Life Cycle Analysis of Fischer-Tropsch Diesel Produced by Tri-Reforming and Fischer-Tropsch Synthesis (TriFTS) of Landfill Gas.

Renewable liquid fuels production from landfill waste provides a promising alternative to conventional carbon-intensive waste management methods and has the potential to contribute to the transition toward low-carbon fuel pathways. In this work, we investigated the life cycle greenhouse gas (GHG) emissions of producing Fischer-Tropsch diesel from landfill gas (LFG) using the TriFTS catalytic conversion process and compared it to fossil-based petroleum diesel. A life cycle-based comparison was made between TriFTS diesel and other LFG waste management pathways, LFG-to-Electricity and LFG-to-Compressed renewable natural gas (RNG), on a per kilogram of feedstock basis as well as on a per MJ of energy basis, which also included the LFG-to-Direct Combustion pathway. The study considered flaring of LFG as the common underlying counterfactual scenario for all of the waste-to-energy product pathways. We estimated the life cycle GHG emissions for TriFTS diesel to be -36.4 carbon dioxide equivalent (grams CO2e)/MJ which is significantly lower than its fossil fuel counterpart which was estimated to be 90.5 g CO2e/MJ on a cradle-to-grave basis. The life cycle emission results from both perspectives (per kg feedstock and per MJ energy output) show that TriFTS diesel is a viable alternative energy pathway from LFG when compared to other pathways, primarily due to the main product being a renewable fuel that can serve as a drop-in fuel for diesel-based uses, within both the waste industry as well as the larger market. Further sensitivity analysis was performed based on the production of TriFTS diesel with the counterfactual waste management scenario of LFG-to-Flaring as well as the alternative LFG-to-Electricity waste management pathway. The sensitivity of the carbon intensity for TriFTS diesel to flaring efficiency and the carbon intensity of the electricity grid were also investigated. The study highlights the potential for the TriFTS conversion process technology to contribute to the waste industry's closed loop and decarbonization initiatives and to provide low carbon fuel for transportation.

Implications of CO2 Sourcing on the Life-Cycle Greenhouse Gas Emissions and Costs of Algae Biofuels.

Production of algal biomass and its conversion to biofuels are important technological platforms within the larger umbrella of CO2 capture and utilization. This analysis incorporates a life-cycle assessment (LCA) with respect to global warming potential and techno-economic assessment (TEA) of algae biofuels, focusing on the sourcing and delivery of CO2. This analysis evolves past work in this area to include high-purity biogenic CO2, industrial fossil fuel use, fossil power plants, and direct air capture, and uses a Sherwood plot approach to estimate the CO2 capture energy penalty. We also show that allocation or displacement facilitates a more intuitive distinction between biogenic and fossil sources of carbon. Thus, the LCA better reflects the influence of coproduct handling strategies as compared to previous works. The TEA is also strongly influenced by the CO2 concentration in the flue gas. Currently, when CO2 is sourced from large-point sources, the price of biofuels ($4.5-6.5/GGE) may become comparable to fossil diesel. However, as DAC systems become more economical, they may deliver competitive CO2 sources for biofuels in 2050 with a total cost of <$7/GGE. Based on the net emissions and costs, algae biofuels with CO2 sourced from biogenic sources are consistent with a decarbonized economy as of now, with substantial potential for DAC with decreasing costs.

Comparing Life-Cycle Emissions of Biofuels for Marine Applications: Hydrothermal Liquefaction of Wet Wastes, Pyrolysis of Wood, Fischer-Tropsch Synthesis of Landfill Gas, and Solvolysis of Wood.

