1,721,022 research outputs found
Assessing Greenhouse Gas Emissions Mitigation Potential through the use of Forest Bioenergy
No full textBioenergy production from forest resources offers opportunities to reduce greenhouse gas (GHG) emissions associated with fossil fuel use, reduce non-renewable energy consumption, and provide investment and employment in the forestry sector. These opportunities, however, must be considered within the broader contexts of forest systems. Of particular interest is how bioenergy opportunities impact carbon storage within the forest. This thesis develops a method to integrate life cycle assessment and forest carbon analysis approaches to quantify the total GHG emissions associated with forest bioenergy. Bioenergy production and utilization decisions are then investigated to evaluate opportunities to increase GHG mitigation performance. An accounting method is developed to evaluate the impact of emissions timing on the cost-effectiveness of GHG emissions reductions from biomass-based electricity generation. Applying the integrated life cycle assessment/forest carbon analysis method to a case study of forest bioenergy production in Ontario reveals significant reductions in forest carbon associated with bioenergy production. Wood pellet production from standing trees or harvest residues (displacing coal in electricity generation) would increase total GHG emissions over periods of approximately 40 and 15 years, respectively. Ethanol production (displacing gasoline) would increase GHG emissions throughout the 100-year model period if produced from standing trees; emissions would increase over a period of approximately75 years if produced from harvest residues. Strategic ethanol production decisions (e.g., process energy source, co-location with other processes, co-product selection) can improve GHG mitigation. Co-production of biomass pellets with ethanol performs best among co-product options in terms of GHG emissions; co-location with facilities exporting excess steam and biomass-based electricity further increases GHG mitigation performance. Delayed GHG reductions due to forest carbon impacts the cost of GHG emissions reductions associated with electricity production from forest biomass. Cost-effectiveness is heavily dependent on the time horizon over which global warming impacts are measured and influences the ranking of biomass electricity pathways (biomass co-firing is the most cost-effective pathway between 2020 and 2100; biomass cogeneration is the most cost-effective pathway beyond year 2100). The accounting tools and methods developed within this thesis will to help inform decision-makers in the responsible development of forest bioenergy opportunities and associated policies.Ph
Advancing Life Cycle Comparisons of Future Alternative Light-duty Vehicles
Get PDFThe overall objective of this thesis is to systematically compare the life cycle energy use, air emissions and costs of future alternative light-duty vehicles in a more robust manner than is done in the literature. Models are developed using GREET (Greenhouse Gases, Regulated Emissions, and Energy Use in Transportation), Autonomie vehicle simulation software, Vehicle Attribute Model, Air Pollution Emission Experiments and Policy (APEEP) analysis model, and Crystal Ball (Monte Carlo analysis). Four questions are investigated:
• Should the transportation sector use ethanol or bio-electricity? Life cycle assessment results indicate that neither has a clear advantage in terms of greenhouse gas (GHG) emissions or energy use. This finding is in contrast to those in the literature that favor the use of bio-electricity because this thesis develops pathways with comparable vehicle characteristics.
• Do plug-in electric vehicles provide incremental life cycle air pollutant impact benefits over internal combustion engine vehicles using the same primary energy source? The results based on natural gas-derived fuels show that battery electric vehicles (BEV) may not provide benefits, in terms of climate change and health impacts, over hybrid electric vehicles (HEV). This can be attributed to the many sources of uncertainty and stringent tailpipe emissions regulations.
• How can vehicles be designed to meet future CAFE (Corporate Average Fuel Economy) standards? Case study results for a reference vehicle show that the 66% increase in fuel economy targets between model years 2012 to 2025 can be met with a 10% vehicle price increase (lightweight HEV powertrain), 31% increase in 0-96 km/h acceleration time (smaller engine), 17% interior volume decrease (smaller body), or 94% driving range decrease (BEV powertrain), while other attributes are maintained.
