Digital library

  • Brown seaweeds lack lignin and have a low cellulose content. Thus, seaweeds should be an easier material for biological degradation than land plants. However, seaweeds have a complex composition, and complete degradation of the material necessitates the presence of microorganisms with a broad substrate range. During anaerobic degradation of organic material, energy carriers such as methane and ethanol may be produced. This is a study of two particular species of brown seaweeds; Laminaria hyperborea and Ascophyllum nodosum, which are the most abundant Norwegian species and also the two species that are commercially harvested in Norway. 

    Most of the degradation studies were carried out in batch systems at pH 7 and at 35 °C. The digestion pattern of the seaweeds were studied by measuring gas production, alginate lyase activity, remaining alginate, the concentrations of uronic acids, VS, COD, mannitol, organic acids and polyphenols. NIR spectroscopy was applied as a new method for alginate quantification. Ethanol production was carried out at 30 °C at different pH, both in batch and continuous cultures. Gas production and concentrations of mannitol, laminaran, ethanol and organic acids were measured. 

    Methane is the end product of a mixed microbial community. However, it is the initial steps of hydrolysis and acidogenesis that are specific for the raw material. Alginate forms the major structural component of brown algae, and its degradation is catalysed by alginate lyases. Polyphenols proved to be the most important limiting factor in the biodegradation: the content of polyphenols was much higher in A. nodosum than L. hyperborea, and this led to a reduced biodegradability of A. nodosum. However, when the polyphenols were fixed with formaldehyde, this seaweed was also readily degraded. Manipulation of the content of polyphenols in L. hyperborea gave similar results. This toxic effect was probably caused by direct inhibition of the microbes, especially the methanogenic bacteria, and complexation reactions with algal material and enzymes. Generally, the guluronate content of the remaining alginate increased during biodegradation, probably due to the Ca-linked guluronate junction zones less accessible for alginate lyase. The main organic product of the acidogenesis was acetate, which was easily converted to methane. In this study, it was not attempted to optimise the methane yield. 

    Ethanol is an intermediate in the complete digestion of organic material and is produced by specific microbial strains. Thus, ethanol production should take place under controlled conditions to prevent contamination problems. The complex composition of seaweeds makes it a difficult substrate to ferment to ethanol by one or a few strains of microbes. In this work, laminaran and mannitol extracted from L hyperborea fronds were used as substrate for ethanol production. A bacterium, Zymobacter palmae, was able to produce ethanol from mannitol, but could not utilise laminaran. However, the yeast Pichia angophorae was able to produce ethanol from both substrates simultaneously. Some supply of oxygen was necessary for the fermentation of mannitol, while a too high aeration resulted in the production of organic acids. 

    Thus, it has been shown that both methane and ethanol can be produced from brown seaweeds. However, an optimisation of the processes will be necessary. Energy production from seaweeds will only be economic if the harvesting costs are low. It may be noted that wastes from the alginate industry may be considered a non-cost raw material for energy production. 

    Author(s): Svein Jarle Horn
  • This study describes the method development for bioethanol production from three species of seaweed. Laminaria digitata, Ulva lactuca and for the first time Dilsea carnosa were used as representatives of brown, green and red species of seaweed, respectively. Acid thermo-chemical and entirely aqueous (water) based pre-treatments were evaluated, using a range of sulphuric acid concentrations (0.125–2.5 M) and solids loading contents (5–25 % [w/v]; biomass: reactant) and different reaction times (5–30 min), with the aim of maximising the release of glucose following enzyme hydrolysis. A pre-treatment step for each of the three seaweeds was required and pre-treatment conditions were found to be specific to each seaweed species. Dilsea carnosa and U. lactuca were more suited with an aqueous (water-based) pre-treatment (yielding 125.0 and 360.0 mg of glucose/g of pretreated seaweed, respectively), yet interestingly non pre-treated D. carnosa yielded 106.4 g g−1 glucose. Laminaria digitata required a dilute acid thermo-chemical pre-treatment in order to liberate maximal glucose yields (218.9 mg glucose/g pre-treated seaweed). Fermentations with S. cerevisiae NCYC2592 of the generated hydrolysates gave ethanol yields of 5.4 g L−1, 7.8 g L−1 and 3.2 g L−1 from D. carnosa, U. lactuca and L. digitata, respectively. This study highlighted that entirely aqueous based pretreatments are effective for seaweed biomass, yet bioethanol production alone may not make such bio-processes economically viable at large scale.