Recent restrictions on marine fuel sulfur content and a heightened regulatory focus on maritime decarbonization are driving the deployment of low-carbon and low-sulfur alternative fuels for maritime transport. In this study, we quantified the life-cycle greenhouse gas and sulfur oxide emissions of several novel marine biofuel candidates and benchmarked the results against the emissions reduction targets set by the International Maritime Organization. A total of 11 biofuel pathways via four conversion processes are considered, including (1) biocrudes derived from hydrothermal liquefaction of wastewater sludge and manure, (2) bio-oils from catalytic fast pyrolysis of woody biomass, (3) diesel via Fischer-Tropsch synthesis of landfill gas, and (4) lignin ethanol oil from reductive catalytic fractionation of poplar. Our analysis reveals that marine biofuels' life-cycle greenhouse gas emissions range from -60 to 56 gCO2e MJ-1, representing a 41-163% reduction compared with conventional low-sulfur fuel oil, thus demonstrating a considerable potential for decarbonizing the maritime sector. Due to the net-negative carbon emissions from their life cycles, all waste-based pathways showed over 100% greenhouse gas reduction potential with respect to low-sulfur fuel oil. However, while most biofuel feedstocks have a naturally occurring low-sulfur content, the waste feedstocks considered here have higher sulfur content, requiring hydrotreating prior to use as a marine fuel. Combining the break-even price estimates from a published techno-economic analysis, which was performed concurrently with this study, the marginal greenhouse gas abatement cost was estimated to range from -$120 to $370 tCO2e-1 across the pathways considered. Lower marginal greenhouse gas abatement costs were associated with waste-based pathways, while higher marginal greenhouse gas abatement costs were associated with the other biomass-based pathways. Except for lignin ethanol oil, all candidates show the potential to be competitive with a carbon credit of $200 tCO2e-1 in 2016 dollars, which is within the range of prices recently received in connection with California's low-carbon fuel standard.

Environmental life cycle assessment of treatment and management strategies for food waste and sewage sludge.

A consequential life cycle assessment (LCA) was utilized to compare the environmental impacts of food waste and sewage sludge management strategies. The strategies included a novel two-phase anaerobic digestion (AD) system and alternatives including landfill, waste-to-energy, composting, anaerobic membrane bioreactor, and conventional AD (wet continuous stirred-tank reactor [CSTR]). The co-management of food waste with sewage sludge was also considered for the two-phase AD system and for a conventional AD reactor. A multidimensional LCA approach was taken, considering the five-midpoint impact categories of global warming, smog, human health particulate, acidification, and eutrophication estimated using the U.S. EPA Tool for the Reduction and Assessment of Chemical and Other Environmental Impacts. Co-management of food waste and sewage sludge using the novel two-phase AD system was shown to maximize energy recovery and had a net global warming benefit while reducing other environmental impacts compared with the alternative management strategies. It had similar relative environmental advantages across all categories as conventional AD, with the advantage of a smaller physical footprint. However, both approaches featured net environmental burdens when the background electric grid intensity fell below 0.25 kg CO2-eq kWh-1, as could be expected in a decarbonized electric future. Upgrading the biogas produced from AD to renewable natural gas can displace the use of fossil natural gas for other non-electricity energy requirements that are difficult to decarbonize and may extend the time period of significant environmental benefits of utilizing AD for organic waste management. Treatment of the nutrient-rich supernatant generated by the novel two-phase AD system could be an obstacle for utilities with stringent nutrient discharge limits. Future research and full-scale implementation are needed to demonstrate the benefits of the two-phase AD system predicted through this analysis.

Techno-economic Analysis of Sustainable Biofuels for Marine Transportation.

