the foundation for the first commercial harvests of new oilseed crops—domesticated pennycress and carinata—which provide new sources of fuel and feed without requiring additional cropland. Advancements in biomanufacturing by USDA have resulted in adhesives for grocery PLU stickers that can be composted, bio-asphalts that generate fewer emissions, and biobased antioxidants for stabilization of natural rubber in tires. USDA’s research strives to harness the power of biotechnology and biomanufacturing to expand opportunities for U.S. agricultural producers while also tackling some of our greatest challenges like climate change, nutrition insecurity, environmental justice, emerging diseases and pests, and growing competition overseas.
• The USDA Forest Service has made catalytic investments in the wood-based bioeconomy to support land management, wildfire risk reduction, climate adaptation, and local economies. These projects support the critical connection between healthy and resilient federal, state, tribal and private forests and the wood products economy. Through USDA’s Forest Service, the Biden-Harris Administration has funded 482 projects totaling nearly $190 million in investments to support the wood-based bioeconomy, including supporting innovation, market development and new and expanded manufacturing capacity.
• The State Department has initiated additional extensive international engagement to assess opportunities for global cooperation on the bioeconomy, coordinated by the Office of the Special Envoy for Critical and Emerging Technology. This work complements ongoing bilateral and multilateral efforts led by the Bureaus of Oceans and International Environmental and Scientific Affairs, Economic and Business Affairs, and others. 
• NSF and the Indian Department of Biotechnology signed an implementation arrangement to enable collaborative biotechnology and biomanufacturing research partnerships between engineers and scientists from the United States and India.
• President Biden launched the Global Biofuels Alliance at the 2023 G20 Leader’s Summit to make progress in our shared commitment to deploy cleaner, greener fuels around the world that help meet our decarbonization goals. This alliance between the United States, Argentina, Brazil, India, Italy, Mauritius, and the United Arab Emirates will focus on raising awareness on the benefits of biofuels, policy lessons learned, existing standards and certification; and an emphasis on sustainability, security of supply and affordability principles while avoiding overlap with existing biofuels initiatives.

These critical achievements highlight the Biden-Harris Administration’s government-wide approach to advancing the biotechnology and biomanufacturing towards innovative solutions in health, climate change, energy, food security, agriculture, supply chain resilience, and national and economic security.

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Production of Biodiesel from Underutilized Algae Oil: Prospects and Current Challenges Encountered in Developing Countries

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Simple Summary

The production of biofuel, especially biodiesel, from algae oil receives little attention in developing countries due to poor enlightenment on biotechnology, high poverty rates, and poor funding of research. This study focuses on finding a better understanding of the evolving prospects and current challenges facing biodiesel production from algae oil in developing nations. Interestingly, several species of microalgae that can serves as sustainable feedstocks for biodiesel production have been identified in developing nations. It is evident that microalgae oil has physicochemical properties that qualifies it for the production of biodiesel, with fuel properties that meet ASTM and EN standards.

Biofuel continues to thrive as an outstanding source of renewable energy for the global community. Several resources have been proposed as sources of feedstocks for biofuel; however, some of these have shortcoming. The use of biomass such as algae as a source of feedstock for biofuel is undoubtedly sustainable and green. Unfortunately, the use of algae oil for biodiesel production is underutilized in developing countries. Therefore, this study focuses on finding a better understanding of the evolving prospects and current challenges facing biodiesel production from algae oil in developing countries. The study revealed that less attention is given to the use of algae oil in biodiesel production due to poor enlightenment on biotechnology, high poverty rates, government policies, business strategies, and poor funding of research. Interestingly, several species of algae that can serve as sustainable feedstocks for biodiesel production have been identified in developing countries. It is evident that algae oil has properties that qualify it for the production of biodiesel with fuel properties that meet both the American Society for Testing and Materials and the European standards for biodiesel.

