Carbon Intensity Research Articles

Effects of emissions caps on the costs and feasibility of low-carbon hydrogen in the European ammonia industry

The European ammonia industry emits 36 million tons of carbon dioxide annually, primarily from steam methane reforming (SMR) hydrogen production. These emissions can be mitigated by producing hydrogen via water electrolysis using dedicated renewables with grid backup. This study investigates the impact of decarbonization targets for hydrogen synthesis on the economic viability and technical feasibility of retrofitting existing European ammonia plants for on-site, semi-islanded electrolytic hydrogen production. Results show that electrolytic hydrogen cuts emissions, on average, by 85% (36%-100% based on grid price and carbon intensity), even without enforcing emission limits. However, an optimal lifespan average well-to-gate emission cap of 1 kg carbon dioxide equivalent (CO2e)/kg H2 leads to a 95% reduction (92%-100%) while maintaining cost-competitiveness with SMR in renewable-rich regions (mean levelized cost of hydrogen (LCOH) of 4.1 euro/kg H2). Conversely, a 100% emissions reduction target dramatically increases costs (mean LCOH: 6.3 euro/kg H2) and land area for renewables installations, likely hindering the transition to electrolytic hydrogen in regions with poor renewables and limited land. Increasing plant flexibility effectively reduces costs, particularly in off-grid plants (mean reduction: 32%). This work guides policymakers in defining cost-effective decarbonization targets and identifying region-based strategies to support an electrolytic hydrogen-fed ammonia industry.

Making sense of life cycle assessment results of electrified vehicles

Battery electric vehicles and plug-in hybrid electric vehicles can have life-cycle carbon dioxide emissions that can be close, within 5 % of each other, or very different depending on the efficiencies of the powertrain, relative contributions of battery and combustion engine to the traction power, and source of electricity. Life cycle assessments can provide insight into the variability in carbon dioxide emissions, but they are time consuming. In this work a simplified model that can explain the carbon dioxide emissions during the well-to-wheels portion of the life cycle is developed. The robustness of the simplified model is evaluated by varying parameters and comparing its results with those from the life cycle assessment. Assumptions must be made to conduct the assessment. The assumptions include the efficiencies of the internal combustion engine, the battery, the drivetrain, and regenerative braking, and the relative contribution of the battery to traction power in the plug-in hybrid electric vehicle. Renewable and non-renewable sources of generating electricity are considered. It is concluded that a plug-in hybrid electric vehicle with the same parameters as the battery electric vehicle can potentially be lower emitting only when the emissions factor of the electricity generation and the internal combustion engine efficiency are high. For low carbon intensity electricity generation, the plug-in vehicle emits more carbon dioxide than the battery electric vehicle for the range of internal combustion engine efficiencies considered.

Tracking a Chinese megacity's community-wide carbon footprint and driving forces from a multi-infrastructure perspective

Many urban deep-decarbonization actions are related to multiple infrastructure provisioning sectors; therefore, it is essential to track carbon footprints associated with these infrastructure sectors to guide urban carbon mitigation actions. However, there are fewer temporal analyses of cities' carbon footprints from a multi-infrastructure perspective. This study applied the community-wide trans-boundary infrastructure-based carbon footprinting (CIF) method to Shanghai, China and adopted the logarithmic mean Divisia index (LMDI) approach to explore driving factors in community-wide carbon footprints from 2000 to 2019. Shanghai's total CIF increased by 85%, from 153.2 million tonne CO2-eq in 2000 to 283.5 million tonne in 2019. The energy and mobility sectors contributed to 89%–93% of the total CIF during this period. Although emitting sources within Shanghai contributed to a large proportion, trans-boundary carbon emissions embodied in imported energy, construction materials, and food provisioning increased from 6% of total CIF in 2000 to 28% in 2019. Shanghai significantly reduced city-wide carbon intensity per GDP from 2000 to 2019. Its city-wide carbon footprint per capita was around 11.4 tonne CO2-eq, of which 17.4% was associated with residential consumption. LMDI results showed that improving energy efficiency in economic production and reducing energy demand in residential sector contributed to reducing carbon footprints of these two sectors. The driving effect of carbon intensity was not monotonic in both economic production and residential consumption, indicating future policy should prioritize actions to reduce the carbon intensity of infrastructure provisioning in its carbon neutrality plan.

