Oil-rich Biomass Research Articles

Microalgal-bacterial treatment of ice-cream wastewater to remove organic waste and harvest oil-rich biomass.

The diversity of microalgae and bacteria allows them to form beneficial consortia for efficient wastewater treatment and nutrient recovery. This study aimed to evaluate the feasibility of a new microalgal-bacterial combination in the treatment of ice cream wastewater for biomass harvest. The bacterium Novosphingobium sp. ICW1 was natively isolated from icecream wastewater and the microalga Vischeria sp. WL1 was a terrestrial oil-producing strain of Eustigmatophyceae. The ice cream wastewater was diluted 4 folds for co-cultivation, which was relatively less inhibitory for the growth of Vischeria sp. WL1. Four initial algal-bacterial combinations (v:v) of 150:0 (single algal cultivation), 150:1, 150:2, and 150:4 were assessed. During 24days of co-cultivation, algal pigmentation was dynamically changed, particularly at the algal-bacterial combination of 150:4. Algal growth (in terms of cell number) was slightly promoted during the late phase of co-cultivation at the combinations of 150:2 and 150:4, while in the former the cellular oil yield was obviously elevated. Treated by these algal-bacterial combinations, total carbon was reduced by 67.5 ~ 74.5% and chemical oxygen demand was reduced by 55.0 ~ 60.4%. Although single bacterial treatment was still effective for removing organic nutrients, the removal efficiency was obviously enhanced at the algal-bacterial combination of 150:4. In addition, the harvested oils contained 87.1 ~ 88.3% monounsaturated fatty acids. In general, this study enriches the biotechnological solutions for the sustainable treatment of organic matter-rich food wastewater.

Combined zeolite-based ammonia slow-release and algae-yeast consortia to treat piggery wastewater: Improved nitrogen and carbon migration

Integration of zeolite-based ammonia adsorption and algae-yeast consortia was developed to remediate piggery wastewater (PW) containing high concentrations of total ammonia nitrogen (TAN) and total organic carbon (TOC). After optimizing the conditions of ammonia adsorption in the PW. Zeolite addition mitigated ammonia toxicity, allowing zeolites to gradually release ammonia while effectively attenuating algal oxidative stress caused by high TAN concentration. Coupling zeolite-based adsorption and yeast co-incubation further increased TOC degradation and available C/N ratio, thus improving biomass (4.51 g/L), oil yield (2.11 g/L), and nutrient removal (84.18%-99.14%). The integrated microalgae-based PW treatment exhibited higher carbon migration into biomass (46.14%) and reduced treatment costs than conventional approaches. Simultaneously, the lowest carbon migration to wastewater also meant the smallest carbon emission into water bodies. These findings demonstrate that this novel strategy can remove nutrients in raw PW effectively and produce high oil-rich biomass in a sustainable and environmentally-friendly manner.

Comparative environmental life cycle assessment and operating cost analysis of long-range hydrogen and biofuel fueled transport aircraft

The aviation industry is currently experiencing a social shift in the attitude towards flying due to the increasing awareness of the impact on climate change. This has led governments and industries to set emissions targets, although their achievement for long-range flights is subject to an ongoing debate. Among promising candidates are hydrogen and sustainable aviation fuels such as biofuel. To provide a meaningful ecological and economic assessment, an environmental life cycle assessment method supplemented by a direct operating cost analysis has been developed and is described in this paper. A wide-body transport aircraft (A330 class) serves as a reference design for developing conceptual aircraft designs with a planned entry-into-service in 2040 powered by liquid hydrogen or drop-in biofuels (based on algae, produced with oil-rich biomass (BtL) or hydrogenated vegetable oil (HVO) processes). Due to the large demand for assumptions, the ecological and economic assessment results have to be interpreted as benchmarks. The results for long-range aircraft show that based on the current fuel and energy production methods both hydrogen and biofuel as aviation fuel are more harmful (have a higher environmental impact) than conventional aircraft. For hydrogen aircraft, an increase in energy consumption of 2.87% leads to an increased environmental impact of 14.8%. Due to the high energy demand for biofuel production, its environmental impact increases by 548% (BtL) and 238% (HVO). Nevertheless, for a future scenario based on electrolysis as a hydrogen production process and on renewable energy to generate electricity, both hydrogen and biofuel-powered aircraft are less harmful when compared to the reference aircraft. The environmental impact reduces by 59.5% (hydrogen), 35.8% (BtL), and 112% (HVO). However, the introduction of the new propellants involves a high direct operating cost penalty of 10.8% for hydrogen and 108% for both biofuels.

