Low-carbon Systems Research Articles

A Study on the Evolution Laws of Entrainment Performances Using Different Mixer Structures of Ejectors.

Being the core of the ejector refrigeration system, an ejector with a suitable mixer, conical-cylindrical or cylindrical, is key to high-energy-efficiency and low-carbon systems. To promote the scientific selection of mixers for ejectors based on the theoretical models that have been validated by experiments, the evolution laws of the entrainment ratios in the two types of ejectors are studied under various operating conditions. Furthermore, the influence mechanism of the mixer structures on the entrainment ratio of the ejector is elucidated by comparing the distribution characteristics of the entropy generation rate, pressure lift proportion, and entropy generation rate of the per-unit pressure lift in the two types of ejectors. The efficiencies of the conical-cylindrical mixer ejector and cylindrical mixer ejector exist a crossover, which makes the entrainment ratio of the conical-cylindrical mixer ejector smaller under small compression ratios but larger under large compression ratios. By changing the cylindrical mixer into a conical one, on the one hand, more pressure rise will be distributed in the diffuser, which helps to reduce the entropy increase rate in the pressurization process; on the other hand, the wall impulse effect of the conical mixer will lead to an increase in entropy generation rate of per-unit pressure lift, resulting in a growing entropy generation rate of boosting. The dominant roles are not the same with changing compression ratios, which leads to different relationships of entrainment ratio between the cylindrical and conical mixer ejectors.

Watt sense of community? A human geography agenda on energy communities

Energy communities can potentially advance just transitions towards low-carbon systems by devolving energy production and consumption to local scales. During vibrant debates on evolving energy geographies for more than a decade, human geographers have engaged with conceptualization and emergent models of energy communities in generative ways. We argue for a research agenda where these understandings of space, place and scale enhance research on energy communities. Three points hold particular importance and relevance for this agenda: (a) Pluralising understandings of energy communities, (b) Spatializing perspectives on the potential of energy communities to advance just transitions, and (c) Contextually situating technological-energy innovation strategies.

Techno-Economic and CO2 Emissions Analysis of the Molten Carbonate Fuel Cell Integration in a DRI Production Plant for the Decarbonization of the Steel Industry

Developing low-carbon systems for the steel industry is increasingly considered necessary for contributing to the targets of CO2 emission reduction requested by modern environmental policies. This work focuses on a process for decarbonizing primary steel production by integrating an MCFC system in a DRI production plant based on the Energiron ZR process configuration. An MCFC system can be used to remove CO2 from the flue gases while producing electricity and reducing the net electric consumption of the DRI plant. The reference scenario, the carbon capture case, and an additional hydrogen-based H-DRI system using high temperature electrolysis are simulated using Aspen Plus to evaluate and compare their energy and environmental performance. The results show that even considering the additional power consumption of the complete carbon capture and separation system, the overall electrical consumption of the carbon capture case is decreased by 78 % and the direct CO2 emissions by up to 95 %. Furthermore, reduced electricity consumption reduces scope 2 emissions, increasing the sustainability of the process in the steel industry. On the other hand, the H-DRI case decreases primary energy consumption by 24 % but significantly increase electricity requirement; thus, it represents a better future solution when cheap low-CO2 electricity is available. The plant configurations are compared economically by retrieving investment and operational costs from the open literature to estimate the levelized cost of DRI and the cost of CO2 avoided. The results show that installing the MCFC and the anode purification system increases the investment costs by 38 % compared to a conventional plant. However, the lower electricity consumption and carbon tax expenditure lead to a comparable final DRI product cost. Contrarily, due to the electrolyzer high investment and operational costs, the additional marginal DRI cost of the H-DRI case is 31 % higher. Finally, the sensitivity analysis on the main variable costs shows that, independently from the electricity and natural gas price, the carbon capture case is economically competitive to the reference scenario, considering a carbon tax of 60 €/tCO2 or higher. At the same time, the H-DRI solution requires low electricity prices to be competitive. In conclusion, even if, in the long term, the objective is to completely replace the use of fossil fuels with renewable energy, in the short term, the implementation of MCFC in the DRI plant can significantly reduce the environmental impact of primary steel production without significant economic penalization.

