Deep Decarbonization Pathways Research Articles

Impact of Glasgow Climate Pact and Updated Nationally Determined Contribution on Mercury Mitigation Abiding by the Minamata Convention in India.

India is one of the largest emitters of atmospheric anthropogenic mercury (Hg) and the third-largest emitter of greenhouse gases in the world. In the past decade, India has been committed to the Minamata Convention (2017) in addition to the Paris Climate Change Agreement (2015) and the Glasgow Pact (2021). More than 70% to 80% of India's mercury and carbon dioxide emissions occur because of anthropogenic activities from coal usage. This study explores nine policy scenarios, the nationally determined contribution (NDC) scenario, and two deep decarbonization pathways (DDP) with and without mercury control technologies in the energy and carbon-intensive sectors using a bottom-up, techno-economic model, AIM/Enduse India. It is estimated that NDC scenarios reduce mercury emissions by 4%-10% by 2070; while coal intensive (DDP-CCS) pathways and focus on renewables (DDP-R) reduce emissions by 10%-54% and 15%-59%, respectively. Increase in the renewables share (power sector) can result in a significant reduction in the costs of additional pollution-abating technologies in the DDP-R scenario when compared with the coal intensive DDP-CCS scenario. However, the industry sector, especially iron and steel and metal production, will require stringent policies to encourage installation of pollution-abating technologies to mitigate mercury emissions under all the scenarios.

Transformative disruptiveness or transition? Revealing digitalization and deep decarbonization pathways in the Italian smart electricity meter roll-out

Energy infrastructure digitalization is proposed as key for a just deep decarbonization. However, an integrative literature review reveals the lack of a more profound exploration on normative considerations tied to world perspectives and values, as levers of a lasting transformation in the context of socio-technical transitions. Thus, the paper employs qualitative research methods to investigate how energy infrastructure digitalization contributes to transformative disruption, along which deliberated deep decarbonization pathways, using Italy's smart electricity meter roll-out as a case study. While the roll-out represents a substantial effort in introducing digital devices into the residential sector, concerns persist about its effectiveness, also due to potential societal disruptions. Through in-depth interviews with experts (N = 17) and citizens (N = 23) and content-oriented analysis, the research unveils evolving pathways between ever more disengaged two grand narratives and value systems: energy as a commodity and energy as a common good. The first opts for technological progress, changing consumer behavior, to address energy poverty and social justice, building on market-based instruments and new business models. Conversely, the second harbors skepticism towards technological fixes, emphasizes energy sufficiency and questions energy opulence, linked to environmental justice considerations, and calling for corrective principles by regulatory means. Finally, the paper presents a conceptual framework to re-shape deep deliberative transformation, highlighting the importance of re-connecting to defined values, re-generating actionable knowledge, restructuring institutions in societal experimentation, and recognizing underlying processes such as justice claims. It argues for further research into discourse coalitions capitalizing on defined narratives, to better understand their impact on policy-making processes.

Repurposing, co-processing and greenhouse gas mitigation – The Brazilian refining sector under deep decarbonization scenarios: A case study using integrated assessment modeling

Deep decarbonization scenarios indicate a decline in fossil oil usage in the coming decades, meaning that oil refineries must adapt. This work evaluates the refining sector in deep decarbonization pathways using Brazil as a case study. BLUES – a national integrated assessment model – is employed to investigate the evolution of the sector in mitigation scenarios until 2050. The production of feedstocks for the petrochemical industry, of fuels for the aviation and maritime sectors, and biomass co-processing are analyzed. These strategies may bring resilience to the sector. The potential for avoiding emissions in refineries' operations is also explored. Findings show that the refining sector operates at 70% and 74% of its nameplate capacity in decarbonization scenarios. These results are used as the starting point for a detailed analysis of Brazilian refineries. Results show that the employment of refineries’ assets for purposes aligned with decarbonization targets, along with emissions mitigation in the sector, reduces risks of carbon lock-in and of asset stranding. To our knowledge, this is the first study that evaluates emissions mitigation in the refining sector and also uses an integrated assessment model to investigate oil refining repurposing and co-processing options in the context of decarbonization.

