Large-scale Algae Cultivation Research Articles

Harnessing spin and orbital angular momentum light for optimal algae growth

The present study investigated the difference in transmittance of light carrying opposite spin angular momentum (SAM) and orbital angular momentum (OAM) through chlorella algal fluid with varying concentrations and thicknesses. Our results indicate that, under specific conditions, right-handed light sources exhibit higher transmittance in the algal fluid compared to left-handed light sources. Furthermore, we observed that light with OAM also demonstrated higher transmittance than other types of light sources, leading to faster cell density growth of Chlorella. Interestingly, we also discovered that light with OAM stimulates Chlorella to synthesize more proteins. These findings provide different insights for selecting appropriate light sources for large-scale algae cultivation, and may facilitate the realization of carbon peaking and carbon neutrality in the future.

Phycocyanin Extraction and Production of Crude Bio-Oil from Residual Biomass

Large-scale cultivation of algae is getting increasingly popular to produce environmentally sustainable crude bio-oil and other products. These phototrophs can be cultivated on non-agriculture lands with minimal nutrient requirements. If one gets multiple products from single production unit (biorefinery approach), the overall value increases leading to techno-economically favorable production. Hydrothermal Liquefaction (HTL) converts biomass into biofuels without drying the feedstock, uses water as the reaction medium at high temperature and high pressure. Nitrogen is one of the major rate-limiting factors in hydrothermal liquefaction (HTL) process. Crude bio-oil (CBO) from HTL is not suited for direct fuel applications due to undesired hetero-atoms like nitrogen and oxygen. It needs to be upgraded further, which adds on to the cost of overall processing of biofuel. Here we demonstrated that the reduction of nitrogen by removing pigment protein (phycocyanin) could significantly increase overall HTL efficiency. The CBO and extracted phycocyanin have been fully characterized and reported here.

Development of Cost-Effective Fertilizer-Based Media for the Microalgae Cultivation Aimed at Effective Biomass Production

In the diversification of the world's energy portfolio, microalgae biofuels have gained particular attention as a means of providing carbon-neutral hydrocarbon-based fuels. The progress on this front has been hindered because of expensive and unreliable microalgae cultivation systems, where the preparation of synthetic culture media poses a monetary strain. This study aims to investigate a new microalgae growth media that is readily available and cost-effective. The new microalgae fertilizerbased media (FBM) were designed and compared with Bold Basal media (BBM) in terms of growth parameters, production of lipid and value-added algal by-products (carotenoid and phycobiliprotein). The growth parameters such as cell count and specific growth rate were investigated for FBM and BBM. FBM showed a significant growth rate of 7 million/mL-per day as compared to 2 million/ml per day. A similar growth trend was observed for chlorophyll (a), (b) and carotenes which increased to the values of 5microgram/gram formula weight (µg/gfw), 3 µg/gfw and 2 µg/gfw for FBM. On the other hand, lipid and phycobiliprotein showed a decrease of 18.75 % and 16.66 %, respectively, compared to BBM. Even though some growth parameters are negatively affected by fertilizer-based media, the cost reduction is substantial to allow this drawback to be overlooked. The medium's cost is reduced by a factor of 7 and provides ground for the use of the FBM in the large-scale cultivation of algae for biomass production.

Bio-aviation Fuel: A Comprehensive Review and Analysis of the Supply Chain Components

The undeniable environmental ramifications of continued dependence on oil-derived jet fuel have spurred international efforts in the aviation sector towards alternative solutions. Due to the limited options for decarbonisation, the successful implementation of bio-aviation fuel is crucial in contributing to the roster of greenhouse gas emissions mitigation strategies for the aviation sector. Since fleet replacement with low-carbon technologies may not be a feasible option, due to the long lifetime and significant capital cost of aircraft, ‘drop-in’ alternatives, which can be used in the engines of existing aircraft in a seamless transition, may be required. This paper presents a detailed analysis of the supply chain components of bio-aviation fuel provision: feedstocks, production pathways, storage, and transport. The economic and environmental performance of different potential bio-feedstocks and technologies are investigated and compared in order to make recommendations on short- and long-term strategies that could be employed internationally. Hydroprocessed esters and fatty acids production pathway, utilising second-generation oil-seed crops and waste oils, could be an effective immediate solution with the potential for substantial greenhouse gas emissions savings. Microalgal oil could potentially offer far greater yields of bio-aviation fuel and reductions in greenhouse gas emissions, but the technology for large-scale algae cultivation is inadequately mature at present. Fischer-Tropsch production pathway using lignocellulosic biomass has the potential for the highest greenhouse gas emissions savings, which could potentially be the solution within the medium- to long-term plans of the aviation industry, but further research and optimisation are required prior to its large-scale implementation due to its limited technological maturity and high capital costs. In practice, the ‘ideal’ feedstocks and technologies of the supply chains are heavily dependent on spatial and temporal criteria. Moreover, many of the parameters investigated are interlinked to each other and the measures that are effective in greenhouse gases emissions reduction are largely associated with increased cost. Hence, policies must be streamlined across the supply chain components that could help in the cost-effective and sustainable deployment of bio-aviation fuel.