• How might CAFE standards affect the ability for non-petroleum vehicles to mitigate GHG emissions by displacing petroleum vehicles? Life cycle costing results indicate that there is a financial incentive for automakers to produce CNG vehicles that could emit higher well-to-wheel GHG emissions on a per kilometer basis than gasoline vehicles. This is permitted by CAFE standards because non-petroleum fuel incentives allow vehicles using CNG to be less efficient, and thus potentially more affordable, than those using gasoline.Ph.D
Evaluation of the Greenhouse Gas Emissions of Oil Sands Upgrading Technologies Using a Novel Life Cycle-based Model
Get PDFAs the production of oil sands bitumen and associated final products (e.g., transportation fuels) continues to grow, so do the environmental impacts associated with the life cycle of fuel production and use. This has motivated research on developing novel analytical methods that model these impacts on a life cycle basis. Upgrading generated 23% of the greenhouse gas (GHG) emissions from oil sands operations or 2% of Canada’s GHG emissions in 2016. Upgrading is a stage in the production of oil sands-derived transportation fuels that transforms bitumen into higher value products, most of them refinery feedstocks. A novel life cycle-based model, the Oil Sands Technologies for Upgrading Model (OSTUM), that assesses the direct and indirect energy use and GHG intensities of current and emerging upgrading technologies, was developed and implemented using publicly available data.
OSTUM is applied to commercial upgrading technologies operating in Canada in 2018: delayed coking based- (DC), hydroconversion based- (HC), and combined hydroconversion and fluid coking based upgrading (HC/FC). Two emerging partial upgrading technologies are also modeled: the HI-Q® Process and EST technology. These latter applications demonstrate OSTUM’s flexibility to produce adequate assessments as the oil sands industry evolves. DC’s baseline intensity is 8.5 grams of carbon dioxide equivalent per megajoule of synthetic crude oil (g CO2e/MJ SCO) and range is 6.3–11.2 g CO2e/MJ SCO. HC’s baseline intensity is 10.8 g CO2e/MJ SCO (range: 8.6-14.3 g CO2e/MJ SCO) and HC/FC’s is 12.2 g CO2e/MJ SCO (range: 9.7-14.8 g CO2e/MJ SCO). The baseline, low and high scenario GHG intensities for HI-Q® are 3.7, 2.3 and 6.4 g CO2e/MJ of partially upgraded bitumen (PUB), respectively, and 8.3, 6.6 and 12.3 g CO2e/MJ PUB for EST.
Contributions include 1) the development of a framework to systematically assess/compare the GHG intensities of upgrading technologies using consistent boundaries, assumptions, sources, and methodologies; 2) comprehensive and transparent results obtained with a well-documented model; 3) improved characterization of emission sources/drivers of variability; 4) improved estimation of hydrogen consumption; and 5) estimation of GHG intensities of upgrading co-products of different qualities. OSTUM can provide insight and assist stakeholders in regulating and mitigating upgrading GHG emissions.Ph.D.2021-11-14 00:00:0
Life Cycle and Supply Assessment of Aviation Biofuels in the Canadian Context
Get PDFThe aviation industry established a greenhouse gas (GHG) emission reduction target of 50% by 2050. With aviation biofuels expected to play a key role, this work evaluates the feasibility of achieving this target in terms of potential supply and GHG reductions of aviation biofuels from Canadian oil feedstocks. A life cycle assessment is conducted comparing aviation biofuels derived from used cooking oil (UCO), camelina, carinata, and canola. The results demonstrate significant potential GHG reductions, between 55 and 80 kg COM.A.S.2018-03-01 00:00:0
Assessing Greenhouse Gas Emissions Mitigation Potential through the use of Forest Bioenergy
Get PDFBioenergy production from forest resources offers opportunities to reduce greenhouse gas (GHG) emissions associated with fossil fuel use, reduce non-renewable energy consumption, and provide investment and employment in the forestry sector. These opportunities, however, must be considered within the broader contexts of forest systems. Of particular interest is how bioenergy opportunities impact carbon storage within the forest. This thesis develops a method to integrate life cycle assessment and forest carbon analysis approaches to quantify the total GHG emissions associated with forest bioenergy. Bioenergy production and utilization decisions are then investigated to evaluate opportunities to increase GHG mitigation performance. An accounting method is developed to evaluate the impact of emissions timing on the cost-effectiveness of GHG emissions reductions from biomass-based electricity generation. Applying the integrated life cycle assessment/forest carbon analysis method to a case study of forest bioenergy production in Ontario reveals significant reductions in forest carbon associated with bioenergy production. Wood pellet production from standing trees or harvest residues (displacing coal in electricity generation) would increase total GHG emissions over periods of approximately 40 and 15 years, respectively. Ethanol production (displacing gasoline) would increase GHG emissions throughout the 100-year model period if produced from standing trees; emissions would increase over a period of approximately75 years if produced from harvest residues. Strategic ethanol production decisions (e.g., process energy source, co-location