Carbon Intensity Research Articles

Blending low-carbon hydrogen with natural gas: Impact on energy and life cycle emissions in natural gas pipelines

Hydrogen (H2) is considered an alternative energy carrier to reduce greenhouse gas (GHG) emissions related to power and heat generation. A quantitative analysis was conducted to estimate the energy intensity and GHG emissions associated with the transportation of NG/H2 mixture in high-pressure transmission pipeline, considering blending ratios up to 100% of low-carbon H2. The life cycle emissions were obtained by including upstream supply chain emissions, compression and transportation emissions, and end use combustion emissions of the NG/H2 blend. This study accounts for global warming potential of fugitive methane and H2 emissions associated with pipeline transportation of the blend in the life cycle analysis. A significant reduction in the overall life cycle GHG emissions can be achieved when delivering the same volume throughput but at a reduced energy flow to end users. However, to maintain the nominal energy throughput of the pipeline regardless of the H2 mole fraction, a maximum reduction of about 6% is obtained as the H2 mole fraction in the blend will be practically limited to approximately 30% H2 when the pipeline operates at capacity.

Regulatory compliance and operational efficiency in maritime transport: Strategies and insights

In recent years, with increasing maritime trade, the shipping industry has faced the challenge of mitigating escalating greenhouse gas emissions. This study investigates the cost mitigation strategies of shipping companies in response to three key regulations: the Carbon Intensity Indicator, the EU Emissions Trading System, and the FuelEU Maritime regulation. By proposing optimal speeds for container ships on the Asia–Europe route and examining the potential for carbon leakage, the study aims to predict strategies of shipping companies and derive insights for achieving sustainable regulatory compliance. The results provide a comprehensive analysis of the regulations' impact on operational costs and emissions, with the robustness of the findings confirmed through extensive sensitivity analyses. The discussion highlights the unintended consequences of current regulations that may deviate from the ultimate objectives of reducing GHG emissions and achieving sustainable maritime transport. Ultimately, the study seeks to support the development of effective maritime regulations that align with the operational strategies of shipping companies, emphasizing the need for a holistic approach to achieve the intended outcomes of environmental policies.

Multiscale Equation-Oriented Optimization Decreases the Carbon Intensity of Shale Gas to Liquid Fuel Processes.

Shale gas is revolutionizing the U.S. energy and chemical commodity landscape and can ease the transition to a sustainable decarbonized economy. This work develops an equation-oriented (EO) multiscale modeling framework using the open-source IDAES-PSE platform that tractably incorporates microkinetic detail in process design via reduced-order kinetic (ROK) models. Using multiobjective optimization with embedded heat integration and life-cycle analysis, we simultaneously minimize the minimum selling price of liquid hydrocarbons (e.g., liquid fuels/additives from shale gas) and process emissions (via a CO2 tax). Optimization reduces greenhouse gas emissions per MJ of fuel produced by over 35% compared to the literature and achieves a carbon efficiency of 87%. The optimizer changes the recycling rate, temperatures, and pressures to mitigate the effect of ROK model-form uncertainty on product portfolio predictions. Moreover, we show that the optimal process design is insensitive to changing CO2 tax rates. Finally, the EO framework enables a fast sensitivity analysis of shale gas composition variability across 12 regions of the Eagle Ford basin. These results highlight the benefits of the open-source EO framework: fast, scalable, customized, and reproducible system analysis and optimization for sustainable energy technologies beyond shale utilization.