Identifying and Dealing with Interdependencies and Conflicts between Goals in Manufacturing Companies’ Sustainability Measures

Companies are increasingly focusing on sustainable business practices. Internal and external stakeholders’ expectations manifest in legal requirements, national and international standards, and market and customer expectations, among other things, must be considered. In addition to profit maximization, which is the usual target for corporate management, management must consider environmental sustainability aspects such as resource efficiency, greenhouse gas intensity, and a company’s emissions behavior. In addition, social aspects related to the company’s employees, the immediate urban environment, the situation in the supply chain, and effects on the market environment must increasingly be considered. Specifically, companies are faced with the challenge of dealing with conflicting objectives regarding the various aspects of sustainability and, if necessary, weighing them up against each other. These trade-offs must be made against the company’s socio-economic and ecological environment, corporate strategy, and sustainability goals. This paper provides an overview of current approaches and research gaps on this topic through a literature review. It highlights the lack of methods and frameworks to specifically deal with trade-offs and conflicts between goals.

Straw management adopted by large farms sustains grain yield but mitigates greenhouse gas emissions

ContextStraw incorporation is a globally recommended strategy for enhancing soil fertility. The methods for straw incorporation adopted by large farms usually differ from those used by small households, primarily because of variations in cost affordability. However, the effects of straw management on rice yields and greenhouse gas (GHG) emissions have not been well explored at different farming scales. ObjectivesThis study aims to compare the grain yield and greenhouse gas emissions under different straw management adopted by large farms than small households. MethodsA three-year field experiment using split-plot design, with straw management as the main plot and preceding tillage as the sub-plot, was conducted in a wheat-rice rotation system. Four treatments were given as rotary tillage with straw removal (RT-S), rotary tillage with straw incorporation (RT+S; small households), ploughing tillage with straw removal (PT-S), and ploughing tillage with straw incorporation (PT+S, large farms) in the preceding wheat season. Soil tillage in the rice season was the same, which was rotary tillage after irrigation. ResultsStraw incorporation significantly increased methane (CH4) and nitrous oxide (N2O) emissions, and 60%-62% of CH4 was emitted during the transplanting to jointing stages while 45–73% of N2O was emitted during the jointing to the booting stage. The stimulation of CH4 and N2O emissions by straw incorporation was closely correlated to enhanced soil organic carbon (SOC) and denitrification enzyme activity, respectively. In the last year, PT+S significantly reduced the global warming potential (GWP) compared to RT+S in the whole rice season, which can be attributed to the dramatically decline of CH4 emission, even though N2O emission was increased. Additionally, the decreased CH4 emission was mainly due to lower methanogenic activity, and the increased N2O emission was mainly resulted from lower nosZ abundance under PT+S compared to RT+S. Straw incorporation increased rice yield by 15.73% on average in the last two years, and rice yield of PT+S in the last year was significantly enhanced by 27.50%, resulting in a lower greenhouse gas intensity (GHGI) by 25.54% compared to RT+S. ConclusionStraw management practices adopted by large farms (PT+S) have the potential to synchronize high rice yields with lower GHG emissions compared to small households (RT+S). ImplicationsOur findings provide some evidence that large-scale agricultural organization may be helpful for sustainable rice production in China.

Carbon border adjustment mechanism challenges and implications: The case of Visegrád countries

Stricter climate policies across the European Union are enhancing the phenomenon of free riding by nonacting countries, which translates into carbon leakage and loss of competitiveness. This paper investigates the trade, economic and environmental implications of the future implementation of a carbon border adjustment mechanism (CBAM) in Visegrád countries as EU member states. We exploit trade data to estimate price and income elasticities for emission-intensive trade-exposed (EITE) goods imported from non-EU trading partners to Visegrád countries. Based on these estimates, which are combined with the average carbon intensity of the EU's proposed list of EITE goods, we simulate the implications of six different configurations of restrictiveness of the CBAM imposed on imports from non-EU countries. We find that a high price elasticity and carbon intensity tend to significantly decrease import demand for EITE goods under the CBAM. Moreover, future CBAM implementation will yield a relatively small adverse impact on economic growth in Visegrád countries and a small decrease in total carbon emissions in non-EU countries.

