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• Solar-thermal seaweed biorefinery with offshore intensively grown biomass was analysed. • Co-production of protein, hydrochar, ethanol, distilled water and electricity was analysed. • The overall First Law efficiency is 32% and can reach 40% with energy recovery from aqueous phase. • Seaweed, electricity and protein prices are key for the profitability of the biorefinery. • The lowest environmental impacts are achieved with HDPV cage, PV electricity, and rail transport. Combing solar energy with biomass processing facilities are emerging systems for efficient use of solar energy for electricity generation, energy storage, and production of renewable materials. In this work, we propose a novel combination of solar thermal energy systems with marine macroalgae biorefinery, which requires energy inputs for biomass cultivation and processing. In this work, we analyze a 10-ton dry weight per hour capacity pilot-scale hybrid solar seaweed biorefinery, located at the Mishor Rotem near Dimona, the current location for solar-thermal projects in Israel, where seaweed biomass supply comes from a hypothetical offshore farm located 15 km offshore. Our energy and mass balance analysis show that the overall First Law efficiency of the hybrid solar seaweed biorefinery system for the co-production of protein, hydrochar, ethanol, distilled water, and electricity is 32% and can exceed 40% with additional waste stream recycling. Our cost-benefit analysis of the proposed solar-seaweed biorefinery shows that the prices of seaweed, electricity, and protein are the key drivers of the profitability of the production process. The environmental impacts of the hybrid solar-seaweed biorefinery with intensified offshore cultivated biomass were quantified under various seaweed cultivation, transportation, and processing strategies. [ABSTRACT FROM AUTHOR]

This study proposes a process based on the application of high-voltage pulsed electric field (PEF) in combination with pH shift for protein and solute release from fresh edible seaweed from Gracilaria sp.. The PEF was administered using a custom-made generator within and electroporation cell with sliding electrodes. The applied PEF parameters comprised 1000 V applied voltage, 50 µs pulse duration, 200 pulses delivered at 3 Hz frequency, and an inter-electrode gap ranging from 3.9 to 4.4 mm. The pH shift extraction was performed through a combination of fractions extracted sequentially at pH-shift steps spanning the pH range of 1 to 12. Both PEF and pH played pivotal roles in the fractionation of Gracilaria sp., enhancing protein release compared to water extraction, PEF pre-treatment, or pH shift alone. The combination of PEF and sequential pH washes (pH 1 to 12) resulted in a total solute release of 9.61 ± 0.04% and protein release of 28.02 ± 0.2% with essential amino acid (EAA) content of 63.6 ± 5.3%, and branched amino acids (BCAA) content of 3.47 ± 0.06%. It is noteworthy that PEF significantly increased the EAA and BCAA content of the protein extracts, irrespective of pH shifts. These findings underscore the promising potential of PEF pre-treatment in extracting proteins from edible seaweeds. [ABSTRACT FROM AUTHOR]

Controlling the life cycle of the green macroalga Ulva (Chlorophyta) is essential to maintain its efficient aquaculture. A fundamental shift in cultivation occurs by transforming the thallus cells into gametangia and sporangia (sporulation), with the subsequent release of gametes and zoids. Sporulation occurrence depends on algal age and abiotic stimuli and is controlled by sporulation inhibitors. Thus, quantification of sporulation intensity is critical for identifying the biotic and abiotic factors that influence the transition to reproductive growth. Here, we propose to determine the sporulation index by measuring the number of released gametes using flow cytometry, in proportion to the total number of thallus cells present before the occurrence of the sporulation event. The flow cytometric measurements were validated by manually counting the number of released gametes. We observed a variation in the autofluorescence levels of the gametes which were released from the gametangia. High autofluorescence level correlated to phototactically active behaviour of the gametes. As autofluorescence levels varied between different groups of gametes related to their mobility, flow cytometry can also determine the physiological status of the gametes used as feedstock in seaweed cultivation. [ABSTRACT FROM AUTHOR]

Marine biorefineries, based on macroalgal (seaweed) feedstocks, could provide sustainable alternative sources of food, energy, and materials. Green macroalgae, with their unique chemical composition, can contribute to marine biorefinery systems associated with a wide range of potential products. This review discusses the challenge of developing industrially relevant and environmentally-friendly green seaweed biorefineries. First, we review potential products from green seaweeds and their co-production, the key element in an integrated biorefinery. Second, we discuss large-scale cultivation, hydrothermal treatments, fermentation, anaerobic digestion, and emerging green solvents, pulsed electric field, microwave, and ultrasound processing technologies. Finally, we analyse the main polysaccharides in green seaweeds: sulfated polysaccharides, starch, and cellulose, as products of a cascading biorefinery, with emphasis on applications and technological challenges. We provide a comprehensive state-of-the-art review of green seaweed as feedstock for the biorefinery, analysing opportunities and challenges in the field. [ABSTRACT FROM AUTHOR]

