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The literature analyzing the fuel saving, life cycle greenhouse gas (GHG) emission, and ownership cost impacts of lightweighting vehicles with different powertrains is reviewed. Vehicles with lower powertrain efficiencies have higher fuel consumption. Thus, fuel savings from lightweighting internal combustion engine vehicles can be higher than those of hybrid electric and battery electric vehicles. However, the impact of fuel savings on life cycle costs and GHG emissions depends on fuel prices, fuel carbon intensities and fuel storage requirements. Battery electric vehicle fuel savings enable reduction of battery size without sacrificing driving range. This reduces the battery production cost and mass, the latter results in further fuel savings. The carbon intensity of electricity varies widely and is a major source of uncertainty when evaluating the benefits of fuel savings. Hybrid electric vehicles use gasoline more efficiently than internal combustion engine vehicles and do not require large plug-in batteries. Therefore, the benefits of lightweighting depend on the vehicle powertrain. We discuss the value proposition of the use of lightweight materials and alternative powertrains. Future assessments of the benefits of vehicle lightweighting should capture the unique characteristics of emerging vehicle powertrains. [ABSTRACT FROM AUTHOR]

Emerging oil sands technologies could influence industry-wide greenhouse gas emissions, however projecting future emissions is difficult due to limited public reporting of expected performance and deployment of emerging technologies. An expert elicitation was conducted to gauge how experts anticipate emerging in situ, surface mining and upgrading technologies will be deployed and perform compared to current technologies. All experts project the majority (60–98%) of in situ bitumen production in 2034 will be produced using current technologies or hybrid steam-solvent processes. Experts built boxplots to show how they project commercial projects employing emerging technologies would perform in 2034 compared to a current project employing steam-assisted gravity drainage. Across experts, the median reduction in steam-to-oil ratio for hybrid steam-solvent projects and current in situ projects employing process changes (e.g., better well placement) ranged from 3 to 30% and from 12 to 14%, respectively. Median projections from experts about the change in bitumen recovery rate compared to a current (2014) steam-assisted gravity drainage project ranged from 3 to 30% for hybrid steam-solvents and up to 15% for electro-thermal and in situ combustion projects. The responses show that a slight reduction in energy consumption from the adoption of hybrid steam-solvent processes is expected by experts. Experts projected that emerging in situ technologies, which have the largest potential for adoption, will be used primarily for accessing marginal resources and increasing overall production levels, rather than targeting greenhouse gas emissions reductions. Therefore, deployment of emerging technologies is not expected to contribute substantially to meeting greenhouse gas emissions reduction targets for the industry by 2034 under the regulatory conditions at the time of the elicitation, a key insight for policy makers. [ABSTRACT FROM AUTHOR]

A life cycle-based model, OSTUM (Oil Sands Technologies for Upgrading Model), which evaluates the energy intensity and greenhouse gas (GHG) emissions of current oil sands upgrading technologies, is developed. Upgrading converts oil sands bitumen into high quality synthetic crude oil (SCO), a refinery feedstock. OSTUM's novel attributes include the following: the breadth of technologies and upgrading operations options that can be analyzed, energy intensity and GHG emissions being estimated at the process unit level, it not being dependent on a proprietary process simulator, and use of publicly available data. OSTUM is applied to a hypothetical, but realistic, upgrading operation based on delayed coking, the most common upgrading technology, resulting in emissions of 328 kg CO2e/m3 SCO. The primary contributor to upgrading emissions (45%) is the use of natural gas for hydrogen production through steam methane reforming, followed by the use of natural gas as fuel in the rest of the process units' heaters (39%). OSTUM's results are in agreement with those of a process simulation model developed by CanmetENERGY, other literature, and confidential data of a commercial upgrading operation. For the application of the model, emissions are found to be most sensitive to the amount of natural gas utilized as feedstock by the steam methane reformer. OSTUM is capable of evaluating the impact of different technologies, feedstock qualities, operating conditions, and fuel mixes on upgrading emissions, and its life cycle perspective allows easy incorporation of results into well-to-wheel analyses. [ABSTRACT FROM AUTHOR]

Lignocellulosic ethanol has potential for lower life cycle greenhouse gas emissions compared to gasoline and conventional grain-based ethanol. Ethanol production ‘pathways’ need to meet economic and environmental goals. Numerous life cycle assessments of lignocellulosic ethanol have been published over the last 15 years, but gaps remain in understanding life cycle performance due to insufficient data, and model and methodological issues. We highlight key aspects of these issues, drawing on literature and a case study of corn stover ethanol. Challenges include the complexity of feedstock/ecosystems and market-mediated aspects and the short history of commercial lignocellulosic ethanol facilities, which collectively have led to uncertainty in GHG emissions estimates, and to debates on LCA methods and the role of uncertainty in decision making. [ABSTRACT FROM AUTHOR]