1. Introduction

Biodiesel has long been identified as a sustainable replacement for fossil fuel [ 1 ]. It is a biomass sourced fuel with superb properties that make is superior to fossil fuel. As a renewable source of energy, it is clean, sustainable, and environmentally friendly [ 2 ]. It is produced from forest and agricultural products, as well as from biomass-based domestic and industrial waste products [ 3 ]. Using food and cash crops as feedstock for biodiesel production is more challenging in developing countries battling poverty and other socioeconomic difficulties. Although there have been several approaches suggesting the use bio-industrial wastes, this approach has been limited by a lack of interest from local and multinational industries to develop the approach into a large-scale production in many developing countries, such as those in Africa. Other industrialists and researchers have looked in the direction of agricultural wastes, but the challenges to this solution in developing countries have been poor agricultural infrastructure, inconsistent government support, unfavorable climate change, and substandard personnel. With the new wave of biotechnological development in developing countries, attention is shifting towards the use of algae as an alternative source of lipids required as a feedstock for biodiesel production. It is considered as an alternative to food and cash crops because it is safer, has a faster cultivation rate, and is non-competitive. Presently, algae-sourced lipids are the major feedstock used in biodiesel production [ 4 ], which has caused Brazil to become the largest producer of biodiesel in the world [ 4 ].

Algae is a photosynthetic eukaryotic organism that is non-flowering and typically aquatic [ 5 ]. It ranges from unicellular to multicellular forms, growing up to 50 m in length. It has the capacity to germinate without much concern for waste nutrients [ 6 ]. Algae cultivation strategies are exploited as a means for direct energy sourcing [ 7 ]. In comparison, the lipid yield from an algae cell is higher than that of palm kernel and soyabean cells [ 8 , 9 ]. The oil content varies from about 20 to 80%, which substantiates the use of algae oil as a substantial feedstock for biodiesel production. A study has shown that microalgae have a lipid yield in the range of 30 to 40% [ 4 ], which further supports its use as a source for the feedstock of biodiesel production. They can be cultivated in large scale as lipid source for biodiesel.

Biodiesel from algae oil can be classified as a third-generation biofuel. Algae yield more energy per acre of land cultivated than plant crops cultivated per equal acre of land. This has promoted interest in algaculture for the production of biodiesel. Algae oil can be a suitable starting material for biodiesel production [ 10 ]. However, there are certain challenges hampering the successful use of algae oil for the production of biodiesel in developing countries. Therefore, this study aimed at understanding the prospect and challenges faced in developing countries using algae oil for the production of biodiesel. This study was conducted by reviewing published peer-reviewed research articles, conference proceedings, short communications, and patents from 1995 to 2021.

2. Concept of Algae Oil as a Source of Biodiesel

Biofuel from algae, especially microalgae, is referred to as a third-generation biofuel, which plays a vital role in sustainable energy development. Algae are found in saline and freshwater environments, as well as in sewage systems. Algae require about 2 to 6 days for a complete growth cycle. A short growth period, coupled with their high lipid yield, makes algae—either microalgae or macroalgae—a suitable candidate for a feedstock for biodiesel production. Macroalgae includes brown algae, green seaweed, and red algae. There are over 20,000 kinds of microalgae. When compared with macroalgae, microalgae possess a simpler structure, faster growth, and higher lipid yield.

Microalgae are photosynthetic microorganisms capable of producing biomass rapidly, with about 50% lipid [ 11 ] in the form of triglyceride, and their growth rate is faster than that of terrestrial plants. Triglyceride is the starting material for biodiesel production. Several species of microalgae have been identified for biodiesel production. Some selected species of microalgae for biodiesel production are presented in Table 1 . They are unicellular of about 1 and 50 µm in diameter, having several classifications, ranging from about 200,000 to 800,000 species [ 12 ].

Lipid content of some selected species of microalgae.

Cultivating and harvesting microalgae are crucial stages in achieving its use as a biodiesel source. A previous study has shown that the harvesting of algae species may account for 20 to 30% of the production cost [ 13 ]. The triglyceride content can be converted to biodiesel via the transesterification reaction [ 14 ]; however, the conversion of microalgae whole biomass to biofuel can be classified as thermochemical [ 15 , 16 ] and biochemical [ 17 , 18 ] processes, as described in Figure 1 . Apparently, several other forms of biofuels can be obtained from algae, which makes it a multisource for different forms of biofuel.

Algae biomass conversion process.