Deep decarbonisation pathways of the energy system in times of unprecedented uncertainty in the energy sector

Unprecedented investments in clean energy technology are required for a net-zero carbon energy system before temperatures breach the Paris Agreement goals. By performing a Monte-Carlo Analysis with the detailed ETSAP-TIAM Integrated Assessment Model and by generating 4000 scenarios of the world's energy system, climate and economy, we find that the uncertainty surrounding technology costs, resource potentials, climate sensitivity and the level of decoupling between energy demands and economic growth influence the efficiency of climate policies and accentuate investment risks in clean energy technologies. Contrary to other studies relying on exploring the uncertainty space via model intercomparison, we find that the CO2 emissions and CO2 prices vary convexly and nonlinearly with the discount rate and climate sensitivity over time. Accounting for this uncertainty is important for designing climate policies and carbon prices to accelerate the transition. In 70% of the scenarios, a 1.5 °C temperature overshoot was within this decade, calling for immediate policy action. Delaying this action by ten years may result in 2 °C mitigation costs being similar to those required to reach the 1.5 °C target if started today, with an immediate peak in emissions, a larger uncertainty in the medium-term horizon and a higher effort for net-zero emissions.

Modeling the energy mix and economic costs of deep decarbonization scenarios in a CGE framework

This paper investigates the energy mix and welfare implication of deep decarbonization pathways with net negative emission technologies for North America and globally to 2050 in a computable general equilibrium (CGE) framework. The analysis uses an integrated assessment model (IAM), the Global Change Assessment Model (GCAM), to develop three bounding emission scenarios: i) A business as usual pathway (BAU), ii) A pathway bounded by the Nationally Determined Contributions and attaining a 2°C end of century target (NDC-2°C), and iii) An increasing ambition pathway that attains a 1.5°C end of century target (NDC-1.5°C). The energy mix and economic impacts of these emissions pathways are then evaluated using Environment Canada's Multi-Sector, Multi-Regional (EC-MSMR) CGE model. When bioenergy with carbon capture and storage (BECCS) and direct air capture (DAC) are available, they play an important role in achieving emission reductions. Allowing the use of DAC preserves an additional 5% to 20% of the share of fossil fuels in North America. Including DAC in deep decarbonization pathways lowers the welfare loss by up to ∼1% globally compared to those without DAC in 2050. This finding is robust to both the estimated price of and constraints on DAC deployment. Increasing the potential for fuel switching in the CGE model further reduces the welfare effects for deep decarbonization.

Passenger transport decarbonization in emerging economies: policy lessons from modelling long-term deep decarbonization pathways

ABSTRACT Reaching the goal of the Paris Agreement will not be possible without a deep decarbonization of the passenger transport sector. In emerging economies experiencing rapid economic growth and social transformations, and large-scale development of urban areas and associated infrastructure, opportunities and challenges exist when considering a broader set of mitigation options. In this paper, we apply the Deep Decarbonization Pathways (DDP) approach to develop and report scenarios on the passenger transport sector in Brazil, India, Indonesia, and South Africa. This approach supports an increase in the sectoral ambition of covering all drivers of change in transport mobility and facilitating collective comparison and policy discussions on the barriers and enablers of transitions. The scenario analysis illustrates that all four countries can achieve reductions in emissions per passenger kilometres of 59% and up to 92% by 2050 while meeting growing mobility needs. Lastly, the analysis identifies short-term policy needed to address barriers and promote enablers. Key policy insights The scenarios produced in this paper provide targets and guidance, up to 2050, on required ambition in this sector over coming decades. While current national policies are often limited to introducing low-carbon vehicles and fuels, these pathways suggest the important role of a wide spectrum of mitigation options, including systemic measures related to demand-side options. These scenarios suggest that targeted land-use, social, and urban policies could reduce distances between activities, the costs of mobility and time, thereby improving quality of life and supporting the shift to non-motorized and public transport. They highlight a lack of policies to improve the quality of public transport in terms of time and comfort, not only in terms of cost, to avoid a car dependency model with its externalities. Long-term pathways can help support the development of policy-relevant dialogues about barriers and enablers for the transition, thereby supporting the reinforcement of short-term actions and goals.

