Deep Decarbonization Research Articles

A Numerical Study of the Thermochemical and Aerodynamic States of H2‐intensive Direct Reduction Shaft Furnace

In the urgent pursuit of deep decarbonization, the steel industry has paid significant attention to the hydrogen‐intensive direct reduction process, where the H2‐to‐CO (volume) ratio of feed gas for the shaft furnace (SF) is increased compared to the current level. In this work, the reduction process of iron oxide pellets in the SF is investigated numerically to clarify how the in‐furnace thermochemical and aerodynamic states are affected by increasing hydrogen content, with the goal to provide guidelines for more efficient operations of the unit. Multiscale modeling is conducted to investigate the complicated gas–solid countercurrent reactive flows in the SF where the reduction behavior of an individual iron oxide pellet is described using a three‐interface unreacted shrinking core model. The results show that an increase in the hydrogen content leads to a lower temperature level and hence a deteriorated thermochemical state. It also induces a lower gas pressure drop over the in‐furnace packed bed.

Development and assessment of a biomass-based energy system for green steel production: A thermodynamic study

ABSTRACT Steel is the fundamental pillar of contemporary society, given its significant greenhouse gas emissions, rapid transformation is required for deep decarbonization of the iron and steel industry. This paper proposes a strategy to generate green steel through the H2-DRI-EAF (Hydrogen direct reduced iron processed in an electric arc furnace) process, leveraging biomass as the primary feedstock. The proposed configuration contains a biomass gasifier to generate hydrogen, which is further used in a shaft furnace to reduce iron ore and is fed to an electric arc furnace to produce Green Steel. India serves as the focal point for this study, with agricultural residue from the four most abundant crops selected as the primary feedstock. With these chosen feedstocks, the system demonstrates the capacity to produce approximately 0.1 kg of hydrogen per kg of biomass. Operating with an overall energy efficiency of 29.2% and exergy efficiency of 41.4%, the plant exhibits a crucial characteristic: the ability to seamlessly integrate different feedstocks without significantly affecting its overall performance. The aim of the current study is to promote bioenergy as a viable pathway for the decarbonization of steelmaking processes.

Impact of Carbon Tax on Renewable Energy Development and Environmental–Economic Synergies

Global warming caused by greenhouse gas emissions has become a worldwide environmental problem, posing a great threat to human survival. As the world’s largest emitter of carbon dioxide, China has pledged to reach peak carbon emissions by no later than 2030 and carbon neutrality by 2060. It is found that a carbon tax is a powerful incentive to reduce carbon emissions and promote an energy revolution, but it may have negative socio-economic impacts. Therefore, based on China’s 2020 input–output table, this paper systematically investigates the impacts of a carbon tax on China’s economy, carbon emissions, and energy by applying a computable general equilibrium model to determine the ideal equilibrium between socio-economic and environmental objectives. Based on energy use characteristics, we subdivided the energy sector into five major sectors: coal, oil, natural gas, thermal power generation, and clean power. The results show that when the carbon emission reduction target is less than 15%, that is, when the equilibrium carbon tax price is less than 54 yuan/ton, the implementation of a carbon tax policy can significantly reduce carbon emission and fossil fuel energy consumption, while only slightly reducing economic growth rate, and can achieve the double dividend of environment and economy. Moreover, because the reduction of coal consumption has the greatest impact on reducing carbon emissions, the ad valorem tax rate on coal after the carbon tax is imposed is the highest because coal has the highest carbon emission coefficient among fossil fuels. In addition, as an emerging clean energy source, hydrogen energy is the ideal energy storage medium for achieving clean power generation in power systems. If hydrogen energy can be vigorously developed, it is expected to greatly accelerate the deep decarbonization of power, industry, transportation, construction, and other fields.