Urbanization and greenhouse gas emissions from municipal wastewater in coastal provinces of China: Spatiotemporal patterns, driving factors, and mitigation strategies

Coastal cities, as hubs of social and economic activity, have witnessed rapid urbanization and population growth. This study explores the transformative changes in urban municipal wastewater treatment practices and their profound implications for greenhouse gas (GHG) emissions in Chinese coastal provinces. The approach employed in this study integrates comprehensive data analysis with statistical modeling to elucidate the complex interplay between urbanization, wastewater treatment practices, and GHG emissions. Results reveal a substantial surge in GHG emissions from coastal wastewater treatment, rising from 3367.1 Gg CO2e/yr in 1990–23644.8 Gg CO2e/yr in 2019. Spatially, the top 20 cities contribute 56.0% of emissions, with hotspots in the Bohai Sea Region, Yangtze River Delta, and Pearl River Delta. Initially dominated by emissions from untreated wastewater, post-2004, GHG emissions from treatment processes became the primary source, tied to electricity use. Growing population and urbanization rates escalated wastewater discharge, intensifying GHG emissions. From 1990 to 2019, average GHG intensity ranged between 320.5 and 676.6 g CO2e/m3 wastewater, with an annual increase of 12.3 g CO2e/m3. GHG intensity variations relate to the wastewater treatment rate, impacting CH4, N2O, and CO2 emissions, underscoring the need for targeted strategies to mitigate environmental impact.

Zero-Emission Heavy-Duty, Long-Haul Trucking: Obstacles and Opportunities for Logistics in North America

Background: Pressure is growing in North America for heavy-duty, long-haul trucking to reduce greenhouse gas (GHG) emissions, ultimately to zero. With freight volumes rising, improvement depends on zero-emissions technologies, e.g., battery electric vehicles (BEVs) and fuel cell electric vehicles (FCEVs). However, emissions reductions are constrained by technological and commercial realities. BEVs and FCEVs are expensive. Further, BEVs depend on existing electricity grids and FCEVs rely on steam–methane reforming (SMR) or electrolysis using existing grids to produce hydrogen. Methods: This study assembles publicly available data from reputable sources to estimate breakeven vehicle purchase prices under various conditions to match conventional (diesel) truck prices. It also estimates GHG emissions reductions. Results: BEVs face numerous obstacles, including (1) limited range; (2) heavy batteries and reduced cargo capacity; (3) long recharging time; and (4) uncertain hours-of-service (HOS) implications. On the other hand, FCEVs face two primary obstacles: (1) cost and availability of hydrogen and (2) cost of fuel cells. Conclusions: In estimating emissions reductions and economic feasibility of BEVs and FCEVs versus diesel trucks, the primary contributions of this study involve its consideration of vehicle prices, carbon taxes, and electricity grid capacity constraints and demand fees. As electricity grids reduce their emissions intensity, grid congestion and capacity constraints, opportunities arise for BEVs. On the other hand, rising electricity demand fees benefit FCEVs, with SMR-produced hydrogen a logical starting point. Further, carbon taxation appears to be less important than other factors in the transition to zero-emission trucking.

How artificial intelligence affects carbon intensity: heterogeneous and mediating analyses

How artificial intelligence affects carbon intensity: heterogeneous and mediating analyses

How does extreme heat affect carbon emission intensity? Evidence from county-level data in China

This study investigates the impact of increasingly frequent extreme heat events due to climate change on carbon emission intensities in China. Using spline regressions on county-level data from 2000 to 2019, we identify an asymmetric U-shaped relationship between daily mean temperatures and carbon intensities. Each additional day with temperatures above 33 °C in each location results in a 0.9% rise in the average annual carbon intensity, driven by higher energy consumption for cooling. We also explore the mitigating effects of China's low-carbon city initiatives and emissions trading scheme. By combining our estimation results with future temperature trajectories, we simulate that, in the long run, China's carbon intensity can increase by 8–13% under the SSP1-2.6 scenario and 24–51% under the SSP5-8.5 scenario. Our findings underscore the urgency for policymakers to thoroughly assess the socioeconomic impacts of heat waves and incorporate climate resilience into overall sustainable development plans.

