Techno-economic and environmental assessment of an olive stone based biorefinery

Olive tree cultivation is spreading worldwide as a consequence of beneficial effects of olive oil consumption. Olive oil production process and table olive industries are the major sources of olive stones. Currently, this by-product is used in direct combustion to produce energy as electricity or heat. However, there are other possibilities for taking full advantage of a renewable source of interesting compounds. In this work the techno-economic and environmental assessment of two biorefinery schemes and its comparison with the direct combustion (base case) of this residue are presented. The first biorefinery scheme describes the integrated production of xylitol, furfural, ethanol and poly-3-hydroxybutyrate (PHB). The second biorefinery scheme considers the production of xylitol, furfural, ethanol and PHB integrated to a cogeneration system for producing bioenergy from the solid residues resulting from the mentioned processes. The results showed that in the first biorefinery scheme, the net profit margin is approximately 53%, while the second present a net profit margin of 6%.     

Environmental assessment of propionic acid produced in an agricultural biomass-based biorefinery system

This paper presents an environmental system study of the production of propionic acid in a biorefinery system based on agricultural by-products. Here, propionic acid is produced by fermentation of glycerol, a by-product from biodiesel production, as carbon source and potato juice, a by-product from starch production, as nitrogen source. Biomass-based propionic acid leads to a greenhouse gas reduction of 60% compared to propionic acid from fossil sources. However, the primary energy input is about twice as high for the biomass-based propionic acid. The choice of input energy and the efficiency of the process, as well as the technology applied, have high impacts on the environmental performance of the biorefinery concept. There is a potential for increased integration both on the input of substrates and the output of end products of the biorefinery system, which will further improve its environmental performance.     

Methodological advancements in Life Cycle Process Design: A preliminary outlook

This paper deals with the application of Life Cycle Assessment (LCA) methodology for process design, and presents the initial findings of this analysis qualitatively. The work identifies a need for a methodological development of Life Cycle Process Design (LCPD). This is underpinned by a broad literature review. The literature review shows that the application of LCA as an environmental design instrument is recognized in literature. In contrast to that there is hardly any hint which role Life Cycle Costing (LCC) could play within environmental process design. Most interesting in this line is, how LCA and LCC can be combined for environmental process design to be finally the core instruments of LCPD. The applicability of LCA and LCC within LCPD is shown on the example of a novel biorefinery process under development. Both instruments (LCA and LCC) are already applied during basic process development in this work, parallel to laboratory research. The aim is to identify potential environmental threats at an early stage of process design and also to give a hint on economic feasibility. Additionally a trade-off between environmental and economic issues can be drawn out. On the basis of this analysis the role of LCA during process development is highlighted as well as difficulties and challenges are emphasized. One of the major obstacles is data availability for LCA as well as LCC in the basic design stage of a biotechnological process. The findings of this paper serve as basis for the methodological development of LCPD. It is emphasized that conducting LCA and LCC during basic process development can reveal some relevant action areas for process engineers, which may influence technical as well as economic feasibility. The results presented have to be understood as a first outlook and provide key aspects for future research on the topic of accompanying basic process research projects with LCA and LCC to support future sustainable process design.     

Partial dissolution of ACQ-treated wood in lithium chloride/N-methyl-2-pyrrolidinone: separation of copper from potential lignocellulosic feedstocks

A cellulose solvent system based on lithium chloride (LiCl) in N-methyl-2-pyrrolidinone (NMP) was used to assess the merits of partial dissolutions of coarsely ground wood samples. Alkaline Copper Quaternary (ACQ)-treated pine wood was of particular interest for treatment given the potential to generate a copper-rich stream apart from solid and/or liquid lignocellulosic feedstocks. Treatment with NMP alone gave yields of soluble materials that were higher than typical extractives contents thereby suggesting a limited degree of wood dissolution. Inclusion of LiCl, which disrupts hydrogen bonding, gave lower wood residue recoveries (i.e., higher dissolution) with higher LiCl concentration. Lower wood residue recoveries coincided with lower Klason lignin and hemicellulose-derived sugar contents in the wood residues. After treatment with 8% LiCl in NMP, subsequent filtration afforded 34% of the ACQ-treated sapwood as a wood residue retaining only 2% of the original copper. Pouring the filtrate over an excess of water resulted in the recovery of 30% of the solids and 50% of the copper together as a copper-enriched lignocellulosic precipitate. Results demonstrate a solvent system showing potential as a means to separate heavy metals from preservative-treated wood and to recover lignocellulosic feedstocks that may be suitable for use in a biorefinery.     

Use of residual banana for polyhydroxybutyrate (PHB) production: Case of study in an integrated biorefinery

Polyhydroxybutyrate is a type of biopolymer that can be produced from hydrolyzed polysaccharide materials and could eventually replace polypropylene and polyethylene, being biodegradable, biocompatible and produced from renewable carbon sources. However, polyhydroxybutyrate is not still competitive compared to petrochemical polymers due to their high production costs. The improvement of the production processes requires a search for new alternative raw materials, design of the pretreatment technique and improvement in the fermentation and separation steps. In addition, if the polyhydroxybutyrate production is coupled into a multiproduct biorefinery it could increase the economic and environmental availability of the process through energy and mass integration strategies. In this work alternatives of energy and mass integrations for the production of polyhydroxybutyrate into a biorefinery from residual banana (an agro-industrial waste) were analyzed. The results show that the energetic integration can reduce up to 30.6% the global energy requirements of the process and the mass integration allows a 35% in water savings. Thus, this work demonstrates that energy and mass integration in a biorefinery is a very important way for the optimal use of energy and water resources hence decreasing the production cost and the negative environmental impacts.     

Influence of allocation methods on the environmental performance of biorefinery products—A case study

Life Cycle Assessment (LCA) methodology is the prevailing framework for estimating the environmental performances of a product/service. The application of LCA frequently requires practitioners to address allocation issues, especially when a large number of co-products are produced. The choice of an allocation approach for multifunctional processes is among the most debated methodological aspects in the LCA community, given its potentially large influence on final outcomes. Despite numerous efforts, a uniform consensus on the best allocation practice is still lacking and no single method appears as the most suitable for all situations.The aim of this paper is to assess how different allocation methods affect the environmental performances of a lignocellulosic biorefinery. Biorefinery systems represent a good example of a multifunctional process, since they co-produce multiple energy and material products. The following allocation procedures are applied: system expansion (also named substitution method), partitioning method according to different features of co-products (mass, energy, exergy and economic value), and hybrid approach (given by a combination of the previous ones). In order to enhance the clarity of the discussion, a mathematical notation for these allocation procedures is adopted, and analytical interrelations are investigated. Results show the influence of the allocation methods on the environmental impacts assigned to the individual products, both on a unit and annual flow basis.