Microalgal biofuels: Flexible bioenergies for sustainable development

Abstract – To confront energy shortage, global warming and climate changes, biofuels derived from biomass have received increasing attention from the industry, academia and governments. Of the potential sources of biofuels a most promising one is the simple photosynthetic microalgae, which can be grown in open ponds, photobioreactors and fermenters. The advantages to produce biofuels from microalgae include easy adaption to environmental conditions, high photosynthesis efficiency, high lipid content and noncompetition for farmlands. Nonetheless, the real hallmark of microalgae is the fact that these microscopic organisms can provide the biomass feedstock for the flexible production of several different types of renewable and sustainable biofuels such as biodiesel, bioethanol, biogas, biohydrogen among others via thermochemical and biochemical conversion processes. Amazingly, from a sustainability perspective the integrated algal biofuels production, where biodiesel, bioethanol and biogas are continuously produced from one biomass source, can evidently lead to an increase in the energetic productivity of the microalgal biomass, thus improving the economics of this algal biorefinery approach. Developments in several areas, such as genetic and metabolic engineering, are expected to further improve the costeffectiveness of the biofuels from microalgae in an environmentally sustainable manner.

Source: ScienceDirect, December 2, 2013

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New Tools for Precision Feeding

The Pig Site – The current high feed costs increase the need for developing cost-effective feeding strategies for growing-finishing pigs. Well-tested mathematical models that represent nutrient utilisation for growth allow for a systematic approach to optimising feeding programmes for individual pig units, considering local pig performance potentials and available feed ingredients, as well as environmental and economic conditions.

In this paper, Professor Kees de Lange presented examples are given where the NRC (2012) Nutrient Requirements of Swine model for growing-finishing pigs is used to explore effects of gender, pig performance potentials, feed intake, and use of high-fibre co-products as feed ingredients on nutrient requirements.

These examples stress the need to monitor closely current performance and to evaluate feeding programmes regularly…>>Continue Reading<<

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Estimating the Biodiesel Supply Curve

The CROP Site – The purpose of this post is to derive the biodiesel supply curve from the relationships first presented in the September 25 post.

We begin by reviewing the main results of that earlier post. Figure 1 shows a scatter of monthly biodiesel production and net returns above variable costs for each calendar year between 2010 and 2013. Monthly biodiesel production is estimated by the EIA and monthly biodiesel net production returns above variable costs are based on a model of a representative Iowa biodiesel plant (see the post here).

A best-fit regression line is also shown for each year, with the natural log (ln) of production used as the dependent variable. The data are divided by calendar years because in years when the blenders tax credit is not in place (2010 and 2012) there is little relationship between biodiesel production and returns. Basically, production in these years is “stuck” at the RFS biodiesel mandate regardless of the level of returns.

In the other years (2011 and 2013) market participants expect the credit to expire at the end of a calendar year, so there there is an obvious incentive for blenders to bid up the price of biodiesel in order to increase production and take full advantage of the credit before it expires. In essence, the unusual market circumstances in 2011 and 2013 provide a unique opportunity to identify a biodiesel supply curve even with a seemingly binding RFS mandate in place…>>Continue Reading<<

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Effects of Slaughtering Methods on Protein Denaturation of Frozen Pacu Fillets

Viegas et al, October 2013

Summary – Pacu is an omnivorous, freshwater fish typical of the wetlands located in South Mato Grosso, Brazil, which can also be found in the rivers of the Amazon and Prata basins. It is a species widely cultivated in Brazil due to its fast growth, hardiness and good acceptance by the consumers (MPA, 2010).

The freshwater fish cultivated in Brazil are most commonly stunned and slaughtered by thermal shock (1:1 water and ice); a method that is proven stressful since it does not kill immediately and can affect meat quality.

Due to pacu importance to Brazilian Aquaculture, it is necessary to determine the best slaughtering method in order to improve meat quality. The objective of this study is to evaluate how the usual methods used to slaughter pacu (electrical stunning, thermal shock and CO2 narcosis) influence protein denaturation of frozen fillets stored for 180 days.

Click here to access the complete article

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Assessment of N2O emission from a photobioreactor treating ammonia-rich swine wastewater digestate

Mezarri et al., October, 2013

 

Abstract – This study investigated the interactions between naturally occurring bacteria and the microalgae Chlorella vulgaris within a lab scale photobioreactor treating ammonia-rich swine wastewater digestate effluent. Nitrification and denitrification were assessed by targeting ammonia monoxygenases (amoA), nitrate (narG), nitrite (nirS), nitric oxide (norB) and nitrous oxide (nosZ) reductases genes. Oxygen produced from microalgae photosynthesis stimulated nitrification. Under limiting carbon availability (i.e., <1.44 for mg TOC/mg NO2-N and 1.72 for mg TOC/mg NO3–N), incomplete denitrification led to accumulation of NO2 and NO3. Significant N2O emission (up to 118 μg N2O–N) was linked to NO2 metabolism in Chlorella. The addition of acetate as external carbon source recovered heterotrophic denitrification activity suppressing N2O emission. Effluent methane concentrations trapped within photobioreactor was removed concomitantly with ammonia. Overall, closed photobioreactors can be built to effectively remove nitrogen and mitigate simultaneously greenhouse gases emissions that would occur otherwise in open microalgae-based wastewater treatment systems.