    Author(s): Emily T. Kostas, David A. White, David J. Cook
  • We evaluated the potential of three seaweed species (Ulva pertusa, Saccharina japonica, Gracilariopsis chorda) as biofilters for effluents from black rockfish (Sebastes schlegeli) tanks. The experiments consisted of a fish monoculture system and a fish-seaweed integrated system under identical physical conditions. All species efficiently removed NH 4 + , NO 3 – + NO 2 – , and PO 4 3– from the fish tank effluents. Of the three species evaluated, U. pertusa showed the highest biofil-tering efficiency for NH 4 + (>80%). In contrast to U. pertusa and G. chorda, S. japonica showed a relatively higher prefer-ence for NO 3 – + NO 2 – than for NH 4 + . These results suggest that seaweeds may select nitrogen sources fitting their storage capacity. Therefore, standard fish farm effluents should establish a total nitrogen concentration that includes both NO 3 – and NH 4 + , and the selection of a biofilter seaweed species should be made with consideration of the N forms expelled in effluent. The biofiltering efficiency for PO 4 3– was highest in G. chorda (38.1%) and lowest in S. japonica (20.2%). In all species, tissue N and P contents rapidly increased over the initial values. The data for tissue N and P contents, and C : N and N : P ratios, indicate that neither N nor P was limiting. This suggests that the three species serve as biofilters by stor-ing large amounts of nutrients. These results provide valuable information for selecting optimal seaweed species in fish-seaweed integrated systems and allow land-based integrated aquaculture system operators to understand the behavior of integrated cultures sufficiently for the results herein to be extrapolated to larger-scale cultures.

    Author(s): Yun Hee Kang, Sang Rul Park, Ik Kyo Chung
  • The shortage of fossil fuels is actually a major economic issue in the context of increasing energy demand. Renewableenergies are thus gaining in importance. For instance, microalgae-based fuels are viewed as an alternative. Microalgae aremicroscopic unicellular plants, which typically grow in marine and freshwater environments. They are fast growing, havehigh photosynthetic efciency, and have relatively small land requirement and water consumption in comparison with con-ventional land crops biofuels. Nonetheless, selling biofuels is still limited by high cost. Here, we review biofuel productionfrom microalgae, including cultivation, harvesting, drying, extraction and conversion of microalgal lipids. Cost issues maybe solved by upstream and downstream measures: (1) upstream measures, in which highly productive strains are obtainedby strain selection, genetic engineering and metabolic engineering, and (2) downstream measures, in which high biofuelsyields are obtained by enhancing the cellular lipid content and by advanced conversion of microalgal biomass to biofuels.Maximum biomass and high biofuels production can be achieved by two-stage culture strategies, which is a win–win approachbecause it solves the conficts between cell growth and biomass accumulation.

    Author(s): Licheng Peng , Dongdong Fu, Huaqiang Chu, Zezheng Wang, Huaiyuan Qi
  • Sustainable energy is the need of the 21st century, not because of the numerous environmental and political reasons but because it is necessary to human civilization's energy future. Sustainable energy is loosely grouped into renewable energy, energy conservation, and sustainable transport disciplines. In this review, we deal with the renewable energy aspect focusing on the biomass from bioenergy crops to microalgae to produce biofuels to the utilization of high-throughput omics technologies, in particular proteomics in advancing our understanding and increasing biofuel production. We look at biofuel production by plant- and algal-based sources, and the role proteomics has played therein. 