Access to areas for algae cultivation in Norway

Marine macro algae may play a significant role in the transformation to the future post fossil fuel and low carbon society. Previous research shows that high expectations for future and large-scale algae cultivation in European waters are often followed by identification of a wide range of challenges linked to the same development. This paper specifically investigates the locational challenges for algae cultivation in spatial planning at the local level along the Norwegian coast. Based on statistics from Norwegian Fisheries Directorate and a survey to Norwegian spatial managers, we explore in detail the challenges for communities, when prioritizing and allocating areas for industrial production of algae. The data suggest some areas for concern that a future upscaling effort would likely need to address. First, the possible encroachment on already established aquaculture should not be underestimated. Uncertainty related to the suitability of areas for algae production combined with a generally more area demanding activity contributes to this. Second, this uncertainty also points to a general knowledge gap on the part of local planners. Finally, the data also suggest other areas for concern that a future upscaling effort would likely need to address, namely that an upscaling of algae production needs to be sensitive to local contexts. The data suggest that a lack of expertise on aquaculture is linked to both lower industry satisfaction, higher levels of conflict, less experience with aquaculture in general, and smaller municipalities.

Electromagnetic stratagem to control predator population in algal open pond cultivation

Large scale cultivation of algae is becoming a major challenge due to the impact of biotic (grazers and predators) and abiotic (salinity, light, temperature and pH) stress factors on growth and biomass productivity. Historically, to control grazers and predators, various physical, chemical and biological methods have been used which have had detrimental effects on algae growth and environment. Continuous usage of chemicals on grazers or predators is indirectly or directly encourage the biotics to resist against the applied chemicals leads to crashing of algae by enhancing their growth. To overcome such drawbacks on the usage of chemicals in the present investigation we have demonstrated an electrocution technology (physical strategy) to control grazer population without affecting algal growth and biomass productivity. Initially under lab studies different parameters like current (A)/voltage (V) were optimized to kill grazers and algal sensitivity towards the applied current and voltage. Our results reveal that the bacteria and protozoans were more sensitive to applied current at 5–10 mA compared to algal cells which are able to tolerate lower applied current dosages. Successfully, same technology with best optimum operating conditions is translated in 1 m2 and 20 m2 open ponds with unique multi electrode assembly units.

Effect of temperature control on green algae grown under continuous culture

The large-scale cultivation of algae of commercial value requires a variety of important energy-related inputs to achieve the proposed yields required for economic viability. One specific energy input of interest is temperature control and the associated costs of this control, both in terms of initial capital investment and costs associated with continued cooling or heating. In this work, the green algae Neochloris oleoabundans and Scenedesmus dimorphus were grown in tightly-controlled turbidostat-based photobioreactors to determine the potential benefits of temperature control for biomass production of these organisms versus allowing these cultures to experience temperature fluctuations similar to what would be found in uncontrolled, outdoor open ponds or closed bioreactors. The results of these studies indicate stark differences between these two strains, with N. oleoabundans yielding improved growth rates under conditions of stringent temperature control at 22 °C, while S. dimorphus yielded slightly higher growth under conditions where temperature was allowed to fluctuate based on modeled natural temperature profiles. Further analysis reveals that the utilization of non-conventional temperature profiles could enhance growth yields further for N. oleoabundans, allowing it to overcome the detrimental effects of the natural temperature fluctuation. These results and a discussion of the potential for turbidostat-based algal culture growth are presented.

Mixed culture of Chlorella sp. and wastewater wild algae for enhanced biomass and lipid accumulation in artificial wastewater medium

