Estimating Virtual Nitrogen Inputs to Integrated U.S. Corn Ethanol and Animal Food Systems.

To accurately assess contributions of human activities to nitrogen (N) cycle disruption, we must consider how systems such as food and renewable fuel production are connected. N impacts of food and biofuel systems have been studied separately, but links between them have not been sufficiently considered. Since 2002, corn ethanol production in the United States has increased sixfold, and ethanol coproducts' roles in animal diets have increased similarly. In this study, we estimated virtual N in ethanol fuel and animal products using the commodity-specific Net Anthropogenic Nitrogen Inputs (CSNANI) model, which uses national corn ethanol, crop, and animal production data to estimate animal diets and the corresponding virtual N inputs to agricultural commodities. Virtual N attributable to ethanol fuel was 30 to 35 g N per liter of ethanol. As ethanol coproduct inclusion in animal diets increased from 1997 to 2012, N per kilogram of beef protein decreased by 19% and N per kilogram of milk protein decreased by 13%. With allocation of virtual N between ethanol and ethanol feed coproducts, the virtual N of both ethanol fuel and products from animals consuming ethanol coproducts is reduced relative to estimates from studies that do not consider the connection between these systems.

Dynamic Life Cycle Assessments of a Conventional Green Building and a Net Zero Energy Building: Exploration of Static, Dynamic, Attributional, and Consequential Electricity Grid Models.

Our study assesses the differences between regional average- and marginal-electricity generation mixes as well as the variability between predicted and observed energy consumption of a "conventional green" Leadership in Energy and Environmental Design (LEED) building and a Net-Zero Energy Living Building (NZEB). The aim of our study was to evaluate the importance of using temporally resolved building-level data while capturing the dynamic effects a changing electrical grid has on the life cycle impacts of buildings. Two static and four dynamic life cycle assessment (LCA) models were evaluated for both buildings. Both buildings' results show that the most appropriate models ( hybrid consequential for the LEED Gold building, hourly consequential for the NZEB) significantly modified the use-phase global warming potential (GWP) impacts relative to the design static LCA (49% greater impact for the LEED Gold building; 45% greater reduction for the NZEB). In other words, a "standard" LCA would underestimate the use phase impacts of the LEED Gold building and the benefits of the NZEB in the GWP category. Although the results in this paper are specific to two case study buildings, the methods developed are scalable and can be implemented more widely to improve building life cycle impact estimates.

Evaluating the Life Cycle Environmental Benefits and Trade-Offs of Water Reuse Systems for Net-Zero Buildings.

Aging water infrastructure and increased water scarcity have resulted in higher interest in water reuse and decentralization. Rating systems for high-performance buildings implicitly promote the use of building-scale, decentralized water supply and treatment technologies. It is important to recognize the potential benefits and trade-offs of decentralized and centralized water systems in the context of high-performance buildings. For this reason and to fill a gap in the current literature, we completed a life cycle assessment (LCA) of the decentralized water system of a high-performance, net-zero energy, net-zero water building (NZB) that received multiple green building certifications and compared the results with two modeled buildings (conventional and water efficient) using centralized water systems. We investigated the NZB's impacts over varying lifetimes, conducted a break-even analysis, and included Monte Carlo uncertainty analysis. The results show that, although the NZB performs better in most categories than the conventional building, the water efficient building generally outperforms the NZB. The lifetime of the NZB, septic tank aeration, and use of solar energy have been found to be important factors in the NZB's impacts. While these findings are specific to the case study building, location, and treatment technologies, the framework for comparison of water and wastewater impacts of various buildings can be applied during building design to aid decision making. As we design and operate high-performance buildings, the potential trade-offs of advanced decentralized water treatment systems should be considered.

Biofuels via Fast Pyrolysis of Perennial Grasses: A Life Cycle Evaluation of Energy Consumption and Greenhouse Gas Emissions.

A well-to-wheel (WTW) life cycle assessment (LCA) model is developed to evaluate the environmental profile of producing liquid transportation fuels via fast pyrolysis of perennial grasses: switchgrass and miscanthus. The framework established in this study consists of (1) an agricultural model used to determine biomass growth rates, agrochemical application rates, and other key parameters in the production of miscanthus and switchgrass biofeedstock; (2) an ASPEN model utilized to simulate thermochemical conversion via fast pyrolysis and catalytic upgrading of bio-oil to renewable transportation fuel. Monte Carlo analysis is performed to determine statistical bounds for key sustainability and performance measures including life cycle greenhouse gas (GHG) emissions and Energy Return on Investment (EROI). The results of this work reveal that the EROI and GHG emissions (gCO2e/MJ-fuel) for fast pyrolysis derived fuels range from 1.52 to 2.56 and 22.5 to 61.0 respectively, over the host of scenarios evaluated. Further analysis reveals that the energetic performance and GHG reduction potential of fast pyrolysis-derived fuels are highly sensitive to the choice of coproduct scenario and LCA allocation scheme, and in select cases can change the life cycle carbon balance from meeting to exceeding the renewable fuel standard emissions reduction threshold for cellulosic biofuels.