Process Design Guided by Life Cycle Assessment to Reduce Greenhouse Gas-Related Environmental Impacts of Food Processing

Food processing can generate large amounts of carbohydrate-rich waste that inevitably has environmental and social impacts. Meanwhile, certain heterotrophic marine microorganisms, including algae and thraustochytrids, have the potential to convert carbohydrate-rich substrates into oil-rich biomass over relatively short time frames. To assess the merits of this apparent synergy, an initial conceptual process was developed based on the use of raw potato processing waste as feed in an algal bioreactor to produce bio-oil for further use within the food industry. A practical flowsheet was established with a conventional 200 kL bioreactor whereby the unit processes were identified, the mass balance developed, and estimates made of the various material and energy demands. These inputs were used to develop a baseline life cycle assessment (LCA) model and to identify opportunities for reducing environmental impacts. With the functional unit (FU) being 1 tonne cooking oil, the baseline configuration had a greenhouse gas (GHG) footprint of 2.4 t CO2-e/FU, which is comparable to conventional process routes. More detailed LCA revealed that electricity for stirring the bioreactor contributed approximately 78% of the total GHG footprint. By adjusting the operating conditions, the most promising scenario produced 0.85 t CO2-e/FU—approximately four times less than the conventional process—and shows the potential advantages of applying LCA as a tool to develop and design a new production process.

Developing microalgal oil production for an outdoor photobioreactor

In this paper the preparations are described to develop a production of oil rich microalgal biomass under south European conditions. Ten microalgal species were compared in shake flasks in an incubator for potential for oil production. Potential oil production capacity was assayed as maximum total fatty acid (TFA) concentration and volumetric TFA productivity. TFA concentration ranged from 5 to 40% DW while TFA productivity rate ranged from 0 to 204 mg TFA L−1 day−1. To control the oil enrichment process in the outdoor microalgal batch culture, a quadratic equation was proposed, predicting the TFA concentration based on biomass inverse nitrogen quota. A concentrated substrate was developed to add to sea water, made from natural sea-salt and tap water.

Sugarcane by-products within the biodiesel production chain: Vinasse and molasses as feedstock for oleaginous fungi and conversion to ethyl esters

Oleaginous microorganisms pose a number of technical advantages when compared to first generation oil crops, but a common drawback to their utilization is often linked to the high operational costs involved in media preparation, using mostly industrial-grade sugars as carbon sources. Considering the abundance of by-products generated by the sugarcane industry, the combined use of molasses and vinasse is suggested in this work as culture medium for the fungal strain Mucor circinelloides URM 4182. Results demonstrate that a 3:1 vol% medium (vinasse to diluted molasses ratio) with minor supplementation of organic nitrogen can provide values within the range of 5 g L−1 of oil-rich biomass with 25 wt% of lipids. The microbial oil was then analyzed in terms of fatty acid profile, demonstrating a favorable composition for biodiesel production, and was subjected to simultaneous esterification and transesterification assays using ethanol and heterogeneous catalyst (H3PMo/Al2O3) in a pressurized reactor, demonstrating satisfactory conversions (>95%). The purified ethyl esters possessed viscosity and density values within the regulating standards and lack of triacylglycerols, suggesting a potential biodiesel production system that could be coupled within sugarcane ethanol facilities.

Organic waste streams as feedstock for the production of high volume-low value products.

Valorisation of organic wastes to produce industrially relevant commodity products is a sustainable, cost-effective and viable alternative providing a green platform for chemical production while simultaneously leading to waste disposal management. In the present study, organic wastes such as agricultural residue-derived sugars, oilseed meals, poultry waste and molasses were used for substituting expensive organic fermentation medium components. Moorella thermoacetica and Aurantiochytrium limacinum were adapted on these waste-derived hydrolysates to produce high volume-low value products such as bio-acetic acid (80% theoretical yields) and oil-rich fish/animal feed (more than 85% dry cell weight as compared with conventional nutrient sources) respectively. Use of these waste-derived nutrients led to ~ 75% and ~ 90% reduction in media cost for acetic acid and oil-rich biomass production respectively as compared with that of traditionally used high-priced medium components. The strategy will assist in the cost reduction for high volume-low value products while also ensuring waste recovery.