Forest bioenergy can contribute to climate change mitigation by reducing greenhouse gas ( GHG) emissions associated with energy production. We assessed changes in GHG emissions resulting from displacement of coal with wood pellets for the Atikokan Generating Station located in Northwestern Ontario, Canada. Two contrasting biomass sources were considered for continuous wood pellet production: harvest residue from current harvest operations (residue scenario) and fibre from expanded harvest of standing live trees (stemwood scenario). For the stemwood scenario, two metrics were used to assess the effects of displacing coal with forest biomass on GHG emissions: (i) time to carbon sequestration parity, defined as the time from the beginning of harvest to when the combined GHG benefit of displacing coal with biomass and the amount of carbon in regenerating forest equalled the amount of forest carbon without harvest for energy production; and (ii) time to carbon debt repayment, defined as the time from the beginning of harvest to when the combined GHG benefit of displacing coal with biomass and the amount of carbon in the regenerating forest equalled forest carbon at the time of harvest. Only time to carbon sequestration parity was used for the residue scenario. In the residue scenario, carbon sequestration parity was achieved within 1 year. In the stemwood scenario, times to carbon sequestration parity and carbon debt repayment were 91 and 112 years, respectively. Sensitivity analysis showed that estimates were robust when parameter values were varied. Modelling experiments showed that increasing growth rates for regenerating stands in the stemwood scenario could substantially reduce time to carbon sequestration parity. We discuss the use of the two metrics (time to carbon sequestration parity and time to carbon debt repayment) for assessing the effects of forest bioenergy projects on GHG emissions and make recommendations on terminology and methodologies for forest bioenergy studies. [ABSTRACT FROM AUTHOR]

Automated vehicles can facilitate vehicle sharing within and between households, thus decreasing ownership rates, albeit increasing miles travelled. While electrification can achieve deep reductions in transportation-related greenhouse gas emissions, shared automated electric vehicles will have different charging needs considering their higher mileage. In this study, travel survey data collected in Toronto is used to optimize the charging needs of shared automated electric vehicles, with the objective of reducing greenhouse gas emissions from electricity generation by choosing charging times that are associated with lower marginal emission factors. Optimized charging schedules reduce greenhouse gas emissions by at least 50% relative to vehicles charging once they return home. Life cycle assessment of multiple sharing scenarios indicates that higher levels of sharing increase emissions. Indeed, empty mileage associated with vehicle relocation and higher deterioration lead to a higher fleet turnover. With vehicle sharing, there is a risk of increasing mileage and vehicle production emissions. [ABSTRACT FROM AUTHOR]

Carbonate reservoirs, and in particular, saline aquifers are globally abundant and promising for carbon dioxide (CO 2 ) storage. Pore network modeling of CO 2 storage in porous networks extracted from imaged carbonates provides a tool for evaluating potential storage sites. Capturing the multi-scale porosities (porosity at multiple length scales from nanometers to millimeters) inherent in carbonates is key to producing reliable pore network simulation results. Thresholding techniques that can extract the multi-scale pore space from micro computed tomography (microCT) or scanning electron microscopy (SEM) are needed. In this work, the application and evaluation of thresholding techniques originally developed for sandstones were applied and evaluated for Indiana Limestone and Pink Dolomite, carbonates that exhibit dual porosities (porosities that represent two distinct pore size distributions). The objective was to determine whether there is a single method or imaging technique that can reliably evaluate the porosity of carbonate rocks. The evaluation of the thresholding techniques applied to carbonate rocks showed that one single imaging technique or thresholding method cannot be solely used for all carbonate rocks. Instead, the evaluated porosity is a function of the microporosity, rock type and image resolution. The sensitivities of existing methods to thresholding techniques, imaging method and material structure were shown. This work provides a preliminary assessment of thresholding dual porosity carbonates. [ABSTRACT FROM AUTHOR]

This paper examines impacts of regional factors affecting biomass and process input supply chains and ongoing technology development on the life cycle greenhouse gas (GHG) emissions of ethanol production from corn stover in the U.S. Corn stover supply results in GHG emissions from −6 gCO 2 eq./MJ ethanol (Macon County, Missouri) to 13 gCO 2 eq./MJ ethanol (Hardin County, Iowa), reflecting location-specific soil carbon and N 2 O emissions responses to stover removal. Biorefinery emissions based on the 2011 National Renewable Energy Laboratory (NREL) process model are the single greatest emissions source (18 gCO 2 eq./MJ ethanol) and are approximately double those assessed for the 2002 NREL design model, due primarily to the inclusion of GHG-intensive inputs (caustic, ammonia, glucose). Energy demands of on-site enzyme production included in the 2011 design contribute to reducing the electricity co-product and associated emissions credit, which is also dependent on the GHG-intensity of regional electricity supply. Life cycle emissions vary between 1.5 and 22 gCO 2 eq./MJ ethanol (2011 design) depending on production location (98%–77% reduction vs. gasoline). Using system expansion for co-product allocation, ethanol production in studied locations meet the Energy Independence and Security Act emissions requirements for cellulosic biofuels; however, regional factors and on-going technology developments significantly influence these results. [ABSTRACT FROM AUTHOR]