Comprehensive assessment of refined greenhouse gas emissions from China's livestock sector

Livestock and poultry products are an essential human food source. However, the rapid development of the livestock sector (LS) has caused it to become a significant source of greenhouse gas (GHG) emissions. Consequently, investigating the spatio-temporal characteristics and evolution of GHG emissions is crucial to facilitate the green development of the LS and achieve “peak carbon and carbon neutrality”. This study combined life cycle assessment (LCA) with the IPCC Tier II method to construct a novel GHG emissions inventory. The GHG emissions of 31 provinces in China from 2000 to 2021 were calculated, and their spatio-temporal characteristics were revealed. Then, the stochastic impacts by regression on population, affluence, and technology (STIRPAT) model was used to identify the main driving factors of GHG emissions in six regions of China and explore the emission reduction potential. The results showed that GHG emissions increased and then decreased from 2000 to 2021, following a gradual and steady trend. The peak of 628.55 Mt CO2-eq was reached in 2006. The main GHG-producing segments were enteric fermentation, slaughtering and processing, and manure management, accounting for 45.39 %, 26.34 %, and 23.08 % of total GHG emissions, respectively. Overall, the center of gravity of GHG emissions in China migrated northward, with spatial aggregation observed since 2016. The high emission intensity regions were mainly located west of the “Hu Huanyong line”. Economic efficiency and emissions intensity were the main drivers of GHG emissions. Under the baseline scenario, GHG emissions are not projected to peak until 2050. Therefore, urgent action is needed to promote the low-carbon green development of the LS in China. The results can serve as scientific references for the macro-prevention and control of GHG emissions, aiding strategic decision-making. Additionally, they can provide new ideas for GHG accounting in China and other countries around the world.

The roots of carbon emission differences between China and USA: A quantitative study based on global value chains

China and the USA, as preeminent contributors to global carbon emissions, demonstrate discernible differentials in both magnitude and trajectories of their respective carbon outputs. This article employed two methods, Structural Decomposition Analysis (SDA) and Quantitative Structural Modeling, to scrutinize the underpinnings of these disparities through the lens of the global value chain. Drawing upon data from the World Input-Output Database (WIOD), our analysis revealed that the compounded influences of output composition, input intensity, input composition and input origin collectively elevated China's aggregate carbon footprint from 2000 to 2014, while the scale effect made China's carbon emissions lower than of the USA. Notably, China's carbon emissions surpassed those of USA, with the gap accentuating over time. The quantitative results of the structural model showed that the difference in carbon emissions between China and USA predominantly stem from disparities in productivity, production technology, factor intensity, factor endowment and direct carbon intensity. Differences in trade costs exhibited some discernible impact, their influence remains relatively marginal, whereas distinctions in consumption behaviors and trade imbalances minimally contribute to the observed differentials. These findings have important policy implications for global carbon reduction efforts and China's trajectory towards a low-carbon economic paradigm.

Environmental consequences in lifecycle changes of container shipping vessels

To estimate the average lifespan of container vessels, this study specified their most suitable lifespan distribution function using a comprehensive dataset comprising 2188 container vessels manufactured and retired between 1941 and 2018. The lifecycle CO2 emissions of vessels were estimated under different scenarios with varied average lifespans and average carbon intensity improvements per annum through stock-flow model analysis. The results indicated that a normal distribution best represented the lifespan distribution of container vessels, with an estimated average lifespan of approximately 24 years. Furthermore, scenario analyses revealed that shortening the lifespans of container vessels can effectively reduce lifecycle CO2 emissions. This study demonstrates the synergistic contribution of accelerating the replacement cycle of container vessels and implementing stronger energy efficiency regulations for emissions reduction, highlighting the importance of policies regulating vessel lifespans.

Data Envelopment Analysis-Based Approach to Improving of the Budget Allocation System for Decarbonization Targets

Energy innovation plays an important role in the transition to a zero-carbon economy. Governments in IEA member countries are investing in the R&D, demonstration, and deployment of new energy technologies as part of their energy and climate policies. However, government subsidies for energy innovation are not always efficient in achieving climate policy goals. This paper proposes a two-stage Data Envelopment Analysis model with shared inputs to determine the optimal allocation of public funds for the energy innovation process. The innovation process is divided into two stages: the R&D stage and the commercialization stage. The inputs to the model (budget expenditures for energy innovations) are distributed between the first and second stages. As intermediate products, we use the number of patents in clean energy and hydrocarbon energy. The outputs of the model are the changes in carbon intensity and energy efficiency. This model can be used to assess the effectiveness of government spending on energy innovation. The results show that some IEA member countries should allocate a large part of the fossil fuel technology budget (more than 70%) to the research and development phase. The proposed model can support decision making at the international level to increase the effectiveness of public policies in achieving decarbonization and energy efficiency goals.