A pathway design framework for national freight transport decarbonization strategies

ABSTRACT National and international freight transport emissions represent about 40% of global transport emissions, with demand expected to triple by 2050, which will increase emissions further. However, to meet the 1.5°C climate goal, a rapid decrease in transport emissions is required, along with the achievement of zero emissions as soon as possible around mid-century. Given this context, long-term low-emission national development pathways provide a strategic instrument to align short-term action with long-term objectives and to reduce national freight transport emissions. However, current transport-energy modelling studies often exclude the structural and systemic mitigation options that influence the industrial production and supply chain structure, as well as modal and logistics choices, and instead focus mainly on the technological options related to road freight vehicles and fuels. In addition, such studies lack relevant policy and stakeholder-oriented explanations of the barriers and enablers associated with these options. In this paper, we introduce a new framework to design and compare long-term national and sectoral decarbonization pathways for freight transportation, facilitating the consideration of all decarbonization options and the organization of stakeholder-oriented policy dialogues. The development of this sectoral framework builds on the general Deep Decarbonization Pathways (DDP) framework and a first implementation in France. It is then applied and tested in three emerging countries: Brazil, India and South Africa and the results show that the linking of systemic and technological changes could reduce emissions per tonne-km by at least 60%, and up to 100% by 2050, while also reducing energy consumption and supporting national development.

Mitigating China's process-related greenhouse gas emissions via supply chain management

As the world's largest industrial producer, China's deep decarbonization of industrial process-related greenhouse gas (GHG) emissions is essential in fulfilling the goal of reaching net zero emissions. Previous studies focused more on emission inventories and abatement technologies, however, final demand also plays a significant role in driving China's industrial process-related GHG emissions. Based on the environmentally extended input-output analysis and structural path analysis, this study explores detailed industrial process-related GHG emissions inventory and investigates critical supply chain paths of 17 products and 16 types of GHG emissions. The results show that industrial process-related GHG emissions reached 1887.1 Mt CO2-eq in 2018, of which more than three-fifths was induced by fixed capital formation. The entirety of the Construction sector amounted to 54.6% of the total embodied industrial process-related GHG emissions. After examining the embodied industrial process-related GHG emissions paths, critical economic sectors such as Construction, Nonmetallic Mineral, Chemical, and the paths of “Nonmetallic Mineral → Construction → Fixed capital formation and Nonmetallic Mineral → Nonmetallic Mineral → Construction → Fixed capital formation” were identified as the main contributor. In considering of the enormous challenges during mitigating GHG emissions from process-related industries, it is essential to identify and optimize critical supply chains, which provides new insights into China's industrial process transition towards a low-carbon economy.

Optimal scheduling of boiler electrification for process decarbonization

AbstractProcess heat electrification offers the prospect of deep decarbonization of the chemical and allied industries. Replacing fossil fuel‐fired boilers with electric units can reduce carbon emissions if the power mix has a large share of renewables. For multinational firms with plants in multiple locations, the electrification decisions should be scheduled based on grid carbon intensity projections and should also be coordinated among these subsidiaries. In addition, carbon credits can be traded among the multiple sites to allow lagging plants to reduce their carbon footprints. A novel mathematical model has been developed to optimize process heat electrification plans in multinational corporations. The model determines the optimal timing of electrification at each location, and also the necessary level of carbon trading among subsidiaries. An illustrative case study demonstrates how the model can be used to generate electrification plans that are superior to those based on simple heuristics.

Systematic experiment on adsorption, separation and regeneration of X zeolites for LNG production with different regeneration strategies: vacuum, purging, heating and hybrid combinations

This work experimentally investigated the adsorption, separation and regeneration properties of two X zeolites for natural gas deep decarbonization in liquified natural gas (LNG) production. The regeneration properties of JLOX500 and 13X were compared with relation to regeneration efficiency, energy consumption, desorption and adsorption rate of CO2, and other factors in different pathways: vacuum, purging, heating, and hybrid combinations. The results demonstrated that fresh JLOX500 with more cations and less binders had significantly greater CO2 adsorption capacities and larger separation factor (CO2/CH4) than those of fresh 13X, because of its larger micro-porosity and higher CO2 isosteric heat. Due to higher partial pressure, the adversely significant effect of CH4 competing adsorption against CO2 on adsorbent regeneration is confirmed. The flow rate increases of purge gas had no effects on regeneration efficiency for 13X when the CO2 concentration of desorbed gas reached to zero. Because of a greater cumulative pore volume, JLOX500 after sufficient regeneration has a larger CO2 adsorption capacity and a higher desorption rate of CO2 than 13X, which also makes it more efficient with regards to purge gas and energy consumption utilization. With 150 mL/min of purge gas, the energy consumptions for 13X and JLOX500 regenerated at 150 °C were 4.20 and 2.89 MJ/kg-CO2, respectively. The CH4 recovery relied on the regeneration efficiency of adsorbents, duration of adsorption, and the amount of purge gas used. Both X zeolites regenerated by purging (150 mL/min) or vacuuming at 1 kPa at 150°C could purify the feed to the CO2 content less than 50 ppm, but JLOX500 is more efficient with regards to the overall performance.