Renewable, low-carbon biofuels offer the potential opportunity to decarbonize marine transportation. This paper presents a comparative techno-economic analysis and process sustainability assessment of four conversion pathways: (1) hydrothermal liquefaction (HTL) of wet wastes such as sewage sludge and manure; (2) fast pyrolysis of woody biomass; (3) landfill gas Fischer-Tropsch synthesis; and (4) lignin-ethanol oil from the lignocellulosic ethanol biorefinery utilizing reductive catalytic fractionation. These alternative marine biofuels have a modeled minimum fuel selling price between $1.68 and $3.98 per heavy fuel oil gallon equivalent in 2016 U.S. dollars based on a mature plant assessment. The selected pathways also exhibit good process sustainability performance in terms of water intensity compared to the petroleum refineries. Further, the O and S contents of the biofuels vary widely. While the non-HTL biofuels exhibit negligible S content, the raw biocrudes via HTL pathways from sludge and manure show relatively high S contents (>0.5 wt %). Partial or full hydrotreatment can effectively lower the biocrude S content. Additionally, co-feeding with other low-sulfur wet wastes such as food waste can provide another option to produce raw biocrude with lower S content to meet the target with further hydrotreatment. This study indicates that biofuels could be a cost-effective fuel option for the marine sector. Marine biofuels derived from various feedstocks and conversion technologies could mitigate marine biofuel adoption risk in terms of feedstock availability and biorefinery economics.

Screening and evaluation of biomass upgrading strategies for sustainable transportation fuel production with biomass-derived volatile fatty acids.

Biomass conversion to fuels and chemicals is crucial to decarbonization, but choosing an advantageous upgrading pathway out of many options is challenging. Rigorously evaluating all candidate pathways (process simulation, product property testing) requires a prohibitive amount of research effort; even simple upgrading schemes have hundreds of possible permutations. We present a method enabling high-throughput screening by approximating upgrading unit operations and drop-in compatibility of products (e.g., fuel properties) and apply it to volatile fatty acid (VFA) conversion to liquid transportation fuels via a MATLAB script, VFA Upgrading to Liquid Transportation fUels Refinery Estimation (VULTURE). VULTURE selects upgrading configurations that maximize fuel blend bio-derived content. We validate VULTURE's approximations through surrogate fuel property testing and process simulation. Techno-economic and life cycle analyses suggest that VFA upgrading processes down-selected by VULTURE are profitable and have low carbon intensities, demonstrating the potential for the strategy to accelerate process development timelines at decreased costs.

Life Cycle Greenhouse Gas Emissions of Biodiesel and Renewable Diesel Production in the United States.

This study presents a life-cycle analysis of greenhouse gas (GHG) emissions of biodiesel (fatty acid methyl ester) and renewable diesel (RD, or hydroprocessed easters and fatty acids) production from oilseed crops, distillers corn oil, used cooking oil, and tallow. Updated data for biofuel production and waste fat rendering were collected through industry surveys. Life-cycle GHG emissions reductions for producing biodiesel and RD from soybean, canola, and carinata oils range from 40% to 69% after considering land-use change estimations, compared with petroleum diesel. Converting tallow, used cooking oil, and distillers corn oil to biodiesel and RD could achieve higher GHG reductions of 79% to 86% lower than petroleum diesel. The biodiesel route has lower GHG emissions for oilseed-based pathways than the RD route because transesterification is less energy-intensive than hydro-processing. In contrast, processing feedstocks with high free fatty acid such as tallow via the biodiesel route results in slightly higher GHG emissions than the RD route, mainly due to higher energy use for pretreatment. Besides land-use change and allocation methods, key factors driving biodiesel and RD life-cycle GHG emissions include fertilizer use and nitrous oxide emissions for crop farming, energy use for grease rendering, and energy and chemicals input for biofuel conversion.

Derivation and assessment of regional electricity generation emission factors in the USA.

