Techno-Economic and Life Cycle Impacts Analysis of Direct Methanation of Glycerol to Bio-Synthetic Natural Gas at a Biodiesel Refinery

An economic and environmental feasibility study were carried out on the thermochemical conversion of glycerol to medium methane content biological synthetic natural gas (bio-SNG). A plant that processed 497 kg·h‾¹ of glycerol to bio-SNG was modelled as an on-site addition to a soybean biodiesel plant based in Missouri (USA) that produced 30 million litres of soybean biodiesel per year. Assuming the glycerol contained only 80 wt% free glycerol, the bio-SNG could substitute up to 24% of the natural gas at the soybean biodiesel plant. The discounted cash flow analysis showed it was possible to generate positive NPVs and achieve internal rates of return within the hurdle rate (12%) for biomass gasification technologies. From the environmental analysis it was found that the bio-SNG could reduce global warming potential by 28% when compared to conventional natural gas in the USA and translates to roughly 7% reduction in biodiesel natural gas emissions, if the maximum 24% of natural gas were to be substituted by bio-SNG. The work highlights the potential to divert waste glycerol to an onsite energy vector at soybean biodiesel plants with minimal change to the main biodiesel production process and potential reductions to soybean biodiesel global warming potential

Effect of Hydrodynamic Conditions of Photobioreactors on Lipids Productivity in Microalgae

This research presents the effect of hydrodynamic conditions at different rates of aeration (1.4, 1.8, and 2.3 vvm) and the geometry of two photobioreactors with internal lighting on lipid productivity and other parameters of Chlorella vulgaris. A two-step nitrogen-reduction cultivation mode was applied for promoting lipid accumulation. The inoculum was cultivated initially at 90 mg L−1 N-NH4+, and at the end of the exponential phase, it was fed to 11 L photobioreactor at 20 mg L−1 of N-NH4+. The results showed that with similar aeration rates, the hydrodynamic regime in both photobioreactors was different. However, the increase in shear rate and agitation did not cause cell damage or photoinhibition. The maximum cell growth was 12 × 106 cells mL−1. The highest consumption of nitrogen was 19% and shear rates were of 120-340 s−1. The highest lipid productivity was reached in bubble column at 1.8 vvm with 0.650 mg·L−1 d−1

High-risk human papillomavirus (HPV) screening and detection in healthy patient saliva samples: a pilot study

<p>Abstract</p> <p>Background</p> <p>The human papillomaviruses (HPV) are a large family of non-enveloped DNA viruses, mainly associated with cervical cancers. Recent epidemiologic evidence has suggested that HPV may be an independent risk factor for oropharyngeal cancers. Evidence now suggests HPV may modulate the malignancy process in some tobacco- and alcohol-induced oropharynx tumors, but might also be the primary oncogenic factor for inducing carcinogenesis among some non-smokers. More evidence, however, is needed regarding oral HPV prevalence among healthy adults to estimate risk. The goal of this study was to perform an HPV screening of normal healthy adults to assess oral HPV prevalence.</p> <p>Methods</p> <p>Healthy adult patients at a US dental school were selected to participate in this pilot study. DNA was isolated from saliva samples and screened for high-risk HPV strains HPV16 and HPV18 and further processed using qPCR for quantification and to confirm analytical sensitivity and specificity.</p> <p>Results</p> <p>Chi-square analysis revealed the patient sample was representative of the general clinic population with respect to gender, race and age (<it>p </it>< 0.05). Four patient samples were found to harbor HPV16 DNA, representing 2.6% of the total (n = 151). Three of the four HPV16-positive samples were from patients under 65 years of age and all four were female and Hispanic (non-White). No samples tested positive for HPV18.</p> <p>Conclusions</p> <p>The successful recruitment and screening of healthy adult patients revealed HPV16, but not HPV18, was present in a small subset. These results provide new information about oral HPV status, which may help to contextualize results from other studies that demonstrate oral cancer rates have risen in the US among both females and minorities and in some geographic areas that are not solely explained by rates of tobacco and alcohol use. The results of this study may be of significant value to further our understanding of oral health and disease risk, as well as to help design future studies exploring the role of other factors that influence oral HPV exposure, as well as the short- and long-term consequences of oral HPV infection.</p

System analyses of high-value chemicals and fuels from a waste high-density polyethylene refinery. Part 1: Conceptual design and techno-economic assessment

The increasing amount of plastic waste generation has become an important concern for the chemical industry and government agencies due to high disposal and environmental leakage rates. Chemical recycling is a promising technology due to the potential reduction of pollutant emissions and the establishment of a circular economy through the production of monomers and fuels. However, there is scarce information on industrial scale processes of this technology and their energetic, economic, and environmental performance. Therefore, the present process modeling study presents a novel multiproduct pyrolysis-based refinery for the conversion of 500 tonnes/day of waste high-density polyethylene (HDPE). The products obtained from the modeled refinery were chemical grade ethylene and propylene, an aromatics mixture, and low- and high-molecular weight hydrocarbon mixtures (MWHCs). Part 1 of this study focuses on the energetic and economic evaluation of the refinery and the potential effects of heat integration. The energy efficiency was 68% and 73% for the base case and the heat integrated refinery, respectively. The net present values (NPVs) were 367 and 383 million U.S. dollars (MM USD), for the base case and the heat integrated process, respectively. These results suggest energetic and economic sustainability of the design and its promising application on an industrial scale

System analyses of high-value chemicals and fuels from a waste high-density polyethylene refinery. Part 2: Carbon footprint analysis and regional electricity effects

