Algae remain an attractive target for bioenergy applications over the longer term because of their high photosynthetic efficiency. However, near-term prospects for primary algae-based energy/fuels production remain poor due to the cost of cultivating and harvesting algae. While there has been substantial technical progress on algae-based bioenergy production in recent years, persisting low fossil fuel prices are causing the algae-based industry to shift its focus from biofuels/bioenergy products to higher value (non-fuel/energy) products that can be profitable today. Ultimately, the vision is that algal biomass-based co-products will provide the additional revenue needed to reduce the net cost of producing algal-based biofuels. As such, a biorefinery approach that enables multiple high-value products to be produced will be essential to fully valorize algal biomass and enable bioenergy coproduction. To accelerate implementation of algae-based production, progress in minimizing the energy, water, nutrients and land use footprints of integrated algal-based operations needs to be a primary objective of future larger scale demonstrations. This presentation will summarize findings of a recently completed IEA Bioenergy report on the status and prospects for using microalgae and macroalgae as feedstocks for biofuels and bioenergy production; the report is available at www.ieabioenergy.com. The scope of the areas covered includes international activities advancing bioenergy and non-energy bio-products from algae, bioenergy from macroalgae (both cast and cultivated seaweeds), distinct biochemical and thermochemical conversion pathways, biorefining opportunities, as well as process economics and sustainability issues.
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The importance of seaweeds as a marine resource has recently been emphasized due to the increasing demand for them as food and raw materials in the manufacture of industrial colloids, e.g. agars, carrageenan, and alginates which find varied uses in industries. In addition, the production of seaweeds through culture is now recognized as a very productive alternative source of livelihood and employment especially in developing countries in tropical Asia where a large portion of the shallow coastal fishery resources have been or are being depleted. With some exception, the present seaweed production in the tropics comes from the harvesting of wild stocks which if not regulated can result to the depletion of these stocks. Thus, it is necessary that culture and management of local stocks should be developed for the economic species to enhance and maintain their productivity.
The farming and gathering of economic species of seaweeds are labour-intensive form of activities which can help increase employment opportunities among the coastal communities and thus play an important role in enhancing their socio-economic conditions. The general ecology and productivity of shallow subtidal areas have been shown to greatly improve upon the introduction of seaweed farming. Additionally, the introduction of a management scheme for the gathering of local stocks shall also help conserve them.
The training of fishery extension workers, farm managers, and future seaweed farmers in the practical methods of culturing economic speices on Eucheuma, Gracilaria and Caulerpa, will promote further expansion of seaweed farming; on the inventory and assessment of local stocks of useful seaweeds shall promote and enhance the productivity and conservation of these species. It is for these reasons that this regional training was organized and implemented.
This training course was designed to develop and promote qualified expertise in seaweed farming to help in food production, provide cash crops and open new alternative employment to enhance the socio-economic welfare of coastal communities as well as offer practical training on seaweed farming and management of natural stocks of economically important seaweed species; improve technical knowledge about seaweeds and acquire practical skills in seaweed farming techniques, processing and marketing.
The course consisted of lectures and field training on the culture of Eucheuma, Caulerpa and Gracilaria, assessment and rational utilization of natural stocks of ecomomic species such as Sargassum, post-harvest and quality control of the produce and field study visits to existing farms. Basic lectures on the biology and ecology of seaweeds as well as methods on the identification and preparation of seaweed materials for research were also included as background information.
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The experiment shows that the seaweeds Gracilaria sp. can be used in maintaining water quality in closed culture systems by ready uptake of nitrogenous wastes excreted by the cultured organisms. The advantages of water reuse systems incorporating biological agents such as seaweeds for water management in closed systems.
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Gelidialian red algae, that contain rhizoidal filaments, except the family Gelidiellaceae were processed to make bleached pulps, which can be used as raw materials for papermaking. Red algae consist of rhizoidal filaments, cortical cells usually reddish in color, and medullary cells filled with mucilaginous carbohy- drates. Red algae pulp consists of mostly rhizoidal filaments.
Red algae pulp of high brightness can be produced by extracting mucilaginous carbohydrates after heating the algae in an aqueous medium and subsequently treating the extracted with bleaching chemicals. In this study, we prepared paper samples from bleached pulps obtained from two red algae species (Gelidium amansii and Gelidium corneum) and compared their properties to those of bleached wood chemical pulps.
