Background: Similar to biofuels, numerous chemicals produced from petroleum resources can also be made from biomass. In this research we investigate cradle to biorefinery exit gate life cycle impacts of producing acetic acid from poplar biomass using a bioconversion process. A key step in developing acetic acid for commercial markets is producing a product with 99.8% purity. This process has been shown to be potentially energy intensive and in this work two distillation and liquid-liquid extraction methods are evaluated to produce glacial bio-acetic acid. Method one uses ethyl acetate for extraction. Method two uses alamine and diisobutyl ketone. Additionally two different options for meeting energy demands at the biorefinery are modeled. Option one involves burning lignin and natural gas onsite to meet heat/steam and electricity demands. Option two uses only natural gas onsite to meet heat/steam demands, purchases electricity from the grid to meet biorefinery needs, and sells lignin from the poplar biomass as a co-product to a coal burning power plant to be co-fired with coal. System expansion is used to account for by-products and co-products for the main life cycle assessment. Allocation assessments are also performed to compare the life cycle tradeoffs of using system expansion, mass allocation, or economic allocation for bio-acetic acid production. Finally, a sensitivity analysis is conducted to determine potential effects of a decrease in the fermentation of glucose to acetic acid. Results: Global warming potential (GWP) and fossil fuel use (FFU) for ethyl acetate extraction range from 1000-2500 kg CO 2 eq. and 32-56 GJ per tonne of acetic acid, respectively. Alamine and diisobutyl ketone extraction method GWP and FFU ranges from −370-180 kg CO 2 eq. and 15−25 GJ per tonne of acetic acid, respectively. Conclusions: Overall the alamine/diisobutyl ketone extraction method results in lower GWP and FFU values compared to the ethyl acetate extraction method. Only the alamine/diisobutyl extraction method finds GWP and FFU values lower than those of petroleum based acetic acid. For both extraction methods, exporting lignin as a co-product produced larger GWPs and FFU values compared to burning the lignin at the biorefinery.

BackgroundLow cost of raw materials and good process yields are necessary for future lignocellulosic biomass biorefineries to be sustainable and profitable. A low cost feedstock will be diverse, changing as a function of seasonality and price and will most likely be available from multiple sources to the biorefinery. The efficacy of the bioconversion process using mixed biomass, however, has not been thoroughly investigated. Considering the seasonal availability of wheat straw and the year round availability of hybrid poplar in the Pacific Northwest, this study aims to determine the impact of mixing wheat straw and hybrid poplar biomass on the overall sugar production via steam pretreatment and enzymatic saccharification.ResultsSteam pretreatment proved to be effective for processing different mixtures of hybrid poplar and wheat straw. Following SO2-catalyzed steam explosion pretreatment, on average 22 % more sugar monomers were recovered using mixed feedstock than either single biomass. Improved sugar recovery with mixtures of poplar and wheat straw continued through enzymatic hydrolysis. After steam pretreatment and saccharification, the mixtures showed 20 % higher sugar yields than that produced from hybrid poplar and wheat straw alone.ConclusionsBlending hybrid poplar and wheat straw resulted in more monomeric sugar recovery and less sugar degradation. This synergistic effect is attributable to interaction of hybrid poplar’s high acetic acid content and the presence of ash supplied by wheat straw. As a consequence on average 20 % more sugar was yielded by using the different biomass mixtures. Combining hybrid poplar and wheat straw enables sourcing of the lowest cost biomass, reduces seasonal dependency, and results in increasing biofuels and chemicals productivity in a cellulosic biorefinery.Electronic supplementary materialThe online version of this article (doi:10.1186/s13068-015-0414-9) contains supplementary material, which is available to authorized users.

Most of the current commercial production of glacial acetic acid (GAA) is by petrochemical routes, primarily methanol carbonylation. GAA is an intermediate in the production of plastics, textiles, dyes, and paints. GAA production from biomass might be an economically viable and sustainable alternative to petroleum-derived routes. Separation of acetic acid from water is a major expense and requires considerable energy. This study evaluates and compares the technical and economic feasibility of GAA production via bioconversion using either ethyl acetate or alamine in diisobutylkerosene (DIBK) as organic solvents for purification. Models of a GAA biorefinery with a production of 120,650 tons/year were simulated in Aspen software. This biorefinery follows the path of pretreatment, enzymatic hydrolysis, acetogen fermentation, and acid purification. Estimated capital costs for different scenarios ranged from USD 186 to 245 million. Recovery of GGA using alamine/DIBK was a more economical process and consumed 64% less energy, due to lower steam demand in the recovery distillation columns. The estimated average minimum selling prices of GGA were USD 756 and 877/ton for alamine/DIBK and ethyl acetate scenarios, respectively. This work establishes a feasible and sustainable approach to produce GGA from poplar biomass via fermentation.