Life cycle environmental performance of lignocellulosic ethanol produced through different production pathways and having different co-products has rarely been reported in the literature, with most studies focusing on a single pre-treatment and single co-product (electricity). The aim of this paper is to understand the life cycle energy use and greenhouse gas (GHG) emissions implications of alternative pre-treatment technologies (dilute acid hydrolysis, ammonia fiber expansion and autohydrolysis) and co-products (electricity, pellet, protein and xylitol) through developing a consistent life cycle framework for ethanol production from corn stover. Results show that the choices of pre-treatment technology and co-product(s) can impact ethanol yield, life cycle energy use and GHG emissions. Dilute acid pathways generally exhibit higher ethanol yields (20-25%) and lower net total energy use (15-25%) than the autohydrolysis and ammonia fiber expansion pathways. Similar GHG emissions are found for the pre-treatment technologies when producing the same co-product. Xylitol co-production diverts xylose from ethanol production and results in the lowest ethanol yield (200 L per dry t of stover). Compared to producing only electricity as a co-product, the co-production of pellets and xylitol decreases life cycle GHG emissions associated with the ethanol, while protein production increases emissions. The life cycle GHG emissions of blended ethanol fuel (85% denatured ethanol by volume) range from -38.5-37.2 g CO2 eq/MJ of fuel produced, reducing emissions by 61-141% relative to gasoline. All ethanol pathways result in major reductions of fossil energy use relative to gasoline, at least by 47%. [ABSTRACT FROM AUTHOR]

Policy initiatives have motivated a search for environmentally sustainable alternatives to fossil-fuel-based electricity generation. Agricultural residues such as corn cobs may be a suitable feedstock. A life cycle approach was used to estimate the greenhouse gas ( GHG) emission impacts associated with the use of pellets produced from corn cobs as the sole fuel for the generation of electricity at a hypothetically retrofitted coal-fired generating station in Ontario, Canada. Pellets are compared with current coal and hypothetical natural gas combined cycle ( NGCC) facilities. A life cycle model and soil carbon model calibrated for the agricultural region of interest were combined to quantify the GHG emissions of the biomass product system. The corn cob product system's life cycle emissions (240 g CO2eq kWh−1) are 40% and 80% lower than those of the NGCC and coal product systems, respectively. If corn cobs are left in the field to decompose, some carbon is sequestered in the soil, thus their removal from the field and combustion at the generation station represents a net GHG emission, accounting for 60% of life cycle emissions. In addition to the GHG impacts of combustion, removing agricultural residues from fields may reduce soil health, increase erosion and affect soil fertility through loss of soil organic carbon and nutrients. Their sustainable use should therefore consider the maintenance of soil fertility over the long-term. Nevertheless, the use of the feedstock in place of coal may provide substantial GHG emissions mitigation. [ABSTRACT FROM AUTHOR]

Replacement of fossil fuels with sustainably produced biomass crops for energy purposes has the potential to make progress in addressing climate change concerns, nonrenewable resource use, and energy security. The perennial grass Miscanthus is a dedicated energy crop candidate being field tested in Ontario, Canada, and elsewhere. Miscanthus could potentially be grown in areas of the province that differ substantially in terms of agricultural land class, environmental factors and current land use. These differences could significantly affect Miscanthus yields, input requirements, production practices, and the types of crops being displaced by Miscanthus establishment. This study assesses implications on life cycle greenhouse gas ( GHG) emissions of these differences through evaluating five Miscanthus production scenarios within the Ontario context. Emissions associated with electricity generation with Miscanthus pellets in a hypothetically retrofitted coal generating station are examined. Indirect land use change impacts are not quantified but are discussed. The net life cycle emissions for Miscanthus production varied greatly among scenarios (−90-170 kg CO2eq per oven dry tonne of Miscanthus bales at the farm gate). In some cases, the carbon stock dynamics of the agricultural system offset the combined emissions of all other life cycle stages (i.e., production, harvest, transport, and processing of biomass). Yield and soil C of the displaced agricultural systems are key parameters affecting emissions. The systems with the highest potential to provide reductions in GHG emissions are those with high yields, or systems established on land with low soil carbon. All scenarios have substantially lower life cycle emissions (−20-190 g CO2eq kWh−1) compared with coal-generated electricity (1130 g CO2eq kWh−1). Policy development should consider the implication of land class, environmental factors, and current land use on Miscanthus production. [ABSTRACT FROM AUTHOR]