On the Adoption of Rooftop Photovoltaics Integrated with Electric Vehicles toward Sustainable Bangkok City, Thailand

Realizing urban energy systems with net-zero CO2 emissions by 2050 is a major goal of global societies in building sustainable and livable cities. Developing cities hold a key to meeting this goal, as they will expand rapidly in the next decades with increasing energy demand, potentially associated with rising CO2 emissions and air pollution if fossil fuels continue to be utilized. Therefore, identifying equitable, cost-effective, and deep decarbonization pathways for developing cities is essential. Here, we analyzed Bangkok City, Thailand, using the System Advisor Model (SAM) for techno-economic analysis to evaluate the decarbonization potential of rooftop photovoltaics (PV) integrated with electric vehicles (EVs) as batteries on a city scale. The analyses took into consideration hourly local weather conditions, electricity demand, electricity tariffs, feed-in-tariffs, degradation, declining costs of PV and EV, etc., specific to Bangkok. As the prices of PV and EVs decrease over the next several decades, the “PV + EV” system may provide a basis for new urban power infrastructure with high energy efficiency, low energy cost, and large CO2 emission reduction. The results show that the “PV + EV” scenario in 2030 has the highest CO2 emission reduction of 73% from electricity and vehicle usage, supplying 71% of the electricity demand of the city. The “PV + EV” system may reduce energy costs by 59% with estimated technology costs in 2030. Most of the energy generated from rooftop PV is consumed owing to large EV battery capacities, which can contribute to the rapid decarbonization of Bangkok City by 2050.

Equitable, affordable, and deep decarbonization pathways for low-latitude developing cities by rooftop photovoltaics integrated with electric vehicles

Identifying effective development and rapid decarbonization pathways for developing countries are essential to realize sustainable and equitable future global societies. Increasingly cheaper solar photovoltaics (PV) on rooftop is one of the keys to build such urban power systems, integrated with battery and/or electric vehicles (EVs). Here, we explore potentials of rooftop PV combined with EVs for urban decarbonization of Jakarta, Indonesia using techno-economic analysis, in comparison to Kyoto City, Japan. We found that rooftop PV system is already cost-competitive in Jakarta in 2019 but with cost-saving of only 3–4 %. However, “PV only” system becomes increasingly cost-effective (cost-saving of 8–15 %) by 2030. Further, by combining with EV as battery, rooftop PV system can supply affordable CO2 free electricity to 75–76 % of Jakarta’s electricity demands with 33–34 % potential cost saving and 76–77 % of CO2 emission reduction from electricity generation and driving, which also greatly improve air quality in the city. Notably, Jakarta has no space heating demand through a year but persistent cooling demand positively correlating with PV generation, which increases decarbonization potentials of “PV + EV” system by 9 % than that of Kyoto. Also, rooftop PV generation in Jakarta is less affected by rooftop slope angle and orientation than those of Kyoto owing to year-round higher “sun altitude angle” in Jakarta. As the Indonesia government aims to reach the level of developed country by 2045, rooftop “PV + EV” system can be a no-regret strategy for the rapid growth and decarbonization for Indonesia, and so for other low-latitude developing cities.

Modelling least-cost technology pathways to decarbonise the New South Wales energy system by 2050

Deep decarbonisation pathways can enable the state of New South Wales (NSW) in Australia to reach a net-zero emissions reduction goal and contribute to global mitigation efforts to limit temperature rise to 1.5 °C by mid-century. This paper explores minimum cost solutions for achieving the corresponding greenhouse gas (GHG) emissions reduction target for NSW, using an Australian implementation of the TIMES (The Integrated MARKAL-EFOM System) energy system modelling framework. This paper investigated possible decarbonisation pathways and available technology options to reach the target. It includes both a higher emissions reference case scenario and a scenario implementing the NSW state government's target of net-zero emissions by 2050 under the NSW Climate Change Policy Framework, consistent with the international Paris Agreement on climate change, with available and viable well-developed technologies. The findings show that the NSW energy system can continue its shift from fossil fuels to renewables like solar, wind, and hydro and can entirely phase out coal- and gas-fired electricity generation by 2050. The deployment of zero-emissions technologies along with policy supports are crucial to achieving deep decarbonisation of the NSW economy by 2050. In addition, electrification and energy efficiency improvements play a significant role in the end-use sector's energy consumption reduction in the coming decades. This paper shows that the electricity sector is the dominant contributor to emission reductions up to the year 2030, while transport, buildings, and industry sectors are set to decarbonise later in the projection period (2030–2050) along this least-cost trajectory. However, the NSW government's aspirational target of net-zero emissions by 2050 can be achieved by 2039 by offsetting negative emissions.