 

Click here to access the article at ScienceDirect

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Optimization methods applied to renewable and sustainable energy: A review

Science Direct (Summary) – Energy is a vital input for social and economic development. As a result of the generalization of agricultural, industrial and domestic activities the demand for energy has increased remarkably, especially in emergent countries. This has meant rapid grower in the level of greenhouse gas emissions and the increase in fuel prices, which are the main driving forces behind efforts to utilize renewable energy sources more effectively, i.e. energy which comes from natural resources and is also naturally replenished. Despite the obvious advantages of renewable energy, it presents important drawbacks, such as the discontinuity of generation, as most renewable energy resources depend on the climate, which is why their use requires complex design, planning and control optimization methods.

Biofuels from microalgae—A review of technologies for production, processing, and extractions of biofuels and co-products

Science Direct (Summary) – Sustainability is a key principle in natural resource management, and it involves operational efficiency, minimisation of environmental impact and socio-economic considerations; all of which are interdependent. It has become increasingly obvious that continued reliance on fossil fuel energy resources is unsustainable, owing to both depleting world reserves and the green house gas emissions associated with their use. Therefore, there are vigorous research initiatives aimed at developing alternative renewable and potentially carbon neutral solid, liquid and gaseous biofuels as alternative energy resources. However, alternate energy resources akin to first generation biofuels derived from terrestrial crops such as sugarcane, sugar beet, maize and rapeseed place an enormous strain on world food markets, contribute to water shortages and precipitate the destruction of the world’s forests. Second generation biofuels derived from lignocellulosic agriculture and forest residues and from non-food crop feedstocks address some of the above problems; however there is concern over competing land use or required land use changes.

Microalgae for biodiesel production and other applications: A review

Science Direct – (Summary) –  Sustainable production of renewable energy is being hotly debated globally since it is increasingly understood that first generation biofuels, primarily produced from food crops and mostly oil seeds are limited in their ability to achieve targets for biofuel production, climate change mitigation and economic growth. These concerns have increased the interest in developing second generation biofuels produced from non-food feedstocks such as microalgae, which potentially offer greatest opportunities in the longer term. This paper reviews the current status of microalgae use for biodiesel production, including their cultivation, harvesting, and processing. The microalgae species most used for biodiesel production are presented and their main advantages described in comparison with other available biodiesel feedstocks. The various aspects associated with the design of microalgae production units are described, giving an overview of the current state of development of algae cultivation systems (photo-bioreactors and open ponds). Other potential applications and products from microalgae are also presented such as for biological sequestration of CO2, wastewater treatment, in human health, as food additive, and for aquaculture…>>Continue reading<<

Source: Science Direct

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Dissecting yield-associated loci in super hybrid rice by resequencing recombinant inbred lines and improving parental genome sequences

Abstract – The growing world population and shrinkage of arable land demand yield improvement of rice, one of the most important staple crops. To elucidate the genetic basis of yield and uncover its associated loci in rice, we resequenced the core recombinant inbred lines of Liang–You–Pei–Jiu, the widely cultivated super hybrid rice, and constructed a high-resolution linkage map. We detected 43 yield-associated quantitative trait loci, of which 20 are unique. Based on the high-density physical map, the genome sequences of paternal variety 93–11 and maternal cultivar PA64s of Liang–You–Pei–Jiu were significantly improved. The large recombinant inbred line population combined with plentiful high-quality single nucleotide polymorphisms and insertions/deletions between parental genomes allowed us to fine-map two quantitative trait loci, qSN8 and qSPB1, and to identify days to heading8 and lax panicle1 as candidate genes, respectively. The quantitative trait locus qSN8 was further confirmed to be days to heading8 by a complementation test. Our study provided an ideal platform for molecular breeding by targeting and dissecting yield-associated loci in rice.

Source: PNAS, 10th April, 2013

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Dynamic Emergy Valuation of Water Hyacinth Biomass in Wetlands: an ecological approach

Buller et al.
Summary – The water hyacinth (Eicchornia spp), characterized by elevated growth rates, is a native aquatic weed in the Pantanal wetland and represents the main species in aquatic floating mats that are carried by the Paraguay River according to the wetland flood pulse dynamics. The floating mats have a role in nutrient cycling to consumers of detritivorous food webs, such as typical fish of the region. Nonetheless there are potentials of using water hyacinth biomass to produce biofuels and biomaterials through biomass conversion techniques like anaerobic digestion and pyrolysis. Biomass growth of water hyacinth was modeled in the floodplain of the Upper Paraguay River basin to identify the underlying dynamics by means of emergy analysis. Emergy modeling has permitted to obtain monthly unit emergy values (UEVs) useful to evaluate the economic feasibility of water hyacinth biomass use in phase with the flood pulse of the Pantanal wetland. This approach can be replicated to other natural or constructed wetlands where the aquatic weeds growth is excessive.

Source: ScienceDirect, 16th May, 2013
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