No abstract

The cost of cellulase enzymes is a main contributor to the operational cost of a biorefinery producing ethanol from lignocellulosic material. Therefore, onsite production of enzymes using low-value substrates might be an option to make a bio-based facility more economical, while improving environmental sustainability. Food manufacturing wastes (FMWs), such as olive mill solids, tomato pomace, and grape pomace, are some of the main wastes produced by the food industry in Chile. FMWs are mostly composed of lignocellulosic material, which is primarily made of cellulose. A fungal strain obtained from olive stones was identified as a Trichoderma sp. and characterized by molecular and morphological techniques. This strain was able to grow on three FMWs in both liquid and solid cultures. In liquid cultures, cellulase and β-glucosidase activities from the culture supernatants were quantified. Identification of extracellular proteins using mass spectrometry revealed the presence of endoglucanases, exoglucanases, and β-glucosidases. Cellulase production from agroindustrial residues could be an excellent opportunity to utilize FMWs as well as decrease enzyme production costs in biorefinery processes.

Currently, recycling or degradation treatments for tires are an enormous challenge. Despite efforts to dispose of or recycle it, rubber waste is increasing year by year worldwide. To create a rubber-recycling system, several researchers have proposed tire desulfurization. In this study, we compare two methods: one biological, using Acidobacillus ferroxidans in shake 250 ml flask experiments, and one chemical using, for the first time, microwaves and an aqueous solution. The results of these methods were analyzed through sulfate quantification, cross-linking differences, Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy with energy disperse spectroscopy (SEM-EDS). We observed that the amount of sulfates generated by the chemical system was 22.40 (mg/L)/g of rubber, which was 22-times higher than the biological system, which generated 1.06 (mg/L)/g of rubber. Similarly, after cross-linking studies, a 36% higher decrease after the chemical treatment was observed. When using FTIR analysis, the disappearance of characteristic bands corresponding to functional groups containing sulfur bonds and metal oxides were observed by treating the sample with both desulfurization methods. Morphological changes on the rubber surface structure was also demonstrated by SEM-EDS analysis with the appearance of holes, cracks and changes in the porosity of the material. This work analyzed two different non-aggressive desulfurization approaches that might be used as methods for rubber recycling processes.

While high-rise mass-timber construction is booming worldwide as a more sustainable alternative to mainstream cement and steel, in South America, there are still many gaps to overcome regarding sourcing, design, and environmental performance. The aim of this study was to assess the carbon emission footprint of using mass-timber products to build a mid-rise low-energy residential building in central Chile (CCL). The design presented at a solar decathlon contest in Santiago was assessed through lifecycle analysis (LCA) and compared to an equivalent mainstream concrete building. Greenhouse gas emissions, expressed as global warming potential (GWP), from cradle-to-usage over a 50-year life span, were lower for the timber design, with 131 kg CO2 eq/m2 of floor area (compared to 353 kg CO2 eq/m2) and a biogenic carbon storage of 447 tons of CO2 eq/m2 based on sustainable forestry practices. From cradle-to-construction, the embodied emissions of the mass-timber building were 42% lower (101 kg CO2 eq/m2) than those of the equivalent concrete building (167 kg CO2 eq/m2). The embodied energy of the mass-timber building was 37% higher than that of its equivalent concrete building and its envelope design helped reduce space-conditioning emissions by as much as 83%, from 187 kg CO2 eq/m2 as estimated for the equivalent concrete building to 31 kg CO2 eq/m2 50-yr. Overall, provided that further efforts are made to address residual energy end-uses and end-of-life waste management options, the use of mass-timber products offers a promising potential in CCL for delivering zero carbon residential multistory buildings.

As the need to address climate change grows more urgent, policymakers, businesses, and others are seeking innovative approaches to remove carbon dioxide emissions from the atmosphere and decarbonize hard-to-abate sectors. Forests can play a role in reducing atmospheric carbon. However, there is disagreement over whether forests are most effective in reducing carbon emissions when left alone versus managed for sustainable harvesting and wood product production. Cross-laminated timber is at the forefront of the mass timber movement, which is enabling designers, engineers, and other stakeholders to build taller wood buildings. Several recent studies have shown that substituting mass timber for steel and concrete in mid-rise buildings can reduce the emissions associated with manufacturing, transporting, and installing building materials by 13%-26.5%. However, the prospect of increased utilization of wood products as a climate solution also raises questions about the impact of increased demand for wood on forest carbon stocks, on forest condition, and on the provision of the many other critical social and environmental benefits that healthy forests can provide. A holistic assessment of the total climate impact of forest product demand across product substitution, carbon storage in materials, current and future forest carbon stock, and forest area and condition is challenging, but it is important to understand the impact of increased mass timber utilization on forests and climate, and therefore also on which safeguards might be necessary to ensure positive outcomes. To thus assess the potential impacts, both positive and negative, of greater mass timber utilization on forests ecosystems and emissions associated with the built environment, The Nature Conservancy (TNC) initiated a global mass timber impact assessment (GMTIA), a five-part, highly collaborative research program focused on understanding the potential benefits and risks of increased demand for mass timber products on forests and identifying appropriate safeguards to ensure positive outcomes.