Our study evaluates life cycle energy use and GHG emissions of lignocellulosic ethanol and bioelectricity use in U.S. light-duty vehicles. The well-to-pump, pump-to-wheel, and vehicle cycle stages are modeled. All ethanol (E85) and bioelectricity pathways have similar life cycle fossil energy use ( ~100 MJ/100 vehicle kilometers traveled (VKT)) and net GHG emissions (~5 kg CO2eq./100 VKT), considerably lower (65-85%) than those of reference gasoline and U.S. grid-electricity pathways. E85 use in a hybrid vehicle and bioelectricity use in a fully electric vehicle also have similar life cycle biomass and total energy use ( ~350 and ~450 MJ/100 VKT, respectively); differences in well-to-pump and pump-to-wheel efficiencies can largely offset each other. Our energy use and net GHG emissions results contrast with findings in literature, which report better performance on these metrics for bioelectricity compared to ethanol. The primary source of differences in the studies is related to our development of pathways with comparable vehicle characteristics. Ethanol or vehicle electrification can reduce petroleum use, while bioelectricity may displace nonpetroleum energy sources. Regional characteristics may create conditions under which either ethanol or bioelectricity may be the superior option; however, neither has a clear advantage in terms of GHG emissions or energy use. [ABSTRACT FROM AUTHOR]

A method combining life cycle assessment (LCA) and real options analyses is developed to predict project environmental and financial performance over time, under market uncertainties and decision-making flexibility. The method is applied to examine alternative uses for oil sands coke, a carbonaceous byproduct of processing the unconventional petroleum found in northern Alberta, Canada. Under uncertainties in natural gas price and the imposition of a carbon price, our method identifies that selling the coke to China for electricity generation by integrated gasification combined cycle is likely to be financially preferred initially, but eventually hydrogen production in Alberta is likely to be preferred. Compared to the results of a previous study that used life cycle costing to identify the financially preferred alternative, the inclusion of real options analysis adds value as it accounts for flexibility in decision-making (e.g., to delay investment), increasing the project's expected net present value by 25% and decreasing the expected life cycle greenhouse gas emissions by 11%. Different formulations of the carbon pricing policy or changes to the natural gas price forecast alter these findings. The combined LCA/real options method provides researchers and decision-makers with more comprehensive information than can be provided by either technique alone. [ABSTRACT FROM AUTHOR]

The cost of cellulases remains a key issue in the production of cellulosic ethanol, and the impact of enzymes on greenhouse gas ( GHG) emissions of cellulosic ethanol has received little attention. This study evaluates life cycle emissions and cellulase production costs for bioethanol production, considering on-site and off-site production options. A complete enzyme production process was simulated using AspenPlus, generating mass and energy balance information required to calculate GHG emissions and financial metrics. GHG emissions for cellulase production range from 10.2 to 16.0 g CO2 eq g-1 enzyme protein, depending on on-site or off-site production and the method of transportation. Enzyme GHG emissions are predicted to be 258 g CO2 eq. L-1 of ethanol for on-site production, versus 403 g CO2 eq. L-1 for off-site production, based on a 150 MMLY ethanol plant using 11.5 mg enzyme g-1 substrate and a cellulase fermentation yield of 90%. Cellulase production costs were estimated for a range of conditions, including ethanol plant size, enzyme dose and protein yield for on-site production, and enzyme plant size, protein yield and return on investment for off-site production. On-site production costs range between $3.80 and $6.75 kg-1 protein, versus $4.00 to $8.80 kg-1 for off-site production. In both scenarios, the lowest cost corresponds to a 90% protein yield, and a high enzyme demand and production capacity. An enzyme production cost of $4.70 USD kg-1 corresponds to an enzyme cost of 0.46 USD gal-1 ($0.12 L-1) of ethanol in a 150 MMLY plant using 11.5 mg enzyme g-1 substrate. © 2013 Society of Chemical Industry and John Wiley & Sons, Ltd [ABSTRACT FROM AUTHOR]

Life cycle greenhouse gas (GHG) emissions associated with two major recovery and extraction processes currently utilized in Alberta's oil sands, surface mining and in situ, are quantified. Process modules are developed and integrated into a life cycle model-GHOST (GreenHouse gas emissions of current Oil Sands Technologies) developed in prior work. Recovery and extraction of bitumen through surface mining and in situ processes result in 3-9 and 9-16 g CO2eq/MJ bitumen, respectively; upgrading emissions are an additional 6-17 g CO2eq/MJ synthetic crude oil (SCO) (all results are on a HHV basis). Although a high degree of variability exists in well-to-wheel emissions due to differences in technologies employed, operating conditions, and product characteristics, the surface mining dilbit and the in situ SCO pathways have the lowest and highest emissions, 88 and 120 g CO2eq/MJ reformulated gasoline. Through the use of improved data obtained from operating oil sands projects, we present ranges of emissions that overlap with emissions in literature for conventional crude oil. An increased focus is recommended in policy discussions on understanding interproject variability of emissions of both oil sands and conventional crudes, as this has not been adequately represented in previous studies. [ABSTRACT FROM AUTHOR]

Reducing greenhouse gas emissions (GHG) is an important social goal to mitigate climate change. A common mitigation paradigm is to consider strategy "wedges" that can be applied to different activities to achieve desired GHG reductions. In this policy analysis piece, we consider a wide range of possible strategies to reduce light-duty vehicle GHG emissions, including fuel and vehicle options, low carbon and renewable power, travel demand management and land use changes. We conclude that no one strategy will be sufficient to meet GHG emissions reduction goals to avoid climate change. However, many of these changes have positive combinatorial effects, so the best strategy is to pursue combinations of transportation GHG reduction strategies to meet reduction goals. Agencies need to broaden their agendas to incorporate such combination in their planning. [ABSTRACT FROM AUTHOR]

