Energy-related Emissions Research Articles

The environmental challenge of HPC: finding green power and cooling solutions for supercomputers

In today's world, High-Performance Computing (HPC) is driving scientific research forward at an astonishing rate, but behind every top HPC device lies a high-load power grid, which has sparked deep concern among environmentalists. This study develops a mathematical model to evaluate the power consumption of global HPC equipment and quantify its environmental impact, providing a basis for energy optimization and sustainable development. By systematically analyzing the global environmental impact of HPC through a series of models focused on energy consumption and related emissions, we first created a GPU survival function to estimate the global number of HPC devices in 2023. Using Monte Carlo simulation and Markov chain models, we estimated the power consumption of individual HPC centers under both full load and average utilization conditions, subsequently calculating the total annual power consumption of global HPC centers. Next, we developed models to estimate the total carbon emissions from global HPC energy consumption, considering various energy production methods and energy mix scenarios. Additionally, we created a gray prediction model to forecast the GPU market value in 2030, combining it with the GPU survival function to predict the number of global HPC centers in 2030. We also developed an electricity price fluctuation model to account for increased energy demand from other sectors and analyzed the environmental impact of global HPC centers in 2030 under different energy mix structures. Furthermore, we extended the model to assess the impact of increasing renewable energy (specifically wind energy) to 100% in the energy mix, evaluating its potential to reduce carbon emissions. Finally, we conducted a sensitivity analysis, incorporating seawater cooling for HPC centers and artificial intelligence to dynamically adjust GPU power based on wind speed predictions.

Exploring the influence of air fractions on the performance of a vapor compression refrigeration system: an energy, exergy, and environmental analysis

The ingress of air into the vapor compression refrigeration system is a frequent occurrence, typically occurring during installation, maintenance, or charging. Air, being a non-condensable gas relative to the refrigerant gas within the system, leads to system degradation mostly due to elevated condensing pressure. This experimental study investigates the impact of non-condensable gas (air) contamination on the performance of a vapor compression refrigeration system using R134a refrigerant. A chest freezer was tested under steady-state conditions with air fractions of 0%, 1.7%, 2.5%, and 3.3% at an ambient temperature of 32 °C. Energy, exergy, and environmental analyses were conducted to evaluate system efficiency, power consumption, and sustainability. Results revealed that increasing air fractions significantly degraded performance: at 3.3% air, power consumption rose by 37.1%, while the coefficient of performance dropped by 42.8% compared to the air-free system. Also, exergy destruction rate increased by 189%, and exergy efficiency decreased by 119.1%, indicating severe thermodynamic inefficiencies. Additionally, higher air fractions led to elevated compressor temperatures, increased noise, and greater environmental impact due to higher energy-related emissions. The study highlights the critical need for rigorous system evacuation and leak prevention in refrigeration systems to maintain optimal efficiency and reduce operational costs.

Estimating the Climate Impacts of Hydrogen Emissions in a Net-Zero U.S. Economy

Abstract Hydrogen is not a greenhouse gas, but its interactions with other species in the atmosphere indirectly induce radiative forcing. This study evaluates the relative impacts of hydrogen emissions across 23 different net-zero scenarios from five prominent U.S. economy-wide analyses. Hydrogen emissions associated with venting and leakages across energy supply chains are considered. The magnitude of these energy-related hydrogen emissions is estimated and compared to the remaining positive energy-related carbon dioxide and methane emissions in the 23 U.S. net-zero scenarios. This methodology facilitates consideration of the potential magnitude of hydrogen emissions relative to the other emissions reductions and/or carbon dioxide removal strategies that would be required to balance those hydrogen emissions across a wide range of possible net-zero scenarios. Magnitudes of energy-related hydrogen and methane emissions are estimated for each scenario across a range of possible emissions rates (Low, Central, and High) and global warming potentials based on literature. The results indicate that when evaluated over a 100-year horizon, hydrogen emissions span a range of 0.02–0.15 GtCO2e/yr and are lower than remaining positive carbon dioxide emissions in the Central emissions case of all 23 scenarios. In the 19 scenarios that do not constrain fossil fuels, hydrogen emissions (0.02–0.11 GtCO2e/yr) account for less than 14% of combined hydrogen, methane, and carbon dioxide emissions. The four scenarios that constrain fossil fuels have higher levels of hydrogen consumption and correspondingly higher levels of hydrogen emissions (0.10–0.15 GtCO2e/yr). These results suggest that hydrogen emissions are non-negligible in net-zero energy systems; however, the potential climate impacts associated with hydrogen emissions can be balanced through relatively small reductions in remaining positive emissions and/or increases in carbon dioxide removal. Further effort is needed to advance hydrogen emissions measurement, quantification, and mitigation strategies to maximize the potential climate benefits of hydrogen for decarbonization.