The Threefold Role of the University in Fostering the Energy Transition: The Case of Bologna and Its Cesena Campus

As acceleration toward the transition to a carbon-neutral energy production becomes an urgent imperative, universities are called to play a multifaceted role: to produce knowledge and cutting-edge research for the pursuit of energy transition; to transform infrastructures to promote circular economy practices and a more sustainable use of their building stock; and to promote energy citizenship through formal and informal education. The authors aim to move from these considerations to critically present some actions and programs in education, research, and campus operations in which the University of Bologna is engaged. The first part presents an overview of the role of universities in this transition, with a focus on the UI GreenMetric international standard for assessing the different dimensions of sustainability. In the core section, an empirical focus is provided on Bologna and its Cesena campus through three directions: the University’s multicampus sustainable strategy (campus operations), the relevant research–action projects on energy justice and the energy transition (research), and the EN-ACTION project to foster energy citizenship and behavioral change in students and citizens (education). This study concludes that the comprehensive approach of the University of Bologna in integrating sustainability into its operations, education, and research while fostering student engagement in energy citizenship, provides a replicable model for other institutions. It highlights the need for consistent and ongoing support to ensure the long-term impact and effectiveness of sustainability initiatives. The integration of social components and engagement with civil society is crucial for fostering a collective behavioral shift toward low-carbon systems, which can be further supported by interdisciplinary and transdisciplinary research approaches.

Energy hub management for integrated energy systems: A multi-objective optimization control strategy based on distributed output and energy conversion characteristics

To improve the comprehensive utilization efficiency of energy, a multi-objective optimization control strategy applied to the energy hub (EH) within the system is proposed to address the electrical and thermal load distribution of the integrated energy system (IES) and the low-carbon economic operation. First, a model of the electrical and thermal energy outputs is established based on the characteristics of the IES network and the multidimensional “load parameter” evolution law. Moreover, a distributed control strategy is proposed that utilizes the information interaction between neighboring EHs to accurately share the electrical and thermal loads, which reduces the communication burden of the system while avoiding overloads. Furthermore, to coordinate the optimal operation of the devices within the hub, based on the energy conversion characteristics of the EH, a multi-objective optimization model is proposed that considers low-carbon and economic aspects to realize efficient energy use. Simulation results show that the proposed strategy effectively improves the robustness of the system while realizing proportional load distribution and low-carbon economic operation. Under the same load, when focusing on system economics, the operating cost is 2.182/¥ lower than when focusing on low-carbon systems, but carbon emission is 1.6753/kg CO2 higher.

Decarbonizing the cement industry: Findings from coupling prospective life cycle assessment of clinker with integrated assessment model scenarios

In the race to achieve global climate neutrality, carbon intensive industries like the clinker and cement industry are required to decarbonize rapidly. The environmental impacts related to potential transition pathways to low-carbon systems can be evaluated using prospective life cycle assessment (pLCA). This study conducts a pLCA for future global clinker production, integrating long-term transition pathways from the IMAGE integrated assessment model (IAM) to maintain global consistency. It systematically modifies the ecoinvent v3.9.1 database using the Python library premise to create future database versions representing future clinker production embedded in a future economy according to a 3.5°C-baseline, a 2°C-compliant and a 1.5°C-compliant scenario. Our study indicates that climate change impacts of clinker production may decrease from about 1.03 kg CO2-eq/kg clinker in 2020 to 0.94 (3.5°C-baseline), 0.20 (2°C-compliant), and 0.16 (1.5°C-compliant) kg CO2-eq/kg clinker in 2060 for the global average. This corresponds to a 10% (3.5°C-baseline), 81% (2°C-compliant) and 84% (1.5°C-compliant) decrease by 2060 compared to 2020. Under these scenarios, global clinker production alone would require 5%–11% of the remaining end-of-century carbon budget for the 2 °C and 1.5 °C-target, respectively. While the climate change impacts are substantially reduced, our study also indicates that the transition pathways shift the burden towards other impact categories, such as ionizing radiation, ozone depletion, material resources and land use. Developing IAM-compatible scenarios for more product groups helps to increase the coherence of pLCA studies. As this study is based on an IAM heavily reliant on carbon capture and storage and bioenergy, future research should explore the effects of different technology pathways and alternative mitigation strategies.