Improving a ship's energy efficiency in Korean coastal waters using tidal current information

This study investigates the impact of tidal currents on a ship’s speed, fuel consumption, and energy efficiency for Greenhouse Gas (GHG) reduction. The research was conducted in Korean coastal waters from Busan Port to Incheon Port during spring and neap tides. The results show that if a tanker sails with the most favorable tidal current, it can improve fuel efficiency by up to 2.46 % and reduce sailing hours by up to 2.17 hr. This change can also improve the Carbon Intensity Indicator (CII) Rating from "B" to "A". The study concludes that utilizing tidal currents can enhance energy efficiency and contribute to GHG reduction without any financial investment.

Exploring a pathway to optimise the carbon tax policy in terms of the economy, the environment and health: A scenario-based system dynamics approach

The carbon tax, a pivotal policy instrument in tackling climate change, holds the potential to significantly influence the development of society. To comprehensively analyse the effectiveness of the policy on carbon taxation and explore its possible optimisation path, this study utilizes system dynamics theory to establish a simulation model. A detailed analysis and evaluation of this policy is then conducted from the perspectives of the economy, the environment, and health. To guarantee the precision of the simulation model, a new, comprehensive evaluation method is proposed, which can test the degree of fit of the relative trend and absolute data of the simulation model with reality. The findings reveal that, despite its negative economic implications, a carbon tax policy has positive ramifications for the environment, energy, health, industrial structure, and carbon intensity targets. Furthermore, the synergistic reinforcement effect of R&D and new energy support policies on carbon taxation surpasses the impact of any individual policy alone. Notably, the influence of auxiliary policies has a temporal difference on this policy. Based on these insights, the study concludes with practical policy recommendations.

Different types of environmental regulations and carbon intensity: empirical analysis of China’s garment industry

Different types of environmental regulations and carbon intensity: empirical analysis of China’s garment industry

Examining the portfolio carbon footprint of Indian banking system

This paper examines the portfolio carbon footprint of Indian banking system. To this end, we combine the emissions data from India's Biennial Update Reports to UNFCCC and Reserve Bank of India's bank database from 2010 to 2016; apply Network for Greening the Financial System's backward-looking methodology and Partnership for Carbon Accounting Financials Standards in conjunction with Leontief's Input-Output technique to estimate the weighted average carbon intensity (WACI) of bank's loans portfolio at three levels – System level, Bank group level and Spatial level. Our major findings include-first, at system level, the carbon footprint of Indian banks shows a rising trend over the study period with the aggregate WACI of bank loans increasing by 9.4% from 332.5 tCO2e/US$ million in 2010 to 363.7 tCO2e/US$ million in 2016. Second, at the group level, while the financed emissions of public sector banks have plateaued, for private sector banks they have nearly doubled during the study period, suggesting the increased exposure to carbon intensive assets. Third, on the spatial level, top five regions by WACI include Delhi, Maharashtra, Gujarat, Tamil Nadu, and Telangana in descending order.

Economic and environmental analysis of Malaysia's 2025 renewable and sustainable energy targets in the generation mix

In pursuing the goals of sustainable development and transiting from fossil fuel-dependent electricity generation to renewable and sustainable alternatives as endorsed by COP28, Malaysia set a 31 % target for renewable-energy in the power generation mix by 2025. This underlines Malaysia's commitment to combat climate change, mainly by reducing its economy-wide GDP carbon intensity by 45 % from the 2005 levels by 2030. To better understand the effects of renewable energy expansion on the economy, environment, electricity output and input-mix, a computable general equilibrium model is applied using an updated benchmark. The simulation results show that increasing the share of coal and gas in the power generation mix compromises emission reduction targets. Further, there is a trade-off between subsidized natural gas supplies and power generation and exports. The results also show that a larger proportion of renewable energy leads to improved welfare. As the share of gas and coal in renewable energy generation is not very high, its impact on carbon emissions is limited. However, if renewable energy expansion is complemented by subsidy rationalizations, the positive impacts are more pronounced. In terms of policy implications, the findings suggest that Malaysia must step up its emission reduction efforts by augmenting the generation of renewable rather than non-renewable resources. Complementary initiatives such as emission abatement policies and consumption subsidies for refined oil products and fossil-fuel power generation should be rationalized to expand renewable resources, improve energy security, and attain emission reductions.