A Study on Factors Influencing Cost Management in Green Building Construction

Green buildings represent a crucial solution for reducing carbon emissions in the construction sector, which accounts for approximately one-third of global energy-related emissions. However, high initial costs remain a significant barrier to widespread adoption of sustainable construction practices. This study addresses the critical gap in understanding how cost factors interconnect throughout the entire lifecycle of green building projects. Using a comprehensive life cycle approach combined with Interpretive Structural Modeling (ISM) and MICMAC (Matrix of Cross-Impact Multiplications Applied to Classification) methodologies, this research examines 20 key factors influencing green building construction costs across four major phases: planning and design, construction and building, maintenance and recovery, and policy and environment. The analysis reveals that "Policy Support" functions as the primary root cause factor, exerting the strongest influence on green building design, certification requirements, and operational strategies. Energy-saving technologies and green construction standards emerge as critical mediating factors within the system hierarchy. The ISM analysis constructs a seven-level hierarchical structure, while MICMAC classification identifies independent, dependent, and interactive factor categories based on their driving power and dependence relationships. This research provides the first systematic mapping of cost factor interdependencies in green building projects, offering both theoretical advancement in cost analysis methodologies and practical guidance for governments, developers, and investors. The framework enables stakeholders to optimize cost efficiency, prioritize regulatory interventions, and develop strategies that promote economically viable sustainable construction practices.

Short-term energy and meteorological impacts on Thanksgiving CO2 in Salt Lake City

Abstract Long-term, high-frequency atmospheric CO2 measurements at multiple sites in Salt Lake City (SLC), Utah, reveal that annual and monthly CO2 variability aligns with a priori estimates of emissions from anthropogenic and biological sources. In this study, we investigate whether short-term fluctuations in anthropogenic emissions, as captured in the Vulcan3 dataset for the United States, can be detected in atmospheric CO2 observations. Specifically, we focus on Thanksgiving holidays, when traffic and energy usage patterns differ from the rest of November. Onroad CO2 emissions exhibit a double peak during weekday morning and evening rush hours but remain relatively low on weekends and Thanksgiving. Interestingly, CO2 mole fractions during Thanksgiving were higher than the rest of November at all SLC monitoring sites, particularly from 2008 to 2013. This increase is partially attributed to elevated energy-related emissions — especially residential sources — and meteorological factors such as weak wind speeds, cold temperature, and a low planetary boundary layer height (PBLH). While CO2 emissions and mole fraction patterns align over time, notable spatial differences exist. For instance, the near-highway site in Murray shows the highest CO2 mole fractions despite low local emissions, suggesting pollution transport via highways and wind advection. Random Forest model-based SHapley Additive exPlanations (SHAP) analysis reveals that onroad emissions dominate CO2 contributions on weekdays and weekends, while energy-related emissions play a larger role during Thanksgiving, alongside meteorological drivers such as wind speed and PBLH. Across six urban cities, CO2 emissions display a consistent pattern: residential and commercial emissions peak during Thanksgiving with substantial year-to-year variability, while onroad emissions peak during weekdays, with minimal variability. These findings highlight that urban CO2 variability is driven by the combined influence of emissions and meteorology, underscoring the need for integrated mitigation strategies. Additionally, multi-site measurements are essential for accurate source attribution and effective policy interventions.

