Embiruçu M and Ghirardi ML, Comparative energy life-cycle analyses of microalgal biomass production in open ponds and photobioreactors

Department of Environmental Engineering, Bahia Center for Clean Technologies, Federal University of Bahia, Rua Aristides Novis No. 2, 4 degrees andar, Polytechnique Institute, Salvador 40.210-630, BA, Brazil.
Bioresource Technology (Impact Factor: 4.49). 10/2009; 101(4):1406-13. DOI: 10.1016/j.biortech.2009.09.038
Source: PubMed


An analysis of the energy life-cycle for production of biomass using the oil-rich microalgae Nannochloropsis sp. was performed, which included both raceway ponds, tubular and flat-plate photobioreactors for algal cultivation. The net energy ratio (NER) for each process was calculated. The results showed that the use of horizontal tubular photobioreactors (PBRs) is not economically feasible ([NER]<1) and that the estimated NERs for flat-plate PBRs and raceway ponds is >1. The NER for ponds and flat-plate PBRs could be raised to significantly higher values if the lipid content of the biomass were increased to 60% dw/cwd. Although neither system is currently competitive with petroleum, the threshold oil cost at which this would occur was also estimated.

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    • "Photosynthetic activity of microalgae is highly efficient [5]. Advantages of algae over other energy crops includes rapid growth rate [2], higher CO 2 fixation [6] and high lipid content [7]. Moreover, the production of microalgae does not require high quality arable land, and therefore does not compete with food crops [5] "
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    ABSTRACT: Many LCA based viability studies have already been done for the production of green diesel from microalgae, still a comprehensive LCA, has not yet been undertaken. Current study aims to find out if the Net Energy Balance(NEB) can further be increased by using a combination of many available agronomical practices & the techniques of production of green diesel from microalgae. The results show that neither open raceway pond nor Photobioreactor routes (Wet and dry routes) yield positive energy balance. The production of green diesel via open raceway pond, both in dry as well as wet route, have less negative NEB and comparatively higher NER than the photobioreactors. Comparison says that open raceway pond dry route has slightly higher value for NER than the wet route. Even with the best possible route (open raceway pond dry route), the total energy use is almost 5 times more than the energy produced, with a negative NEB of 4.07 MJ & very low NER value of 0.20. Study concludes that R & D in the area of green diesel production from microalgae has yet to go a long way & has a huge scope to further lower its input energy demand for biofuel production.
    Renewable Energy 09/2015; 86:623-632. DOI:10.1016/j.renene.2015.08.064 · 3.48 Impact Factor
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    • "The medium components are directly exposed to the atmosphere. These types of systems are widely used in commercial scale for cultivation of algae and cyanobacteria like Spirulina sp, Chlorella sp, Anabaena sp and many others (Jorquera et al. 2010). "
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    DESCRIPTION: The present investigation deals with the biosorption of lead from aqueous solutions in open race way pond using edible and live Spirulina (Arthospira) maxima, Spirulina (Arthospira) indica, Spirulina (Arthospira) platensis. Studies on various initial lead (II) ion concentrations, biosorbent dosage, pH and bioaccumulation potential were evaluated. The organisms are tolerant up to 4 mg/l and after that slight growth inhibition was found. Spirulina (Arthospira) indica showed more tolerance when compared with Spirulina (Arthospira) maxima and Spirulina (Arthospira) plantensis. The adsorption rate data was fitted to pseudo second order kinetics. The Langmuir and Freundlich models were applied to the experimental data and their equilibrium parameters were determined. Further optimization of initial lead (II) ion concentration, solution pH, agitation speed and biosorbent dosage were done using Box-Behnken experimental design coupled with artificial neural networks. This study provides a deep insight for exploring potential of using algal open race way ponds for biosorption of heavy metals. The diversity of the results can be expanded still further for other algal species and heavy metals.
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    • "Furthermore, the assumption that a higher areal biomass productivity of 6 g m −2 day −1 can be reached (personal communication) and more biomass could be harvested (5% instead of 1.9%), possibly by small modifications to the coalescers, is made. According to the studies of Jorquera et al. (2010) and Lardon et al. (2009), even higher biomass productivities can be achieved in open pond systems (e.g., 11 g m −2 day −1 and 24 g m 2 day −1 , respectively). However, accounting for the climate conditions of The Netherlands, it is assumed that a maximum of approximately 20 t DM ha −1 year −1 could be established. "
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    ABSTRACT: Keywords: Biorefinery Life cycle analysis (LCA) Protein-rich feed ingredient Algae Soybeans a b s t r a c t Sustainability in terms of the natural resource demands of protein-rich algal meal for livestock feed applications was examined. In The Netherlands, an integrated microalgal biorefinery delivered the following products: digestate, electricity, heat available for a nearby bio-ethanol facility and algae oil and meal. Pilot scale (500 m 2) data were used to conduct an exergy analysis (EA), which revealed the process inefficiencies of energy-intensive processes such as drying (44.01%) and inoculum production (54.98%). An attributional life cycle assessment (LCA) using system expansion exposed the high contribution of biomass digestion to the total resource footprint of the biorefinery (72.74%) due to the high daily demand for biomass and electricity consumption of the dosage system. In this study, algal meal was compared with soybean meal, which is the most commonly used protein-rich animal feed ingredient; it is produced in Brazil and transported to The Netherlands. Because algae production is a young, small-scale technology , the resource footprint of the large-scale soy meal production was a factor of 10 2 lower, mainly as a result of the energy-intensive algae cultivation stages. A sensitivity analysis showed that the resource footprint of algal meal production could be comparable with soy meal when, overall, the areal biomass productivity increases, electricity production is based on more renewable sources (wind) and the energy consumption from mixing and blowing flue gases into the ponds decreases.
    Resources Conservation and Recycling 05/2015; 101:61-72. DOI:10.1016/j.resconrec.2015.05.013 · 2.56 Impact Factor
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