A PDF Power Point of "Evaluation of Biofuel Co-products as Ingredients for Aquafeeds".
Digital library
-
-
Presentation with no abstract
-
An excess of organic waste, containing up to 60% cellulose and hemicellulose is prodqced worldwide. The conversion of this cellulosic material to ethanol is discussed: The two-step process consisting of a hydrolysis step to glucose and the subsequent fermentation by yeasts; and the one-step process, a fermentation of the cellulose by the anaerobic thermophile Clostridium thermocellum, or by a thermophilic, anaerobic, defined mixed culture. The use of the latter seems to be very feasible. To achieve an economic process, it is suggested to combine this approach with a thermophilic fermentation of the effluent and/or stillage obtained to produce methane.
-
We quantified the effects of temperature, light and nitrogen availability on the growth and fatty acids (FAs) in three isolates of the green seaweed Derbesia tenuissima to portion the environmental and the genotypic (between isolates) components of variation. Growth ranged from 13 to 33% day−1 and 27% of the variation was between isolates and 48% of variation was explained by light intensity. The content of total FA (TFA) ranged from 34 to 55 mg g−1 dw and 49% of the variation was between isolates, while the TFA was 20% lower in the high light and low nitrogen treatment combination. The proportion of omega-3 polyunsaturated FA (PUFA(n-3)) ranged from 31 to 46% of TFA with a strong interactive effect of isolate and temperature. In two isolates, the proportion of PUFA(n-3) increased by 20% under cultivation at low temperature while in a third isolate temperature had no effect. Increases in PUFA(n-3) occurred with a stable content of TFA and high growth rates, leading to net increases in PUFA(n-3) productivity in two isolates. This research highlights the potential for environmental manipulation and strain selection to further improve the productivity and quality of fatty acids in seaweed.
-
Introduction
The objective of the MacroFuels project is to advance the technologies for producing liquid transportation biofuels from cultivated seaweed (or macroalgae). As a result, it is hoped that it will be possible to provide more sustainable transport fuels.
The MacroFuels concept sets out to progress the technologies for producing third generation biofuels from seaweed by assessing current system design concepts. These designs are informed by lab scale testing, field trials and modelling completed within the other work packages of the MacroFuels project. The biofuels production scenarios targeted as part of the MacroFuels concept are:
• Bio-ethanol via fermentation (EtOH process);
• Bio-butanol and bioethanol via ABE (acetone, butanol and ethanol) fermentation (ABE Process); and
• Bio-furanics via biphasic reaction with toluene and water, and reaction with bio-butanol and hydrogen.
This study reports an environmental life cycle assessment (LCA) of those biofuels which could be produced under the MacroFuels concept. The LCA evaluates the full value chain and thereby provides a better understanding of the potential environmental impacts of the large-scale cultivation of seaweed and its use as a feedstock for the production of biofuels.
A key driver for the development of biofuels in Europe is the renewable Energy Directive (2018/2001/EC) (the RED). The RED sets a target of 14% of energy for transport to come from renewable sources by 2030. For a biofuel to count towards this target, it must fulfil certain sustainability criteria set out in the RED with respect to greenhouse gas (GHG) emissions and should be identified as no / low risk for additional impacts from indirect land use change. Indirect land use change can increase the net GHG emissions from terrestrial crops used as biofuels, but seaweed is seen as a low risk crop in this context, as it is grown in the sea and will not displace land used to grow food.
Goal and Scope of the Study
The goal of this LCA was to conduct a ‘cradle-to-grave’ assessment of the MacroFuels concept. This will inform its future development by appraising the potential environmental impact of producing biofuels from seaweed for use as transport fuels and allow comparison of the calculated GHG emissions of these fuels with reported values for those produced from other sources.
The objectives of the LCA are as follows:
1. To increase MacroFuels’ understanding of the life cycle environmental impacts of the biofuels from seaweed concept;
2. Identify where the main environmental impacts occur (the so-called ‘hotspots’) in the full value chain for the production of biofuels from seaweed to support the design of systems for seaweed cultivation and processing to biofuel;
3. Compare the life cycle impacts of the ethanol, butanol and furanic fuels produced; and
4. Benchmark the biofuels assessed under the MacroFuels project against:
a. Equivalent conventional, fossil-based, fuels and currently available biofuels; and
b. Sustainability criteria for GHG emissions under the Renewable Energy Directive (2018/2001).