Two main types of microalgae are known—the filamentous and the phytoplankton. In terms of relative abundance, three prominent families of microalgae have been identified: Chlorophyceae (green algae), Bacillariophyceae (diatoms), and Chrysophyceae (golden algae). The cultivation of microalgae has taken different turns over the years, but the most common technique are the use of open ponds and photobioreactors [ 19 ]. Microalgae are cultured in the temperature range of 17 to 22 °C. The open pond technique is less expensive and is the most practiced method in developing countries; however, it is very vulnerable to contamination. Several methods have been used for harvesting microalgae, including flocculation, flotation, gravity sedimentation, filtration, electrophoresis, and filtration. These methods are sometimes used in combination to achieve optimum results. Furthermore, the method(s) selected for its harvesting depends on the properties of the microalgae. Oil extraction from microalgae is an important step in preparing the feedstock for biodiesel production [ 20 ]. The extraction can be carried out in two steps: mechanical crushing and solvent extraction. Other methods previously proposed for algae oil extraction include pyrolysis, sonication, autoclaving, and microwaving. However, solvent extraction and supercritical CO 2 fluid extraction remain the most commonly used methods of extraction. The oil yield of some selected microalgae is presented in Tabe 1. The yield varies for different species, suggesting that microalgae is an excellent lipid source for biodiesel production. The various reported fatty acid compositions for different microalgae oils are shown in Table 2 . Common fatty acids from microalgae oil include oleic, palmitic, linoleic, stearic, and linolenic acids. The oils from microalgae are predominantly polyunsaturated, which are prone to oxidation. The susceptibility of the oil to oxidation or oxidative rancidity is a concern when considering the shelf-life or stability of biodiesel produced from microalgae oil. Based on quality composition and oil yield, microalgae such as Chlorella vulgaris , Chlorella protothecoides , Nannochloropsis sp., Nitzchia sp., Chlamydomonas reinhardtii , Schizochytrium sp., Scenedesmus obliques and Neochloris oleabundans have been identified as good sources for biodiesel production [ 21 ].

Major fatty acid composition of some selected species of microalgae [ 22 ].

A study on Symbiodinium clade C revealed an oil yield of 38.39 ± 6.58% [ 23 ]. Oil was extracted from Anabaena PCC 7120 via the solvothermal microwave technique, which revealed a yield of 10.14% per gram of dry biomass [ 24 ]. The oil obtained from Anabaena PCC 7120 was subjected to biodiesel production using a titanium oxide catalyst, providing a biodiesel yield of 98.41%. Another study reported an oil yield of 42% from Neochloris oleoabundans , with major fatty acids composition being oleic, palmitic, and linoleic acids [ 25 ]. The oil was converted to biodiesel via an ultrasonic-assisted transesterification method, with a biodiesel yield of 91%. Spirulina sp. oil has also been reported to produce biodiesel containing oleic, palmitic, linoleic, and stearic acids as the major fatty acid contents [ 26 ]. Biodiesel has been prepared from microalgae Botryococcus , with a biodiesel yield of 84% [ 27 , 28 , 29 ]; analysis of the biodiesel from Botryococcus using gas chromatography and nuclear magnetic resonance revealed the presence of palmitic, oleic, elaidic, and stearic acids. A study on Chlorella protothecoides showed an oil yield of 55% in a process that combined bioengineering and transesterification for biodiesel production [ 30 ]. Biodiesel produced from microalgae oil has exhibited properties similar to those of petro-diesel fuels and are in line with the standards recommended by the American Society for Testing and Materials (ASTM) and the European standard for biodiesel (EN).

3. Challenges and Prospects

3.1. microalgae processing for biodiesel production.

The common methods used for the cultivation of algae include open ponds, closed photobioreactors, and hybrid systems. Photobioreactors are the most commonly used methods in developed countries. Based on structural design, photobioreactors may include airlift, tubular, stirred tank, torus, conical and column photobioreactors [ 29 , 31 , 32 ]. The tubular forms are the most commonly used photobioreactors in developed countries, since they are most suitable for the outdoor microalgae cultivation. They have a large surface area for biomass production. They include inexpensive with simple production designs for the optimum utilization of sunlight. Although they are affordable, local algae cultivators in very low-income countries in Africa still find it difficult to make use of standard tubular photobioreactors due to their inability to afford the overall operational cost; therefore, they improvise with locally sourced materials, which makes the process prone to contamination of all kinds. This has been a challenge to productivity and yield, making it difficult and discouraging for local engagement in algae agriculture in developing countries.