The performance of solvent-based direct air capture across geospatial and temporal climate regimes

IntroductionLiquid-solvent direct air capture (DAC) is a prominent approach for carbon dioxide removal but knowing where to site these systems is challenging because it requires considering a multitude of interrelated geospatial factors. Two of the most pressing factors are: (1) how should DAC be powered to provide the greatest net removal of CO2 and (2) how does weather impact its performance?.MethodsTo investigate these questions, this study develops a process-level model of a liquid-solvent DAC system and couples it to a 20-year dataset of temperature and humidity conditions at a ~9km resolution across the contiguous US.Results and discussionWe find that the amount of CO2 sequestered could be 30% to 50% greater than the amount of CO2 removed from the atmosphere if natural gas is burned on site to power DAC, but that the optimal way to power DAC is independent of capture rate (i.e., weather), depending solely on the upstream GHG intensity of electricity and natural gas. Regardless of how it is powered, air temperature and humidity conditions can change the performance of DAC by up to ~3x and can also vary substantially across weather years. Across the continuous US, we find that southern states (e.g., Gulf Coast) are preferrable locations for a variety of reasons, including higher and less variable air temperature and relative humidity. Lastly, we also find the performance of liquid-solvent DAC calculated with monthly means is within 2% of the estimated performance calculated with hourly data for more than a third of the country, including in the states with weather most favorable for liquid-solvent DAC.

Predictive models of embodied carbon emissions in building design phases: Machine learning approaches based on residential buildings in China

As one of the major architectural forms, residential building construction consumes considerable resources, and it has been regarded as a crucial factor for the implementation of carbon peaking and neutrality targets. Estimation of carbon emissions is essential for making informed decisions regarding building design and carbon reduction measures. Some studies have established predictive models for building operational carbon emissions. However, there are relatively few studies concerning the prediction of embodied carbon emissions. This study established a dataset containing 850 residential building samples. Based on the trade-offs and combinations of different explanatory variables, including building features and material use, this study developed two-phase models. These models, incorporating six scenarios, predicted embodied carbon intensities using twelve machine learning algorithms. For the planning design phase, an extremely randomized tree model using the building height, structural form, seismic fortification intensity, delivery form, geographical region, and material cost as inputs was favored considering R2 as 0.821 on the testing dataset. For the preliminary design phase, an extreme gradient boosting model using both building features and material intensities provided superior performance with R2 and MAPE values of 0.917 and 0.038, respectively. The optimal models and relevant feature importance analysis can be helpful for efficiently predicting embodied carbon emissions, and therefore, facilitate low-carbon designs.

Clarifying the levers of carbon emission reduction in compact cities in China: A multi-sectoral approach

Compact city policies have gained global attention for their potential to combat urban sprawl, conserve suburban open spaces, reduce energy consumption, and cultivate vibrant urban living environments. While these policies are widely believed to contribute to urban low-carbon objectives, empirical evidence has been lacking. This study focuses on the pivotal elements of compact city development, investigating impacts on sectoral urban carbon emissions and uncovering spatial heterogeneity. The research outcomes affirm that density and accessibility indicators exert significant negative influences on carbon intensity for the energy, industrial, household, and transportation sectors. While public transport, despite its fundamental role in compact city theory, does not show effectiveness in reducing urban carbon emissions as expected. The study highlights that as an approach toward achieving urban sustainability under the scope of climate change adaptation, compact city development strategies necessitate a careful balance in their application. Further, we underscore the importance of complementing compact city policies with greener energy strategies to effectively realize low-carbon urban transportation goals.