Возможности использования шлаков в зеленом строительстве в контексте устойчивого развития Арктики

This article explores the potential of using concrete made from a cement mixture with blast furnace slag additives for construction in the Russian Arctic to promote sustainable development in the region. Utilizing industrial waste as recycled raw materials aligns with the principles of green and circular economy. Recent observations have shown local symbiotic effects, such as reduced material costs and mitigated environmental impacts. Replacing clinkers with mineral additives during cement production has been noted to reduce the carbon intensity of the final product. Further reductions in greenhouse gas and pollutant emissions can be achieved due to the long-term preservation of thermal insulating properties and the relatively slow degradation of the structure. Comparative laboratory tests were conducted on concrete samples made from cement with 15% (by weight) mineral slag and cement without additives. The dynamic indicators of density and hardness of the cement samples were assessed under simulated natural conditions. The inclusion of mineral additives alters the chemical reactions during the hardening of the concrete in contact with air and water, without prolonging the process, and increases hardness, even with frequent cycles of freezing/thawing and hydration/dehydration, thereby extending the service life of the structures. The obtained data were extrapolated to evaluate the environmental and economic indicators of construction and maintenance; accessibility, suitability, durability, and resource efficiency were identified as the key characteristics. The study concludes that using cement with mineral additives from blast furnace slag in the Arctic is feasible.

Renewable Adoption, Energy Reliance, and CO2 Emissions: A Comparison of Developed and Developing Economies

Emerging economies and ecosystems rely heavily on fossil fuels, and a country’s energy dependence is a strong indicator of its reliance on foreign suppliers. This study investigates the impact of energy dependence on energy intensity, CO2 emission intensity, and the exploitation of renewable resources in 35 developing and 20 developed nations. It also explores the correlation between renewable energy, GDP growth, and CO2 emissions. This study utilizes the Generalized Linear Model (GLM) and the Robust Least Squares (RLS) method to investigate the negative correlation between renewable energy and policymakers in established and emerging economies. It also employs distinctive linear panel estimation techniques spanning from 1970 to 2022. This study examines the impact of renewable energy on economic growth, energy consumption, and CO2 emissions across four continents. Developing countries see an increase in per capita CO2 emissions when their utilization of renewable energy exceeds their capacity. Even with the introduction of several proxies for renewable energy use using changed techniques, this discovery remains valid. Moreover, this is particularly crucial for industrialized nations with well-established institutions. Energy dependency has increased the energy and carbon intensity needed for expansion across all components, which is surprising. The regional study discovered a spillover impact in most regions, indicating that the consequences of energy reliance are similar in neighboring countries. Regional energy exchange unions play a vital role in reducing the adverse environmental and economic impacts of energy dependence, which is essential for the growth of the renewable energy sector and the decrease in greenhouse gas emissions. Undeveloped countries need to enhance their investment in research and development to advance technologically.

Using BIM and LCA to Calculate the Life Cycle Carbon Emissions of Inpatient Building: A Case Study in China

Hospital buildings provide healthcare services at the costs of significant amounts of energy consumption and carbon emissions, further exacerbating the environmental load. Because of the limited research on the life cycle carbon emissions of Chinese hospitals, this study conducted a detailed carbon-accounting and comparative study. Firstly, BIM and LCA were used to quantify the carbon emissions of the inpatient building in each stage of the life cycle. Secondly, the differences in carbon emissions by stage were compared on the basis of 20 cases of public buildings. The results show that the whole-life carbon emissions of the inpatient building was 10,459.94 kgCO2/m2. The proportion of operational carbon emissions was 94.68%, with HVAC (52.57%), equipment (27.85%), and lighting (10.11%) being the main sources. Embodied carbon emissions accounted for 4.54%, and HRB400 steel and C30 concrete were the main sources of carbon emissions. Hospitals are second only to emporiums in terms of operational carbon intensity, being 1.71 and 1.41 times that of schools and office buildings, with inpatient buildings being 3 and 1.7 times that of medical complexes and outpatient buildings, respectively. The future sustainable development of hospital buildings should promote efficient building performance and good environmental quality, both in terms of energy efficiency and carbon reduction.