with other processes, co-product selection) can improve GHG mitigation. Co-production of biomass pellets with ethanol performs best among co-product options in terms of GHG emissions; co-location with facilities exporting excess steam and biomass-based electricity further increases GHG mitigation performance. Delayed GHG reductions due to forest carbon impacts the cost of GHG emissions reductions associated with electricity production from forest biomass. Cost-effectiveness is heavily dependent on the time horizon over which global warming impacts are measured and influences the ranking of biomass electricity pathways (biomass co-firing is the most cost-effective pathway between 2020 and 2100; biomass cogeneration is the most cost-effective pathway beyond year 2100). The accounting tools and methods developed within this thesis will to help inform decision-makers in the responsible development of forest bioenergy opportunities and associated policies.Ph
Techno-economic and Environmental Assessments of Replacing Conventional Fossil Fuels: Oil Sands Industry Case Studies
Get PDFConventional fossil fuels are widely used, however there are growing concerns about the security of their supply, volatility in their prices and the environmental impacts of their extraction and use. The objective of this research is to investigate the potential for replacing conventional fuels in various applications, focusing on the Alberta oil sands industry. Such investigations require systems-level approaches able to handle multiple criteria, uncertainty, and the views of multiple stakeholders. To address this need, the following are developed: life cycle assessment (LCA) and life cycle costing models of polygeneration systems; a life cycle-based framework for multi-sectoral resource use decisions; and a method combining LCA and real options analyses to yield environmental and financial insights into projects. These tools are applied to options for utilizing oil sands outputs, both the petroleum resource (bitumen) and by-products of its processing (e.g., asphaltenes, coke), within the oil sands industry and across other sectors. For oil sands on-site use, multiple fuels are assessed for the polygeneration of electricity, steam and hydrogen, in terms of life cycle environmental and financial impacts; asphaltenes gasification with carbon capture and storage (CCS) is the most promising option, able to reduce greenhouse gas (GHG) emissions to 25% of those of current natural gas-based systems. Coke management options are assessed with the life cycle-based framework; the most promising options are identified as: Electricity generation in China through integrated gasification combined cycle; and, hydrogen production in Alberta, either for sale or use by the oil sands industry. Without CCS, these options have amortized project values ranging from 160/t coke. The application of the combined LCA and real options analyses method finds that uncertainty in natural gas and potential carbon prices over time significantly impacts decisions on coke management; the formulated decision tree identifies increases of 29% and 11% in the financial and GHG emissions performance, respectively, of the overall coke management project compared to pursuing the decision identified by the life cycle-based framework. While promising options for replacing conventional fossil fuels are identified through systems-level analyses, there are trade-offs to be made among the financial, risk and environmental criteria.Ph
Advancing Life Cycle Comparisons of Future Alternative Light-duty Vehicles
No full textThe overall objective of this thesis is to systematically compare the life cycle energy use, air emissions and costs of future alternative light-duty vehicles in a more robust manner than is done in the literature. Models are developed using GREET (Greenhouse Gases, Regulated Emissions, and Energy Use in Transportation), Autonomie vehicle simulation software, Vehicle Attribute Model, Air Pollution Emission Experiments and Policy (APEEP) analysis model, and Crystal Ball (Monte Carlo analysis). Four questions are investigated:
• Should the transportation sector use ethanol or bio-electricity? Life cycle assessment results indicate that neither has a clear advantage in terms of greenhouse gas (GHG) emissions or energy use. This finding is in contrast to those in the literature that favor the use of bio-electricity because this thesis develops pathways with comparable vehicle characteristics.
• Do plug-in electric vehicles provide incremental life cycle air pollutant impact benefits over internal combustion engine vehicles using the same primary energy source? The results based on natural gas-derived fuels show that battery electric vehicles (BEV) may not provide benefits, in terms of climate change and health impacts, over hybrid electric vehicles (HEV). This can be attributed to the many sources of uncertainty and stringent tailpipe emissions regulations.
• How can vehicles be designed to meet future CAFE (Corporate Average Fuel Economy) standards? Case study results for a reference vehicle show that the 66% increase in fuel economy targets between model years 2012 to 2025 can be met with a 10% vehicle price increase (lightweight HEV powertrain), 31% increase in 0-96 km/h acceleration time (smaller engine), 17% interior volume decrease (smaller body), or 94% driving range decrease (BEV powertrain), while other attributes are maintained.