Algae to HEFA: Economics and potential deployment in the United States

AbstractTo reach the goals set by the US Department of Energy's Sustainable Aviation Fuel (SAF) Grand Challenge, currently available feedstocks may be insufficient. Giving priority to developing, prototyping and reducing the cost of algal feedstock before investing and lining up locations is important. As the production of algal feedstocks advances, a simplified conversion approach using more mature technologies can help reduce the investment risk for algae‐based fuels. Reducing process complexity to the steps described here [namely, conversion of lipids to HEFA (hydroprocessed esters and fatty acids) fuels and relegating the remainder of the biomass to anaerobic digestion or food/feed production] enables the near‐term production of algal SAF but presents challenging economics depending on achievable cultivation costs and compositional quality. However, these economics can be improved by present‐day policy incentives. With these incentives, the modeled algae‐to‐HEFA pathway could reach a minimum fuel selling price as low as $4.7 per gasoline gallon equivalent depending on the carbon intensity reduction that can be achieved compared with petroleum. Uncertainty about algal feedstock production maturity in the current state of technology and the future will play a large role in determining the economic feasibility of building algae‐to‐HEFA facilities. For example, if immaturity increases the feedstock price by even 10%, SAF production in 2050 is about 58% of the production which could have been achieved with mature feedstock. Additionally, growth in this conversion pathway can be notably boosted through the inclusion of subsidies, and also through higher‐value coproducts or higher lipid yields beyond the scope of the process considered here.

Effect of in-situ emulsification on CO2/N2-based cyclic solvent injection process for enhancing heavy oil recovery and CO2 storage

Surfactant-assisted CO2/N2-based CSI (SA CO2/N2-CSI) process emerges as a strategic solution to migrate the high energy consumption and carbon intensity associated with traditional thermal operations for heavy oil recovery. However, the interphase mass transfer makes the emulsification behavior in this process complex. In this study, the effect of in-situ emulsification on CO2/N2-CSI is assessed using a sandpack model and microchannel chip. Mesoscopically, SA CO2/N2-CSI outperforms conventional CO2/N2-CSI in terms of both oil recovery and CO2 storage, owing to the enhanced CO2 diffusion, oil solubilization, and foamy oil stability due to emulsification. Microscopically, the impact of emulsifier injection rate on oil removal efficiency in the dead-end pores becomes negligible when the injection rate exceeds 50 nL/min, providing insights to the emulsification mechanisms underlying the optimal pressure depletion rate (9 kPa/min) in SA CO2/N2-CSI. This study demonstrates the applicability of the SA CO2/N2-CSI in fostering sustainable heavy oil production and CO2 storage.

Assessing the impact of environmental performance on corporate financial performance: A firm-level study of GHG emissions in Africa

Utilizing comprehensive firm-level data from 2005 to 2021 across various African nations, our study investigates the effect of a firm's greenhouse gas (GHG) emissions on its corporate financial performance (CFP). The research yields the following findings. First, we find that GHG emission intensity exerts a significantly negative impact on CFP measured by return on assets (ROA) and return on equity (ROE). This effect is consistently substantiated across different measurements of GHG emission intensity and CFP. Second, our analysis includes a series of stringent robustness assessments, all of which affirm the stability and resilience of our primary findings. Third, following the Paris Agreement, a decrease in GHG emission intensity correlates with a further rise in ROA and ROE. Additionally, we emphasize the pivotal role of industry-specific characteristics and regional variables in shaping the connection between GHG emission intensity and CFP. Our findings underscore that the influence of GHG intensity on a firm's financial performance is particularly pronounced within high-emission sectors in contrast to their low-emission counterparts. Furthermore, we show that the impacts of GHG emission intensity on CFP are primarily driven by firms operating in Southern Africa. Fourth, to recognize potential endogeneity concerns within the GHG emission-CFP relationship, we employ a two-stage least-squares regression (2SLS) approach. This method utilizes industry-level GHG emission intensity as the principal instrumental variable (IV), and in order to further mitigate endogeneity issues, we incorporate both lagged GHG intensity and the instrument proposed by Lewbel (2012) based on heteroskedasticity as additional IVs alongside the kinky least squares method by Kiviet (2020). The results derived from our 2SLS estimates consistently corroborate the negative effect of GHG emission intensity on CFP. Finally, our empirical findings carry significant implications for both corporations and policymakers.