Evaluation of Neochloris oleoabundans as sustainable source of oil-rich biomass

In microalgae biotechnology, several strategies have been used aiming to increase biomass productivity and oil content, for example, by exploring novel bioreactor design and cultivation techniques. In the present study, the influence of stressing agents (sodium thiosulphate, sodium chloride, and glycerol), under nitrogen starvation, were evaluated for lipid accumulation in Neochloris oleoabundans. Additionally, different light regimes and the use of LED were also evaluated. The results showed that sodium thiosulfate, glycerol, and sodium chloride addition resulted in a reduction in biomass concentration, but, at the same time, an increase in lipid content. 2.5 mM of sodium thiosulfate provided the highest percentage of lipid content up to 44.7%. In a tubular photobioreactor, despite the twofold increase in biomass concentration, there was a decrease in lipid content, compared with cultures in Erlenmeyer flasks. Also, the use of white LED in combination with traditional fluorescent lamp (12 h:12 h) could efficiently replace 24 h light with fluorescent lamp for producing oil-rich N. oleoabundans biomass.

Evaluation of the Oleaginous Rhizopus stolonifer capability for Lipid Production Using Agricultural Wastes as cheap nutritional sources for Biodiesel production.

Depletion of fossil fuels and increasing the environmental concerns against pollution accelerate the research in renewable energy with much efforts directed for the production of biodiesel by the promising oil-rich biomass, like oleaginous fungi, growing on inexpensive agricultural and industrial wastes. Rhizopus stolonifer was found to be the most potent lipid producer among the tested fungi in the present study; its growth was optimized at pH=6, glucose as C-source, NaNO3 as N-source, with agitation rate of 120 rpm, incubation temperature of 28 C after 6 days growth; which gave an observable lipid content of 57.9% dry wt. on non-detoxified liquid hydrolysate (NDLH) medium with saturated aliphatic long chains as revealed by GC-MS analysis. R. stolonifer gave noticeable activity of released sugar consumption (92.2%) on flax straw as a row material higher than rice, wheat straws and orange peel, forming high lipid content (54.33%) on flax; that was transesterified into biodiesel with cetane number of 61.48, that was higher than cetane number of the standard non-processed liquid diesel (< 47). So R. stolonifer can be considered as a good lipid producer on the depolymerized flax straw as a cheap source for biodiesel production.

A novel one-step method for oil-rich biomass production and harvesting by co-cultivating microalgae with filamentous fungi in molasses wastewater

Aiming at simplifying the harvesting procedure, reducing the production cost, and improving the quality of microalgae-based biodiesel, herein, a novel one-step method for oil-rich biomass production and harvesting was proposed by growing Chlorella sp. with Aspergillus sp. in molasses wastewater. Lipid content and fatty acid profile were measured to assess the suitability of microalgal-fungal biomass for biodiesel production. The results showed that the highest biomass yield (4.215 g/L) was obtained when the inoculation ratio of fungi and microalgae was 100. Activities of fungi positive impacted the decolorization of wastewater and the removal of suspended solids. Thus, co-cultivation system had better performance than mono-system of microalgae in the removal of nutrients in wastewater. Analysis of biomass compositions showed that compared with mono-system of microalgae, co-cultivation system produced biomass with higher lipid content (35.2%) and yield microbial cell oil with lower unsaturation degree, potentially increasing the quality of microbial-cell-lipid based biodiesel.

Bilateral and simultaneous accumulation of lipid and biomass in the novel oleaginous green microalga Tetradesmus bernardii under mixotrophic growth

A new oleaginous strain of Tetradesmus bernardii exhibiting various trophic modes was isolated from an inland water body of South China. In the present study, the biomass and lipid accumulation capacity of T. bernardii in addition to its fatty acid composition were evaluated under photoautotrophic, heterotrophic, and mixotrophic cultivation conditions. T. bernardii accumulated high lipid contents up to 65.8% of dry weight under low nitrogen conditions (1 mM) in photoautotrophic cultivation. Biomass yields under heterotrophic cultivation were much higher than in photoautotrophic cultures, while lipid contents were reduced. However, T. bernardii accumulated higher biomass yields and lipid contents (54.7% of dry weight) under mixotrophic growth and high nitrogen availability (18 mM). Thus, T. bernardii achieved maximum lipid productivity due to the bilateral and synchronous enhancement of lipid content and biomass production. The fatty acid composition of T. bernardii comprised over 70% of saturated fatty acids (i.e., palmitic acid (C16:0), stearic acid (C18:0)) and monounsaturated fatty acids (i.e., palmitoleic acid (C16:1), oleic acid (C18:1)). Specifically, the mixotrophic cultivation of T. bernardii would be the preferable means for oil-rich biomass.