The cultivation of microalgae in open ponds may include the use of natural and artificial pond systems. One major advantage of this method in developing countries is the simplicity and low-cost of production. The production yield is amazingly high, as long as contamination from other sources is minimized. Although waste from sewage and water treatment plants can serve as sources of nutrient supply for the algae ponds, unfortunately, most developing countries still lack adequate structures for handling wastes from sewage and water treatment plants, creating a disadvantage for developing countries with poorly structured waste management schemes. The method is further prone to the effects of climate change. With the current devastating global impact of climate change, the practice of open ponds in developing countries is at a disadvantage, facing severe challenges. For example, there is currently a drought in the Eastern African countries (Ethiopia, Somalia, and Kenya), while some countries in Western Africa (Nigeria, Ghana, and Gambia) presently suffer from flooding. Environmental pollution from gases released from industrial waste has contributed to the challenges faced by algae cultivation using the open ponds. Examples include countries in Asia, due to rapid industrial growth. Countries such as China and India are at the receiving end, where the pH and salinity of environmental water sources change due to the level of dissolved gases from the environment. The abrupt change in pH and water chemistry affects the practice of using open ponds for algae cultivation in such countries. Unfortunately, most local algae farmers cannot afford the more advanced algae cultivation processes. There may be a need to pretreat open water resources used for biofuel cultivation. The pretreatment varies, depending on the nature of the water source and the level of contaminants compared to microalgae growth in the water. The pretreatment given to the water resource is an additional measure that increases production costs.

Currently, research is ongoing for the development of procedures that will be cheap and appropriate for the cultivation of algae with a high lipid yield. Figure 2 shows a simple laboratory-scale photobioreactor model for cultivating algae. Although several other closed-door methods are used alone, or to complement the open pond method [ 33 ], they are not still as cheap as using the natural open pond method. Developing or simplifying the currently used approaches to make them affordable in low-income countries is still challenging for researchers. This might be a good area of research worth investigating for scientists in developing countries.

Laboratory-scale photobioreactor model for cultivating algae.

Apart from cultivation, the processes employed in developing countries for harvesting microalgae also face some challenges, which include their design, management, and cost. Some popular harvesting methods are electrophoresis, ultrafiltration, coagulation, centrifugation, filtration, flocculation, and air-flotation [ 34 , 35 ]. Other methods are currently being developed or modified from time to time. The method chosen is usually based on the cultivation process and the desired product. For biodiesel production in most developing countries, coagulation and flocculation are commonly used. One major challenge faced when using these approaches in developing countries is the process of energy consumption. The coagulation process is mainly an ‘electrolytic coagulation process,’ which requires energy intake. The provision of electrical energy is always disrupted in low-income countries. Therefore, the provision and supply of a stable source of electricity come at an extra price, increasing process costs. However, it is important to minimize energy consumption as much as possible. Sometimes, the combination of coagulation and flocculation is used. The combined methods help reduce the number of chemicals used in the harvesting process and the process time for effective results. The microalgae obtained can then be dried before proceeding with oil extraction using suitable solvents and transesterification for biodiesel production. The steps involved in most developing countries are described in Figure 3 ; these steps may be different for more advanced processes in developed countries.

Description of biodiesel production from microalgae in developing countries.

The harvesting process may be a batch process, continuous, or semi-continuous process, depending on production scale and cost [ 36 , 37 ]. The batch process is easy to control; however, the cost evaluation of the continuous or semi-continuous process is cheaper for long-term usage. Despite the fact that the continuous and semi-continuous processes are cheaper, sustaining them in developing countries is difficult due to poor technology and infrastructure development. Table 3 compares batch and semi-continuous processes for some selected microalgae. The table shows the amount of microalgae produced per culture medium (amount of biomass, g L −1 ), oil yield from the microalgae obtained (% wt wt −1 ), and the amount of oil obtained from the cultivated microalgae medium per day (oil production, mg L −1 day −1 ). Obviously, the final oil production from the semi-continuous process is higher than that obtained using a batch process. There may be the need to pay more attention to developing simple and affordable semi-continuous processes for developing countries to promote the use of microalgae oil, especially for its use as a feedstock for biodiesel production.

Comparison of cultivation process for microalgae oil production of some selected species of microalgae reported in literature.