• How might CAFE standards affect the ability for non-petroleum vehicles to mitigate GHG emissions by displacing petroleum vehicles? Life cycle costing results indicate that there is a financial incentive for automakers to produce CNG vehicles that could emit higher well-to-wheel GHG emissions on a per kilometer basis than gasoline vehicles. This is permitted by CAFE standards because non-petroleum fuel incentives allow vehicles using CNG to be less efficient, and thus potentially more affordable, than those using gasoline.Ph.D
Life Cycle and Supply Assessment of Aviation Biofuels in the Canadian Context
No full textThe aviation industry established a greenhouse gas (GHG) emission reduction target of 50% by 2050. With aviation biofuels expected to play a key role, this work evaluates the feasibility of achieving this target in terms of potential supply and GHG reductions of aviation biofuels from Canadian oil feedstocks. A life cycle assessment is conducted comparing aviation biofuels derived from used cooking oil (UCO), camelina, carinata, and canola. The results demonstrate significant potential GHG reductions, between 55 and 80 kg COM.A.S.2018-03-01 00:00:0
Effectiveness and Cost-effectiveness of Vehicle Lifespan Caps for Reducing Light-duty Vehicle Fleet GHG Emissions in the U.S.
Get PDFAccelerated vehicle turnover gets new technologies on the road faster but increases the rate of vehicle production and purchases. By combining vehicle fleet modelling, life cycle assessment (LCA), and total ownership costing this work estimates the GHG emissions and costs for the U.S. light-duty vehicle fleet from 2020 – 2050 under a forced early retirement program. We estimate that under current EV sales projections, even when combined with vehicle light-weighting, fuel consumption improvement, and vehicle size reduction, vehicle lifespan caps are ineffective at reducing GHG emissions. While under a 100% EV sales target by 2035, applying a 12-year lifespan cap on conventional light-duty vehicles can be effective, reducing cumulative GHG emissions from 2020 through 2050 by 6%. However, the abatement costs for this method are high, near 2020 USD 1000/tCO2e, placing either a high burden on the government for providing incentives or markedly increasing average vehicle ownership costs.M.A.S
Accounting for Variability and Uncertainty in Life Cycle Assessments: Oil Sands Case Studies
Get PDFAlong the life cycle of oil sands-derived products, variability in terms of resource heterogeneity, operating decisions, as well as extraction and processing technologies affect a project’s GHG intensity. Previous LCAs that have quantified emissions from bitumen production and processing have not captured all sources of variability along the life cycle, either by including only some projects or employing simplified refinery modeling or modeling refining only of some crude types. Three studies are completed to address this literature gap.
In the first study, a statistically-enhanced version of the GreenHouse gas emissions of current Oil Sands Technologies model (GHOST-SE) is developed. Median lifetime GHG intensities for projects producing synthetic crude oil (SCO) range from 89-137 kg CO2eq/bbl SCO and for the project producing dilbit are 51 kg CO2eq/bbl dilbit. Projects show significant temporal variability. No project reaches steady-state in terms of GHG intensity. Next, GHOST-SE is integrated with a pipeline transportation model (COPTEM) and a refinery model (PRELIM) and
variability in life cycle emissions intensities are quantified. Allocation to products affects the relative GHG intensities of different projects (e.g., Project 1 has lowest median life cycle GHG intensity per MJ gasoline but highest per MJ diesel). These results demonstrate that there is no
representative project or crude type, even across projects within the same pathway (e.g., Mining SCO pathway).
In the final study, expert elicitation methods are employed to assess the potential role for emerging technologies to decrease upstream GHG intensity between 2014 and 2034. Experts surveyed do not expect emerging technologies to play a major role in reducing upstream oil
sands energy consumption but are more likely to be applied to access marginal resources not economic with current production technologies.
Accurate characterizations of the emissions from the life cycle of oil-sands derived fuels has the potential to assist oil sands operators and policymakers to: set benchmarks, develop projections of future emissions, and identify opportunities for GHG intensity reductions along the life cycle of the fuel. The findings of this thesis can also inform operators and policymakers about the potential unintended consequences of policy decisions.Ph.D.2021-07-21 00:00:0
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