Factors affecting the bioconversion of Philippine tung seed by black soldier fly larvae for the production of protein and oil-rich biomass

Abstract A systematic study on the use of Philippine tung (Reutealis trisperma) seed as a substrate for the cultivation of black soldier fly larvae (Hermetia illucens) was performed. The characteristics of Reutealis trisperma seed from two different locations: West Java and Papua, were determined. The seed has a relatively high oil (37.6–39.2%, dry weight) and protein content (14.9–28.2%, dry weight). The effect of cake content in the substrate (0–20%, wet weight), moisture content in the substrate (50–70%, wet weight), feeding rate (50–100 mg/larva/d), lighting condition (dark-light) and substrate depth in a rearing container (4–10 cm) was performed. An optimum prepupal biomass productivity of 123.4 g/m2/d was obtained (20%, wet weight of cake content in the substrate, 60%, wet weight of moisture content in the substrate, 100 mg/larva/d, dark, 6 cm substrate depth). The protein and oil content of the biomass were also determined to evaluate the effect of Reutealis trisperma seed as a substrate for the cultivation of black soldier fly larvae to produce protein and oil-rich biomass. The oil content in the biomass was also extracted and the fatty acid composition was identified. The prepupal biomass has a relatively high amount of protein (45%, dry weight) and oil content (26.6%, dry weight) and is suitable for cattle feed application.

Wnt5a Decreases mTORC1/SREBP2 Activity and Promotes Endosomal Cholesterol Trafficking to the ER in Mice and in Human Vascular Smooth Muscle Cells

A systematic study on the use of Philippine tung (Reutealis trisperma) seed as a substrate for the cultivation of black soldier fly larvae (Hermetia illucens) was performed. The characteristics of Reutealis trisperma seed from two different locations: West Java and Papua, were determined. The seed has a relatively high oil (37.6–39.2%, dry weight) and protein content (14.9–28.2%, dry weight). The effect of cake content in the substrate (0–20%, wet weight), moisture content in the substrate (50–70%, wet weight), feeding rate (50–100 mg/larva/d), lighting condition (dark-light) and substrate depth in a rearing container (4–10 cm) was performed. An optimum prepupal biomass productivity of 123.4 g/m2/d was obtained (20%, wet weight of cake content in the substrate, 60%, wet weight of moisture content in the substrate, 100 mg/larva/d, dark, 6 cm substrate depth). The protein and oil content of the biomass were also determined to evaluate the effect of Reutealis trisperma seed as a substrate for the cultivation of black soldier fly larvae to produce protein and oil-rich biomass. The oil content in the biomass was also extracted and the fatty acid composition was identified. The prepupal biomass has a relatively high amount of protein (45%, dry weight) and oil content (26.6%, dry weight) and is suitable for cattle feed application.

Life Cycle Inventory for winter and spring rapeseed production in Northern Europe

Abstract Rapeseed is currently cultivated as an industrial crop in Latvia as a source of oil rich biomass to contribute to renewable energy goals of the European Union. However, rapeseed oil can also be used as a feedstock biobased polyurethane production. Latvian State Institute of Wood Chemistry have developed polyols based on rapeseed oil and have developed biobased and volatile organic compounds-free polyurethane coatings. The main aim of this study was to present a Life Cycle Inventory of spring and winter rapeseed produced in Northern European country Latvia based on primary data of agricultural practices used in this region. The study was carried in accordance with ISO 14040 and ISO 14044. Data were collected from a large crop company in Latvia to ensure a specific and accurate data collection for the definition of the complete supply chain. The reference unit of this study was defined as 1 ha, time horizon 2008–2016, stages from the raw materials production to the seed harvesting were considered. The data presented will add to and expand the existing knowledge of rapeseed production in other European countries. Lastly, this paper is the first in a series of papers that will result in a complete Life Cycle Assessment for these develop polyurethane coatings based on rapeseed oil polyols to avoid black box unit process and provide transparent results.

Conversion of Agricultural Streams and Food-Processing By-Products to Value-Added Compounds Using Filamentous Fungi.