Evaluation of Climate Change Mitigation Policies in Developed Vs Developing Countries

Purpose: The aim of the study was to analyzing the evaluation of climate change mitigation policies in developed vs developing countries. Methodology: This study adopted a desk methodology. A desk study research design is commonly known as secondary data collection. This is basically collecting data from existing resources preferably because of its low cost advantage as compared to a field research. Our current study looked into already published studies and reports as the data was easily accessed through online journals and libraries. Findings: The evaluation of climate change mitigation policies reveals distinct findings between developed and developing countries. Developed nations typically show higher levels of policy implementation and technological adoption aimed at reducing greenhouse gas emissions, resulting in measurable declines in carbon intensity across sectors. Unique Contribution to Theory, Practice and Policy: Environmental kuznets curve (EKC) theory, diffusion of innovations theory & dependency theory may be used to anchor future studies on evaluation of climate change mitigation policies in developed vs developing countries. Prioritizing capacity building initiatives and technology transfer programs in developing countries supports practical implementation of climate mitigation strategies. Advocating for equitable climate finance mechanisms ensures adequate funding and financial incentives for developing countries to implement climate mitigation actions.

Marine aquaculture can deliver 40% lower carbon footprints than freshwater aquaculture based on feed, energy and biogeochemical cycles.

Freshwater aquaculture is an increasingly important source of blue foods but produces substantial methane and nitrous oxide emissions. Marine aquaculture, also known as mariculture, is a smaller sector with a large growth potential, but its climate impacts are challenging to accurately quantify. Here we assess the greenhouse gas emissions from mariculture's aquatic environment in global potentially suitable areas at 10 km resolution on the basis of marine biogeochemical cycles, greenhouse gas measurements from research cruises and satellite-observed net primary productivity. Mariculture's aquatic emissions intensities are estimated to be 1-6 g CH4 kg-1 carcass weight and 0.05-0.2 g N2O kg-1 carcass weight, >98% and >80% lower than freshwater systems. Using a life-cycle assessment approach, we show that mariculture's carbon footprints are ~40% lower than those of freshwater aquaculture based on feed, energy use and the aquatic environment emissions. Adoption of mariculture alongside freshwater aquaculture production could offer considerable climate benefits to meet future dietary protein and nutritional needs.

The impact of digital inclusive finance on the collaborative reduction of pollutant and carbon emissions: spatial spillover and mechanism analysis

In light of the escalating global climate risks threatening human survival, there is a global consensus on the necessity for collaborative reduction of pollutant and carbon emissions (CRPC). Within this context, digital inclusive finance (DIF) is recognized for its unique inclusiveness and digital characteristics as a critical factor in promoting environmentally friendly and sustainable development. DIF provides advantageous channels for environmental governance, thereby making the achievement of CRPC objectives feasible. However, the impact of DIF on CRPC has not been fully explored. This study employs a spatial econometric model to investigate the impact of DIF on CRPC in 278 prefecture-level cities in China from 2011 to 2020. The findings indicate that DIF has a positive impact on CRPC, with significant spatial spillover effects. The analysis highlights the pivotal mediating roles played by technology effect and electrified effect of the energy mix, while environmental regulation effect plays a moderating role. Notably, disparities in the impact of DIF on CRPC are evident, particularly in non-resource-based cities, cities with low carbon intensity, and eastern regions where spatial spillover effects are more pronounced. These experiences enrich the relevant thesis in terms of DIF on CRPC, providing a theoretical basis for formulating CRPC schemes.