3.2. Availability of Microalgae Species

Microalgae biotechnology is receiving significant attention in some low-income countries due to recent prospective applications in pharmaceutical, bioremediation, food, and nanotechnology fields [ 42 ]. Many developing countries have reported several species of high oil-yielding microalgae [ 43 ]. Most developing countries have climatic conditions that favor the survival of the microalgae. Moreover, the weather conditions and level of natural light penetration, CO 2 availability, water, and temperature in most developing countries in Africa and Asia favor natural habitats for microalgae survival. These are encouraging factors that promote the use of microalgae in developing countries. In a theoretical estimation, microalgae can utilize 9% of incoming solar irradiation to generate 280 tons of dry biomass per hectare per year, while using 513 tons of CO 2 [ 42 , 44 ]. With the abundance of sunlight in developing countries, the survival of microalgae is certain. Apart from this, microalgae can help reduce the fear of the greenhouse effect due to pollution from CO 2 . Microalgae thrive in wastewater, saline, and brackish water environments. A large amount of wastewater generated can find application in microalgae cultivation in developing countries. Furthermore, microalgae can survive or be easily cultured in saline or brackish water systems in low-income countries in the Middle East, where there is limited supply of natural freshwater. Among the microalgae found in developing countries are Chlorella pyrenoidosa, Prymnesium parvum , Tetraselmis chuii, Tetraselmis suecica, Isochrysis galbana, Tetraselmis suecica , Chlorella stigmatophora, Nanochloropsis gaditana, Nanochloropsis oculate, Euglena gracilis, Botryococcus braunii , Neochloris oleoabundans, Phaeodactylum tricornutum, and Dunaliella tertiolecta . However, freshwater-sourced microalgae, such as O leoabundans sp., and marine microalgae, such as Nannochloropsis sp., are well known as good sources of oil for biodiesel production.

Currently, Egypt is the leader in aquaculture in Africa, with about 987 tons produced in 2011, and even higher production estimating for the coming years [ 42 , 45 , 46 ]. Microalgae are known to serve as a food source for the larvae of fish and crustaceans. However, in the past, little attention has been paid to microalgae as a possible source of oil for biofuel. Interestingly, with the abundance of different microalgae species in developing countries, the future is bright for biofuel production from a renewable resource with the potential of being sustainable in the developing world. The currently envisaged challenge might be a competitive demand for microalgae as an animal feed and colorant for crustaceans [ 42 , 47 , 48 ]. As of 2004, the market for microalgae-sourced colorant was valued at USD 200 million, with an estimated USD 2500 per kilogram [ 47 ]. Pigments such as phycobilins have been isolated in microalgae [ 49 ]. A study reported the biosynthesis of phycocyanin (blue pigment) by Spirulina platensis [ 50 ]. In Asia, China is one of the countries where microalgae, such as cyanobacteria Nostoc, are used as food. A similar case was found in the Republic of Chad, where cyanobacteria Arthrospira are considered to be a food source [ 42 ]. The nutritional value of Nostoc sphaeroides as food has been reported [ 51 ]. Furthermore, Chlorella , Spirulina , Tetraselmis , Isochrysis, and Nannochloropsis have been reported for their nutritional (human consumption) and bioactive potentials [ 52 ]. These microalgae have exhibited antioxidant, antihypertensive, antidiabetic, antihyperlipidemic, and immunomodulatory capacities in human and other animals [ 52 ]. This multi-functionality of microalgae has made them competitive as foods and colorants, which is an emerging limitation challenging their global use as a feedstock for biodiesel production. This is not only a challenge in developing countries, but is also a global phenomenon.

3.3. Government Policy and Business Strategy

Government policies on biofuel are at different developmental stages in different countries of the world. Governments in countries with a large deposit of fossil fuels are reluctant to enact policies that favor biofuel production due to their dependence on crude oil fossil for income revenue. The lack of willpower to support policies promoting biodiesel production growth is a significant challenge in most developing countries. Despite the global progress made in biogenetic engineering to drive gene modification, there is still an underrepresentation of skill acquisition in this field in developing countries. There is limited state-of-the-art equipment to drive research or large-scale modification of microalgae genes for industrial production. It cannot be emphasized enough that genomics can play an important role in boosting the profile of microalgae for biofuel production. A recent study reported the genetic modification of microalgae as a means of enhancing biorefinery [ 53 ]. Various studies have reported different approaches to genetic modification to improve lipid biosynthesis in microalgae, as shown in Table 4 . Unfortunately, most of these reports from research endeavors remain merely as published articles or chapters in books, without being used in real-life applications. It is important that governments in developing countries help bring research findings on biofuel into commercial application by creating enabling environment in terms of providing suitable legal frameworks and financial support.

Previously reported genetic and metabolic engineering modification of microalgae for the enhancement of lipid biosynthesis.