From natural gas to hydrogen: Climate impacts of current and future gas transmission networks in Germany

Hydrogen emissions arise from leakage during its production, transport, storage and use, leading to an increase in atmospheric hydrogen concentrations. These emissions also cause an indirect climate effect, which has been quantified in the literature with a global warming potential over 100 years (GWP100) of about 11.6, placing hydrogen between carbon dioxide (1) and methane (29.8). There is increasing debate about the climate impact of an energy transition based on hydrogen. As a case study, we have therefore evaluated the expected climate impact of switching from the long-distance natural gas transmission network to the outlined future “hydrogen core network” in Germany. Our analysis focuses on the relevant sources and network components of emissions. Our results show that the emissions from the network itself represent only about 1.8% of total emissions from the transmission of hydrogen, with 98% attributed to energy-related compressor emissions and only 2% to fugitive and operational hydrogen leakage. Compared to the current natural gas transmission network, we calculate a 99% reduction in total network emissions and a 97% reduction in specific emissions per transported unit of energy. In the discussion, we show that when considering the entire life cycle, which also includes emissions from the upstream and end-use phases, the switch to hydrogen reduces the overall climate impact by almost 90%. However, while our results show a significantly lower climate impact of hydrogen compared to natural gas, minimising any remaining emissions remains crucial to achieve carbon neutrality by 2045, as set in Germany’s Federal Climate Action Act. Hence, we recommend further reducing the emissions intensity of hydrogen supply and minimising the indirect emissions associated with the energy supply of compressors.

Accelerating land use carbon emissions in shrinking counties: a systematic analysis of land use dynamics in the Beijing-Tianjin-Hebei region, 2000–2020

Urban shrinkage, characterized by population loss and economic decline, poses unique challenges to carbon neutrality goals. While existing studies focus on energy-related emissions in shrinking cities, the role of land use dynamics remains underexplored. This study systematically investigates land use carbon emissions (LUCE) in shrinking counties to address this gap. Focusing on the Beijing-Tianjin-Hebei (BTH) region (2000–2020), we integrated population indices, land use data, energy statistics, and nightlight imagery to classify counties into non-shrinking, continuous, temporary, and potential shrinkage types. Direct and indirect carbon emissions were estimated using emission coefficients and energy consumption models. Key findings include: (1) Non-shrinking counties, concentrated in urban cores, exhibit higher LUCE but slower growth rates, whereas shrinking peripheral counties show lower emissions but faster LUCE growth. (2) Continuous shrinkage counties experience the highest LUCE growth due to inefficient built-up area expansion, despite having significant carbon sinks. (3) Severe shrinkage counties demonstrate the fastest total carbon emissions (TCE) growth, with per capita emissions (PCE) positively correlated to shrinkage intensity. These findings highlight the need for differentiated policies: prioritizing land-use efficiency in shrinking counties, integrating regional equity into emission governance, and leveraging carbon sinks in ecologically rich areas.

Trend-based multi-period decomposition and decoupling methodology for energy-related carbon dioxide emissions: A case study of Portugal

Trend-based multi-period decomposition and decoupling methodology for energy-related carbon dioxide emissions: A case study of Portugal

Balancing economic growth and sustainability for environmental protection in Southeast Asia: a regional perspective