Distributed energy technologies, decentralizing systems and the future of African cities

Within global debates, decentralization with respect to renewable electricity is positioned as pivotal in overlapping calls for decarbonization, energy access and just transitions. The promise is that technologies that are smaller and distributed will deliver a range of benefits, including enabling infrastructural innovations and expanding sustainable access, notably by empowering local authorities. While shifting to low-carbon systems is imperative, in this paper we call for attention to the complexity, opportunities and risks of commonly celebrated experiments in distributed electricity technologies when applied to African contexts. We draw on the case of Uganda, unpacking a series of four innovative electricity projects currently under way. For each case, we look at the actors involved and the imagined relationship between the projects and the incumbent grid. From these cases, we argue that, in this African context characterized by contested urban governance and fragmented networks, careful attention to supporting urban scale institutional and infrastructural development is necessary, although in many cases bypassed.

Spatially resolved land and grid model of carbon neutrality in China

China has committed to achieve net carbon neutrality by 2060 to combat global climate change, which will require unprecedented deployment of negative emissions technologies, renewable energies (RE), and complementary infrastructure. At terawatt-scale deployment, land use limitations interact with operational and economic features of power systems. To address this, we developed a spatially resolved resource assessment and power systems planning optimization that models a full year of power system operations, sub-provincial RE siting criteria, and transmission connections. Our modeling results show that wind and solar must be expanded to 2,000 to 3,900 GW each, with one plausible pathway leading to 300 GW/yr combined annual additions in 2046 to 2060, a three-fold increase from today. Over 80% of solar and 55% of wind is constructed within 100 km of major load centers when accounting for current policies regarding land use. Large-scale low-carbon systems must balance key trade-offs in land use, RE resource quality, grid integration, and costs. Under more restrictive RE siting policies, at least 740 GW of distributed solar would become economically feasible in regions with high demand, where utility-scale deployment is limited by competition with agricultural land. Effective planning and policy formulation are necessary to achieve China's climate goals.

Carbon peak prediction and emission reduction pathways of China’s low-carbon pilot cities: A case study of Wuxi city in Jiangsu province

Carbon peaking is a research hotspot in China, aiming to reduce the impact of human activities on global climate change, promote the transformation of Low-carbon economy and realize high-quality development. The article takes Wuxi City in China's Jiangsu Province as a pilot low-carbon city to study its carbon emissions characters, then introduces the KAYA model, and sets different scenarios for the influencing factors, further predicts carbon emissions peak in 2019∼2030, and finally proposes the corresponding carbon reduction pathways. Results show that the total of carbon emissions in the study area is still in the upward period of the Kuznets' inverted U-shaped curve, the main factors are population growth rate, economic growth rate, energy consumption intensity and energy structure. If the enhanced carbon reduction scenario is adopted, carbon emissions peak will occur in 2025 or 2026, and the total carbon emissions will be between 120 million tCO2 e to 130 million tCO2 e, and the per capita carbon level will be about 17.5–19.5 tCO2 e. On the future, ten emission reduction pathways for China's low-carbon cities are put forward: strengthening urban spatial planning, upgrading economic structure, developing low-carbon systems in energy, industry, housing, transportation, and agriculture, encouraging low-carbon lifestyles, reforming low-carbon boosting mechanism, and improving low-carbon governance capability.

Extended power to hydrogen operations for enhanced grid flexibility in low carbon systems

Power-to-hydrogen (P2H) systems are increasingly recognized as a promising solution to expedite the integration of Renewable Energy (RE) in various energy sectors. P2H in Hydrogen Consuming Industries (HCIs) can serve hydrogen demands and the much-needed flexibility for power system operations. However, consideration of these systems for significant industrial and power sector use cases requires modelling fidelities for exact operational and economic reflections. P2H operational modelling for flexibility focuses on excess renewable energy evacuation and storage only while often oversimplifying their models by using constant efficiency models or neglecting specific Hydrogen Electrolyzer (HE) overvoltage components. Under variable operations and downstream HCI demands, this can lead to inaccurate assessments, undermining existing flexibility quantum from HCIs. Another prevalent issue with P2H adoption is its costs, which are directly linked with P2H operating ranges. These systems are presently modelled with constrained operations, leading to increased costs and limited ability to provide grid services. Therefore, appropriate modelling of HCIs considering P2H device working characteristics and its inherent flexibilities is essential. It can allow cost-effective operations and the exchange of accurate flexible margins with electrical grids. In this regard, this work proposes a comprehensive extended electro-chemical HE model for HCIs allowing high current density working through the extended operation of P2H. The considered model inherits intrinsic working characteristics of electrolyser operation, i.e., variable current, nonlinear efficiency, and loading, to cater to the hydrogen demands of HCI. The effect of high current density operations is elucidated through device operations under reaction kinetics. The results highlight that the proposed model integrated with the electrical grid provides actual operational costs and flexibility margins. A comparison of various modelling approaches and their effect on adjustable margins demonstrates a considerable difference in P2H loading, working efficiency, operating costs, and adjustable margins with the proposed model.