Characterization of Atmospheric Electrical Discharge in Pin-water Configuration at Different NaCl Concentrations

The interaction between a pin-plate and plasma are representing an interest subject in plasma technology and applications. In this research, the influence of added NaCl to distilled water on the discharge characteristics that formed in the gap between pin-water surfaces was investigated in more details. Their electrical and optical characteristics serve as identifiers. It's found that all optical emissions intensity peaks as a results that detected are decreased with increasing of NaCl concentrations (300,400, and 500 mg). As well as, the emission intensity of neutral emission peaks are much higher than that of the ionic emission peaks. The addition of NaCl changes the liquid accessibility, which alters the kinetics of the discharge that forms in the pin-water surface gap. Also, its observed that the NaCl concentrations affected on the I-V characteristics. The data detected that the plasma frequency ((377.1176 - 279.1951)*1011 rad/sec), electron number density ((4.4519 – 2.4401)*1017 cm-3) and electron temperature (2.1537 – 1.663 eV) decreased with increases of NaCl concentrations except the Debye length ((1.6342 – 1.93989)*10-6 cm) shown a different behavior with increase of NaCl concentrations.

From policy stringency to environmental resilience: Unraveling the dose-response dynamics of environmental parameters in OECD countries

In the pursuit of sustainable development and the mitigation of negative externalities arising from environmental stressors, a multitude of member countries within the Organization for Economic Co-operation and Development (OECD) have embraced various environmental policies. Nevertheless, previous empirical research has largely overlooked investigating the causal relationship between the Environmental Policy Stringency (EPS) and environmental indicators. To bridge this gap, we conduct an empirical study to examine the dose-response relationship between EPS, as a continuous treatment variable, and selected environmental indicators. Our findings reveal evidence of a mixed treatment effect of policy stringency on the environment. Notably, the implementation of EPS leads to a reduction in carbon emissions per capita and an overall decline in ecological footprint. However, despite OECD countries moving towards a negative trajectory to preserve the environment, carbon intensity remains steadfastly on a positive path. Moreover, the intensification of policy stringency demonstrates positive effects on total renewable energy production, encompassing solar, wind, and eco-innovation. Building upon these empirical results, we offer several policy implications for the adoption and implementation of environmental policies within OECD countries.

Carbon emissions changes of animal husbandry in China: Trends, attributions, and solutions: A spatial shift-share analysis

China is a major livestock producer confronting the dual challenges of rising demand for animal-based food consumption and decreasing carbon emissions. To effectively address these issues, it is crucial to understand the trends of carbon emissions from animal husbandry and the competitive advantages of carbon emission reduction in different regions. This study uses panel data from 31 provinces from 2004 to 2020 to investigate the contributing factors to carbon emissions and explore ways to reduce carbon intensity in animal husbandry. The analysis employs spatial shift-share analysis and the spatial Durbin model. Our findings indicate that life-cycle carbon emissions associated with animal husbandry in China decreased from 572.411 Mt CO2eq to 520.413 Mt CO2eq over time, with an average annual decline of 0.568 %. The annual contribution of output value and internal industry-mix adjustment to carbon emission growth is 22.639 MT CO2eq and 6.226 MT CO2eq, respectively. On the other hand, the annual contribution of carbon efficiency improvement to carbon emission reduction is much higher, at 36.316 MT CO2eq. However, there is significant regional heterogeneity in the spatial decomposition of the carbon efficiency change component. The Northeastern region, Northwest and along the Great Wall demonstrate neighborhood advantages in enhancing carbon efficiency. In contrast, the South China and Southwest regions rely more on local carbon efficiency advantages to reduce the carbon intensity of animal husbandry. Furthermore, the carbon intensity in local and neighboring areas can be reduced through environmental regulations and industrial agglomeration. While technical progress significantly negatively impacts carbon intensity in neighboring regions, it does not contribute to reducing the carbon intensity of local animal husbandry. The findings provide valuable insights for local governments, aiding them in recognizing the pros and cons of carbon reduction in animal husbandry and strengthening regional cooperation in emission reduction management.