PurposeThis paper examines the complex relationship between environmental protection and economic growth in Southeast Asia, focusing on the region’s efforts at balancing rapid development with environmental sustainability. It analyzes current challenges, emerging trends and potential solutions for achieving sustainable development while maintaining economic growth.Design/methodology/approachThe study employs a comprehensive literature review methodology, analyzing academic sources, government reports and international organization publications from 1998 to 2025. It combines qualitative analysis of policy frameworks and case studies with quantitative assessment of environmental impacts and economic costs. The research framework integrates multiple perspectives on environmental governance, technological innovation and sustainable development.FindingsThe analysis reveals that Southeast Asia contributes approximately 40% of global greenhouse gas emissions, with energy-related emissions projected to rise by 34–147% between 2017 and 2040. Environmental degradation costs the region 1–9% of their GDP. However, promising developments include increasing renewable energy adoption (projected 35% solar photovoltaic technology by 2025), improved sustainability reporting frameworks and innovative financial instruments. The study identifies key challenges in institutional capacity, policy implementation and resource management while highlighting successful initiatives in countries like Singapore and Vietnam.Originality/valueThis article brings together important historical events, present problems and expected future changes in Southeast Asian economic growth and environmental protection. By linking environmental governance, technological progress and economic growth, it gives lawmakers, companies and academics useful ideas and analysis. The study is especially helpful for figuring out how emerging countries can deal with environmental problems and still grow in a way that does not harm the environment.

Additional emissions of vehicle-to-grid technology considering China’s geographical heterogeneity

Vehicle-to-Grid (V2G) technology is regarded as a promising distributed energy storage solution that can help address grid challenges arising from the integration of renewable energy and the large-scale uncoordinated charging of electric vehicles. However, issues such as additional battery degradation and energy efficiency losses induced by V2G may lead to increased greenhouse gas (GHG) emissions in providing energy storage services, thereby reducing its overall potential to contribute to power system decarbonization. Existing studies on the additional GHG emissions of energy storage technologies have largely overlooked V2G technology. To fill this research gap, this study develops a comprehensive life cycle assessment model for V2G technology in China. The model first simulates the charging and discharging processes of EV batteries in V2G applications, as well as the additional battery degradation caused by V2G participation. Building on this technical modeling and incorporating multidimensional geographic heterogeneity data, a high-resolution assessment of V2G’s lifecycle additional GHG emissions is conducted across 337 cities in China. The results reveal that V2G’s additional GHG emissions for frequency regulation (FR) and peak shaving and valley filling (PSVF) services range from 0.046-0.152 and 0.036-0.148 kgCO2-eq/kWh, respectively. Energy-related GHG emissions constitute the largest proportion, accounting for 59.0% and 66.8% of total emissions for FR and PSVF services, respectively. From a geographic perspective, the additional GHG emissions of V2G are lowest in southwestern China and highest in the northeast. The findings of this study highlight significant regional variations in the environmental impacts of V2G technology in China and underscore the importance of region-specific strategies for the effective and sustainable deployment of V2G technology.

Spatiotemporal Patterns and Influencing Factors of Carbon Emissions in the Yangtze River Basin: A Shrinkage Perspective

This study categorizes 45 cities into four types based on population dynamics using census data (2000–2020). Methods such as ArcGIS10.8, carbon emission estimation, LISA clustering, and association analysis are employed to explore the spatiotemporal distribution of shrinking cities and carbon emissions. This study analyzes carbon emission patterns and influencing factors for the four city types and provides policy recommendations. The findings are as follows: (1) Lasting-growth cities show a “two-end mass, middle-point” pattern, while stage-growth and stage-shrinking cities are “point” distributed. Lasting-shrinking cities are mainly distributed in the middle and lower reaches of the Yangtze River. (2) Total carbon emissions are rising, showing two clusters of high-value areas. Carbon emission intensity is falling quickly, being higher in the west and lower in the east. (3) Lasting-growth cities have the fastest direct carbon emission growth rate, stage-growth cities have the fastest energy-related indirect emission growth rate, and cities undergoing population increase have the fastest growth rate for other indirect carbon emissions. In terms of carbon reduction, lasting-growth cities perform best, whereas stage-growth cities perform worst. (4) Regional GDP, per capita regional GDP, urban construction area, and hospital beds per 10,000 people promote carbon emission reduction in the four city types, while a higher number of industrial enterprises inhibits it. Birth rate, aging rate, and mortality rate have no significant impact. This study addresses the gaps in previous research on shrinking cities and carbon emission reduction by considering the dynamic nature of shrinking processes and analyzing carbon emission patterns.