The purpose of this work is to study the co-cultivation of Chlorella sp. and wastewater wild algae under different cultivation conditions (i.e. CO2, light intensity, cultivation time, and inoculation ratio) for enhanced algal biomass and lipid productivity in wastewater medium using Response Surface Methodology (RSM). The results show that mixed cultures of Chlorella sp. and wastewater wild algae increase biomass and lipid yield. Additionally, findings indicate that CO2, light intensity and cultivation time significantly affect algal productivity. Furthermore, CO2 concentration and light intensity, and CO2 concentration and algal composition, have an interactive effect on biomass productivity. Under different cultivation conditions, the response of algal biomass, cell count, and lipid productivity ranges from 2.5 to 10.2 mg/mL, 1.1 × 106 to 8.2 × 108 cells/mL, and 1.1 × 1012 to 6.8 × 1012 total fluorescent units/mL, respectively. The optimum conditions for simultaneous biomass and lipid accumulation are 3.6% of CO2 (v/v), 160 µmol/m2/s of light intensity, 1.6/2.4 of inoculation ratio (wastewater-algae/Chlorella), and 8.3 days of cultivation time. The optimal productivity is 9.8 (g/L) for dry biomass, 8.6 E + 08 (cells/mL) for cell count, and 6.8 E + 12 (Total FL units per mL) for lipid yield, achieving up to four times, eight times, and seven times higher productivity compared to nonoptimized conditions. Provided is a supportive methodology to improve mixed algal culture for bioenergy feedstock generation and to optimize cultivation conditions in complex wastewater environments. This work is an important step forward in the development of sustainable large-scale algae cultivation for cost-efficient generation of biofuel.

Evaluation of the potentials and feasibility of microalgae production in Iran

Supplying affordable, acceptable, and adequate sources of energy is one of the most important concerns of the communities. Due to the unbalanced distribution of fossil fuels, as well as their environmental effects, the utilization of renewable energies sources has been one of the main strategies. Due to the importance of transportation for societies, biofuels technologies is important part of researches, in particular algae. Algae are a type of single or multi-cellular organisms that are multiplying rapidly, and have photosynthesis-based growth and evolution. In this paper, after classifying and determining the main factors affecting the production of liquid fuels from microalgae, the feasibility and the best regions for production are discussed in the case study, Iran. The analysis method is multi criteria decision making in order to rank the best locations for microalgae growing. The results show that Iran has a high potential for microalgae utilization and the coastlines of Oman Sea and the Persian Gulf are the best regions for large-scale algae cultivation and processing projects.

Integrated System for Capturing CO2 as Feedstock for Algae Production

In view of its promise as sustainable process for CO2 capture and its potential in the production of feed, food and natural high value products such as omega-3 fatty acids and anti-oxidants such as astaxanthin, large scale algae cultivation is gaining commercial interest. Currently, most systems are based on directly contacting CO2 containing gas, e.g. flue gas, with the algae culture. However, applicable on small scale, this approach is not applicable on a commercially relevant large scale due to mass transfer limitations. There is need for a cost effective and scalable system. TNO has developed a scalable system for efficient capture of CO2 as feedstock for algae production. In this system, CO2 is absorbed in an absorption liquid as bicarbonate. Subsequently, the enriched absorption liquid is fed to the algae, which convert the solubilized CO2 into biomass and biobased products. Finally, biomass is recovered and the lean absorption liquid is recycled. TNO's integrated process concept was successfully demonstrated with continuous algae cultivation on a 2 L-scale for more than 150 days of which 40 days using flue gas as CO2 source.

Dynamic flux balance modeling to increase the production of high-value compounds in green microalgae.

BackgroundPhotosynthetic organisms can be used for renewable and sustainable production of fuels and high-value compounds from natural resources. Costs for design and operation of large-scale algae cultivation systems can be reduced if data from laboratory scale cultivations are combined with detailed mathematical models to evaluate and optimize the process.ResultsIn this work we present a flexible modeling formulation for accumulation of high-value storage molecules in microalgae that provides quantitative predictions under various light and nutrient conditions. The modeling approach is based on dynamic flux balance analysis (DFBA) and includes regulatory models to predict the accumulation of pigment molecules. The accuracy of the model predictions is validated through independent experimental data followed by a subsequent model-based fed-batch optimization. In our experimentally validated fed-batch optimization study we increase biomass and upbeta-carotene density by factors of about 2.5 and 2.1, respectively.ConclusionsThe analysis shows that a model-based approach can be used to develop and significantly improve biotechnological processes for biofuels and pigments.

Optimization of culture conditions for Chlorella sorokiniana using swine manure wastewater