On the other hand, poor business strategy is also hampering the growth of biofuel from microalgae in developing countries. The government’s approach towards developing local energy industries is flawed. The government needs to ease the tax rate on biofuel. In Nigeria, the government pays subsidies on petroleum from fossil fuels, whereas this is not the case for biofuel. Presently, the petroleum pump price in Nigeria is about 50% subsidized by the government. If similar support is given to biofuel sales, it will go a long way towards promoting biofuel and a green environment. Most developing countries are not attractive to foreign investors, due to a lack of security. A good example is the case of social unrest and ethnic clashes in Africa. Economic instability relating to social insecurity has discouraged several multinational companies from investing in the biofuel business in some developing countries. This challenge has a negative impact on biofuel commercialization in developing countries. Another factor is the fluctuation in local currency. Local investors risk losing financial strength due to the conversion rate of local currency to the dollar, which is the international trading currency. Many local industries in developing countries have folded up due to a sudden crash in the bargaining power of local currency against the dollar. It is important to create a business-enabling environment for biofuel by putting a legal framework in place that will help formulate policies that promote biofuel’s survival in developing countries.

3.4. Economic Feasibility and Commercialization

The strength, weakness, opportunity, and threat (SWOT) analysis, and life cycle assessment to understand the advantages and disadvantages of sourcing biofuel from microalgae have been reported [ 63 ]. It became apparent that the production of biofuel from microalgae will consume a significant amount of energy. It is also certain that microalgae biofuel output is higher than that of other terrestrial crops. However, the production of biofuel from microalgae requires more energy consumption than other biomass feedstock. It is also known that some green gases may be released into the environment during the processing of microalgae for biofuel. Therefore, such gases must be contained in order to minimize pollution and process contamination. Another study revealed that the cultivation of microalgae may require the use of fertilizer, which is an additional cost [ 64 ]; when such fertilizer is nitrogen or phosphorus-based, any excess nitrogen or phosphorus must be recycled. The amount of water required for the cultivation is more than what is required for the cultivation of other biomass feedstocks; a previous publication from the National Academy of Sciences of the United States of America revealed that about 3.15 to 3.65 liters of water are required to produce 1 liter of microalgae biofuel [ 63 ]. Furthermore, about 39 billion liters of algae oil can be generated using 123 billion liters of water. Therefore, the suggestion that a high amount of water and fertilizer supply is required for microalgae cultivation for biofuel production is critical [ 65 ]. The lack of sustainable water resources has been a challenge in low-income countries in the Middle East. However, there has been an effort involve in cloud seeding and water harvesting to boost water availability [ 66 ].

The production of biodiesel from microalgae oil is still in its infancy in most developing countries, with the exception of Brazil, China, and Argentina, with more robust prospects for biotechnological advancement in converting microalgae oil to biodiesel. The cost of producing algae biomass in an open pond was previously reported to range between 0.3 to 0.4 € kg −1 [ 67 ]. However, for the photobioreactor, the cost ranged between 3.8 and 4.5 € kg −1 [ 67 ]. The significant difference in cost between the open pond and photobioreactor methods was attributed to the higher electricity consumption for the reactor’s mechanical operation. The low production cost must be maintained to effectively commercialize the creation of biodiesel from microalgae oil. When the oil production from the microalgae biomass was considered, it was concluded in a recent study that depending on the method used for expelling the oil, the price ranged from 0.81 to 2.43 USD kg −1 [ 68 ]. Therefore, many factors, such as pretreatment, electricity consumption, CO 2 consumption, pressure, etc, will have to be considered before determining on the final cost of production. One significant advantage in developing countries is that the cost of labor per capita is cheap, which helps keep production costs to a minimum. With the high population rate, abundant natural resources for open ponds, and large waste generation per annum, the future of biofuel from microalgae is bright in developing nations.