Abstract: Increased use of ethanol as a vehicle fuel worldwide warrants the need to understand air quality impacts of replacing gasoline with ethanol. This study evaluates the impacts of dedicated E85 (85% ethanol/15% gasoline) light-duty vehicles on emissions, ozone and particulate matter (PM) concentrations in the United States for a future year (2022) using a 3-D photochemical model, detailed emissions inventories that account for changes in all sectors studied, and winter and summer meteorology that occurred in 2002. Use of E85 introduces new emissions from ethanol production and distribution, reduces petrochemical industry emissions due to lower gasoline consumption, changes on-road vehicle emissions and alters biogenic emissions due to land use changes. Three scenarios with increased ethanol production for dedicated E85 light-duty vehicles were compared to a base case without increased ethanol production. Increased use of E85 caused both increases and decreases in ozone and PM, driven mainly by changes in NO x emissions related to biogenic and upstream petrochemical industry sources. In all states modeled, adoption of dedicated E85 vehicles caused negligible change in average higher ozone and PM concentrations of importance for air quality management strategies. Ozone and PM changes are relatively insensitive to how land area is allocated for switchgrass production. The findings are subject to various uncertainties, especially those in vehicle technology and emissions from cellulosic ethanol production. [Copyright &y& Elsevier]

A life cycle-based model, GHOST (GreenHouse gas emissions of current Oil Sands Technologies), which quantifies emissions associated with production of diluted bitumen and synthetic crude oil (SCO) is developed. GHOST has the potential to analyze a large set of process configurations, is based on confidential oil sands project operating data, and reports ranges of resulting emissions, improvements over prior studies, which primarily included a limited set of indirect activities, utilized theoretical design data, and reported point estimates. GHOST is demonstrated through application to a major oil sands process, steam-assisted gravity drainage (SAGD). The variability in potential performance of SAGD technologies results in wide ranges of "well-to-refinery entrance gate" emissions (comprising direct and indirect emissions): 18-41 g CO2eq/MJ SCO, 9-18 g CO2eq/MJ dilbit, and 13-24 g CO2eq/MJ synbit. The primary contributor to SAGD's emissions is the combustion of natural gas to produce process steam, making a project's steam-to-oil ratio the most critical parameter in determining GHG performance. The demonstration (a) illustrates that a broad range of technology options, operating conditions, and resulting emissions exist among current oil sands operations, even when considering a single extraction technology, and (b) provides guidance about the feasibility of lowering SAGD project emissions. [ABSTRACT FROM AUTHOR]

The potential of forest-based bioenergy to reduce greenhouse gas (GHG) emissions when displacing fossil-based energy must be balanced with forest carbon implications related to biomass harvest. We integrate life cycle assessment (LCA) and forest carbon analysis to assess total GHG emissions of forest bioenergy over time. Application of the method to case studies of wood pellet and ethanol production from forest biomass reveals a substantial reduction in forest carbon due to bioenergy production. For all cases, harvest-related forest carbon reductions and associated GHG emissions initially exceed avoided fossil fuel-related emissions, temporarily increasing overall emissions. In the long term, electricity generation from pellets reduces overall emissions relative to coal, although forest carbon losses delay net GHG mitigation by 16-38 years, depending on biomass source (harvest residues/standing trees). Ethanol produced from standing trees increases overall emissions throughout 100 years of continuous production: ethanol from residues achieves reductions after a 74 year delay. Forest carbon more significantly affects bioenergy emissions when biomass is sourced from standing trees compared to residues and when less GHG-intensive fuels are displaced. In all cases, forest carbon dynamics are significant. Although study results are not generalizable to all forests, we suggest the integrated LCA/forest carbon approach be undertaken for bioenergy studies. [ABSTRACT FROM AUTHOR]

The use of coal is responsible for 1/5 of global greenhouse gas (GHG) emissions. Substitution of coal with biomass fuels is one of a limited set of near-term options to significantly reduce these emissions. We investigate, on a life cycle basis, 100% wood pellet firing and cofiring with coal in two coal generating stations (GS) is Ontario, Canada. GHG and criteria air pollutant emissions are compared with current coal and hypothetical natural gas combined cycle (NGCC) facilities. 100% pellet utilization provides the greatest GHG benefit on a kilowatt-hour basis, reducing emissions by 91% and 78% relative to coal and NGCC systems, respectively. Compared to coal, using 100% pellets reduces NOx emissions by 40-47% and SOx emissions by 76-81%. At $160/metric ton of pellets and $7/GJ natural gas, either cofiring or NGCC provides the most cost-effective GRG mitigation ($70 and $47/metric ton of CO2 equivalent, respectively). The differences in coal price, electricity generation cost, and emissions at the two GS are responsible for the different options being preferred. A sensitivity analysis on fuel costs reveals considerable overlap in results for all options. A lower pellet price (S100/metric ton) results in a mitigation cost of $34/metric ton of CO2 equivalent for 10% cofiring at one of the GS. The study results suggest that biomass utilization in coal GS should be considered for its potential to cost-effectively mitigate GHGs from coal-based electricity in the near term. [ABSTRACT FROM AUTHOR]