Modelling the integrated achievement of clean cooking access and climate mitigation goals: An energy systems optimization approach

The United Nations Sustainable Development Goal target 7.1, to provide universal access to affordable, reliable and modern energy by 2030, must be achieved in the context of rapid reductions in global greenhouse gas (GHG) emissions. While replacing solid cooking fuels with liquid petroleum gas (LPG) opens questions about the compatibility of energy access and climate mitigation objectives, the environmental impact of 2.6 billion people continuing to rely on solid fuel for cooking and heating is significant. However, models used to map deep decarbonization pathways typically do not feature a granular pathway for universal clean cooking access, which limits the representation of these two interconnected transitions, mitigating climate change and achieving universal energy access. Here, we present a novel methodology for representing residential cooking pathways within the TIMES energy systems optimization model (ESOM) framework. The methodology is demonstrated using India as a proof-of-concept case study, where scenario analysis explores solutions that reach universal clean cooking access in the context of GHG emissions reductions. The model presented here is published and publicly available to access.

Equitable deep decarbonization: A framework to facilitate energy justice-based multidisciplinary modeling

Persistent, systemic harms have resulted in inequalities in wealth distribution, energy insecurity, infrastructure reliability, heat island exposure, and preexisting health conditions, all of which have exacerbated climate change driven damages. Efforts to decarbonize our energy system to address the climate crisis must seize the opportunity to reduce inequality. Doing so requires a multidisciplinary approach to assess the tradeoffs between alternative decarbonization pathways. In this Perspective we introduce an Equitable Deep Decarbonization Framework for mapping the tenets of energy justice to the practice of large-scale deep decarbonization pathways modeling designed to facilitate this multidisciplinary effort. We provide discussion of key considerations for each step of the framework to enable modeling that accounts for adaptation co-benefits associated with systematic climate risks to vulnerable communities.

Technological roadmap towards optimal decarbonization development of China's iron and steel industry

China's iron and steel (IS) industry contributes approximately 16 % of the nation's total CO2 emissions. This study evaluates the environmental impact of each step in the production process based on the life cycle assessment method. It then explores potential deep decarbonisation pathways, developing an integrated dynamic model to meet the carbon neutrality target. The results reveal three primary findings. (1) In 2020, the blast furnace-basic oxygen furnace contributed significantly to the global warming potential −1.77 E−8 kg CO2 equivalents per year (eq/yr) higher than the electric arc furnace—and the blast furnace process makes the largest contribution in ironmaking (8.9E−9 kg CO2 eq/yr). (2) Converter negative energy steelmaking technology has the highest energy savings at 39.07 million tons of coal equivalent (Mtce) and an emissions-reduction potential of 72.01 Mt. Its mitigation cost is 69 CNY/t CO2, followed by thick-layer sintering (30.21 Mtce, 61.21 Mt. and 70 CNY/t CO2) and the application of dry vacuum system for molten steel degassing circulation (26.17 Mtce, 56.03 Mt. and 102 CNY/t CO2). (3) Technological improvement could significantly impact the IS industry, reducing CO2 emissions through production structure improvement, technological development and ultra-low emissions technology, from 789 Mt. in a business-as-usual scenario to 516 Mt., 261 Mt. and 157 Mt. in 2060, respectively.

Survey of Simulation Tools to Assess Techno-Economic Benefits of Smart Grid Technology in Integrated T&D Systems