Unions, fossil fuel workers, and the energy transition: learning from plant closures in Finland and the U.S.

ABSTRACT Energy-related emissions account for nearly 85 percent of global carbon dioxide emissions. Consequently, the energy sector is a primary focus of climate policies aimed at mitigating global warming, and a transition to low-carbon and net-zero energy systems and economies is at the focus of many national and international decarbonization policies. Like other economic restructuring projects, the energy transition is not a singular process but instead is unfolding as multiple interdependent processes across geographical and temporal scales. In these processes, transitions to renewable and low-carbon energy sources also translate to transitioning away from hydrocarbons and their attendant socio-economic and socio-cultural production systems. In their most tangible form, these low-carbon transitions manifest themselves in local contexts as plant-level and industry closures that – unless carefully managed – have the potential to not only upend local socioeconomic realities but also to fuel discontent against the broader societal programme of the low-carbon transition. In this article, we take a focus on two such local low-carbon transitions – the closure of coal-fired Hanasaari power plant in Helsinki, Finland and the sudden closure of the Marathon Petroleum oil refinery in Contra Costa County, California, US – as case studies of plant-level closures that reflect several experienced transition injustices. However, our analysis goes beyond merely documenting and comparing injustices across these transition contexts. Against the backdrop of literatures on radical energy justice and the role of labour unions as just transition actors, our analysis sheds light on both the interpretations of justice labour unions work to advance and different ways in which union responses in individual plant closure contexts have broadened the unions’ scope of interest and agency in just transition related broader political and societal agendas.

Embodied energy and associated carbon emission of key building materials in Nepal

The number of concrete buildings in Nepal increased by 23.90 percent within the last decade. Life Cycle Assessment (LCA) of the buildings shows that Cement, Brick and Reinforcement steel are the three major building materials which account for about half of the total life cycle energy use and emission from the building materials. However, there is no national database for energy use and emissions from these building materials in Nepal. So, the study aims to evaluate energy use and its associated emissions in the production of these materials using the LCA framework and guidelines from ISO 14040: 2006 and ISO 14044: 2006. The data from embodied energy is based on the energy audits of 26 cement industries, 21 metal industries, and 27 brick industries sampled across the country. The study shows that the production of one tonne of cement accounts for 6051.07 MJ energy and is responsible for 739.49 kgCO2-eq.; the production of 1000 pieces of standard size burnt brick from fixed chimney bull trench kiln accounts for 4124.56 MJ energy and 502.89 kgCO2-eq. emission; and the production of one tonne of reinforcement steel accounts for 26,033.14 MJ energy and 2565.5 kgCO2-eq emission. The major source of energy and emission in building material production is coal. A shift in energy sources from coal to hydroelectricity would reduce the energy-related emissions from the materials production. Also replacing high emission construction materials with locally available natural materials like stone, wood and bamboo could minimize the emissions from the built environment.

Energy, Health, and Climate Costs of Carbon-Capture and Direct-Air-Capture versus 100%-Wind-Water-Solar Climate Policies in 149 Countries.