The environmental and human health impacts of engineering activities have reshaped the way engineers make decisions. Increasingly, engineering decision-making is taking into consideration the full life cycle implications of engineering activities. This paper details the development and application of a national economic input–output-based life cycle assessment model, a tool for guiding engineering decision-making, for the Canadian economy. The model consists of 61 industries and 103 commodities and incorporates economic and environmental–resource data, including marginal resource consumption, energy use, releases of National Pollutant Release Inventory compounds, and emissions of greenhouse gases. The model is useful for evaluating various development strategies and analyzing the potential direct and indirect impacts of alternative public policies on the Canadian economy and environment. The model is applied to various sectors of the Canadian economy, and the life-cycle implications of demands for different commodities are determined, including demand for electricity and construction materials for highway design. [ABSTRACT FROM AUTHOR]

Life cycle assessments can help inform decision-making about greenhouse gas (GHG) emission reduction opportunities but are often not embraced by stakeholders associated with industries where study results are highly scrutinized and often contentious. This project was motivated by stakeholder interest in understanding open source life cycle models (the Oil Production Greenhouse Gas Emissions Estimator, OPGEE, and the Petroleum Refinery Life Cycle Inventory Model, PRELIM) and how accurately they can estimate emissions for existing oil sands projects and emerging technologies. We evaluate the robustness of these models and improve them using data from three existing oil sands projects (mining + upgrading, mining + dilution, and steam assisted gravity drainage, SAGD, + dilution). The models are then applied to estimate the GHG emissions reduction potential for two emerging in situ oil sands technologies. We find that, when boundaries are aligned, OPGEE can generate upstream GHG emissions estimates for the projects modeled within 1-4% of company reported GHG emissions data. Extending the boundary to include indirect (life cycle) emissions can lead to a doubling in upstream GHG emissions intensity. The two emerging technologies evaluated in the study can reduce upstream emissions by 14-19% compared to a SAGD project operating at the same reservoir, or 1.4-1.9% on a well-to-wheel basis. This work contributes a revised process of conducting LCAs that includes stakeholder input throughout and results in more robust and transparent estimates of emissions from deploying existing and emerging technologies. • New method to engage stakeholders in life cycle assessment of oil sands projects. • Open source models estimate emissions within 1–4% of reported upstream emissions. • New technologies reduce upstream emissions 14–19% relative to current technology. • Well-to-wheel emissions decrease 1.6–1.9% with adoption of new technologies. • Adopting regional factors in open source models reduces upstream emissions 14–35%. [ABSTRACT FROM AUTHOR]

The refurbished Don Valley Brick Works' Kiln Building, in Toronto, Canada, now the TD Future Cities Centre, is designed to have net zero carbon emissions. This is to be achieved through the reuse of existing materials and structures, selection of lower-carbon materials purchased from local sources, installation of renewable energy systems, natural lighting and improved thermal insulation of the building's envelope, as well as developing a carbon offset strategy. The heritage designation of the building imposed restrictions on the design of the project (e.g., preventing insulation of exterior walls). In collaboration with the owner and constructor, the project team completed a life cycle assessment (LCA) consisting of an assessment of embodied emissions of the building's restoration from cradle to grave, accompanied by a scoping estimate of greenhouse gas emissions associated with its future operational energy use. Primary construction data for the newly-added materials, transport, and construction activities were used. Life cycle inventory analysis and impact assessment were implemented in the One Click LCA software. Use phase carbon intensity was estimated using design and literature data. In addition to the 'core and shell' LCA scope typically applied to buildings, the team also tracked materials and processes that are often not included in building LCA studies such as HVAC, plumbing, and renewable energy systems. Embodied carbon for the restoration project, assuming a 60-year lifetime, is calculated as 1250 tonnes carbon dioxide equivalent (tCO 2 e). Sixty-nine percent of the carbon comes from the materials (extraction to manufacturing) used in construction, 20% is due to replacement of materials during the building's service life, and most of the remaining 11% is from on-site construction energy (5%) and waste disposal at end-of-life (4%). The main building elements contributing to the embodied carbon are the renewable energy systems (31%) and the raised concrete floor (26%). Building envelope and foundation play minor roles, as they are mostly pre-existing. The embodied carbon added to the building through the restoration project is forecast to be balanced by savings in operational energy related to heating, cooling and lighting, within 3–13 years, depending on whether natural gas or electricity use are avoided, respectively. Uncertainties in the analysis arise from partial or missing data, modeling assumptions and future scenario unknowns. The model is sensitive to the useable lifetime of the building, local or non-local sourcing of building materials, modeling of certain components used in large quantities, and changes in the recycled content of steel. This study of a net zero carbon refurbishment project of a heritage building provides insights for assessments of future projects as such refurbishments become more commonplace. The methods and recommendations regarding data sources, data collection, and approach to uncertainty evaluation will be useful for LCA of any construction project. • A brick kiln building was refurbished as an event space targeting net zero carbon. • Existing structures were upgraded and a geo-solar exchange system installed. • Total project embodied carbon is estimated at 255 kgCO 2 e/m2, given a 60-year lifetime. • 69% of estimated GHG emissions are embodied in materials purchased during construction. • Results are sensitive to building lifetime, datapoint modeling and other parameters. [ABSTRACT FROM AUTHOR]