    Author(s): Bongani Kaiser Ndimba , Roya Janeen Ndimba, T. Sudhakar Johnson, Rungaroon Waditee-Sirisattha, Masato Baba, Sophon Sirisattha, Yoshihiro Shiraiwa, Ganesh Kumar Agrawal, Randeep Rakwal
  • The Aquatic Feeds and Nutrition Department (AFN) of the Oceanic Institute hosted a workshop on the use and processing of biofuel co-products in feeds for fish, shrimp, urchin and shellfish. The continuing demand for alternative energy sources is driving innovative uses of plant products as feedstock for biofuels. This means that an array of new co-products are becoming available for potential use in aquafeeds.

    Author(s): Aquafeed.com Staff
  • Production and use of transport biofuels have a history of considerable length. The prototype of the Otto motor, which currently powers gasoline cars, was developed for burning ethanol and sponsored by a sugar factory. The Ford Model T (Tin Lizzy) did run on ethanol. In the early twentieth century, ethanol-fuelled cars were praised because they experienced less wear and tear, were quieter and produced a less smoky exhaust than gasoline-fuelled cars (Dimitri and Effland 2007). Also in the early twentieth century, a significant part of train locomotives in Germany were powered by ethanol (Antoni et al. 2007). In the same country, ethanol from potato starch was used in gasoline as an anti-knocking additive between 1925 and 1945 (Antoni et al. 2007). In the 1930s, ethanol produced from starch or sugar made something of a comeback as road transport fuel in the Midwestern states of the USA, because agricultural prices were very depressed (Solomon et al. 2007). Also in the 1930s, the Brazilian government stimulated gasoline blends with 5% bioethanol. 

    Early demonstrations of the diesel motor around 1900 in Paris and St Peters- burg were with a variety of plant- and animal-derived oils. These were thought especially interesting for use in tropical and subtropical countries, where the rela- tively high viscosity of such oils, if compared with fossil diesel, is less of a problem than in colder countries (Knothe 2001). The first patent on making fatty acid esters (biodiesel) was awarded in 1937 and applied in 1938 to powering buses in Belgium (Knothe 2001). During the Second World War, vegetable oils re-emerged as fuels for diesel motors in countries like Brazil, Argentina and China (Knothe 2001). In Japan, soybean oil was used to power ships, pine root oil was used as a high-octane motor fuel and biogenic butanol was used in airplanes (Tsutsui 2003). The Japanese navy conducted extensive research on the production of diesel fuel from coconut oil, birch bark, orange peel and pine needles (Tsutsui 2003). Also, during the Second World War, substitutes for mineral-oil-based gasoline and kerosene were produced in China by the catalytic cracking of vegetable oils (Knothe 2001). Furthermore, thermal destruction of wood was used for producing road transport fuel during the World Wars in Europe (Reed and Lerner 1973). 

    The post-World War II re-emergence of transport biofuel use dates from the 1973 hike in petroleum prices, or the ‘first oil crisis’. Tax reductions, subsidies, support for research and development, obligations to fuel providers and artificially high fuel economy ratings for flex fuel cars, which are suitable for high percentages of biofuel in transport fuel, were important government instruments used in this re-emergence (Demirbas ̧ 2007; Szklo et al. 2007; Tyner 2007; Wiesenthal et al. 2008). By now, large sums of money are involved in such support. It has been estimated that in 2006, about US $11 billion was spent on public support measures by the USA, Canada and the European Union (OECD 2008). 