Estimating the emissions reductions from supply-side fossil fuel interventions

Supply-side interventions that retire highly emitting fossil fuel assets have received increased attention from policymakers and private actors alike. Yet concerns about market leakage—wherein reduced supply from one source is partially offset by increased production from other sources—have raised questions about how much emissions reductions they can achieve. In this paper, we estimate the effects of these supply-side interventions on global emissions, accounting for both market leakage as well as the relative greenhouse gas (GHG) intensity of different sources of supply. We account for uncertainty in market leakage rates and the emissions intensities of the curtailed and substitute sources of supply through a Monte Carlo analysis, drawing on supply and demand elasticities from the economics literature and emissions intensity data from the state-of-the-art Oil Climate Index plus Gas (OCI+) dataset on 586 oil and gas fields around the world. We find a rough band of central estimates for life-cycle emissions reductions from permanent and additional supply-side interventions in the range of 40–50% of the gross life-cycle emissions of each barrel curtailed, depending on the relative emissions intensity of the curtailed and substitute sources of supply. Further, across all of 1.53 million Monte Carlo simulations we conduct, we find very high confidence of net emissions reductions from supply-side interventions (nearly 99% of cases). Finally, targeting the most emissions-intensive sources of oil supply could achieve yet further emissions reductions. How one compares methane and CO2 emissions also has important consequences for which sources to target. Importantly, all estimated emissions reductions we estimate hinge upon a given supply-side intervention being credibly permanent and additional, and our estimates do not assess the uncertainties of those criteria being met due to the idiosyncratic nature of those assessments.

Spatially Varying Costs of GHG Abatement with Alternative Cellulosic Feedstocks for Sustainable Aviation Fuels.

Cellulosic biomass-based sustainable aviation fuels (SAFs) can be produced from various feedstocks. The breakeven price and carbon intensity of these feedstock-to-SAF pathways are likely to differ across feedstocks and across spatial locations due to differences in feedstock attributes, productivity, opportunity costs of land for feedstock production, soil carbon effects, and feedstock composition. We integrate feedstock to fuel supply chain economics and life-cycle carbon accounting using the same system boundary to quantify and compare the spatially varying greenhouse gas (GHG) intensities and costs of GHG abatement with SAFs derived from four feedstocks (switchgrass, miscanthus, energy sorghum, and corn stover) at 4 km resolution across the U.S. rainfed region. We show that the optimal feedstock for each location differs depending on whether the incentive is to lower breakeven price, carbon intensity, or cost of carbon abatement with biomass or to have high biomass production per unit land. The cost of abating GHG emissions with SAF ranges from $181 Mg-1 CO2e to more than $444 Mg-1 CO2e and is lowest with miscanthus in the Midwest, switchgrass in the south, and energy sorghum in a relatively small region in the Great Plains. While corn stover-based SAF has the lowest breakeven price per gallon, it has the highest cost of abatement due to its relatively high GHG intensity. Our findings imply that different types of policies, such as volumetric targets, tax credits, and low carbon fuel standards, will differ in the mix of feedstocks they incentivize and locations where they are produced in the U.S. rainfed region.

Towards low-carbon development through innovation: Empirical evidence from China

Innovation is crucial for countries to achieve their carbon peak and carbon neutrality goals. To explore how and to what extent innovation contributes to low-carbon development, this study utilizes data from 272 Chinese cities, applying both staggered difference-in-differences and spatial econometric approaches to comprehensively assess the direct and spatial spillover effects of China's innovative city pilot policy on urban low-carbon development. The findings are as follows: First, the innovative city pilot policy has reduced urban carbon intensity by 4.62 % and increased carbon total factor productivity by 3.03 %, with the effect being more significant in larger cities. Second, mechanism analysis indicates that the innovative city pilot policy primarily promotes urban low-carbon development through innovation financing and talent attraction, rather than optimizing industrial structures Third, spatial analysis reveals that the innovative city pilot policy has a low-carbon spillover effect, indicating it can promote low-carbon development in neighboring cities. Finally, this paper proposes policy recommendations for combining innovative city pilot policies with climate policies, focusing on the underlying mechanisms, and exploring cross-regional linkages.