Although the life cycle greenhouse gas (GHG) emissions associated with Canadian oil sands have been investigated in recent years, questions remain regarding the source and impact of variability in emissions in this industry over time. This study combines publicly-available data from the fifteen largest operating in situ extraction projects, i.e., cyclic steam stimulation (CSS) and steam assisted gravity drainage (SAGD) with a statistically-enhanced life cycle model to investigate variability in well-to-wheel (WTW) GHG emissions. We estimate that the WTW GHG emissions from CSS-derived gasoline range from 99 to 114 g CO 2 eq/MJ (80% confidence interval), 6–22% higher than the RFS2 baseline. The corresponding range for SAGD-derived gasoline is 98–133 g CO 2 eq/MJ, 5–42% higher than the RFS2 baseline. SAGD-derived gasoline has more variability as some operators "upgrade" their crudes, emitting GHGs, whereas no CSS operator employs upgrading. Without upgrading, the 90th percentile for SAGD emissions would be 114 g CO 2 eq/MJ. Upstream variability in GHG emissions drives the positively skewed WTW GHG distributions. This demonstrates the importance of understanding the nature and magnitude of variability and uncertainty in decision making. • Source and impact of variability in oil sands LC GHG estimates are understudied. • SAGD LC GHG emissions 5–22% higher than EPA RFS2 gasoline (w/o upgrading). • CSS LC GHG emissions 6–22% higher than EPA RFS2 gasoline (w/o upgrading). • LC emissions variability driven by upstream inputs and if upgrading is used. [ABSTRACT FROM AUTHOR]

Replacing conventional gasoline with mid-level ethanol blends (15–30% ethanol by volume) can reduce fossil fuel use and greenhouse gas (GHG) emissions but require vehicle compatibility. This study quantifies the changes in fuel volumes and well-to-wheel (WTW) GHG emissions associated with potential mid-level ethanol blend deployment in Canada's light-duty vehicle fleet from 2018 to 2030. We develop a Canadian fleet model that projects the number of vehicles by vehicle technology and production year from 2015 to 2030, their fuel blend compatibilities, and their annual fuel use, considering the potential effects of ethanol blend level on vehicle fuel consumption and associated GHG emissions. The results show that the deployment of low and mid-level ethanol blends, such as E10, E15 or E25, could reduce petroleum gasoline use by 12% in 2030, while tripling ethanol use, from 2.6 to 7.2 billion liters annually. Incorporating emission factors from the GHGenius model suggests that mid-level blends can reduce fleet WTW GHG emissions in 2030 by 7.2% assuming the use of corn and wheat ethanol, and by up to 13.4% assuming cellulosic ethanol. The octane enhancing effect of ethanol is responsible for up to 30% of the reductions. Achieving the above reductions would require coordination among vehicle manufacturers, refiners and policymakers. Overall, mid-level blends can materially reduce GHG emissions of the Canadian light-duty fleet, but represent less than 1/5 of the reductions required for the light-duty fleet to achieve emissions that are 30% below 2005 levels (Canada's pledge under the Paris Agreement). • We estimate the GHG emission implications of mid-level ethanol blends in Canada. • Conventional mid-level ethanol blends could reduce WTW GHG emissions 7.2% in 2030. • Cellulosic mid-level ethanol blends could reduce WTW GHG emissions 13.4% in 2030. • Octane enhancing effect of ethanol accounts for 30% of GHG emissions reduction. • Reductions require coordination among vehicle manufacturers, refiners and policymakers. [ABSTRACT FROM AUTHOR]