The growing generation of plastic waste (PW) is placing severe burdens in the terrestrial and marine environments due to its inappropriate management at end of life. Governments are aware of this situation and have proposed production bans or initiatives to minimize the amount of PW that is landfilled and encourage recycling or energy recovery. Circular economy is a strategy that reuses PW to produce new polymers while avoiding its disposal and displacing the use of virgin materials. This study reports on a refinery design that employs fast pyrolysis of waste high-density polyethylene and downstream separations to obtain monomers, aromatics, and hydrocarbon fuels. This study focuses on a life cycle carbon footprint analysis (CFA) and the effects of regional electricity grids on cradle-to-gate greenhouse gas emissions using process simulation for life cycle assessment inputs. The effects of heat integration on greenhouse gas (GHG) emissions were investigated in scenarios, as well as the investigation of parameter sensitivity and uncertainty. The CFA results show that the GHG emissions of ethylene, propylene, and aromatics mixture (1.08, 1.10, and 1.16 kg CO2 equiv/kg, respectively) are equal to or less than those of fossil products when heat integration is included assuming U.S. average electricity grid. The evaluation of regional electricity grids on GHG emissions for all products was conducted for 50 states in the U.S

Potential effects of the Mexican energy reform on life cycle impacts of electricity generation in Mexico and the Yucatan region

© 2017 Elsevier Ltd A national energy strategy in Mexico to 2028, derived from the recent energy reform, projects a considerable shift in the national power generation mix leading to changes on its environmental profile. Therefore, this paper aims to compare the potential environmental impacts of the electricity generation under previous, current and projected energy mixes in Mexico at a national and regional scale considering the Yucatan state as the regional case study. These were estimated with a cradle-to-grave Life Cycle Assessment (LCA) following the CML–IA 2000 V2.05 methodology and including the baseline environmental impact categories. Results indicate that the environmental impacts per generated kWh of electricity have decreased in Mexico from 2007 to 2013 and would keep decreasing at a faster rate until 2028 according to current projections. In Yucatan, the environmental impacts increased from 2007 to 2013 due to an increased diesel consumption, but would decrease by 2028 reaching lower levels than in 2007. From 2007 to 2013 almost all the environmental impacts in Yucatan were lower than the country average due to a higher contribution of natural gas in the power generation mix, while in 2028 they would be similar. Overall, there is a significant difference between the national and regional estimations of the potential environmental impacts due to differences in their power generation mix. Furthermore, the potential introduction of shifts derived from the energy reform in Mexico will have a strong positive influence on the environmental impacts from the electricity generation

Conceptual design of a dedicated-crop biorefinery for Jatropha curcas using a systematic sustainability evaluation

The sustainability of two scenarios for the exploitation of Jatropha curcas biomass was assessed using a suitable sustainability framework. The first scenario, or base case (BC), was set up as a traditional biodiesel process with crude glycerin as the only co-product. The second scenario was a biorefinery plant (BR) that builds on the BC by including thermochemical transformations of lignocellulosic biomass into bio-oil, bio-char, and heat and power for internal consumption. The process lifecycle was divided in two stages: cultivation and transformation. The BC scenario was only sustainable in the Renewability category. Expanding the system to a biorefinery (BR scenario) improved performance on all other indicators. The biorefinery was also sustainable in the Economics, Community development, and Mitigation categories. None of the scenarios was sustainable in the fossils-based products Displacement category. The main areas for improvement were the use of water for irrigation, and the high inputs of agrochemicals (fertilizers, pesticides, insecticides, and herbicides). Seed yield is a critical variable that affects most sustainability indicators. The capital investment would be recovered after year 10 in the current economic context. The cultivation stage is largely responsible for the impacts of both cases as it contributes the most to the production costs (62–77%), environmental impacts, non-renewable energy consumption (66–68%), and freshwater consumption (97–98%). Hence, even though diversifying the products portfolio improves the values of all sustainability indicators, it is clear that optimizing the agronomic stage is crucial for attaining the sustainability of the overall system. © 2018 Society of Chemical Industry and John Wiley & Sons, Ltd

A Selection Method for Restoration Mortars Using Sustainability and Compatibility Criteria

This work proposes sustainability criteria for the selection or design of restoration mortars based on their physical and mechanical properties, durability, price in the French market, and the environmental impact estimated by the global warming potential. A score is assigned to the mortars based on normalized values of their physical and mechanical properties. A total of 24 formulations of restoration mortars were characterized, and their scores were compared. A case study showing the application of the proposed selection method is presented, focused on the restoration of historical monuments in Paris, France, built with Lutetian and Euville stones. In this case, hydraulic lime mortars were the most sustainable options. The application of the method is also projected for global application, as showcased for the restoration of Mayan stones in Southern Mexico

A Selection Method for Restoration Mortars Using Sustainability and Compatibility Criteria

This work proposes sustainability criteria for the selection or design of restoration mortars based on their physical and mechanical properties, durability, price in the French market, and the environmental impact estimated by the global warming potential. A score is assigned to the mortars based on normalized values of their physical and mechanical properties. A total of 24 formulations of restoration mortars were characterized, and their scores were compared. A case study showing the application of the proposed selection method is presented, focused on the restoration of historical monuments in Paris, France, built with Lutetian and Euville stones. In this case, hydraulic lime mortars were the most sustainable options. The application of the method is also projected for global application, as showcased for the restoration of Mayan stones in Southern Mexico