Purpose: Electricity production is one of the largest sources of environmental emissions-especially greenhouse gases (GHGs)-in the USA. Emission factors (EFs) vary from region to region, which requires the use of spatially relevant EF data for electricity production while performing life cycle assessments (LCAs). Uncertainty information, which is sought by LCA practitioners, is rarely supplied with available life cycle inventories (LCIs). Methods: To address these challenges, we present a method for collecting data from different sources for electricity generation and environmental emissions; discuss the challenges involved in agglomerating such data; provide relevant suggestions and solutions to merge the information; and calculate EFs for electricity generation processes from various fuel sources for different spatial regions and spatial resolutions. The EFs from the US 2016 Electricity Life Cycle Inventory (eLCI) are analyzed and explored in this study. We also explore the method of uncertainty information derivation for the EFs. Results and discussion: We explore the EFs from different technologies across Emissions & Generation Resource Integrated Database (eGRID) regions in the USA. We find that for certain eGRID regions, the same electricity production technology may have worse emissions. This may be a result of the age of the plants in the region, the quality of fuel used, or other underlying factors. Region-wise life cycle impact assessment (LCIA) ISO 14040 impacts for total generation mix activities provide an overview of the total sustainability profile of electricity production in a particular region, rather than only global warming potential (GWP). We also find that, for different LCIA impacts, several eGRID regions are consistently worse than the US average LCIA impact for every unit of electricity generated. Conclusion: This work describes the development of an electricity production LCI at different spatial resolutions by combining and harmonizing information from several databases. The inventory consists of emissions, fuel inputs, and electricity and steam outputs from different electricity production technologies located across various regions of the USA. This LCI for electricity production in the USA will prove to be an enormous resource for all LCA researchers-considering the detailed sources of the information and the breadth of emissions covered by it.

Material Flows of Polyurethane in the United States.

Today, polyurethanes are effectively not recycled and are made principally from nonrenewable, fossil-fuel-derived resources. This study provides the first high-resolution material flow analysis of polyurethane flows through the U.S. economy, tracking back to fossil fuels and covering polyurethane-relevant raw materials, trade, production, manufacturing, uses, historical stocks, and waste management. According to our analysis, in 2016, 2900 thousand tonnes (kt) of polyurethane were produced in the United States and 920 kt were imported for consumption, 2000 kt entered the postconsumer waste streams, and 390 kt were recycled and returned to the market in the form of carpet underlayment. The domestic production of polyurethane consumed 1100 kt of crude oil and 1100 kt of natural gas. With the developed polyurethane flow map, we point out the limitation of the existing mechanical recycling methods and identify that glycolysis, a chemical recycling method, can be used to recycle the main components of postconsumer polyurethane waste. We also explore how targeting biobased pathways could influence the supply chain and downstream markets of polyurethane and reduce the consumption of fossil fuels and the exposure to toxic precursors in polyurethane production.

Biofuel Options for Marine Applications: Technoeconomic and Life-Cycle Analyses.

This study performed technoeconomic and life-cycle analyses to assess the economic feasibility and emission benefits and tradeoffs of various biofuel production pathways as an alternative to conventional marine fuels. We analyzed production pathways for (1) Fischer-Tropsch diesel from biomass and cofeeding biomass with natural gas or coal, (2) renewable diesel via hydroprocessed esters and fatty acids from yellow grease and cofeeding yellow grease with heavy oil, and (3) bio-oil via fast pyrolysis of low-ash woody feedstock. We also developed a new version of the Greenhouse gases, Regulated Emissions, and Energy use in Transportation (GREET) marine fuel module for the estimation of life-cycle greenhouse gas (GHG) and criteria air pollutant (CAP) emissions of conventional and biobased marine fuels. The alternative fuels considered have a minimum fuel selling price between 2.36 and 4.58 $/heavy fuel oil gallon equivalent (HFOGE), and all exhibit improved life-cycle GHG emissions compared to heavy fuel oil (HFO), with reductions ranging from 40 to 93%. The alternative fuels also exhibit reductions in sulfur oxides and particulate matter emissions. Additionally, when compared with marine gas oil and liquified natural gas, they perform favorably across most emission categories except for cases where carbon and sulfur emissions are increased by the cofed fossil feedstocks. The pyrolysis bio-oil offers the most promising marginal CO2 abatement cost at less than $100/tonne CO2e for HFO prices >$1.09/HFOGE followed by Fischer-Tropsch diesel from biomass and natural gas pathways, which fall below $100/tonne CO2e for HFO prices >$2.25/HFOGE. Pathways that cofeed fossil feedstocks with biomass do not perform as well for marginal CO2 abatement cost, particularly at low HFO prices. This study indicates that biofuels could be a cost-effective means of reducing GHG, sulfur oxide, and particulate matter emissions from the maritime shipping industry and that cofeeding biomass with natural gas could be a practical approach to smooth a transition to biofuels by reducing alternative fuel costs while still lowering GHG emissions, although marginal CO2 abatement costs are less favorable for the fossil cofeed pathways.

