An examination of biofuels production systems from a resilience perspective

The recent boom and collapse of the corn ethanol industry calls into question the long-term sustainability of biofuels, and traditional approaches to optimization of biofuels production systems. Compared with production of petroleum based transportation fuels, biofuels production is so closely connected and heavily influenced by natural systems that it has to deal with high degrees of complexity, variability, and connectivity within and between systems involved in the entire life cycle of biofuels. As such, unpredictability is an inherent feature of biofuels production. This requires the system to be designed not based on a narrowly defined efficiency, but for resilience (indicated by diversity, efficiency, cohesion and adaptability) to absorb unexpected disruptions and changes. Also, biofuels production systems must be endowed with transformability to allow for “creative destruction” when current fuels are eventually supplanted by new transportation technologies. This dissertation addresses important concepts (i.e., resistance, resilience, adaptability and transformability) in the design of engineered systems that are closely coupled with ecological systems at multiple scales. Several biofuels conversion technologies are examined from a resilience perspective. Multiple technologies should be applied to enhance diversity and flexibility of the entire biofuel industry. Two measures are proposed to examine resilience of biofuels refineries quantitatively. Measure R is based on stability analysis on coefficient of variance (CV) of input and output variables, which addresses engineering resilience (i.e., resistance) of the plant. Measure R\u27 uses net present value (NPV) as an indicator for economic resilience of the plant, which represents an ecological approach to quantify resilience. Strategies are proposed to examine how diverse feedstocks, diverse products and flexible products influence R and R\u27 of a biofuels refinery with the thermo-chemical conversion. Model simulations show that those strategies could improve stability measures (R) by 50%–80% and resilience measures (R\u27) in a wide range of 2% to 140%. Of all strategies discussed, the flexible products have the largest influence on both stability and resilience. To improve resilience, the bio-refinery has to apply multiple strategies into its design. Meanwhile, through controlling characteristics of biomass feedstock and products, the plant could improve its stability and resilience as well

Impacts on vegetable yields, nutrient contents and soil fertility in a community garden with different compost amendments

This study aimed to test impacts on soil fertility, plant yield, and plant nutrient content when growing vegetables (Arugula and Radish) at different compost treatments rates (10%, 30%, 50% and 70% v/v) and with synthetic fertilizer. The compost used in this study was produced from food wastes in combination of wood chips. The results showed the impacts on vegetable growth and soil fertility varied exceptionally by the compost amendment rate. Specifically, the leafy crop experienced an increased yield with the incremented compost ratio and therefore the highest treatment (70%) generated a harvest several times larger to that of non-treated soil. For the root vegetable, the largest output was observed at a medium treatment rate (50%). Additionally, the applications revealed compost treatments at high percentages generally promoted elements N, P, K, Na, Mn, Zn and Mg within the vegetable contents. On the contrary, a low compost amount (10%) boosted Ca, Al, and Fe levels. In terms of soil fertility enrichment, the compost can improve C, N, K and Zn at medium to high treatment rates (30% to 70%). Particularly, at such amounts, the compost enhanced C and N contents within the ground soil more than the fertilizer application. Based on the gathered outcomes, root vegetables will thrive at 50% compost treatment allowing for the replacement of complete synthetic fertilizer use without significant reduction on yields and nutrients. As for leafy green vegetables, the 70 % compost concentration permits the replacement of more than half the total fertilizer usage

Life cycle assessment of bottled water: A case study of Green2O products

This study conducted a full life cycle analysis of bottled water on four types of bottles: ENSO, PLA (corn based), recycled PET, and regular (petroleum based) PET, to discern which bottle material is more beneficial to use in terms of environmental impacts. PET bottles are the conventional bottles used that are not biodegradable and accumulate in landfills. PLA corn based bottles are derived from an organic substance and are degradable under certain environmental conditions. Recycled PET bottles are purified PET bottles that were disposed of and are used in a closed loop system. An ENSO bottle contains a special additive which is designed to help the plastic bottle degrade after disposed of in a landfill. The results showed that of all fourteen impact categories examined, the recycled PET and ENSO bottles were generally better than the PLA and regular PET bottles; however, the ENSO had the highest impacts in the categories of global warming and respiratory organics, and the recycled PET had the highest impact in the eutrophication category. The life cycle stages that were found to have the highest environmental impacts were the bottle manufacturing stage and the bottled water distribution to storage stage. Analysis of the mixed bottle material based on recycled PET resin and regular PET resin was discussed as well, in which key impact categories were identified. The PLA bottle contained extremely low impacts in the carcinogens, respiratory organics and global warming categories, yet it still contained the highest impacts in seven of the fourteen categories. Overall, the results demonstrate that the usage of more sustainable bottles, such as biodegradable ENSO bottles and recycled PET bottles, appears to be a viable option for decreasing impacts of the bottled water industry on the environment

Environmental and economic analysis of an in-vessel food waste composting system at Kean University in the U.S.