In order to succeed in the energy transition, the power system must become more flexible in order to enable the economical hosting of more intermittent distributed energy resources (DER) and smart grid technologies. New technical solutions, generally based on the connection of various components coupled to the power system via smart power electronic converters or through ICT, can help to take up these challenges. Such innovations (e.g., decarbonization technologies and smart grids) may reduce the costs of future power systems and the environmental footprint. In this regard, the techno-economic assessment of smart grid technologies is a matter of interest, especially in the urge to develop more credible options for deep decarbonization pathways over the long term. This work presents a literature survey of existing simulation tools to assess the techno-economic benefits of smart grid technologies in integrated T&D systems. We include the state-of-the-art tools and categorize them in their multiple aspects, cover smart grid technology, approach methods, and research topics, and include (or complete) the analysis with other dimensions (smart-grid related) of key interest for future power systems analysis such as environmental considerations, techno-economic aspects (social welfare), spatial scope, time resolution (granularity), and temporal scope, among others. We surveyed more than 40 publications, and 36 approaches were identified for the analysis of integrated T&D systems. As a relatively new research area, there are various promising candidates to properly simulate integrated T&D systems. Nevertheless, there is not yet a consensus on a specific framework that should be adopted by researchers in academia and industry. Moreover, as the power system is evolving rapidly towards a smart grid system, novel technologies and flexibility solutions are still under study to be integrated on a large scale. This review aims to offer new criteria for researchers in terms of smart-grid related dimensions and the state-of-the-art trending of simulation tools that holistically evaluate techno-economic aspects of the future power systems in an integrated T&D systems environment. As an imperative research matter for future energy systems, this article seeks to contribute to the discussion of which pathway the scientific community should focus on for a successful shift towards decarbonized energy systems.

Carbon removals from nature restoration are no substitute for steep emission reductions

Carbon removals from nature restoration are no substitute for steep emission reductions

Exploring pathways to deep de-carbonization and the associated environmental impact in China’s ammonia industry

China is the largest producer of synthetic ammonia, accounting for one-third of the world’s total production. Ammonia is mainly used to produce fertilizer and is also considered as a potential fuel and new energy carrier for the future. Concomitantly, the ammonia industry is the largest energy consumer and CO2 emitter in China’s chemical industry. In this study, we developed the MESSAGEix-ammonia model with detailed process descriptions to evaluate the energy-saving and emission reduction potential that can be generated by energy efficiency (EE) improvement, as well as the transition path and emission characteristics in the context of deep emission reduction. Results show that the cost-effective EE measures implemented under the EE scenario could reduce fresh water, fuel coal, and electricity consumptions by 7%, 25%, and 16%, as well as reduce CO2, PM2.5, SO2, and NOx emissions by 33%, 24%, 24%, and 24%, respectively, by 2060. Regarding the exploration of the deep de-carbonization path, carbon capture and storage technology (CCS) increases the CO2 reduction potential to 62%, but it requires additional electricity. Meanwhile, electrolysis technology not only saves additional fresh water and fuel coal, but also reduces CO2, PM2.5, SO2, and NOx by 80%, 84%, 86%, and 84%, respectively. Furthermore, the integration of electrolysis technology and CCS can bring 98% carbon emission reduction, which is close to net-zero emission status. With the development of renewable electricity, sufficient, clean, and affordable electricity can be provided for electrolysis devices. Our recommendation to policy makers is that electrolysis of water to produce ammonia using renewable electricity is a feasible deep de-carbonization pathway.

Technology, technology, technology: An integrated assessment of deep decarbonization pathways for the Canadian oil sands

As a party to the Paris Agreement, Canada has an ambitious climate target of net-zero emissions by 2050. The country also holds the world's third largest oil reserves in the Alberta oil sands. Given increasing emissions from the oil sands sector, achieving Canada's net-zero target requires significant oil sands decarbonization. If, while phasing out fossil fuels, there is still a demand for Canadian oil sands, then the decarbonization of the resource production process becomes crucial. In this study, we use an enhanced version of the Global Change Analysis Model (GCAM) with a detailed unconventional oil sector for Canada, including mining and in situ resources. We ask, what is the future of the oil sands sector in deeply decarbonized global and Canadian economies? We address this question under four mitigation scenarios with varying global net-zero GHG emissions constraints, three additional representative lower carbon extraction technologies available for the oil sands sector, as well as global direct air capture (DAC) deployment. We find that lower carbon technology deployment allows a 20%–44% increase in oil sands production by 2050 for scenarios with net-zero GHG emissions in 2100 or 2075. DAC helps maintain oil sands production in the most ambitious global decarbonization scenario (net-zero GHG by 2050), without which low international oil demand makes Canadian oil sands production uncompetitive. Canadian oil sands production thus depends highly on the availability of lower carbon extraction technologies and international oil demand, which to a certain extent relies on the availability and global deployment of negative emissions technologies.