The Significance of Environmental Attributes as Indicators of the Life Cycle Environmental Impacts of Packaging and Food Service Ware.

The environmental impacts of packaging and food service ware (FSW) are increasingly the subject of government policy, public discourse, and industry commitments. While some consideration is given to reducing the impacts of packaging across its entire life cycle, most of the focus is on packaging waste or feedstock substitution. Efforts typically focus on specific packaging characteristics, or material attributes, commonly perceived to be environmentally preferable. This article summarizes an extensive meta-review of existing published literature that was performed to determine whether the material attributes recyclability, recycled content, compostability, and biobased, commonly considered to be environmentally beneficial, correlate with lower net environmental impacts across the full life cycle of the packaging and FSW. Seventy-one unique life cycle assessment (LCA) studies that quantify the environmental impacts throughout the entire life cycle of packaging and FSW were analyzed. These studies included over 5000 comparisons for 13 impact categories commonly analyzed in LCA studies. The results from the meta-review identified a number of instances where material attributes do not correlate with environmental benefits for packaging and FSW. Rather, other characteristics such as material choice or mass of the packaging/FSW products can have higher influence in determining life cycle impacts.

Critical Review of Eutrophication Models for Life Cycle Assessment.

This paper evaluates the current state of life cycle impact assessment (LCIA) methods used to estimate potential eutrophication impacts in freshwater and marine ecosystems and presents a critical review of the underlying surface water quality, watershed, marine, and air fate and transport (F&T) models. Using a criteria rubric, we assess the potential of each method and model to contribute to further refinements of life cycle assessment (LCA) eutrophication mechanisms and nutrient transformation processes as well as model structure, availability, geographic scope, and spatial and temporal resolution. We describe recent advances in LCIA modeling and provide guidance on the best available sources of fate and exposure factors, with a focus on midpoint indicators. The critical review identifies gaps in LCIA characterization modeling regarding the availability and spatial resolution of fate factors in the soil compartment and identifies strategies to characterize emissions from soil. Additional opportunities are identified to leverage detailed F&T models that strengthen existing approaches to LCIA or that have the potential to link LCIA modeling more closely with the spatial and temporal realities of the effects of eutrophication.

USEEIO: a New and Transparent United States Environmentally-Extended Input-Output Model.

National-scope environmental life cycle models of goods and services may be used for many purposes, not limited to quantifying impacts of production and consumption of nations, assessing organization-wide impacts, identifying purchasing hotspots, analyzing environmental impacts of policies, and performing streamlined life cycle assessment. USEEIO is a new environmentally-extended input-output model of the United States fit for such purposes and other sustainable materials management applications. USEEIO melds data on economic transactions between 389 industry sectors with environmental data for these sectors covering land, water, energy and mineral usage and emissions of greenhouse gases, criteria air pollutants, nutrients and toxics, to build a life cycle model of 385 US goods and services. In comparison with existing US models, USEEIO is more current with most data representing year 2013, more extensive in its coverage of resources and emissions, more deliberate and detailed in its interpretation and combination of data sources, and includes formal data quality evaluation and description. USEEIO is assembled with a new Python module called the IO Model Builder capable of assembling and calculating results of user-defined input-output models and exporting the models into LCA software. The model and data quality evaluation capabilities are demonstrated with an analysis of the environmental performance of an average hospital in the US. All USEEIO files are publicly available bringing a new level of transparency for environmentally-extended input-output models.

