Depletion of fossil fuel sources and their emissions have triggered a vigorous research in finding alter- native and renewable energy sources. In this regard, algae are being exploited as a third generation feedstock for the production of biofuels such as bioethanol, biodiesel, biogas, and biohydrogen. However, algal based biofuel does not reach successful peak due to the higher cost issues in cultivation, harvesting and extraction steps. Therefore, this review presents an extensive detail of deriving biofuels from algal biomass starting from various algae cultivation systems like raceway pond and photobioreactors and its bottlenecks. Evolution of biofuel feedstocks from edible oils to algae have been addressed in the initial section of the manuscript to provide insights on the different generation of biofuel. Different configu- ration of photobioreactor systems used to reduce contamination risk and improve biomass productivity were extensively discussed. Photobioreactor performance greatly relies on the conditions under which it is operated. Hence, the importance of such conditions alike temperature, light intensity, inoculum size, CO2, nutrient concentration, and mixing in bioreactor performance have been described. As the lipid is the main component in biodiesel production, several pretreatment methods such as physical, chemical and biological for disrupting cell membrane to extract lipid were comprehensively reviewed and pre- sented. This review article had put forth the recent advancement in the pretreatment methods like hydrothermal processing of algal biomasses using acid or alkali. Eventually, challenges and future di- mensions in algal cultivation and pretreatment process were discussed in detail for making an economically viable algal biofuel.
Digital library
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IEA Advanced Motor Fuels algal biofuels summary report.
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In a historic day for the algae industry, the U.S. Senate Tuesday approved a Farm Bill compromise that dramatically expands federal support for algae agriculture. The bill sets U.S. farm policy through 2023. It is expected to pass the House of Representatives as soon as today and receive President Trump’s signature before Christmas. Among the bill’s more than 800 pages is a suite of provisions placing algae among the nation’s top priorities for new crop deployment and providing support for the development of algae and related technologies in nutrient management, soil health, carbon recycling and other farm and rural applicationsfarmers for establishment, production and delivery of new biomass crops
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Airborne hyperspectral and thermal infrared imagery collected over the Florida Current provide a view of the disintegration of a Sargassum drift line in 5 m s−1 winds. The drift line consists mostly of rafts 20–80 m2 in size, though aggregations larger than 1000 m2 also occur. Rafts tend to be elongated, curved in the upwind direction, and 0.1–0.5 °C warmer than the surrounding ocean surface. Long weed ‘trails’ extending upwind from the rafts are evidence of plants dropping out and being left behind more rapidly drifting rafts. The raft line may be a remnant of an earlier Sargassum frontal band, which is detectible as an upwind thermal front and areas of submerged weed. Issues are identified that require future field measurements.Research highlights► A Sargassum drift line disintegrates under a wind speed of 5 m s−1. ► Weed left behind more rapidly drifting rafts form long upwind ‘trails’. ► Wave drag may be creating a distinct raft-and-trail morphology. ► Remnant frontal accumulations of only submerged Sargassum occur upwind.
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Bromoform (CHBr3) is the largest single source of organic bromine for the atmosphere and of importance for the reactive halogen budgets in troposphere and lower stratosphere. Its photochemical products may contribute 10-20% to inorganic bromine in the troposphere and >50% in the lower stratosphere. The sea-to-air flux, originating with macroalgae and plankton, is the main source for atmospheric bromoform. We address the relevance of bromoform to atmospheric chemistry, as well as oceanic source and sink processes. We have performed a reassessment of oceanic emissions, based on published aqueous and airborne concentration data, global climatological parameters, and incorporation of knowledge about bromoforms coastal and biogenic sources. The goal is partly to estimate the global source strength and partly to identify key regions that may contribute bromoform to the atmosphere and hence require further investigation. We have therefore calculated annual integrated fluxes of bromoform for different latitudes and oceanic biogeochemical provinces. We obtain a global flux in the order of 9-13 Gmol Br yr-1 (as CHBr3), which is still associated with significant uncertainties. Coastal, shelf and open ocean regions contribute 13-17%, 44-48% and 34-43% to our calculated total respectively. Anthropogenic sources of ~0.3 Gmol Br yr-1 (as CHBr3) are negligible globally. Our estimate of the global oceanic source is >3x higher than recent estimates based on the modelling of atmospheric sinks. Reasons for the discrepancy could lie with the limited regional and temporal data available and broad assumptions that underlie our flux calculations. Alternatively, atmospheric sink calculations, often calculated on the basis of background CHBr3 levels, may neglect the influence of strong but highly localised sources (e.g. from some coastal regions). We believe that our approach is useful for attempting a first approximation of the flux based on known factors affecting the oceanic bromoform distribution. In the future, as more data become available, alternative schemes should certainly be developed and tested. The sea-to- air flux is spatially and temporally variable with tropical, subtropical and shelf waters identified as potentially important source regions. The strongly variable and poorly characterised source, together with bromoform's short atmospheric lifetime, complicates model-based estimation of the distribution of reactive Br resulting from its atmospheric degradation. An integrated program of marine and atmospheric observations, atmospheric modelling and mechanistic studies of oceanic bromoform production is required to better constrain present and future Br delivery to the atmosphere.