Anticipatory Life Cycle Analysis of In Vitro Biomass Cultivation for Cultured Meat Production in the United States.

Cultured, or in vitro, meat consists of edible biomass grown from animal stem cells in a factory, or carnery. In the coming decades, in vitro biomass cultivation could enable the production of meat without the need to raise livestock. Using an anticipatory life cycle analysis framework, the study described herein examines the environmental implications of this emerging technology and compares the results with published impacts of beef, pork, poultry, and another speculative analysis of cultured biomass. While uncertainty ranges are large, the findings suggest that in vitro biomass cultivation could require smaller quantities of agricultural inputs and land than livestock; however, those benefits could come at the expense of more intensive energy use as biological functions such as digestion and nutrient circulation are replaced by industrial equivalents. From this perspective, large-scale cultivation of in vitro meat and other bioengineered products could represent a new phase of industrialization with inherently complex and challenging trade-offs.

Environmental impacts of surgical procedures: life cycle assessment of hysterectomy in the United States.

The healthcare sector is a driver of economic growth in the U.S., with spending on healthcare in 2012 reaching $2.8 trillion, or 17% of the U.S. gross domestic product, but it is also a significant source of emissions that adversely impact environmental and public health. The current state of the healthcare industry offers significant opportunities for environmental efficiency improvements, potentially leading to reductions in costs, resource use, and waste without compromising patient care. However, limited research exists that can provide quantitative, sustainable solutions. The operating room is the most resource-intensive area of a hospital, and surgery is therefore an important focal point to understand healthcare-related emissions. Hybrid life cycle assessment (LCA) was used to quantify environmental emissions from four different surgical approaches (abdominal, vaginal, laparoscopic, and robotic) used in the second most common major procedure for women in the U.S., the hysterectomy. Data were collected from 62 cases of hysterectomy. Life cycle assessment results show that major sources of environmental emissions include the production of disposable materials and single-use surgical devices, energy used for heating, ventilation, and air conditioning, and anesthetic gases. By scientifically evaluating emissions, the healthcare industry can strategically optimize its transition to a more sustainable system.

Eutrophication potential of food consumption patterns.

Although the environmental impacts and carbon footprints of foods are gaining more public attention and scientific debate, few studies have systematically evaluated the life cycle nitrogen and phosphorus flows among different food types. Disruption of natural nitrogen and phosphorus cycles already result in serious environmental quality degradation and economic losses, such as loss of fisheries due to hypoxia in the Gulf of Mexico. This study characterizes the nutrient flows during food production, processing, packaging, and distribution stages for eight food types; compares carbon footprints and nitrogen equivalent footprints of food groups; evaluates solutions to reduce excessive nitrogen outputs; and estimates effectiveness and efficiency of possible solutions. Different food groups exhibit a highly variable nitrogen-intensity; on average, red meat and dairy products require much more nitrogen than cereals/carbohydrates. The ranking of foods' nitrogen footprints is not consistent with their carbon footprints. For example, dairy products and chicken/eggs have relatively high nitrogen footprint and low carbon footprints. Finally, the study evaluates shifting food consumption patterns. Dietary shifts from dairy products and red meat to cereals can be an effective approach for lowering the personal nitrogen footprint.

Sustainability metrics: life cycle assessment and green design in polymers.