The design of new food products and increased agricultural activities have produced a diversity of waste streams or by-products that contain a high load of organic matter. The underutilization of these streams presents a serious threat to the environment and to the financial viability of the agricultural sector and the food industry. Oleaginous microorganisms, such as yeast and microalgae, have been used to convert the organic matter present in many agricultural waste streams into an oil-rich biomass. Filamentous fungi are promising oleaginous microorganisms because of their high lipid accumulation potential and simple biomass recovery, the latter being related to their pellet-like growth morphology in submerged cultivation. This review highlights the use of oleaginous filamentous fungi to convert food by-products into value-added components, including the effect of cultivation conditions on biomass yield and composition. Special attention is given to downstream processing for the commercial production of fungal oil. Also discussed are innovative techniques to optimize the biomass oil yield and to minimize the challenges associated with biomass harvesting and oil extraction at industrial scale.

Oil-rich nonseed tissues for enhancing plant oil production.

Abstract Plants are being engineered for enhanced ethanol production; however, challenges remain in meeting the demand for bioenergy that is expected to double by 2030. Therefore, targeting carbon accumulation in the form of energy-dense oils in nonseed biomass is considered a superior alternative for bioenergy production. Although oils in the form of triacylglycerols (TAGs) are typically stored in seed tissues, various nonseed tissues such as mesocarp, tubers, stems and leaves also serve as storage tissues for TAG accumulation in plants. Moreover, the biomass of these tissues is generally far greater than seed biomass. In order to increase oil content in nonseed biomass for bioenergy and nutritional purposes, it is important to understand how such plants naturally accumulate TAG in nonseed tissues. Several molecular approaches, including transcriptomics, have been undertaken to elucidate the metabolic and regulatory mechanisms of carbon partitioning in oil-rich nonseed tissues. Such studies are expected to generate important transgenic tools that can be used to alter fatty acid metabolism and engineer plants to produce oil-rich biomass successfully. This review focuses on the potential of different oil-rich nonseed tissues and the strategies developed for enhancing oil biomass.

Deep Sequencing of the Fruit Transcriptome and Lipid Accumulation in a Non-Seed Tissue of Chinese Tallow, a Potential Biofuel Crop.

Chinese tallow (Triadica sebifera) is a valuable oilseed-producing tree that can grow in a variety of conditions without competing for food production, and is a promising biofuel feedstock candidate. The fruits are unique in that they contain both saturated and unsaturated fat present in the tallow and seed layer, respectively. The tallow layer is poorly studied and is considered only as an external fatty deposition secreted from the seed. In this study we show that tallow is in fact a non-seed cellular tissue capable of triglyceride synthesis. Knowledge of lipid synthesis and storage mechanisms in tissues other than seed is limited but essential to generate oil-rich biomass crops. Here, we describe the annotated transcriptome assembly generated from the fruit coat, tallow and seed tissues of Chinese tallow. The final assembly was functionally annotated, allowing for the identification of candidate genes and reconstruction of lipid pathways. A tallow tissue-specific paralog for the transcription factor gene WRINKLED1 (WRI1) and lipid droplet-associated protein genes, distinct from those expressed in seed tissue, were found to be active in tallow, underpinning the mode of oil synthesis and packaging in this tissue. Our data have established an excellent knowledge base that can provide genetic and biochemical insights for engineering non-seed tissues to accumulate large amounts of oil. In addition to the large data set of annotated transcripts, the study also provides gene-based simple sequence repeat and single nucleotide polymorphism markers.

Oil biosynthesis in a basal angiosperm: transcriptome analysis of Persea Americana mesocarp.