A previous report revealed that during the pre-Covid-19 period, petroleum diesel was sold for USD 3.24 per gallon, while biodiesel cost USD 3.55 [ 69 , 70 ]. Interestingly, a study conducted an evaluation that compared the cost of producing biodiesel with that of petroleum-based biodiesel and concluded that the production of biodiesel might be estimated as USD 2.29 kg −1 . In contrast, the production cost of petroleum diesel may be estimated at USD 1.08 kg −1 [ 71 ]. The higher price of biodiesel from microalgae was attributed to the higher production and operation cost [ 72 ]. This showed that the cost of production and processing may be reduced by improving the cultivation and harvesting processes. The profit from microalgae biodiesel is currently low, with an annual benefit of USD 4.82 million generated as revenue [ 73 ]. This profit is estimated to increase with the use of wastewater as a water resource for microalgae cultivation [ 73 , 74 ]. More importantly, a study obtained an estimated cost of EUR 2.01 kg −1 for the production of microalgae biomass on a 15 hectare of land for small-scale operation, whereas a corresponding estimation of EUR 0.33 L −1 was obtained for biodiesel production on the same scale [ 72 , 73 ]. However, an earlier study showed that when biodiesel production was increased from 10,000 to 100,000 tons, the gross production cost was reduced from USD 8.1 to USD 6.3 [ 73 , 75 ]. Therefore, high scale biodiesel production may serve as a means of reducing production costs. With the high population index in most developing countries, the demand for biodiesel from microalgae is expected to be high.

4. Current Status and Future Perspective

Several projects have been taken up regarding the use of microalgae to create biofuel in many developed countries; for example, the United States of America green energy program and Arizona Public Service co-established a microalgae production system with a biofuel yield reaching 5000–10,000 gallon per acre per year [ 63 ]. As a follow up, the national energy board of the United State launched the ‘Mini-Manhattan Project’ to improve microalgae oil production (Keune, 2012). The European Union has also launched an algae bioenergy development action plan project (EnAlgae), with the aim of improving algae production in Europe [ 63 ].

The use of biodiesel as an alternative replacement for petro-diesel is not popular in science and technology lagging countries (STLCs) due to the factors listed above. Major biodiesel producing countries among developing countries are: Indonesia, Brazil, China, Argentina, India, Thailand, South Africa, Malaysia, the Philippines, Ghana, Mexico, Uruguay, Paraguay, Croatia, and Colombia [ 76 , 77 , 78 , 79 , 80 ]. Although fresh and waste cooking oils are the common feedstocks used for biodiesel production in developing countries, the use of microalgae oil is catching up. The development is small in African countries, except for in South Africa, Egypt, Morocco, and Ghana. Economic globallization might be an assured pathway to the solution in developing countries [ 80 ]. With the exception of some countries in Asia and South America, laboratory-based research work on the use of microalgae for biodiesel is scarce. This goes mainly for African countries. It is important to note that despite the ongoing awakening going on in developing countries to encourage the use of biodiesel, the process is still hampered by the conditions discussed above.

Among the developing countries, China is playing a significant role in microalgae cultivation projects. In this regard, the Chinese Academy of Sciences has developed efficient techniques for achieving this purpose. Several trainings on scaled-up production have been undertaken [ 63 , 81 ]. Brazil has also made a significant contribution in promoting the creation of biodiesel from microalgae oil [ 82 , 83 , 84 ]. Currently, the Petrobras company, Brazil, is researching and investing in microalgae production in the petrochemical sector, while the Ministério da Ciência, Tecnologia e Inovação (MCTI), through the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), is committed to investing significant funding in research endeavors in the tertiary institutions and research institutes to promote cutting edge research on obtaining biofuel from algae [ 82 , 84 , 85 ]. Countries in Africa are far behind in this regard, and there is a need for them to do more and to become committed to promoting the production and commercialization of biofuel.

Economic instability and lack of technological infrastructure in developing countries are serious drawbacks to the production of biodiesel from microalgae oil. The situation is very poor in developing countries in Europe, such as Moldova, Albani, Bosnia and Herzegovina, Serbia, and Montenegro. Due to poor cultivation of microalgae in most African countries, attention is mainly on the use of waste cooking oil. However, with the current advocacy to promote the eradication of hunger (Sustainable Development Goal 2) by the African Union, attention may shift towards microalgae oil in the coming years in order to prevent overdependence on this food crop, which will go a long way in making the arid land available for growing enough food for the African populace. The rural regions in developing countries are a large reservoir of biological resources, including microalgae [ 86 , 87 ]. The potential of these rural regions is not sufficiently harnessed [ 87 , 88 ].