Large Ensemble Exploration of Global Energy Transitions Under National Emissions Pledges

AbstractGlobal climate goals require a transition to a deeply decarbonized energy system. Meeting the objectives of the Paris Agreement through countries' nationally determined contributions and long‐term strategies represents a complex problem with consequences across multiple systems shrouded by deep uncertainty. Robust, large‐ensemble methods and analyses mapping a wide range of possible future states of the world are needed to help policymakers design effective strategies to meet emissions reduction goals. This study contributes a scenario discovery analysis applied to a large ensemble of 5,760 model realizations generated using the Global Change Analysis Model. Eleven energy‐related uncertainties are systematically varied, representing national mitigation pledges, institutional factors, and techno‐economic parameters, among others. The resulting ensemble maps how uncertainties impact common energy system metrics used to characterize national and global pathways toward deep decarbonization. Results show globally consistent but regionally variable energy transitions as measured by multiple metrics, including electricity costs and stranded assets. Larger economies and developing regions experience more severe economic outcomes across a broad sampling of uncertainty. The scale of CO2 removal globally determines how much the energy system can continue to emit, but the relative role of different CO2 removal options in meeting decarbonization goals varies across regions. Previous studies characterizing uncertainty have typically focused on a few scenarios, and other large‐ensemble work has not (to our knowledge) combined this framework with national emissions pledges or institutional factors. Our results underscore the value of large‐ensemble scenario discovery for decision support as countries begin to design strategies to meet their goals.

Global carbon transition in the passenger transportation sector over 2000–2021

The high-emitting and hard-to-abate passenger transport sector plays a crucial role in global deep decarbonization. To lead an equitable and rapid transition in the passenger transportation, this work is the first to develop a bottom-up modeling framework integrated with the latest decomposing structural decomposition methodology to assess and compare historical emission patterns and decarbonization efforts of 28 countries over the past two decades. Results indicate: (1) Carbon emissions from the global passenger transport sector increased between 2000 and 2021, peaking in 2019, with GDP per capita and population size being key drivers of rising carbon emissions across countries. (2) The decarbonization efforts of the global passenger transport sector varied by traffic mode. The largest contributors were passenger buses [−0.46 megatons of carbon dioxide per year (Mt CO2/yr)], followed by trains (−0.4 Mt CO2/yr), and airplanes (−0.28 Mt CO2/yr), while passenger cars (1.04 Mt CO2/yr) hindered the decarbonization process. (3) Although the global passenger transport sector has cumulatively decarbonized 3005.9 Mt CO2 and achieved a decarbonization rate of 5.1 %, regional performance varied significantly, exhibiting uneven and inadequate progress. Overall, the study provides an effective data-driven assessment framework for reviewing and comparing global and national passenger transport decarbonization performance, which will facilitate the planning of decarbonization pathways by global emitters and the early achievement of zero-carbon transport.

Study on the planning and scheduling strategies of the hydrogen supply network for road transportation in deep decarbonization scenarios

As the energy decarbonization continues to advance, hydrogen is gaining momentum. With the increasing demand for hydrogen and the lack of hydrogen infrastructure, it is urgent to solve the problem of hydrogen supply network layout planning. In order to reduce redundant construction of hydrogen supply network infrastructure and increase the rationality of its layout, this paper conducts research on the optimal layout planning of hydrogen supply network infrastructure in the transportation sector. By constructing a two-stage real-time scheduling model of hydrogen supply network, the unit cost composition of hydrogen supply network is more complete and accurate, and the location, technology type and quantity of each link of hydrogen supply network are obtained. The results show that the unit cost of China's hydrogen supply network is 27.8 CNY/kg in 2035 and 19.04 CNY/kg in 2050 under the baseline scenario. Compared with the results of existing literature, the two-stage real-time scheduling model can reduce by 7 % of the hydrogen energy supply network unit cost by decreasing the transportation vehicles and the investment capacity of fixed hydrogen storage equipment. The proposed method of the hydrogen supply network planning can provide policy-makers with the selection of sustainability pathways for dynamic hydrogen infrastructure development planning.