    Due to the first oil crisis of 1973, Brazil decided to reduce its dependence on the import of mineral oil by establishing a National Alcohol Program to supply ve- hicles. This program started in 1975, using sugar cane as a feedstock. A second program stimulating the use of ethanol began in the USA in 1978, using mainly corn and to a much lesser extent sorghum as feedstocks (Wheals et al. 1999; Wang et al. 2008a). In the USA, arguments for subsidizing the production of bioethanol since 1978 have included energy security, supporting farm prices and incomes and improvement of air quality (Tyner 2007). Several Canadian provinces started out using 5–10% ethanol–gasoline mixtures in the 1980s (Szklo et al. 2007). The ‘re- discovery’ of biodiesel occurred in the 1980s. Biodiesel initiatives were announced in 1981 in South Africa and in 1982 in Germany, New Zealand and Austria (Kör- bitz 1999). In Europe, substantial production of biodiesel started from about 1987 and in the USA from the 1990s (Knothe 2001). The relatively large production of biofuels in countries such as Germany, France, Italy, Austria and Spain had much to do with an interest in the development of new agricultural markets (Di Lucia and Nilsson 2007). Geopolitical worries about the supply of crude mineral oil and price rises affecting this dominating feedstock for current transport fuels furthered a rapid increase in biofuel production in the twenty-first century, especially after 2004 (Heiman and Solomon 2007). 

    The production of conventional mineral oil is likely to peak in the coming decades (GAO 2007; Bentley et al. 2007; Kaufmann and Shiers 2008). An adequate supply thereof may therefore become increasingly expensive and difficult. This has led to calls to – in the words of former US president G. W. Bush – kick the oil ‘ad- diction’ (Bush 2006). Timeliness of a transition to alternative fuels has been stressed (Kaufmann and Shiers 2008). ‘Home-grown’ biofuels, especially, have been argued to be suitable for energy security (Tyner 2007). There is also much concern about the pollution originating in the burning of fossil fuels. Recently, the effects thereof on climate have become important on the international political agenda. This, in turn, has led to increasing calls to reduce the emission of greenhouse gases, such as CO2. Such calls extend to transportation because worldwide transport accounts for about 22% of the total use of primary energy and is overwhelmingly mineral oil based (de la Rue du Can and Price 2008). For instance, regarding the USA, min- eral oil accounted in 2006 for about 97.8% of total transport energy use (Heiman 

    1.2 ThePhysicalBasisforBiofuels 3 

    and Solomon 2007). Worldwide, the consumption of petroleum products represents 94% of energy use in the transportation sector (de la Rue du Can and Price 2008), whereas in 2004, about 60% of all mineral oil was used for transportation (Quadrelli and Peterson 2007). Proponents of biofuels have argued that replacement of mineral oil by biofuels is a good way to reduce greenhouse gas emissions. 

    It has furthermore been stated that the potential for replacing fossil transport fuels with biofuels is very substantial indeed. de Vries et al. (2007) have suggested that by 2050, up to 300 EJ (= 300 × 1018 J) of liquid biofuels may be produced worldwide. An even higher estimate for liquid biofuel production by 2050 (455 EJ) has been proposed by Moreira (2006). Such amounts can in all probability cover demand for transport fuels in 2050, as the 2007 primary energy consumption for transport amounted to about 100 EJ (de la Rue du Can and Price 2008). Use of transport fuels by means of transport (‘end use’) was probably in the 85–90 EJ range, with the remaining amount used for winning, refining and distribution (Colella et al. 2005; EUCAR et al. 2007; Winebrake et al. 2007). The potential importance of biofuels in replacing fossil transport fuels is by now much stressed by the Brazilian government. In Brazil, ethanol from sugar cane is currently a substantial transport biofuel. In 2004, its share in energy for road transport was near 14% and in 2007 about 20% (OECD 2008). In 2006, 70% of the new cars sold in Brazil were ‘flex cars’, able to run on either 100% ethanol or a fossil fuel–ethanol blend (Quadrelli and Peterson 2007). The claims about the benefits and potential of transport biofuels have, however, been contested. And the resulting debate has been much fuelled by the high food prices in 2008, which have been partially linked to increasing transport biofuel production (OECD-FAO 2007). 