A Nitrogen Physical Input-Output Model for Illinois.

Nitrogen (N) presents an important challenge for sustainability. Human intervention in the global nitrogen cycle has been pivotal in in providing goods and services to society. However, release of N beyond its intended societal use has many negative health and environmental consequences. Several systems modeling approaches have been developed to understand the trade-offs between the beneficial and harmful effects of N. These efforts include life cycle modeling, integrated management practices and sustainability metrics for individuals and communities. However, these approaches do not connect economic and ecological N flows in physical units throughout the system, which could better represent these trade-offs for decision-makers. Physical Input-Output Table (PIOT) based models present a viable complementary solution to overcome this limitation. We developed a N-PIOT for Illinois representing the interdependence of sectors in 2002, using N mass units. This allows studying the total N flow required to produce a certain amount of N in the final product. An Environmentally Extended Input Output (EEIO) based approach was used to connect the physical economic production to environmental losses; allowing quantification of total environmental impact to support agricultural production in Illinois. A bottom up approach was used to develop the N-PIOT using Material Flow Analysis (MFA) tracking N flows associated with top 3 commodities (Corn, Soybean and Wheat). These three commodities cover 99% of N fertilizer use in Illinois. The PIOT shows that of all the N inputs to corn production the state exported 68% of N embedded in useful products, 9% went to animal feed manufacturing and only 0.03% was consumed directly within the state. Approximately 35% of N input to soybean farming ended up in animal feed. Release of N to the environment was highest from corn farming, at about 21.8% of total N fertilizer inputs, followed by soybean (9.2%) and wheat farming (4.2%). The model also allowed the calculation of life cycle N use efficiency for N based on physical flows in the economy. Hence, PIOTs prove to be a viable tool for developing a holistic approach to manage disrupted biogeochemical cycles, since these provide a detailed insight into physical flows in economic systems and allow physical coupling with ecological N flows.

Cost, energy, global warming, eutrophication and local human health impacts of community water and sanitation service options.

We compared water and sanitation system options for a coastal community across selected sustainability metrics, including environmental impact (i.e., life cycle eutrophication potential, energy consumption, and global warming potential), equivalent annual cost, and local human health impact. We computed normalized metric scores, which we used to discuss the options' strengths and weaknesses, and conducted sensitivity analysis of the scores to changes in variable and uncertain input parameters. The alternative systems, which combined centralized drinking water with sanitation services based on the concepts of energy and nutrient recovery as well as on-site water reuse, had reduced environmental and local human health impacts and costs than the conventional, centralized option. Of the selected sustainability metrics, the greatest advantages of the alternative community water systems (compared to the conventional system) were in terms of local human health impact and eutrophication potential, despite large, outstanding uncertainties. Of the alternative options, the systems with on-site water reuse and energy recovery technologies had the least local human health impact; however, the cost of these options was highly variable and the energy consumption was comparable to on-site alternatives without water reuse or energy recovery, due to on-site reuse treatment. Future work should aim to reduce the uncertainty in the energy recovery process and explore the health risks associated with less costly, on-site water treatment options.

Identifying/Quantifying Environmental Trade-offs Inherent in GHG Reduction Strategies for Coal-Fired Power.

Improvements to coal power plant technology and the cofired combustion of biomass promise direct greenhouse gas (GHG) reductions for existing coal-fired power plants. Questions remain as to what the reduction potentials are from a life cycle perspective and if it will result in unintended increases in impacts to air and water quality and human health. This study provides a unique analysis of the potential environmental impact reductions from upgrading existing subcritical pulverized coal power plants to increase their efficiency, improving environmental controls, cofiring biomass, and exporting steam for industrial use. The climate impacts are examined in both a traditional-100 year GWP-method and a time series analysis that accounts for emission and uptake timing over the life of the power plant. Compared to fleet average pulverized bed boilers (33% efficiency), we find that circulating fluidized bed boilers (39% efficiency) may provide GHG reductions of about 13% when using 100% coal and reductions of about 20-37% when cofiring with 30% biomass. Additional greenhouse gas reductions from combined heat and power are minimal if the steam coproduct displaces steam from an efficient natural gas boiler. These upgrades and cofiring biomass can also reduce other life cycle impacts, although there may be increased impacts to water quality (eutrophication) when using biomass from an intensely cultivated source. Climate change impacts are sensitive to the timing of emissions and carbon sequestration as well as the time horizon over which impacts are considered, particularly for long growth woody biomass.