Catalyzing deep decarbonization with federated battery diagnosis and prognosis for better data management in energy storage systems

Catalyzing deep decarbonization with federated battery diagnosis and prognosis for better data management in energy storage systems

International cooperation for the decarbonization of energy-intensive industries: unlocking the full potential

ABSTRACT This article investigates the state of global governance for the deep decarbonization of energy-intensive industries (EIIs) and identifies key options for mobilizing the so far underexploited potential of this global governance. Focusing on four main EIIs (i.e. iron and steel, cement and concrete, chemicals, and aluminium) the analysis is advanced in three steps. First, we establish the theoretical potential of international institutions to address the main barriers to EII decarbonization focusing on six main governance functions. Second, the article provides an up-to-date account of the global governance landscape for EII decarbonization and the contribution it has made to addressing the main barriers. This assessment also identifies major gaps and underexploited potentials of global governance. Finally, we systematically appraise key options for advancing global governance for EII decarbonization based on clear assessment criteria (membership, institutional capacity, legitimacy, feasibility). The major findings are that: (a) global governance has advanced significantly in the 2020s across all governance functions, in particular through the emergence of several initiatives focused on industrial decarbonization, including the recent Climate Club; (b) key priorities for advancing global EII decarbonization concern rules for collective action, means of implementation, landscape orchestration/coordination, and a more equal coverage of different sub-sectors and regions. We argue that the main barrier to addressing these priorities is rooted in (geo)politics rather than a lack of suitable institutions. Consequently, the global governance for EII decarbonization may best be advanced through incrementally developing existing rather than creating major new institutions.

Early Opportunities for Onshore and Offshore CCUS Deployment in the Chinese Cement Industry

The promotion of deep decarbonization in the cement industry is crucial for mitigating global climate change, a key component of which is carbon capture, utilization, and storage (CCUS) technology. Despite its importance, there is a lack of empirical assessments of early opportunities for CCUS implementation in the cement sector. In this study, a comprehensive onshore and offshore source–sink matching optimization assessment framework for CCUS retrofitting in the cement industry, called the SSM-Cement framework, is proposed. The framework comprises four main modules: the cement plant suitability screening module, the storage site assessment module, the source–sink matching optimization model module, and the economic assessment module. By applying this framework to China, 919 candidates are initially screened from 1132 existing cement plants. Further, 603 CCUS-ready cement plants are identified, and are found to achieve a cumulative emission reduction of 18.5 Gt CO2 from 2030 to 2060 by meeting the CCUS feasibility conditions for constructing both onshore and offshore CO2 transportation routes. The levelized cost of cement (LCOC) is found to range from 30 to 96 (mean 73) USD·(t cement)−1, while the levelized carbon avoidance cost (LCAC) ranges from −5 to 140 (mean 88) USD·(t CO2)−1. The northeastern and northwestern regions of China are considered priority areas for CCUS implementation, with the LCAC concentrated in the range of 35 to 70 USD·(t CO2)−1. In addition to onshore storage of 15.8 Gt CO2 from 2030 to 2060, offshore storage would contribute 2.7 Gt of decarbonization for coastal cement plants, with comparable LCACs around 90 USD·(t CO2)−1.

The AFOLU sector’s role in national decarbonization: a comparative analysis of low-GHG development pathways in Brazil, India and Indonesia