    This book will give a seed-to-wheel perspective on biofuels for road transport and will deal with a number of environmental issues that have emerged in the current biofuel debate. This first chapter is introductory and structured as follows: firstly, Sects. 1.2–1.6 will deal with the physical basis and the variety of biofuels and the ways to produce and apply them in transport. Secondly, in Sect. 1.7, developments in production volume, costs and prices will be discussed. Thereafter, in Sect. 1.8, the debate on the pros and cons of transport biofuels that has emerged will be briefly surveyed, and the rest of the book will be outlined. 

    Author(s): Lucas Reijnders , Mark A. J. Huijbregts
  •  

    It has been argued that the energy output from microalgal biofuel pro- duction should at least be 58 times the energy input, apart from solar irradiation driving algal photosynthesis. There is as yet no commercial production of microalgal biodiesel or large-scale demonstration project to check whether this criterion regarding the energy balance can be met in actual practice. There is, however, a set of relatively well-documented peer-reviewed scientific papers esti- mating energy inputs and outputs of future autotrophic microalgal biodiesel pro- duction. Energy balances for biodiesel from autotrophic microalgae grown in ponds tend to be better than for biodiesel from such microalgae grown in bioreactors. The studies regarding energy balances for biodiesel derived from microalgae grown in open ponds are considered here. None of these energy balances meets the criterion that the energy output should exceed the energy input by a factor 58. Estimated energy balances are variable due to divergent assumptions about microalgal vari- eties, applied algal and biodiesel production technologies, assumed parameters and yields and due to differences in system boundaries, allocation, and the use of credits. The studies considered here could have done better in handling uncer- tainties in estimated energy balances.

     

     
    Author(s): Lucas Reijnders
  • The industrial potential of ethanol has been tested early in 1800 to be used as an engine fuel after the invention of an internal combustion engine. Currently, there are three generations of bioethanol that have been flourished based on different feedstocks. The first-generation bioethanol is derived from fermentation of glucose contained in starch and/or sugar crops. USA and Brazil are the main producers of bioethanol worldwide utilizing corn and sugarcane, while potato, wheat, and sugar beet are the common feedstocks for bioethanol in Europe. The term second-generation bioethanolemerged as a boon to overcome the food versus fuelthat occurs by the first-generation bioethanol. The second generation also referred to as advanced biofuelsis produced by innovative processes mainly using lignocellulosic feedstock and agricultural forest residues. The emergence of the third-generation bioethanol provides more benefits as compared to the first and second generations and is focused on the use of microalgae and cyanobacteria. These organisms represent as a promising alternative feedstock due to its high lipid and carbohydrate contents, easy cultivation in a wide variety of water environment, relatively low land usage and carbon dioxide absorption. This chapter will discuss the use of microalgae for the ethanol production and the main technological routes, i.e., enzymatic hydrolysis and yeast fermentation of microalgal biomass, metabolic pathways in dark conditions, and photofermentation.

    Author(s): Reinaldo Gaspar Bastos
  • Rapid industrialization and urbanization are mainly responsible for the energy crisis, environmental pollution and climate change. In addition, depletion of the fossil fuels is a major concern now. To confront these problems, it is essential to produce energy from sustainable and renewable energy sources. Hydrogen is widely considered as a clean and efficient energy carrier for the future because it does not produce carbon-based emission and has the highest energy density among any other known fuels. Due to the environmental and socioeconomic limitation associated with conventional processes for the hydrogen production, new approa- ches of producing hydrogen from biological sources have been greatly encouraged. From the perspective of sustainability, microalgae offer a promising source and have several advantages for the biohydrogen production. Microalgae are charac- terized as high rate of cell growth with superior photosynthetic efficiency and can be grown in brackish or wastewater on non-arable land. In recent years, biohy- drogen production from microalgae via photolysis or being used as substrate in dark fermentation is gaining considerable interest. The present chapter describes the different methods involved in hydrogen production from microalgae. Suitability of the microalgae as a feedstock for the dark fermentation is discussed. This review also includes the challenges faced in hydrogen production from microalgae as well as the genetic and metabolic engineering approaches for the enhancement of bio- hydrogen production.

    Author(s): Harshita Singh, Debabrata Das

Pages