This study evaluates the efficacy of green design principles such as the "12 Principles of Green Chemistry," and the "12 Principles of Green Engineering" with respect to environmental impacts found using life cycle assessment (LCA) methodology. A case study of 12 polymers is presented, seven derived from petroleum, four derived from biological sources, and one derived from both. The environmental impacts of each polymer's production are assessed using LCA methodology standardized by the International Organization for Standardization (ISO). Each polymer is also assessed for its adherence to green design principles using metrics generated specifically for this paper. Metrics include atom economy, mass from renewable sources, biodegradability, percent recycled, distance of furthest feedstock, price, life cycle health hazards and life cycle energy use. A decision matrix is used to generate single value metrics for each polymer evaluating either adherence to green design principles or life-cycle environmental impacts. Results from this study show a qualified positive correlation between adherence to green design principles and a reduction of the environmental impacts of production. The qualification results from a disparity between biopolymers and petroleum polymers. While biopolymers rank highly in terms of green design, they exhibit relatively large environmental impacts from production. Biopolymers rank 1, 2, 3, and 4 based on green design metrics; however they rank in the middle of the LCA rankings. Polyolefins rank 1, 2, and 3 in the LCA rankings, whereas complex polymers, such as PET, PVC, and PC place at the bottom of both ranking systems.

Enhancing anaerobic digestion of food waste through biochemical methane potential assays at different substrate: inoculum ratios.

Food waste has a high energy potential that can be converted into useful energy in the form of methane via anaerobic digestion. Biochemical Methane Potential assays (BMPs) were conducted to quantify the impacts on methane production of different ratios of food waste. Anaerobic digester sludge (ADS) was used as the inoculum, and BMPs were performed at food waste:inoculum ratios of 0.42, 1.42, and 3.0g chemical oxygen demand/g volatile solids (VS). The 1.42 ratio had the highest CH4-COD recovery: 90% of the initial total chemical oxygen demand (TCOD) was from food waste, followed by ratios 0.42 and 3.0 at 69% and 57%, respectively. Addition of food waste above 0.42 caused a lag time for CH4 production that increased with higher ratios, which highlighted the negative impacts of overloading with food waste. The Gompertz equation was able to represent the results well, and it gave lag times of 0, 3.6 and 30days and maximum methane productions of 370, 910, and 1950mL for ratios 0.42, 1.42 and 3.0, respectively. While ratio 3.0 endured a long lag phase and low VSS destruction, ratio 1.42 achieved satisfactory results for all performance criteria. These results provide practical guidance on food-waste-to-inoculum ratios that can lead to optimizing methanogenic yield.

Do single-use medical devices containing biopolymers reduce the environmental impacts of surgical procedures compared with their plastic equivalents?

Background While petroleum-based plastics are extensively used in health care, recent developments in biopolymer manufacturing have created new opportunities for increased integration of biopolymers into medical products, devices and services. This study compared the environmental impacts of single-use disposable devices with increased biopolymer content versus typically manufactured devices in hysterectomy. Methods A comparative life cycle assessment of single-use disposable medical products containing plastic(s) versus the same single-use medical devices with biopolymers substituted for plastic(s) at Magee-Women's Hospital (Magee) in Pittsburgh, PA and the products used in four types of hysterectomies that contained plastics potentially suitable for biopolymer substitution. Magee is a 360-bed teaching hospital, which performs approximately 1400 hysterectomies annually. Results There are life cycle environmental impact tradeoffs when substituting biopolymers for petroplastics in procedures such as hysterectomies. The substitution of biopolymers for petroleum-based plastics increased smog-related impacts by approximately 900% for laparoscopic and robotic hysterectomies, and increased ozone depletion-related impacts by approximately 125% for laparoscopic and robotic hysterectomies. Conversely, biopolymers reduced life cycle human health impacts, acidification and cumulative energy demand for the four hysterectomy procedures. The integration of biopolymers into medical products is correlated with reductions in carcinogenic impacts, non-carcinogenic impacts and respiratory effects. However, the significant agricultural inputs associated with manufacturing biopolymers exacerbate environmental impacts of products and devices made using biopolymers. Conclusions The integration of biopolymers into medical products is correlated with reductions in carcinogenic impacts, non-carcinogenic impacts and respiratory effects; however, the significant agricultural inputs associated with manufacturing biopolymers exacerbate environmental impacts.

Toward zero waste: composting and recycling for sustainable venue based events.

This study evaluated seven different waste management strategies for venue-based events and characterized the impacts of event waste management via waste audits and the Waste Reduction Model (WARM). The seven waste management scenarios included traditional waste handling methods (e.g. recycle and landfill) and management of the waste stream via composting, including purchasing where only compostable food service items were used during the events. Waste audits were conducted at four Arizona State University (ASU) baseball games, including a three game series. The findings demonstrate a tradeoff among CO2 equivalent emissions, energy use, and landfill diversion rates. Of the seven waste management scenarios assessed, the recycling scenarios provide the greatest reductions in CO2 eq. emissions and energy use because of the retention of high value materials but are compounded by the difficulty in managing a two or three bin collection system. The compost only scenario achieves complete landfill diversion but does not perform as well with respect to CO2 eq. emissions or energy. The three game series was used to test the impact of staffed bins on contamination rates; the first game served as a baseline, the second game employed staffed bins, and the third game had non staffed bins to determine the effect of staffing on contamination rates. Contamination rates in both the recycling and compost bins were tracked throughout the series. Contamination rates were reduced from 34% in the first game to 11% on the second night (with the staffed bins) and 23% contamination rates at the third game.