Critical insights for a sustainability framework to address integrated community water services: Technical metrics and approaches.

Planning for sustainable community water systems requires a comprehensive understanding and assessment of the integrated source-drinking-wastewater systems over their life-cycles. Although traditional life cycle assessment and similar tools (e.g. footprints and emergy) have been applied to elements of these water services (i.e. water resources, drinking water, stormwater or wastewater treatment alone), we argue for the importance of developing and combining the system-based tools and metrics in order to holistically evaluate the complete water service system based on the concept of integrated resource management. We analyzed the strengths and weaknesses of key system-based tools and metrics, and discuss future directions to identify more sustainable municipal water services. Such efforts may include the need for novel metrics that address system adaptability to future changes and infrastructure robustness. Caution is also necessary when coupling fundamentally different tools so to avoid misunderstanding and consequently misleading decision-making.

Comparative human health risk analysis of coastal community water and waste service options.

As a pilot approach to describe adverse human health effects from alternative decentralized community water systems compared to conventional centralized services (business-as-usual [BAU]), selected chemical and microbial hazards were assessed using disability adjusted life years (DALYs) as the common metric. The alternatives included: (1) composting toilets with septic system, (2) urine-diverting toilets with septic system, (3) low flush toilets with blackwater pressure sewer and on-site greywater collection and treatment for nonpotable reuse, and (4) alternative 3 with on-site rainwater treatment and use. Various pathogens (viral, bacterial, and protozoan) and chemicals (disinfection byproducts [DBPs]) were used as reference hazards. The exposure pathways for BAU included accidental ingestion of contaminated recreational water, ingestion of cross-connected sewage to drinking water, and shower exposures to DBPs. The alternative systems included ingestion of treated greywater from garden irrigation, toilet flushing, and crop consumption; and ingestion of treated rainwater while showering. The pathways with the highest health impact included the ingestion of cross-connected drinking water and ingestion of recreational water contaminated by septic seepage. These were also among the most uncertain when characterizing input parameters, particularly the scale of the cross-connection event, and the removal of pathogens during groundwater transport of septic seepage. A comparison of the health burdens indicated potential health benefits by switching from BAU to decentralized water and wastewater systems.

Life cycle assessment of domestic and agricultural rainwater harvesting systems.

To further understanding of the environmental implications of rainwater harvesting and its water savings potential relative to conventional U.S. water delivery infrastructure, we present a method to perform life cycle assessment of domestic rainwater harvesting (DRWH) and agricultural rainwater harvesting (ARWH) systems. We also summarize the design aspects of DRWH and ARWH systems adapted to the Back Creek watershed, Virginia. The baseline design reveals that the pump and pumping electricity are the main components of DRWH and ARWH impacts. For nonpotable uses, the minimal design of DRWH (with shortened distribution distance and no pump) outperforms municipal drinking water in all environmental impact categories except ecotoxicity. The minimal design of ARWH outperforms well water in all impact categories. In terms of watershed sustainability, the two minimal designs reduced environmental impacts, from 58% to 78% energy use and 67% to 88% human health criteria pollutants, as well as avoiding up to 20% blue water (surface/groundwater) losses, compared to municipal drinking water and well water. We address potential environmental and human health impacts of urban and rural RWH systems in the region. The Building for Environmental and Economic Sustainability (BEES) model-based life cycle inventory data were used for this study.