A composting system provides many benefits towards achieving sustainability such as, replacing fertilizer use, increasing the quantity of produce sold, and diverting organic wastes from landfills. This study delves into the many benefits a composting system provided by utilizing an established composting system at Kean University (KU) in New Jersey, as a scale project to examine the composters’ environmental and economic impacts. The results from the study showed that composting food wastes in an in-vessel composter when compared to typical disposal means by landfilling, had lower impacts in the categories of fossil fuel, GHG emissions, eutrophication, smog formation and respiratory effects; whereas, its had higher impacts in ozone depletion, acidification human health impacts, and ecotoxicity. The environmental impacts were mainly raised from the manufacturing of the composter and the electricity use for operation. Applying compost to the garden can replace fertilizers and also lock carbon and nutrients in soil, which reduced all of the environmental impact categories examined. In particular, the plant growth and use stage reduced up to 80% of respiratory effects in the life cycle of food waste composting. A cost-benefit analysis showed that the composting system could generate a profit of $13,200 a year by selling vegetables grown with compost to the student cafeteria at Kean and to local communities. When educational and environmental benefits were included in the analysis, the revenue increased to$23,550. The results suggest that in-vessel composting and the subsequent usage of a vegetable garden should be utilized by Universities or food markets that generate intensive food wastes across the U.S

A life cycle assessment and economic analysis of the Scum-to-Biodiesel technology in wastewater treatment plants

This study used life cycle assessment and technical economic analysis tools in evaluating a novel Scum-to-Biodiesel technology and compares the technology with scum digestion and combustion processes. The key variables that control environmental and economic performance are identified and discussed. The results show that all impacts examined for the Scum-to-Biodiesel technology are below zero indicating significant environmental benefits could be drawn from it. Of the three technologies examined, the Scum-to-Biodiesel technology has the best environmental performance in fossil fuel depletion, GHG emissions, and eutrophication, whereas combustion has the best performance on acidification. Of all process inputs assessed, process heat, glycerol, and methanol uses had the highest impacts, much more than any other inputs considered. The Scum-to-Biodiesel technology also makes higher revenue than other technologies. The diesel price is a key variable for its economic performance. The research demonstrates the feasibility and benefits in developing Scum-to-Biodiesel technology in wastewater treatment facilities

Life cycle assessment and nutrient analysis of various processing pathways in algal biofuel production

This study focuses on analyzing nutrient distributions and environmental impacts of nutrient recycling, reusing, and discharging in algal biofuels production. The three biomass conversion pathways compared in this study were: hydrothermal liquefaction technology (HTL), hydrothermal hydrolysis pretreatment +HTL (HTP), and wet lipid extraction (WLE). Carbon, nitrogen, and phosphorous (C, N, P) flows were described in each pathway. A primary cost analysis was conducted to evaluate the economic performance. The LCA results show that the HTP reduced life cycle NOxemissions by 10% from HTL, but increased fossil fuel use, greenhouse gas emissions, and eutrophication potential by 14%, 5%, and 28% respectively. The cost of per gallon biodiesel produced in HTP was less than in HTL. To further reduce emissions, efforts should be focused on improving nutrient uptake rates in algae cultivation, increasing biomass carbon detention in hydrothermal hydrolysis, and/or enhancing biomass conversion rates in the biooil upgrading processes

Economical feasibility of bio-oil production from sewage sludge through pyrolysis

Pyrolysis can lower the environmental impacts and improve resource utilization. A multi-stage comprehensive assessment model was developed to assess the economic feasibility of sludge pyrolysis. The indicator of gross process yield was used to evaluate the energy conversion efficiency of the different pathways. A comprehensive technoeconomic analysis was used to quantify the technical and economic performance of the pathway through uniform monetary measurement standards. Sensitivity analysis was used to determine the uncertainty and risk. The pathway with the highest gross process yield was selected to assess the feasibility using comprehensive techno-economic analysis considering different value. The estimated break even selling price of bio-oil was very close to the average crude oil of recent five years when considering economic, social, and environmental value. The main key factors affecting the economics of system were crude oil price, bio-oil lower heating value, bio-oil yield, and energy consumption of the pyrolysis process

Economical feasibility of bio-oil production from sewage sludge through pyrolysis

Pyrolysis can lower the environmental impacts and improve resource utilization. A multi-stage comprehensive assessment model was developed to assess the economic feasibility of sludge pyrolysis. The indicator of gross process yield was used to evaluate the energy conversion efficiency of the different pathways. A comprehensive technoeconomic analysis was used to quantify the technical and economic performance of the pathway through uniform monetary measurement standards. Sensitivity analysis was used to determine the uncertainty and risk. The pathway with the highest gross process yield was selected to assess the feasibility using comprehensive techno-economic analysis considering different value. The estimated break even selling price of bio-oil was very close to the average crude oil of recent five years when considering economic, social, and environmental value. The main key factors affecting the economics of system were crude oil price, bio-oil lower heating value, bio-oil yield, and energy consumption of the pyrolysis process