Effects of co-products on the life-cycle impacts of microalgal biodiesel.

Microalgal biodiesel production has been investigated for decades, yet it is not commercially available. Part of the problem is that the production process is energy and chemical intensive due, in part, to the high portion of microalgal biomass left as residues. This study investigated cradle-to-gate life-cycle environmental impacts from six different scenarios of microalgal biodiesel and its co-products. Ozone depletion, global warming, photochemical smog formation, acidification and eutrophication potentials were assessed using the Tool for the Reduction and Assessment of Chemical and other environmental Impacts (TRACI). Monte Carlo Analysis was conducted to investigate the processes with major contribution in each impact category. The market opportunity for each co-product was examined based on supply, demand and prices of the products that could potentially be substituted by the co-products. The results indicated that the scenario with the least life-cycle environmental impacts in all the five impact categories with the highest net energy ratio was the scenario utilizing a multitude of co-products including bioethanol from lipid-extracted microalgae (LEA), biomethane (to produce electricity and heat) from simultaneous saccharification-fermentation (SSF) residues, land-applied material from SSF residue anaerobic digestion (AD) solid digestate, recycling nutrients from SSF residue AD liquid digestate and CO2 recovered from SSF process contributed. Decreasing the energy consumption of the centrifuge in the land-applied material production process and increasing the lipid content of microalgae can reduce environmental footprints of the co-products. The same scenario also had the highest total income indicating their potential as co-products in the market.

Process energy comparison for the production and harvesting of algal biomass as a biofuel feedstock.

Harvesting and drying are often described as the most energy intensive stages of microalgal biofuel production. This study analyzes two cultivation and eleven harvest technologies for the production of microalgae biomass with and without the use of drying. These technologies were combined to form 122 different production scenarios. The results of this study present a calculation methodology and optimization of total energy demand for the production of algal biomass for biofuel production. The energetic interaction between unit processes and total process energy demand are compared for each scenario. Energy requirements are shown to be highly dependent on final mass concentration, with thermal drying being the largest energy consumer. Scenarios that omit thermal drying in favor of lipid extraction from wet biomass show the most promise for energy efficient biofuel production. Scenarios which used open ponds for cultivation, followed by settling and membrane filtration were the most energy efficient.

Life cycle assessment perspectives on delivering an infant in the US.

This study introduces life cycle assessment as a tool to analyze one aspect of sustainability in healthcare: the birth of a baby. The process life cycle assessment case study presented evaluates two common procedures in a hospital, a cesarean section and a vaginal birth. This case study was conducted at Magee-Womens Hospital of the University of Pittsburgh Medical Center, which delivers over 10,000 infants per year. The results show that heating, ventilation, and air conditioning (HVAC), waste disposal, and the production of the disposable custom packs comprise a large percentage of the environmental impacts. Applying the life cycle assessment tool to medical procedures allows hospital decision makers to target and guide efforts to reduce the environmental impacts of healthcare procedures.

Evaluating industrial symbiosis and algae cultivation from a life cycle perspective.

A comparative life cycle assessment (LCA) was conducted on 20 scenarios of microalgae cultivation. These scenarios examined the utilization of nutrients and CO(2) from synthetic sources and waste streams as well as the materials used to construct a photobioreactor (PBR). A 0.2-m(3) closed PBR of Chlorella vulgaris at 30%-oil content by weight with the productivity of 25 g/m(2) × day was used as a case study. Results of the study show that the utilization of resources from waste streams mainly avoided global warming potential (GWP) and eutrophication impacts. Impacts from the production of material used to construct the PBR dominate total impacts in acidification and ozone depletion categories, even over longer PBR lifetimes; thus, the choice of PBR construction materials is important.

Impact of biofuel crop production on the formation of hypoxia in the Gulf of Mexico.