Product System Studied and Functional Unit
The study investigates the potential environmental impacts of the following products produced via the three processes outlined above. An important step in both the EtOH and ABE processes is the hydrolysis of the seaweed prior to fermentation. This can be completed by either acid hydrolysis or enzyme hydrolysis and both processes are considered, as follows.
• Ethanol (EtOH process - acid hydrolysis);
• Ethanol (EtOH process - enzyme hydrolysis);
• Ethanol (ABE process - acid hydrolysis);
• Ethanol (ABE process - enzyme hydrolysis);
• Butanol (ABE process - acid hydrolysis);
• Butanol (ABE process - enzyme hydrolysis);
• Furanics fuel additive; and
• Furanics fuel (10%) / bio-butanol (90%) blend
The functional unit this study is defined as:
1 MJ of biofuel used as transport fuel in an internal combustion engine.
Life Cycle Stages Considered
The LCA carried out was ‘cradle-to-grave’. This means that all significant life cycle stages associated with the product systems studied were considered, from raw materials, through processing and production, to distribution, use, waste collection, recycling or management at end of life.
Energy and material inputs were traced back to the extraction of resources, and emissions and wastes from each life cycle stage were quantified. Figure 0-1 shows the system boundary of the LCA.
Figure 0-1 System boundaries of LCA based on life cycle of biofuel from seaweed according to the MacroFuels concept
The Macrofuels concept considers a biorefinery with a processing capacity of 1.2 Mtonne seaweed (dw) per year, as this equivalent to that of an existing large bioethanol plant in the port of Rotterdam, the Netherlands.
Seaweed cultivation
The study assumes that only brown seaweed (Saccharina latissimi) is used as feedstock in the EtOH and ABE processes and only red seaweed (Palmaria palmate) is used as feedstock for the furanics process. It has been assumed that two harvests a year of these crops is possible. The cultivation systems and yields for both seaweeds are assumed to be the same.
The design of the seaweed cultivation system was based on a concept published in open literature (Groenendaal, Vandendaele, & Vroman, 2017; Sioen, 2015). The growing substrate for the seaweed is sheetnets, made from polyester non-woven material, held horizontally in the water by chains and bouys and arranged in repeating segments for a total effective area of the seaweed field of 18,460 ha. This will produce 1.2 Mtonne seaweed (dw) per year for the biorefinery.
Processing seaweed to biofuel
The data for processing seaweed to biofuel have been sourced from MacroFuels deliverable 6.2, Techno-economic Evaluation and Health and Safety Risk Assessment. Table 0-1below summarises the production processes for each scenario considered in the Macrofuels concept.
-
The impact of aquaculture on the environment and effects of environment on aquaculture production have become important issues in recent years. There is evidence from many countries that environmental deterioration is a major threat to aquaculture production and product quality. There is also evidence that marine and freshwater aquaculture can cause environmental change, which in some cases may adversely affect the long-term viability of the aquaculture operation itself, or result in serious conflicts with other users of aquatic resources. These problems have led to a need to consider aquaculture as one component in the aquatic ecosystem and to plan aquaculture development in a way which makes efficient use of resources. There have been several recent reviews of impacts associated with finfish (Beveridge, 1984; NCC, 1989), mollusc (ICES, 1989; NCC, 1989) and crustacean (Phillips et al, 1990) culture but there is little information on seaweed culture.
The main environmental impacts caused by aquaculture have been reviewed in several recent publications (NCC, 1989; ICES, 1989; NCC, 1990) and can be summarised as follows:
i. physical effects, including effects on water movement, the physical structure of terrestrial and aquatic habitats and aesthetic impacts;
ii. ecological effects, including changes in water quality, primary and secondary productivity and native fisheries.
These effects have arisen in many forms of aquaculture, although impacts vary considerably depending on the nature of the culture system and species cultured, plus the environment where the culture system is located. The main impacts and problems come from intensive aquaculture with high stocking densities and supplementary feeding, but problems have also arisen in extensive aquaculture systems.
Seaweed culture has expanded rapidly over the past few years, and in 1987 3,139,473 tons (wet weight) of seaweed were produced throughout the world, the bulk produced in Eastern Asia (FAO, 1989). This expansion has brought benefits in terms of income, employment and foreign exchange, but has also been accompanied by some conflicts with other users of the coastal zone and concerns over potential environmental impacts. The aim of this review is to consider some of the environmental implications associated with seaweed culture and ways in which issues may be resolved.
