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The cultivation of seaweed as a feedstock for third generation biofuels is gathering interest in Europe, however, many questions remain unanswered in practise, notably regarding scales of operation, energy returns on investment (EROI) and greenhouse gas (GHG) emissions, all of which are crucial to determine commercial viability. This study performed an energy and GHG emissions analysis, using EROI and GHG savings potential respectively, as indicators of commercial viability for two systems: the Swedish Seafarm project's seaweed cultivation (0.5 ha), biogas and fer- tilizer biorefinery, and an estimation of the same system scaled up and adjusted to a cultivation of 10 ha. Based on a conservative estimate of biogas yield, neither the 0.5 ha case nor the up-scaled 10 ha estimates met the (commercial viability) target EROI of 3, nor the European Union Renewable Energy Directive GHG savings target of 60% for biofuels, however the potential for commercial viability was substantially improved by scaling up operations: GHG emissions and energy demand, per unit of biogas, was almost halved by scaling operations up by a factor of twenty, thereby approaching the EROI and GHG savings targets set, under beneficial biogas production conditions. Further analysis identified processes whose optimisations would have a large impact on energy use and emissions (such as anaerobic digestion) as well as others embodying potential for further economies of scale (such as harvest- ing), both of which would be of interest for future developments of kelp to biogas and fertilizer biorefineries.

A solar drying system was designed, constructed and tested for drying of seaweed. Seaweed is a potential source of renewable energy, and it can be converted into energy such as biofuel oil, biodiesel and gas. Red seaweed was dried to the final moisture content of 10% from 90% w.b in 15 h. Drying kinetics of red seaweed were investigated and obtained. The nonlinear regression procedure was used to fit three different drying models. The Page's model clearly showed a better fit to the experimental data between Newton's model and Henderson and Pabis model. The Page's model was resulted in the highest value of R2 and lowest values of MBE and RMSE. At average solar radiation of about 500 W/m2 and air flow rate 0.05 kg/s, the collector, drying system and pick-up efficiencies were found about 35, 27 and 95%, respectively. This study was performed with energy analysis and exergy analyses of the solar drying process of red seaweed. The specific energy consumption (SEC) of 2.62 kWh/kg was obtained. Moreover, the exergy efficiency of solar drying ranged from 1% to 93%, with an average of 30%. The values of improvement potential were found to be in the range of 0.3 and 630 W, with an average of 247 W.

Experiments were conducted with tetrasporophytes of Gelidium pusillum (Stackhouse) Le Jolis, Pterocladia heteroplmos (Boergesen) Umamaheswara Rao & Kaliaperumal, and Gelidiopsis variabilis (Greville) Schmitz, to determine the effects of various environmental factors on the liberation of spores. The ability to liberate spores and the quantity of spores shed by these three red algae varied with the different environmental conditions tested. Submerged condition of the plants, long day condition at low illuminance, sea water of 30 to 40/00 salinity and 25 to 30°C temperature were found to be favourable for maximum sheddingofsporcs at Visakhapatnam. The variability observed in spore-shedding under short- and long-day conditions was considered to be due to the photosynthetic effect also noticed in the growth of certain red algae.

Benthic marine algae, especially Rhodophyta, are within a well-known marine group able to produce secondary metabolites with bioactive properties. Among them are halogenated terpenes, synthesized by vanadium-dependent haloperoxidase (V-BPO). The red alga Ochtodes secundiramea (Montagne) M. Howe produces high amounts of halogenated monoterpenes (HMT) which have the potential to control phytopathogenic fungi. Culture closed a system is a tool used to manipulate conditions to increase the synthesis of HMT and other metabolites. The apical segments of O. secundiramea were cultivated in a bioreactor, either in seawater enriched with half strength von Stosch’s solution (VSES/2) without (control) and with the addition of 250 mg L−1 bromine (treatment). In response to these conditions, specific growth rate, HMT profile, soluble protein, phycobiliproteins, soluble carbohydrate, and chlorophyll as well as the V-BPO activity, uptake, and accumulated bromine within the biomass were evaluated. The treatment did not promote significant alterations in the growth but increased the V-BPO activity and bromine uptake and incorporation (2.5 fold). No changes in the HMT profiles of the extracts from both cultures conditions were observed by gas chromatography–mass spectrometry analyses, whereas the values of total soluble protein and phycobiliproteins were 2- fold higher in samples from the bromine-enriched medium when compared to samples from control. These results support the evidences of protective effects promoted by V-BPO activity. Furthermore, carbohydrate and chlorophyll contents were not affected by experimental conditions. These results provided new low-cost strategies that can be applied to increase of certain biomass components, which here are algal proteins, especially in Rhodophyta-based biotechnological industries for food and agriculture.