Most research works published on the use of microalgae oil in biodiesel production are laboratory-based experiments. There is an urgent need to devote more time to the large-scale cultivation of microalgae and its biodiesel production on a commercial scale. There is a need to further investigate the different steps involved in the cultivation and harvesting process in order to help reduce production costs. There is also a need to develop new strategies and techniques for cheap and affordable microalgae processing. Governments in developing countries are expected to be more committed to enacting policies that will drive the course of microalgae oil production and eventually, its biodiesel production. Effort is required to improve government policies that will favor socioeconomic development, motivating foreign investors and multinationals to invest in biofuel businesses in developing countries. It is paramount to provide support in the form of research funding to works that are focused on renewable energy production in order to enhance technological advancement in this area of development.

The level of enlightenment on the prospect of biofuel is poor in developing countries which may be attributed to high poverty rate and poor socioeconomic development. It is necessary to create more awareness regarding the environmental danger associated with the long-term use of fossil fuel energy. There is a need to build on the research capacity of early and young researchers in developing countries. There is dearth of skills in biotechnology and the use of molecular engineering tools. Therefore, there is an urgent need to build greater research capacity in this area. Governments in developing countries need to increasingly partner with developed countries to build relationships that will result in research collaboration, the exchange of skills, and the transfer of technology.

5. Conclusions

Microalgae continues to be a promising resource for biofuel generation. This study considers the prospects and current challenges encountered in developing countries regarding the use of microalgae oil as a resource for biodiesel production. Currently, the use of microalgae is receiving significant attention, and there is urgent need to invest in finding a cheaper and more sustainable technique that will promote the cultivation of microalgae for biodiesel production in developing countries. It is important to note that the use of microalgae oil for biodiesel production is at different developmental stages in different developing countries of the world. However, factors such as microalgae processing, poor enlightenment on biotechnology, economic feasibility, government policy, business strategy, high poverty rates, and poor research funding have been identified as factors limiting the production of biodiesel from microalgae oil in developing countries. These factors vary from one developing country to another. The worst scenarios involving all of the factors listed above are found in the least-developed countries (low income countries). Despite the abundant prospects, there is still dearth of technical know-how for achieving the commercialization of biodiesel from microalgae oil in developing countries. There is an urgent need for governments in developing countries to focus on the use of biomass resources such as microalgae as a means to circumvent emerging current and future energy crises.

Funding Statement

This research received no external funding.

Institutional Review Board Statement

Informed consent statement, data availability statement, conflicts of interest.

The author declares no conflict of interest.

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United States Biodiesel Industry Research 2024-2032 Featuring Archer Daniels Midland, FutureFuel, Neste's, Renewable Energy Group, Bunge Global, Wilmar, Shell

June 25, 2024 06:55 ET | Source: Research and Markets Research and Markets

Dublin, June 25, 2024 (GLOBE NEWSWIRE) -- The "United States Biodiesel Market Report by Application, Feedstock, States and Company Analysis 2024-2032" report has been added to ResearchAndMarkets.com's offering. The United States biodiesel market is estimated to reach US$ 66.65 billion by 2032, up from US$ 39.27 billion in 2023, with a CAGR of 6.05% from 2024 to 2032. Biodiesel is one of the most demanding renewable fuels in the United States. It is produced from plant-based oils or animal-based fats. Vegetable oils are a leading feedstock for biodiesel production in the United States. This biofuel can be used in diesel engines, either in its pure form or blended form. The government is appealing to adopt biodiesel, reducing carbon dioxide, greenhouse gas emissions, particulate pollution, etc.

Key Attributes:

Company Analysis: Overview, Recent Developments, Revenue

• Archer Daniels Midland Company
• Renewable Energy Group, Inc.
• Bunge Global SA

Application - Market breakup in 3 viewpoints:

• Power Generation

Feedstock - Market breakup in 2 viewpoints:

• Vegetable Oil
• Animal Fats

States - Market breakup of 29 States:

• Pennsylvania
• North Carolina
• Massachusetts
• Connecticut
• South Carolina
• Rest of United States

For more information about this report visit https://www.researchandmarkets.com/r/xd9ix2

About ResearchAndMarkets.com ResearchAndMarkets.com is the world's leading source for international market research reports and market data. We provide you with the latest data on international and regional markets, key industries, the top companies, new products and the latest trends.

• U.S. Biodiesel Market

Related Links

• Global Biodiesel Market by Feedstock (Algae, Animal Fat, Jatropha), Application (Automotive Fuel, Cleaning, Heating Oil) - Forecast 2024-2030
• Biodiesel Market, Size, Share, Global Forecast 2024-2030, Industry Trends, Growth, Insight, Top Companies Analysis
• Biodiesel Global Market Report 2024

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