Algae, an ideal feedstock for biodiesel, can assimilate organic and inorganic pollutants of animal wastewater and convert them into cellular constituents such as lipids and carbohydrates. In the study, the impacts of Chemical Oxygen Demand (COD), Total Nitrogen (TN), and Total Phosphorus (TP) of swine manure wastewater and inoculation concentration of algae seeds on biomass production of algae Chlorella sorokiniana were studied. Our results demonstrated that concentration of TN in wastewater would scarcely affect the algae growth, and inhibition of ammonia nitrogen (NH3-N) on the growth of C. sorokiniana was not so obvious, although NH3-N occupied the overwhelming proportion of nitrogen source. Three factors (COD, TP, and inoculation size) which had significant impact on biomass production of C. sorokiniana using swine manure wastewater were optimized using response surface methodology. The optimal biomass production (128 mg l−1 d−1) was obtained when C. sorokiniana was cultivated in swine manure wastewater containing 345 mg l−1 COD and 45 mg l−1 TP, with the initial inoculation concentration of 136 mg l−1 algae seeds (dry weight). Then the strain was cultivated in 30 l photobioreactor with the optimized condition, a biomass yield (160 mg l−1 d−1) was achieved, accompanied with removal rates of TN (72%), TP (86%), and COD (38%). The study could provide guidance for large-scale cultivation of algae in wastewater.

The scientometric research on macroalgal biomass as a source of biofuel feedstock

We performed a scientometric analysis to determine the main trends and gaps in the studies on macroalgal biomass as a source of biofuel feedstock conducted between 1945 and 2013. We used the database from the Thomson Institute for Scientific Information. We found 160 papers published in 78 journals. The number of papers on using macroalgal biomass as a source of biofuel feedstock over the years has increased, especially in the last four years of the study period. The majority of the publications were from Asia (79 papers) and Europe (60 papers). Ulva spp. and Saccharina spp. were the most studied genera of macroalgae. Nine biofuel types (bio-oil, bioethanol, biodiesel, biogas, biomethane, biohydrogen, biochar, bio-crude and hydrochar) produced from macroalgae were studied, with bioethanol being the most studied. The important gaps in the research that need to be addressed are that few studies have been conducted in countries situated in climatic zones that favor the large-scale cultivation of algae for biofuel production (particularly countries from Africa and South America), as well as on some types of biofuels (e.g., biohydrogen, biochar, and hydrochar).

Possible future effects of large-scale algae cultivation for biofuels on coastal eutrophication in Europe

Biodiesel is increasingly considered as an alternative for fossil diesel. Biodiesel can be produced from rapeseed, palm, sunflower, soybean and algae. In this study, the consequences of large-scale production of biodiesel from micro-algae for eutrophication in four large European seas are analysed. To this end, scenarios for the year 2050 are analysed, assuming that in the 27 countries of the European Union fossil diesel will be replaced by biodiesel from algae. Estimates are made for the required fertiliser inputs to algae parks, and how this may increase concentrations of nitrogen and phosphorus in coastal waters, potentially leading to eutrophication. The Global NEWS (Nutrient Export from WaterSheds) model has been used to estimate the transport of nitrogen and phosphorus to the European coastal waters. The results indicate that the amount of nitrogen and phosphorus in the coastal waters may increase considerably in the future as a result of large-scale production of algae for the production of biodiesel, even in scenarios assuming effective waste water treatment and recycling of waste water in algae production. To ensure sustainable production of biodiesel from micro-algae, it is important to develop cultivation systems with low nutrient losses to the environment.

The place of algae in agriculture: policies for algal biomass production

Algae have been used for food and nutraceuticals for thousands of years, and the large-scale cultivation of algae, or algaculture, has existed for over half a century. More recently algae have been identified and developed as renewable fuel sources, and the cultivation of algal biomass for various products is transitioning to commercial-scale systems. It is crucial during this period that institutional frameworks (i.e., policies) support and promote development and commercialization and anticipate and stimulate the evolution of the algal biomass industry as a source of renewable fuels, high value protein and carbohydrates and low-cost drugs. Large-scale cultivation of algae merges the fundamental aspects of traditional agricultural farming and aquaculture. Despite this overlap, algaculture has not yet been afforded a position within agriculture or the benefits associated with it. Various federal and state agricultural support and assistance programs are currently appropriated for crops, but their extension to algal biomass is uncertain. These programs are essential for nascent industries to encourage investment, build infrastructure, disseminate technical experience and information, and create markets. This review describes the potential agricultural policies and programs that could support algal biomass cultivation, and the barriers to the expansion of these programs to algae.

A closed system for outdoor cultivation of Porphyridium

Experience accumulated during the past few years indicates that the main problems in the large-scale cultivation of algae in open ponds are low productivity and contamination. Thus, the use of closed systems can be an alternative method of cultivation. In the present study, a closed system made of polyethylene sleeves was compared with open ponds with respect to growth and polysaccharide production of two species of Porphyridium: Porphyridium sp. and P. aerugineum. For both species, cell number, biomass, and polysaccharide production were higher in the sleeves than in the ponds. It seems that polyethylene sleeves have the following advantages over open ponds: high light availability, high rate of heating and cooling, improved turbulence, relative lack of contamination, and prevention of evaporation and hence of fluctuation in salinity.