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The world is faced with the vast challenge of meeting ever-increasing food demands placed on the agriculture sector due to a rapidly growing population. In fact, the world population has been increasing by an estimated 78 million each year, about the size of the population of Germany. Challenges around food security – ensuring there is enough food to meet demand – will be exacerbated when the population surpasses 9 billion by 2050 and 10 billion by the turn of the century.
Global food production must be 70 percent greater than today’s level to close the deficit between supply and demand, commonly referred to as the productivity gap. And, it must be done without using substantially more land. With current grain stocks at historically low levels and food demand increasing at rates higher than production, the challenge is not decades into the future, but is here today.
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The U.S. energy problem. The united States imported about 8 million barrels of oil each day in 1979. At a cost approaching $30 per barrel, the annual cost amounted to about 80 billion dollars! Needless to say, excessive dependence on foreign oil imports has resulted in serious trade deficits. Inflation, fueled in part by energy problems, has been unacceptably high. Thus, the soundness of the U.S. dollar, our economic wellbeing and even our national security are all inextricably bound to the energy problem.
There is no overall energy shortage: for all practical purposes the sun radiates an infinite energy supply, nuclear reactions release huge amounts of energy and coal supplies are extensive. But can we manage these vast energy resources in an economically and environmentally acceptable manner?
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The present work is focused on the biosynthesis of the Silver (Ag) Nanoparticles using an aqueous extract of the green seaweed Halimeda gracilis. The visible colour change indicated the biosynthesis of Silver Nanoparticles and the specific peak produced within the UV-Vis spectrum confirmed the biosynthesis of Silver Nanoparticles. The possible functional groups were identified with Fourier Infrared Spectroscopy. The morphological characterization of biosynthesized Silver Nanoparticles was done by Scanning Electron Microscopy and Dynamic light scattering measurements and Zeta potential. The average size distribution of Ag-Nanoparticles were 295.9 (d.nm) and fairly stable with a zeta potential value of-28.6 mV. The size of biosynthesized Ag-Nanoparticles was also measured with X-ray diffraction assay. Due to agglomeration, the size difference of biosynthesized Ag-Nanoparticles in case of SEM and EDX occurred. The biosynthesized Ag-Nanoparticles were assayed for their antibacterial activity against some human pathogens and for their potential on seed germination of Abelmoschus esculentus and Raphanus sativus var. longipinnatus. The antibacterial activity of biosynthesized Ag Nanoparticles was the highest against Proteus mirabilis (2.33±0.2 cm), followed by Klebsiella pneumoniae, (1±0.0 cm). The effect of biosynthesized Ag-Nanoparticles on the seed germination of Raphanus sativus var. longipinnatus was excellent as the germination rate was 100 percent for Ag-Nanoparticles treated seeds, which was better than normal seaweed extract and seaweed liquid fertilizer treated seeds. The seed germination was also good for Abelmoschus esculentus with the treatment of seaweed mediated Ag-Nanoparticles as germination rate was 60 percent. This work proved that seaweed synthesized Ag-Nanoparticles are Phyto-friendly in nature and in future nano-bio fertilizer may be used as the growth promoter and eco-friendly Nano-bio-fertilizer.
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A pioneering project in the Netherlands aims to determine whether offshore wind developments could double up as seaweed farms. The end result could be a nice revenue stream to wind farm operations, at relatively low cost, which is likely to be of interest to renewable power companies.
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Studies were made on the yield and physical properties of agar from Gelidiella aceiosa, Gracilaria arcuata and G. edulis and algin and mannitol from Padim boergesenii, Chnoospom implexa, Sargassum duplkatum, Turbimria conoides and T, ormta growing in eight islands of Lakshadweep. The yield of agar ranged from 16.9 to 43.1 % and gel strength from 42 to 278 gm/cm* in G. acerosa, G. arcuala and G. edulis. Algin varied from 4.4 to 27.3%and mannitol from 1.4 to 9.5% in the brown algae studied. The agar and algin yielding seaweeds can be exploited from Lakshadweep Islands as an additional resource of raw material to the Indian seaweed industries.
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Marine Agronomy Group, CAFNRM, UH-Hilo
200 W. Kawili st., HI 96720, USA
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