BackgroundThe mechanism by which plants synthesize and store high amounts of triacylglycerols (TAG) in tissues other than seeds is not well understood. The comprehension of controls for carbon partitioning and oil accumulation in nonseed tissues is essential to generate oil-rich biomass in perennial bioenergy crops. Persea americana (avocado), a basal angiosperm with unique features that are ancestral to most flowering plants, stores ~ 70 % TAG per dry weight in its mesocarp, a nonseed tissue. Transcriptome analyses of select pathways, from generation of pyruvate and leading up to TAG accumulation, in mesocarp tissues of avocado was conducted and compared with that of oil-rich monocot (oil palm) and dicot (rapeseed and castor) tissues to identify tissue- and species-specific regulation and biosynthesis of TAG in plants.ResultsRNA-Seq analyses of select lipid metabolic pathways of avocado mesocarp revealed patterns similar to that of other oil-rich species. However, only some predominant orthologs of the fatty acid biosynthetic pathway genes in this basal angiosperm were similar to those of monocots and dicots. The accumulation of TAG, rich in oleic acid, was associated with higher transcript levels for a putative stearoyl-ACP desaturase and endoplasmic reticulum (ER)-associated acyl-CoA synthetases, during fruit development. Gene expression levels for enzymes involved in terminal steps to TAG biosynthesis in the ER further indicated that both acyl-CoA-dependent and -independent mechanisms might play a role in TAG assembly, depending on the developmental stage of the fruit. Furthermore, in addition to the expression of an ortholog of WRINKLED1 (WRI1), a regulator of fatty acid biosynthesis, high transcript levels for WRI2-like and WRI3-like suggest a role for additional transcription factors in nonseed oil accumulation. Plastid pyruvate necessary for fatty acid synthesis is likely driven by the upregulation of genes involved in glycolysis and transport of its intermediates. Together, a comparative transcriptome analyses for storage oil biosynthesis in diverse plants and tissues suggested that several distinct and conserved features in this basal angiosperm species might contribute towards its rich TAG content.ConclusionsOur work represents a comprehensive transcriptome resource for a basal angiosperm species and provides insight into their lipid metabolism in mesocarp tissues. Furthermore, comparison of the transcriptome of oil-rich mesocarp of avocado, with oil-rich seed and nonseed tissues of monocot and dicot species, revealed lipid gene orthologs that are highly conserved during evolution. The orthologs that are distinctively expressed in oil-rich mesocarp tissues of this basal angiosperm, such as WRI2, ER-associated acyl-CoA synthetases, and lipid-droplet associated proteins were also identified. This study provides a foundation for future investigations to increase oil-content and has implications for metabolic engineering to enhance storage oil content in nonseed tissues of diverse species.Electronic supplementary materialThe online version of this article (doi:10.1186/s12870-015-0586-2) contains supplementary material, which is available to authorized users.

Energy-input analysis of the life-cycle of microalgal cultivation systems and best scenario for oil-rich biomass production

Abstract An energy-input analysis of the life-cycle of microalgal cultivation systems was performed to study the oil-rich biomass production from fast-growing microalgae, for biodiesel production purposes. We estimated and compared the energy demands for the algal biomass cultivation in open-ponds (OP) with that required in closed-system photobioreactors (PBR) based on the new technologies. We also present the best microalgal candidates that show the highest biomass productivity and lipid yield indoors (laboratory scale), and discuss their potential to be used for full-scale biodiesel production. The results show that the energy requirements are highly dependent on the final mass concentration and/or using industrial wastes, with PBR cultivation being the largest energy consumer. Our offered scenario to minimize energy inputs and to increase algal-oil yields considers the most ideal cases, which could be the most promising model for energy-efficient biofuel production. Although biodiesel production by any of these systems is still not economically competitive with fossil fuel, recent suggestions on how to increase the efficiency of both systems are discussed, based on our energy-input assessment, with a critical evaluation of all stages for large-scale production of oil-rich microalgal biomass.

Life cycle assessment of the production chain of oil-rich biomass to generate BtL aviation fuel derived from micraoalgae

Considerable efforts are made to generate drop-in aviation fuels from microalgae to avoid competitionwith food production. Synthetic biofuel from oil-rich biomass is produced along four process lines: cultivation,harvest, extraction of raw material and conversion to fuel. This study deals with the life cycle assessment of fuelobtained from cultivation of the fresh water alga Auxenochlorella protothecoides and concentrates on the cultivationin open ponds as well as the harvesting steps preconcentration, electroporation and dewatering. Energybalance and environmental impact is analysed using GaBi software and data base. The main goal is to identifythose factors or processes exerting the strongest impact, either environmentally or from the point of view of theenergy balance. Production of one kilogram of dry oil-rich algal biomass (kg DM) consumes 118.56 MJ of primaryenergy. The primary energy demand is apportioned as follows: 71.7 % during proliferation in Erlenmeyerflags and bubble columns, 15.5 % by cultivation in raceway ponds and 12.8 % in preconcentration, electroporationand dewatering. This converts into a net energy ratio (NER) of 0.266 and a CO2-equivalent of 6.45 kg CO2per kg DM. These values are disadvantageous when compared to kerosene (NER=0.867, 0.384 kg CO2 per kgkerosene). Production can be optimized using process energy from regenerative sources such as hydroelectricpower (NER = 0.545, 1.27 CO2 per kg DM). In this case total primary energy input must be corrected for theportion of renewable sources resulting in a NERcorr of 3.04. CO2-equivalents per kg DM remain unfavourablyhigh as compared to kerosene; the main driver responsible for this discrepancy is the usage of freshwater andfertilizer.