Increasing biomass production yields is a critical challenge for macroalgae biorefineries. The continuous tumbling and mixing of free‐floating algae through water or airflow has been shown to increase the productivity of algae in land‐based cultivation systems. This approach has not been tested thoroughly in offshore cultivation. We report, here, a field feasibility study on the increase in green macroalga Ulva sp. growth rates in offshore cages, achieved by the combined effect of tumbling and mixing of the algae using influxes of water and air. The experimental system was tested in a shallow coastal area in central Israel, in the eastern Mediterranean Sea. A maximum daily growth rate of 19.2%, areal productivity of 33.72 g dry weight (DW) day−1 m−2, and volumetric yields of 37.78 g DW day−1 m−3, together with 38.47 ± 0.01% ash and 5.28% protein content on a dry matter basis were achieved in the cages with intensified cultivation in the first week of May 2017. Our study shows that cultivation with tumbling and mixing of biomass with air, and water exchange with the environment is a feasible method to increase Ulva sp. biomass productivity offshore. © 2019 Society of Chemical Industry and John Wiley & Sons, Ltd [ABSTRACT FROM AUTHOR]

The last years have seen the emergence of the bioeconomy. Assessment of these new technologies is a significant challenge. We develop a unique dynamic programming framework to assess the value of the investment in a multi-stage supply chain with the production of bio-feedstock and its processing into multiple outputs. The system allows for adaptive learning in all supply chain stages, which creates a positive learning effect of co-outputs. We apply the framework to macroalgae (seaweed) farming and biorefinery processing into proteins and sugars for the Philippines and Ireland as representatives of developing and developed economies with emerging supply chains. We run Monte Carlo simulations to analyze the uncertainty of learning and prices. The key results indicate that the macroalgae sector that builds on traditional technologies is quite viable. Developing a new algae industry that generates proteins and other high-value products requires significant investment and depends on the dynamics of learning and prices. Even though the production of high-value chemicals is not yet viable, it gains profitability potential from learning of feedstock farming that is currently produced for the lower value application. The learning is much more valuable in feedstock production and processing into proteins than low-value chemicals currently produced (carrageenan). • Original dynamic, two-stage supply chain model with non-linear cost functions, learning, and heterogenous coproducts. • Analysis of impact of learning effects and prices on investment decision in a supply chain of aquaculture. • The co-production allows financing learning in both stages of the supply chain that may transform the non-viable product into a profitable in the long run. • If the combined impact of learning is greater than the discount effect, than the investment in a technology can be profitable even if prices decline. • Payback period in Asia is short, while in the West long-term investment is vital for high learning rates to reach profitability. [ABSTRACT FROM AUTHOR]

Offshore grown macroalgae biomass could provide a sustainable feedstock for biorefineries. However, tools to assess its potential for producing biofuels, food and chemicals are limited. In this work, we determined the net annual primary productivity (NPP) for Ulva sp. (Chlorophyta), using a single layer cultivation in a shallow, coastal site in Israel. We also evaluated the implied potential bioethanol production under literature based conversion rates. Overall, the daily growth rate of Ulva sp. was 4.5 ± 1.1%, corresponding to an annual average productivity of 5.8 ± 1.5 g DW m −2 day −1 . In comparison, laboratory experiments showed that under nutrients saturation conditions Ulva sp. daily growth rate achieved 33 ± 6%. The average NPP of Ulva sp . offshore was 838 ± 201 g C m −2 year −1 , which is higher than the global average of 290 g C m −2 year −1 NPP estimated for terrestrial biomass in the Middle East. These results position Ulva sp. at the high end of potential crops for bioenergy under the prevailing conditions of the Eastern Mediterranean Sea. We found that with 90% confidence, with the respect to the conversion distribution, the annual ethanol production from Ulva sp. biomass, grown in a layer reactor is 229.5 g ethanol m −2 year −1 .This translates to an energy density of 5.74 MJ m −2 year −1 and power density of 0.18 W m −2 . Growth intensification, to the rates observed at the laboratory conditions, with currently reported conversion yields, could increase, with 90% confidence, the annual ethanol production density of Ulva sp. to 1735 g ethanol m −2 year −1 , which translates to an energy density of 43.5 MJ m −2 year −1 and a power density 1.36 W m −2 . Based on the measured NPP, we estimated the size of offshore area allocation required to provide biomass for bioethanol sufficient to replace 5–100% of oil used in transportation in Israel. We also performed a sensitivity analysis on the biomass productivity, national CO 2 emissions reduction, ethanol potential, feedstock costs and sizes of the required allocated areas. [ABSTRACT FROM AUTHOR]

• Hydrothermal processing of the whole Ulva sp. biomass vs. extracted carbohydrate fractions of starch and cellulose. • Glucose is a major released monosaccharide with hydrothermal deconstruction. • Most of the glucose is released from starch. • Whole biomass hydrolysis preferred for PHA fermentation with Haloferax mediterranei. • The highest ash-free hydrochar yield was from Ulva cellulose. In the fermentation and bioenergy industry, terrestrial biomass is usually fractionated and the collected components, such as starch, are processed separately. Such a separation has not been reported for seaweeds. In this work, the direct hydrothermal processing of the whole green seaweed Ulva sp. biomass is compared to processing of separated starch and cellulose, to find the preferable route for monosaccharide, hydrochar, and polyhydroxyalkanoates (PHA) production. Glucose was the major released monosaccharide. A significant share of the glucose yield comes from the starch fraction. The highest hydrochar yield with the lowest ash content was obtained from the separated cellulose fraction. The highest PHA yield was obtained using a whole Ulva sp. hydrolysate fermentation with Haloferax mediterranei. Economic analysis shows the advantage of direct Ulva sp. biomass fermentation to PHA. The co-production of glucose and hydrochar does not add significant economic benefits to the process under plausible prices of the two outputs. [ABSTRACT FROM AUTHOR]