From Low- to Net-Zero Carbon Cities: The Next Global Agenda

This article provides a systematic review of the literature on net-zero carbon cities, their objectives and key features, current efforts, and performance. We discuss how net-zero differs from low-carbon cities, how different visions of a net-zero carbon city relate to urban greenhouse gas accounting, deep decarbonization pathways and their application to cities and urban infrastructure systems, net-zero carbon cities in theory versus practice, lessons learned from net-zero carbon city plans and implementation, and opportunities and challenges in transitioning toward net-zero carbon cities across both sectors and various spatial fabrics within cities. We conclude that it is possible for cities to get to or near net-zero carbon, but this requires systemictransformation. Crucially, a city cannot achieve net-zero by focusing only on reducing emissions within its administrative boundaries. Cities must decarbonize key transboundary supply chains and use urban and regional landscapes to sequester carbon from the atmosphere. Because of carbon lock-in, and the complex interplay between urban infrastructure and behavior, strategic sequencing of mitigation action is essential for cities to achieve net-zero.

Deep decarbonization impacts on electric load shapes and peak demand

The existing literature has shown the important role of electrification in deep decarbonization pathways, increasing electricity demand as end uses decarbonize. However, studies have not focused on the effects of electrification on aggregate load shapes and peak demand, which influence power sector investments, operations, and costs. Here we investigate potential impacts of deep decarbonization on regional load shapes and peak electricity demand using a detailed end-use simulation model linked to an electric sector capacity planning model. Scenario results suggest that electrification may contribute to peak load increases and shifts from summer peaks to winter ones, especially in cooler climates due to space heating electrification. We illustrate how net-zero emissions goals can amplify electrification and may entail 120%–165% increases in electric system capacity by 2050 due to a combination of electrification and high renewables deployment. The intensity and frequency of peak demand can be limited by load flexibility (providing incentives for electric end uses to shift away from periods of high demand, e.g. through deferrable electric vehicle charging), alternate end-use technology configurations (deploying higher efficiency end-use equipment to lower electricity consumption during peaks or using dual-fuel systems such as heat pumps paired with gas furnaces), and carbon removal (displacing higher marginal abatement cost electrification while reaching an equivalent emissions cap). This analysis is a first step toward systematically exploring load curves for electrified and decarbonized energy systems, and the results highlight opportunities for future research to better understand load shape impacts and flexibility.

Demystifying natural gas distribution grid decommissioning: An open-source approach to local deep decarbonization of urban neighborhoods

In this paper, deep decarbonization in an urban neighborhood in Vienna, Austria is proposed focusing on decommissioning of the gas distribution grid for heat supply rather than trying to feed in “green” gas in the future. The core objective is to demonstrate that alternative network infrastructures and energy technologies ensure not only an adequate but also an even superior provision of local heat energy services. Two different deep decarbonization pathways are studied, namely, electrification of almost all energy services and expansion of the district heating network. In addition, future district cooling service supply is considered. The method applied couples and extends two open-source models offering a complete analysis toolkit covering a high spatial and temporal resolution. The results show that deep decarbonization of local multiple-energy carrier systems is possible, without being dependent on the existing distribution grid of natural gas. Possible stranded assets (also at the gas end-user level) must not play a decisive role, especially since the trade-off analyses in this work show that alternative scenarios of lower/zero-emission energy service provision are even more economical in the longer term since the CO2 price is expected to increase in the next decades. Future work may focus, among others, on the energy generation technology mix feeding into the district heating grid, the local mobility service needs, and a higher granularity to improve the assessment of the on-site (building-integrated) renewable generation potential associated with the emergence of energy community concepts.

A deep decarbonization pathway for Peru's rainforest

Peru holds an important portion of the South American rainforest. An average deforestation rate of 145,000 ha a year makes it the largest source of GHG emissions. Based on the drivers of deforestation, this paper proposes a deep decarbonization pathway (DDP) through the year 2050 with the purpose of taking the country closer to achieving the net-zero emissions goal. The impacts of the pathway are estimated using POLYSYS-Peru, an equilibrium displacement model for the integrated analysis of land-use changes and agriculture. The results indicate that the proposed DDP pathway, by preventing the deforestation of 4 million hectares of primary forests, would reduce GHG emissions by an accumulated 1778 Mt CO2 eq. compared to the business as usual scenario, and 497 Mt CO2 eq. more than the Nationally Determined Contributions.