Many studies have compared corn-based ethanol to cellulosic ethanol on a per unit basis and have generally concluded that cellulosic ethanol will result in fewer environmental consequences, including nitrate (NO3(-)) output. This study takes a system-wide approach in considering the NO3(-) output and the relative areal extent of hypoxia in the Northern Gulf of Mexico (NGOM) due to the introduction of additional crops for biofuel production. We stochastically estimate NO3(-) loading to the NGOM and use these results to approximate the areal extent of hypoxia for scenarios that meet the Energy Independence and Security Act of 2007's biofuel goals for 2015 and 2022. Crops for ethanol include corn, corn stover, and switchgrass; all biodiesel is assumed to be from soybeans. Our results indicate that moving from corn to cellulosics for ethanol production may result in a 20-percent decrease (based on mean values) in NO3(-) output from the Mississippi and Atchafalaya River Basin (MARB). This decrease will not meet the EPA target for hypoxic zone reduction. An aggressive nutrient management strategy will be needed to reach the 5000 km2 areal extent of hypoxia in the NGOM goal set forth by the Mississippi River/Gulf of Mexico Watershed Nutrient Task Force even in the absence of biofuels, given current production to meet food, feed, and other industrial needs.

Life cycle of the corn-soybean agroecosystem for biobased production.

Biobased product life cycle assessments (LCAs) have focused largely on energy (fossil fuel) usage and greenhouse gas emissions during the agriculture and production stages. This paper compiles a more comprehensive life cycle inventory (LCI) for use in future bioproduct LCAs that rely on corn or soybean crops as feedstocks. The inventory includes energy, C, N, P, major pesticides, and U.S. EPA criteria air pollutants that result from processes such as fertilizer production, energy production, and on-farm chemical and equipment use. Agroecosystem material flows were modeled using a combination of GREET (the Greenhouse Gases, Regulated Emissions, and Energy Use in Transportation model), a linear fractionation model that describes P biogeochemical cycling, and Monte Carlo Analysis. Results show that the dominant air emissions resulted from crop farming, fertilizers, and on-farm nitrogen flows (e.g., N20 and NO). Seed production and irrigation provided no more than 0.002% to any of the inventory emissions or energy flows and may be neglected in future LCAs of corn or soybeans as feedstocks from the U.S. Corn Belt. Lime contributes significantly (17% of total emissions) to air emissions and should not be neglected in bioproduct LCAs.

A comparative life cycle assessment of petroleum and soybean-based lubricants.

A comparative life cycle assessment examining soybean and petroleum-based lubricants is compiled using Monte Carlo analysis to assess system variability. Experimental data obtained from an aluminum manufacturing facility indicate significantly less soybean lubricant is required to achieve similar or superior performance. With improved performance and a lower use rate, a transition to soybean oil results in lower aggregate impacts of acidification, smog formation, and human health from criteria pollutants. Regardless of quantity consumed, soybean-based lubricants exhibit significant climate change and fossil fuel use benefits; however, eutrophication impacts are much greater due to non-point nutrient emissions. Fundamental tradeoffs in the carbon and nitrogen cycles are addressed in the analysis, demonstrating that a transition to soybean oil may result in climate change benefits at the expense of regional water quality.

Use of Monte Carlo analysis to characterize nitrogen fluxes in agroecosystems.

Intensive agricultural systems are largely responsible for the increase in global reactive nitrogen compounds, which are associated with significant environmental impacts. The nitrogen cycle in agricultural systems is complex and highly variable, which complicates characterization in environmental assessments. Appropriately representing nitrogen inputs into an ecosystem is essential to better understand and predict environmental impacts, such as the extent of seasonally occurring hypoxic zones. Many impacts associated with reactive nitrogen are directly related to annual nitrogen loads, and are not adequately represented by average values that de-emphasize extreme years. To capture the inherent variability in agricultural systems, this paper employs Monte Carlo analysis (MCA) to model major nitrogen exports during crop production, focusing on corn-soybean rotations within the U.S. Corn Belt. This approach yields distributions of possible emission values and is the first step in incorporating variable nutrient fluxes into life cycle assessments (LCA) and environmental impact assessments. Monte Carlo simulations generate distributions of nitrate emissions showing that 80% of values range between 15 and 90 kg NO39-) N/ha (mean 38.5 kg NO3(-) N/ha; median 35.7 kg NO3(-) N/ha) for corn fields and 5-60 kg NO3(-) N/ha (mean 20.8 kg NO3(-) N/ha; median 16.4 kg NO3(-) N/ha) for soybean fields. Data were also generated for grain and residue nitrogen, N2O, NO(x), and NH3. Results indicate model distributions are in agreement with available measured emissions.