Air pollution, global warming, and energy insecurity are three major problems facing the world. This study first examines whether 149 countries can transition 100% of their business-as-usual (BAU) all-sector energy to electricity and heat obtained from 100% wind-water-solar (WWS) sources to solve these problems. WWS eliminates energy-related air pollution deaths and CO2-equivalent emissions while reducing end-use energy needs by ∼54.4%, annual energy costs by ∼59.6%, and annual social (energy plus health plus climate) costs by ∼91.8% among nations, giving energy- and social-cost payback times of 5.9 and 0.78 years, respectively. Conversely, "all-of-the-above" policies promoting carbon capture (CC) and/or synthetic (as opposed to natural) direct air carbon capture (SDACC) to reduce or offset CO2 emissions trigger, with full penetration of CC/SDACC across 149 countries, $60-80 trillion/y in social cost, or 9.1-12.1 times the WWS social cost and only 1.1-25.6% lower social cost than BAU. Even when all CO2 is stored, CC and SDACC increase air pollution, CO2-equivalent emissions (due to capture inefficiencies and not capturing non-CO2 greenhouse gases), energy needs, and equipment costs relative to WWS. Sensitivity tests reinforce this finding. Although full penetration is extreme, any CC/SDACC level increases social cost and emissions substantially versus WWS. Thus, policies promoting CC and SDACC should be abandoned.

Corporate carbon intensity and GDP contribution comparison across 4 countries

The paper analyzes the corporate carbon emissions and GDP contributions of the top ten companies by turnover for 2020–2023 in Germany, South Korea, China and the United Kingdom. Focusing on Scope 1, 2, and 3, the study explores the contribution of these companies to carbon intensity across different sectors and economies. The analysis shows that there are significant gaps in carbon efficiency, with the UK’s and Germany’s firms emitting the lowest emissions per unit of GDP contribution, followed by China and South Korea. Additionally, the study further examines the impact of Economic Policy Uncertainty on both firm carbon intensity and economic productivity. While EPU is positively associated with GDP contributions, its impact on emissions is nuanced. Firms apparently respond to policy uncertainty by increasing energy efficiency in direct (Scope 1) and energy-related (Scope 2) emissions but find it more difficult to manage supply chain emissions (Scope 3) in that case. The results point out the critical role of comprehensive ESG reporting frameworks in enhancing transparency and addressing Scope 3 emissions, which remain the largest and most volatile component of corporate carbon footprints. The paper then emphasizes the importance of standardized ESG reporting and bespoke policy intervention for promoting sustainability, especially in carbon-intensive industries. This research contributes to the understanding of how industrial and policy frameworks affect carbon efficiency and economic growth in different national contexts.

Decarbonisation of Natural Gas Grid: A Review of GIS-Based Approaches on Spatial Biomass Assessment, Plant Siting and Biomethane Grid Injection

Most nations are shifting towards renewable energy sources to reduce energy-related emissions and achieve their net zero emissions targets by mid-century. Consequently, many attempts have been made to invest in clean, accessible, inexpensive, sustainable and reliable renewable energy sources while reducing dependency on fossil fuels. Recently, the production of biogas and upgrading it to produce biomethane is considered a sustainable way to reduce emissions from natural gas consumption. However, uncertainties in the biomass supply chain and less attention to decarbonising the natural gas grid have led to fewer investors in biomethane injection projects. Thus, researchers have applied Geographic Information System (GIS) as the best decision-making tool with spatial analytical and optimisation capabilities to address this issue. This study aims to review GIS-based applications on planning and optimising the biomass supply chain. Accordingly, this review covers different GIS-based biomass assessment methods with the evaluation of feedstock types, GIS-based approaches on selecting and optimising bioenergy plant locations and GIS-based applications on facilitating biomethane injection projects. This review identified four major biomass assessment approaches: Administrative division-based, location-based, cluster-based and grid-based. Sustainability criteria involved in site selection were also discussed, along with suitability and optimality techniques. Most of the optimising studies investigated cost optimisation based on a single objective. However, optimising the whole supply chain, including all operational components of the biomass supply chain, is still seldom investigated. Furthermore, it was found that most studies focus on site selection and logistics, neglecting biomethane process optimisation.