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The valorisation of Anaerobic digestion waste streams into algal biomass to produce a protein alternative to soybeans could have significant commercial and environmental value. It has the benefit of alleviating the pressure of disposal of nutrient-rich digestate that is rich in nitrogen, phosphorous and trace metals, while potentially reducing the cost of microalgae production. Currently, the use of soybean protein in animal feed has significant negative environmental issues and high carbon footprint associated with its use. This study investigates three types of Anaerobic digestion to grow Phaeodactylum tricornutum Bohlin microalgae. The results found that the crude protein in all concentrations of cow waste and food waste digestates were found to produce a significantly higher concentration of crude protein in comparison to the F/2 control. In addition, cow waste 1% and pig waste 1% formulations were found to have favourable fatty acid profiles, which has significant health benefits in the livestock industry. There was no significant difference in the total fatty acids found in cow waste 1% and pig waste 1% digestates compared to the F/2 control, which was in the range of 243.4 to 269.4 mg/g (dry weight). The other formulations produced a significantly lower (p < .05) concentration of total fatty acids compared to the control. Cow waste 1% was found to be richer in omega-3, eicosapentaenoic acid, compared to pig waste 1%, however, no significant difference was found between the eicosapentaenoic acid, concentration of cow waste 1% and the F/2 control. Overall, in terms of highest total fatty acids and crude protein, cow waste 1% digestate was found to perform the best out of all the digestates tested, and outperformed the F/2 control in terms of crude protein. The P. tricornutum grown in digestate was also found to bioaccumulate higher levels of calcium. P. tricornutum grown in cow waste 1% digestate could offer an alternative viable locally grown protein source for the animal feed industry, with the added advantage of being rich in eicosapentaenoic acid and calcium.
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Concerns about fossil fuels depletion has led to seek for new sources of energy. The use of marine biomass (seaweed) to produce biofuels presents widely recognized advantages over terrestrial biomasses such as higher production ratio, higher photosynthetic efficiency or carbon-neutral emissions. In here, interesting seaweed sources as a whole or as a residue from seaweed processing industries for biofuel production were identified and their diverse composition and availability compiled. In addition, the pretreatments used for seaweed fractionation were thoroughly revised as this step is pivotal in a seaweed biorefinery for integral biomass valorization and for enabling biomass-to-biofuel economic feasibility processes. Traditional and emerging technologies were revised, with particular emphasis on green technologies, relating pretreatment not only with the type of biomass but also with the final target product(s) and yields. Current hurdles of marine biomass-to-biofuel processes were pinpointed and discussed and future perspectives on the development of these processes given.
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Thermochemical techniques are being operated for the complete conversion of diverse biomasses to biofuels. Among the feedstocks used for thermochemical processes, algae are the promising biomass sources owing to their advantages over other feedstocks such as biomass productivity, renewability and sustainability. Due to several advantages, algal biomass is considered as a source for third generation biofuel. This review work aims to provide a state-of-the-art on the most commonly used thermochemical methods namely torrefaction, pyrolysis, and gasification processes. Furthermore, the production of biofuels from algal biomass was comprehensively articulated. Different algal strains used in thermochemical techniques and their conditions of operation were compared and discussed. The yield and quality of solid (char), liquid (bio-oil) and gaseous (syngas) products obtained through thermochemical methods were reviewed and analysed to understand the efficacy of each technique. End product percentage, quality and advantages of the torrefaction, pyrolysis, and gasification were summarized. It is found that the biofuel produced from the torrefaction process was easy to store and deliver and had higher utilization efficiency. Among the existing thermochemical methods, the pyrolysis process was widely used for the complete conversion of algal biomass to bio-oil or char. This study also revealed that the gasification (supercritical) method was the most energy efficient process for conversion of wet algal biomass. The reactor used in the thermochemical process and its subprocess was also highlighted. This study revealed that the fixed bed reactor was suitable for small scale production whereas the fluidized bed reactor could be scaled up for industrial production. In addition to that environmental impacts of the products were also spotlighted. Finally, the perspectives and challenges of algal biomass to bioenergy conversion were addressed.
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Pulp & Paper, Bioethanol Made from Red Algae.
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Growth, proximate composition, chlorophyll a, and carotenoid content were estimated in static cultures of micro alga Dunaliella salina (Dunal) Teod (Chlorophycea: Dunaliellaceae) to compare the quality and quantity of biomass produced with seaweed liquid fertilizer (SLF) against Walne’s medium. Culture of micro algae was performed with controlled temperature of 27 ± 1 °C, salinity of 33, and an irradiance of 120 ± 3 μ mol m–2 s –1, and daily samples were taken to estimate the above-mentioned parameters. Mean cellular density from samples of both medium were similar and growth rates were 0.44 and 0.42 doubling per day, respectively.
Maximum values of protein content 5.2 and 5.5 pg per cell were estimated on day 5 in Walne’s medium and SLF, respectively. Carbohydrate and lipid content decreased during the first 4 days corresponding to the culture exponential growth. Higher carbohydrate content was found in both media during the first 2 days and thereafter reduced partially compared to their concentrations. Generally lipid contents in cultures with SLF were significantly higher (P ≤0.05) compared to Walne’s medium. Both pigments also increased exponentially and their concentration was same in both experiments. In conclusion, all the parameters tested were similar when using either media, and hence SLF can be used as an alternate media for micro algal culture.
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Protoplast is an important tool for parasexual modification of genetic content of plant cells (Vasil and Vasil, 1980). Production of algal protoplasts and their fusion are relatively new fields and lag far behind that of terrestrial plants (Berliner 1981, 1983; Cheney et af., 1986). To date, protoplasts have been isolated from several algae, most of which are blue green algae and green algae (Adamich and Hemmingsen, 1980). Protoplasts have been obtained from some marine brown algae (Kloareg and Quantrano, 1987).
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Marine Agronomy Group, CAFNRM, UH-Hilo
200 W. Kawili st., HI 96720, USA
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