ABSTRACT This paper analyses the role that AFOLU (agriculture, forest and other land use) plays in national deep decarbonization scenarios in Brazil, India and Indonesia between 2020 and 2050. It finds that the LULUCF (land use, land use change and forestry) subsector is important for medium-term mitigation (2020–2030) while continuing to contribute to mitigation over the long-term (2030–2050) in the three countries. Mitigation actions in LULUCF include drastically reducing deforestation (Brazil, Indonesia) and peat degradation (Indonesia), re-/afforestation (all), increased sequestration in standing forests (Brazil, Indonesia) and increasing soil carbon in agricultural lands (India). AFOLU further contributes to mitigation in Brazil and Indonesia by producing biomass feedstock for bioenergy. No country significantly reduces N2O and CH4 emissions from either agriculture or via demand-side actions on diets, due to trade-offs with food security, rural livelihoods and economic growth (although all countries reduce the GHG intensity of agricultural products). Furthermore, the paper analyses national policies to manoeuvre co-benefits and trade-offs between mitigation and other sustainable development goals (SDGs), including no poverty (1); zero hunger (2); decent work and economic growth (8); climate action, including both adaptation and mitigation (13); and life on land (15). Common policy areas were identified, including incentives to land managers for conservation or more environmental agricultural practices; changing regulations of land use to protect ecosystems and/or encourage shifts in agricultural practices; and strengthening enforcement capacity of land protection.

Provincial equity and enhanced health are key drivers for China's 2060 carbon neutrality

China's ambitious 2060 carbon neutrality target necessitates innovative strategies to address the country's status as the world's largest greenhouse gas emitter. This study employs the Global Change Analysis Model to develop a provincial-differentiated control strategy (EQU scenario) that not only aims to meet the national carbon neutrality goal but also enhances population health and environmental equity. The EQU scenario forecasts substantial reductions in average population weighted PM2.5 and O3 concentrations to 7 μg/m3 and 34 ppb, respectively, by 2060. In comparison to a baseline scenario (NEU), the EQU scenario offers more equitable air quality improvements and significant health benefits, potentially preventing 39 thousand PM2.5-related and 10 thousand O3-related premature deaths, with minimal additional cost. The Gini coefficient, indicating CO2 emission distribution inequality among provinces, is projected to decrease from 0.58 in NEU to 0.37 in EQU. This scenario anticipates about one-third of provinces achieving carbon neutrality by 2060, with a harmonized provincial carbon neutrality capacity. The study highlights the critical importance of integrating provincially differentiated controls within national decarbonization strategies, advancing equitable deep decarbonization and reinforcing environmental justice in China.

Mutual reinforcement of land-based carbon dioxide removal and international emissions trading in deep decarbonization scenarios

Carbon dioxide removal (CDR) technologies and international emissions trading are both widely represented in climate change mitigation scenarios, but the interplay among them has not been closely examined. By systematically varying key policy and technology assumptions in a global energy-economic model, we find that CDR and international emissions trading are mutually reinforcing in deep decarbonization scenarios. This occurs because CDR potential is not evenly distributed geographically, allowing trade to unlock this potential, and because trading in a net-zero emissions world requires negative emissions, allowing CDR to enable trade. Since carbon prices change in the opposite direction as the quantity of permits traded and CDR deployed, we find that the total amount spent on emissions trading and the revenue received by CDR producers do not vary strongly with constraints on emissions trading or CDR. However, spending is more efficient and GDP is higher when both CDR and trading are available.

(Invited) Single Crystal Ni-Rich Cathode Materials: Synthesis, Scaleup and Validation

Synthesis of high-performance single crystal Ni-rich NMC, especially when Ni≥0.8, poses a challenge. A conflict exists because as Ni content increase in NMC811, a lower calcination temperature is preferred due to Ni reduction at elevated temperatures, while high temperatures favour single crystal growth.Therefore, molten salt is sometimes employed as the reaction media to promote growth of single crystal NMC811. In general, four approaches for synthesizing of Ni-rich NMC single crystals: molten salt, hydrothermal, direct solid-state synthesis and multi-step lithiation. Molten salt and hydrothermal approaches result in the formation of well-segregated large crystals, but they also increase manufacturing cost. Direct solid-state synthesis, which involves ball milling all precursors together followed by calcination, is a time-saving approach. However, it poses challenge for impurity control due to contamination from milling media, and it can damage the material structure. The calcination of TM(OH)2 precursor with LiOH at very high sintering temperatures forms micron-sized primary particles which, however, still exhibit significantly agglomerated. A post-synthesis milling process is required to break down those NMC811 crystal clusters.This talk will discuss an innovative nanoscale phase separation approach for synthesis of high-performance single crystal NMC811 that is readily adaptable for industry manufacturing. The reaction mechanism of single crystal growth is investigated to understand the synthesis-morphology-performance relationship in growing single crystal NMC811 in the absence of molten salts. The scaled single crystal NMC811 is then further validated in a 2Ah Li-ion pouch cells, demonstrating 1000 stable cycling, confirming the feasibility of this new synthesis approach. This work provides new insights that are broadly applicable for cost-efficient large-scale synthesis of single crystals for different advanced battery technologies to accelerate deep decarbonization process.