Assessment of the Applicability of Waste Concrete Fine Powder as a Raw Material for Cement Clinker

The cement industry is responsible for a significant portion of global CO2 emissions, primarily due to the decarbonatization of limestone during clinker production. To mitigate this environmental impact, this study investigated the feasibility of using waste concrete fine powder, produced during the recycling of waste concrete, as a decarbonized raw material in cement clinker production. As a decarbonized material, waste concrete fine powder presents a valuable opportunity to reduce CO2 emissions typically produced during the decarbonatization of limestone in clinker production. In addition, its use supports the recycling of construction waste, contributing to both emissions reduction and resource sustainability. In this study, samples were collected from 20 intermediate treatment plants in South Korea, where the chemical composition, particle size distribution, and carbonation rate of the fine powders were analyzed. The experimental results show that the properties of waste concrete fine powder vary significantly depending on the recycling process. Road construction aggregate production plants, which typically involve two to three crushing stages, produce fine powders with higher CaO content (28–31%) and consistent particle size distributions. In contrast, plants producing aggregates for concrete, which involve four to six crushing stages, produce powders with lower CaO content (around 20%) and greater variability in particle size. The average carbonation rate of 7.44% suggests that these fine powders can replace limestone in clinker production. It is estimated that substituting 5% of limestone with waste concrete fine powder could reduce CO2 emissions from limestone decarbonatization by approximately 952,560 tons in 2023, representing a 3.34% decrease in total emissions from clinker production. However, it is important to note that the CO2 emissions reduction calculation is not from a lifecycle perspective, without considering the energy-related emissions from recycling waste concrete fine powder. Nevertheless, this study highlights the potential for waste concrete fine powder to serve as a sustainable raw material for the cement industry, contributing to both CO2 reduction and efficient recycling of construction waste.

Kaya factor decomposition assessment of energy-related carbon dioxide emissions in Spain: A multi-period and multi-sector approach

Kaya factor decomposition assessment of energy-related carbon dioxide emissions in Spain: A multi-period and multi-sector approach

Estimating greenhouse gas emissions from the health sector in Canada: Mind the gap

Healthcare is a surprisingly large contributor to climate change, responsible for a significant quantity of global Greenhouse Gas (GHG) emissions. Global commitments to achieve “net zero” health systems, including by the federal government in Canada, suggest a growing need to understand and mobilize capacity for GHG emissions estimation across Canada’s health sector. Our analysis highlights efforts by public sector healthcare organizations in Canada to estimate an increasingly broad scope of GHG emissions, building on longstanding efforts to report or reduce energy-related emissions from facilities. It also identifies why such efforts will not be sufficient. Developing capacity for routine system-wide greenhouse gas emissions estimation can help Canada’s health systems to better understand their progress, including through international comparison. Yet emissions estimation is itself an investment, one that should not displace efforts to reduce the full scope of pollutants from the healthcare enterprise, and to build a truly sustainable health system.

Load-Shifting Strategies for Cost-Effective Emission Reductions at Wastewater Facilities.

Significant hourly variation in the carbon intensity of electricity supplied to wastewater facilities introduces an opportunity to lower emissions by shifting the timing of their energy demand. This shift could be accomplished by storing wastewater, biogas from sludge digestion, or electricity from on-site biogas generation. However, the life cycle emissions and cost implications of these options are not clear. We present a multiobjective optimization framework for comparing cost- and emission-minimizing load-shifting strategies at a California case study facility with a relatively low carbon intensity grid and high spread in peak and off-peak electricity prices. We evaluate cost and emission trade-offs from the optimal flexible operation of both existing infrastructure and optimally sized energy flexibility upgrades. We estimate energy-related emission reductions of up to 9.0% with flexible operation of existing infrastructure and up to 16.8% with optimally sized storage upgrades. Only a fraction of these potential savings are realized under actual industrial energy tariffs and the EPA's recommended social cost of carbon. Energy flexibility may hold promise as a short-term emission-saving solution for the wastewater sector, but the extent of savings is heavily dependent on the cost of carbon, electricity tariffs, and emission intensity of the regional electricity grid.