Existing life cycle assessments of concrete containing supplementary cementitious materials (SCMs) hinge on methodological procedures that might skew the results towards the conclusion that increasing the use of SCMs in concrete always decreases greenhouse gas (GHG) emissions. These procedures relate to the treatment of co-products and selection of functional units. Co-production is typically addressed via cut-off procedures and by-products are always considered to be unconstrained resources, while functional units often do not account for exposure conditions and concrete properties such as strength and workability. To address this limitation, the aim of this study was to investigate the GHG benefits of using SCMs by (1) adopting different approaches to solve multifunctionality (cut-off vs. substitution) and (2) including strength, workability and exposure conditions of concrete in the functional unit. Ontario (Canada) was used as case study, and both SCMs currently used there (i.e., slag, silica fume and metakaolin) and a wide range of alternative cementitious materials used around the world (i.e., fly ash, oil shale ash, calcium carbide residue, volcanic ash, coal bottom ash and rice husk ash) were investigated. The new contribution of this study reveals that different conclusions can be drawn when different methodological procedures are adopted. If the market for SCM is constrained (i.e., by-products are already fully utilized) and the unconstrained alternative on the market is Portland cement, the benefits of using SCM are greatly reduced, or even reversed, if the substitution approach is adopted. In contrast, unconstrained SCMs result in considerable GHG savings unless they significantly reduce the water-to-binder ratio to reach a prescribed strength and require long distance transport. • Market constraints of SCMs should be included in LCA studies of concrete. • Concrete properties and exposure conditions must be included in the functional unit. • If the SCM is constrained, overall GHG benefits of using it are greatly reduced. • Increasing SCMs in concrete does not always decrease its GHG emissions. • The use of alternative unconstrained SCMs should be further explored and promoted. [ABSTRACT FROM AUTHOR]

How oil sands bitumen is produced (through mining or in situ methods) and how the crude is processed (either upgraded to synthetic crude oil, SCO, or diluted to produce dilbit) result in a range of crude properties with distinct downstream emissions. Previous life cycle studies of the greenhouse gas (GHG) intensities of transportation fuels derived from oil sands bitumen have not accounted for this downstream variability. We quantify, on a project basis as well as across the industry, variability in well-to-wheel (WTW) GHG intensities of transportation fuels from mined oil sands bitumen using detailed upstream, crude transport, and refinery models. Across projects, the mining project producing dilbit has lower median WTW GHG intensity per MJ (low heating value basis) gasoline (median: 96; 80% confidence interval: 93–101 g CO2eq/MJ gasoline) versus SCO projects (median: 108–114; 80% confidence interval across all SCO projects: 106–123 g CO2eq/MJ gasoline) but is strongly influenced by assumptions regarding refinery configuration and allocation to refinery products. Intraproject variability exceeds interproject variability, with 80% confidence intervals for individual projects varying up to 16 g CO2eq/MJ, and is driven in approximately equal proportions by the upstream and refining stages, although their relative contributions vary across projects. Compared to the U.S. EPA baselines, the mining project producing dilbit has a WTW GHG intensities that range from 1% (lower) to 8% (higher) and 2% (lower) to 6% (higher) for gasoline and diesel, respectively (80% confidence intervals). Across mining projects producing SCO, WTW GHG intensities range from 10 to 32% higher and 2–25% higher than the U.S. EPA baselines for gasoline and diesel, respectively. We show how downstream modeling decisions (e.g., allocation of refinery emissions to products such as gasoline) influence WTW GHG intensity distributions, compare mining and in situ bitumen production methods' GHG intensities, and discuss implications for meeting intensity-based targets. • We quantify life cycle variability in GHG intensity of fuels from bitumen mining. • Detailed refinery modeling accounts for differences in crude properties. • Variability in emissions is greater within than across projects with upgraders. • For dilbit, variability in refinery emissions exceeds upstream variability. • Refinery configuration and allocation drive variability in refinery emissions. [ABSTRACT FROM AUTHOR]

This paper presents three scenarios of urban growth, energy use and greenhouse gas (GHG) emissions in Dar es Salaam using narratives that are consistent with the Shared Socio-Economic Pathways (SSPs). We estimate residential energy demand and GHG emissions from 2015 to 2050 for household activities (including upstream electricity generation) and passenger (road) transport (Scopes 1 and 2). We project that by 2050, Dar es Salaam's total residential emissions would increase from 1,400 ktCO 2 e (in 2015) up to 25,000–33,000 ktCO 2 e (SSP1); 11,000–19,000 ktCO 2 e (SSP2); and 5,700–11,000 ktCO 2 e (SSP3), with ranges corresponding to different assumptions about household size. This correlates with an increase in per capita emissions from 0.2 tCO 2 e in 2015 to 1.5–2 tCO 2 e (SSP1); 0.7–1.3 tCO 2 e (SSP2); and 0.5–0.9 tCO 2 e (SSP3). Higher emissions in SSP1 (the sustainability scenario) are driven by a higher urban population in 2050 and increased energy access and electricity consumption. Through aggressive GHG mitigation policies focused on decarbonization of the electricity sector and road transport, total emissions under SSP1 can be reduced by ∼66% in 2050. Study insights aim to inform policies that identify and capture synergies between low-GHG investments and broader socio-economic development goals in Sub-Saharan African cities. • Provides the first projection of residential energy use and GHG emissions in Dar es Salaam and demonstrates the use of the SSPs at the city scale. • Analyzes the key drivers of residential energy use and GHG emissions in a large SSA city, Dar es Salaam, offering new insights for the region. • Demonstrates a method for projecting emissions in a data-poor environment. • Shows the wide uncertainty in these future projections, while also demonstrating the order of magnitude jump in emissions that can be expected in Dar es Salaam to 2050. [ABSTRACT FROM AUTHOR]