-
Coupling algae growth on wastewater with hydrothermal liquefaction (HTL) is regarded as an environmentenhancing pathway for wastewater management, biomass amplification, sustainable energy generation and value-added products generation. Through this integrated pathway, microalgae can not only recover nitrogen and phosphorus, but also absorb heavy metals from the wastewater. The migration and transformation of heavy metals need to be specifically assessed and considered due to the environmental concerns associated with metal toxicity. This work reviewed recent advances with respect to bioremediation mechanisms. Particular emphasis was placed on the heavy metal migration, transformation, and the key factors involved in algal wastewater treatment and biomass conversion. Additionally, the challenges of coupling algae wastewater treatment, hydrothermal conversion, and heavy metal control were addressed. Finally, a paradigm involving enhanced algal wastewater treatment and bioenergy production for field application was proposed.
-
The potential of algae-based biofuels to replace petroleum fuels and mitigate greenhouse gas production through microalgal photosynthesis has long been recognized. However, currently there are no commercial algae-to-fuels technologies that can overcome techno-economic barriers and address serious sustainability concerns. Coupling microalgae cultivation with wastewater treatment is considered as one of the most promising routes to produce bio-energy and bio-based byproducts in an economically viable and environmentally friendly way. This paper critically reviews the current status of this specific niche research area covering utilization of different types of wastewaters as media for algae cultivation, microalgae selection, bioreactor type, cultivation mode, environmental factors and operational parameters as well as harvesting techniques and production of a broad spectrum of biofuels and byproducts through various conversion pathways. Future development of practical solutions to key problems and integration of advanced algae cultivation and wastewater treatment, and system analysis approach to the evaluation of economic feasibility and sustainability of wastewater-based algal biofuel production are also discussed in depth.
-
The use of seaweed extracts as biostimulants to promote enhancements in other seaweed crops is gaining momentum. Here we examined if the seaweed-derived biostimulant Ascophyllum marine plant extract powder – AMPEP, enhanced growth and thermal tolerance of cultured thalli of Neopyropia yezoensis when grown under optimal and sub-optimal temperature conditions. We also examined if enhancements could be transferred to new blades through archeospore germination. Area, specific growth rate, reactive oxygen species (ROS) and protein content of thalli were measured as indicators of potential enhancement. The application of AMPEP significantly increased growth rates in thalli of N. yezoensis grown under optimal temperature conditions, whilst the thalli showed no indications of improved thermal tolerance. The collated data suggested that growth enhancement could be transferred from treated thalli to newly formed blades, which developed from archeospores. This study provides new evidence of the far-reaching potential of using extracts of selected seaweeds as biostimulants to support the cultivation of economically important Neopyropia species.
-
Intensive algal cultivation usually requires a high flux of dissolved inorganic carbon (Ci) to support productivity, particularly for high density algal cultures. Carbon dioxide (CO2) enrichment can be used to overcome Ci limitation and enhance productivity of algae in intensive culture, however, it is unclear whether algal species with the ability to utilise bicarbonate (HCO32) as a carbon source for photosynthesis will benefit from CO2 enrichment. This study quantified the HCO32 affinity of three green tide algal species, Cladophora coelothrix, Cladophora patentiramea and Chaetomorpha linum, targeted for biomass and bioenergy production. Subsequently, we quantified productivity and carbon, nitrogen and ash content in response to CO2 enrichment. All three species had similar high pH compensation points (9.7–9.9), and grew at similar rates up to pH 9, demonstrating HCO32 utilization. Algal cultures enriched with CO2 as a carbon source had 30% more total Ci available, supplying twenty five times more CO2 than the control. This higher Ci significantly enhanced the productivity of Cladophora coelothrix (26%), Chaetomorpha linum (24%) and to a lesser extent for Cladophora patentiramea (11%), compared to controls. We demonstrated that supplying carbon as CO2 can enhance the productivity of targeted green tide algal species under intensive culture, despite their clear ability to utilise HCO32.
Pages
Marine Agronomy Group, CAFNRM, UH-Hilo
200 W. Kawili st., HI 96720, USA
Contact: Marine.Agronomy.Group@gmail.com
Funding for this web portal is provided by the World Wildlife Fund and the University of Hawaii-Hilo.