(Invited) A Hybrid Electrochemical and Catalytic Compression System for Direct Generation of High-Pressure Hydrogen at 350 Atmospheric Pressure

Hydrogen is becoming the center piece in the global de-carbonatization efforts in multiple industrial sectors. Gaseous hydrogen at high pressures in gas tanks is the most common approach for H2 storage, transportation and hydrogen refueling for fuel cell vehicles. Gaseous hydrogen at high pressures is also heavily used in the Haber process for ammonia production and hydro-cracking of heavy petroleum. In the long term, low-cost high pressure H2 will also play a critical role in the future long-duration grid storage for deep decarbonization and improved resilience.In this talk, I will share some recent development on a hybrid electrochemical/catalytic approach for direct generation of high-pressure H2 in collaboration with Pacific Northwest National Laboratory (PNNL). The hybrid system oxidizes water to oxygen at the anode, reduces V3+ to V2+ at the cathode, and stores proton in the catholyte during the “electrochemical charging” step. We demonstrated that the charged catholyte is then capable of generating H2 at >350 bar in the subsequent “catalytic discharging” step without any additional energy input. This concept leverages the electrochemical Nernst potential difference between the redox couple (V2+/3+) and the hydrogen evolution reaction and delivers a unique system that is capable of generating H2 at demand and at high pressure without any mechanical or electrochemical compression. We estimate a cost of <$0.19/kg-H2 for compression, representing >80% of the cost reduction compared to the traditional multi-stage compressor approach.

(Invited) Exploring Catalyst Characteristics through in-Situ Studies of Solid-Liquid Interfaces

Scientists are driven by the urgent need to combat global climate warming and environmental pollution, leading to the development of highly efficient and eco-friendly energy technologies. Hydrogen, a key player in achieving deep decarbonization for net-zero carbon dioxide emissions by 2050, is currently produced through the widely used steam-methane reforming process, which, unfortunately, relies on fossil fuels and generates significant CO2 as a byproduct. This process is environmentally unfriendly and unsustainable, emphasizing the necessity for green hydrogen production. The sun emerges as a clean, renewable, and abundant energy source, offering an ideal solution to the environmental challenges posed by fossil fuels. Hydrogen, an excellent fuel for fuel cell applications, must be generated from renewable and carbon-free resources, particularly utilizing natural energies like sunlight. Enter the photoelectrochemical cell, a promising method for hydrogen generation. This cell comprises semiconductor photoelectrodes capable of harnessing light energy to directly split water. Photocatalysis, leveraging light energy for chemical reactions, holds the key to large-scale solar energy storage, overcoming challenges such as cost and efficiency. Despite over four decades of dedicated research, photocatalysis still faces hurdles in terms of cost and efficiency, hindering progress in this crucial field. A major obstacle lies in the limited understanding of the mechanisms underlying its low performance. To address this challenge, I will overview several experimental studies that have successfully unveiled catalytic reactions at solid/liquid interfaces in real time, focusing on the electrochemical interface of photocatalysis and electrocatalysis. These studies utilize operando X-ray characterization, providing unique insights into the actual reaction mechanisms.

Dynamic determinants of optimal global climate policy

We explore the impact of dynamic characteristics of greenhouse-gas emitting systems, such as inertia, induced innovation, and path-dependency, on optimal responses to climate change. Our compact and analytically tractable model, applied with stylized damage assumptions to derive optimal pathways, highlights how simple dynamic parameters affect responses including the optimal current effort and the cost of delay. The conventional cost-benefit result (i.e., an optimal policy with rising marginal costs that reflects discounted climate damages) arises only as a special case in which the dynamic characteristics of emitting systems are assumed to be insignificant. Our analysis highlights and distinguishes from the (often implicit) assumption in many cost-benefit models, which neglect inertia and assume exogenous technology progress. This tends to defer action. More generally, our model yields useful policy insights for the transition to deep decarbonization, showing that enhanced early action may greatly reduce both damages and abatement costs in the long run.