Reinforcement learning and mixed-integer programming for power plant scheduling in low carbon systems: Comparison and hybridisation

Decarbonisation is driving dramatic growth in renewable power generation. This increases uncertainty in the load to be served by power plants and makes their efficient scheduling, known as the unit commitment (UC) problem, more difficult. UC is solved in practice by mixed-integer programming (MIP) methods; however, there is growing interest in emerging data-driven methods including reinforcement learning (RL). In this paper, we extensively test two MIP (deterministic and stochastic) and two RL (model-free and with lookahead) scheduling methods over a large set of test days and problem sizes, for the first time comparing the state-of-the-art of these two approaches on a level playing field. We find that deterministic and stochastic MIP consistently produce lower-cost UC schedules than RL, exhibiting better reliability and scalability with problem size. Average operating costs of RL are more than 2 times larger than stochastic MIP for a 50-generator test case, while the cost is 13 times larger in the worst instance. However, the key strength of RL is the ability to produce solutions practically instantly, irrespective of problem size. We leverage this advantage to produce various initial solutions for warm starting concurrent stochastic MIP solves. By producing several near-optimal solutions simultaneously and then evaluating them using Monte Carlo methods, the differences between the true cost function and the discrete approximation required to formulate the MIP are exploited. The resulting hybrid technique outperforms both the RL and MIP methods individually, reducing total operating costs by 0.3% on average.

The Effects of System Pressure on Low-Carbon Innovation in Firms: A Case Study from China

With the signing and implementation of the Paris Agreement, low-carbon models have become the general trend for future development. In this context, many countries have successively introduced relevant low-carbon systems within their companies. These systems bring a lot of pressure on traditional manufacturing enterprises. This study deeply explores the influential mechanism of system pressure on the theory of low-carbon innovation of enterprises. It analyzed 328 questionnaires from 107 enterprises in China by using theoretical models based on the upper echelons theory and the dynamic capability theory. The results of the study indicate that (1) system pressure significantly promotes enterprises’ low-carbon innovation; (2) low-carbon dynamic capability mediates between system pressure and enterprise low-carbon innovation; (3) executives’ low-carbon awareness positively moderates the relationship between system pressure and low-carbon dynamic capability; (4) executive low-carbon awareness moderates the intermediary role of low-carbon dynamic capability between system pressure and enterprise low-carbon innovation. Theoretically, this study deepens empirical studies on system pressure and enterprise low-carbon innovation. This study contributes to the application of the upper echelons theory, dynamic ability theory and enterprise behavior theory in the field of low-carbon research. In view of this, this study intends to serve as a reference material for future low-carbon innovation-related research and a guide for the low-carbon management of enterprises.

Energy scheduling of a fuel cell based residential cogeneration system using stochastic dynamic programming

Decarbonization of residential systems is one of the effective ways to achieve the low carbon goal. Due to the advantages of cleanness, efficiency and flexibility, hydrogen fuel cells play a key role in driving the transition to low carbon or carbon-neutral systems. This paper studies the optimal energy scheduling of an off-grid residential cogeneration system composed of a fuel cell, photovoltaic (PV) device, battery, thermal energy storage (TES) and heat pump. With the objective function being fuel cost, the economic optimization scheduling model is developed based on security constraints of devices and power balances of supply and demand. To handle the system uncertainties and achieve global optimality, the stochastic dynamic programming (SDP) algorithm is used, where the random variables are modeled as time-varying Markov chains. Simulation results under the typical winter day scenarios show that the SDP algorithm can achieve efficient scheduling while enhancing the device sustainability. Besides, comparison results with dynamic programming (DP) in scenarios with different uncertainty degrees demonstrate the optimality and robustness of SDP. Additionally, the impact of TES capacity on the system operation is also discussed, which has certain instructive significance for system capacity configuration in terms of economy and sustainability.

Optimal coordination of spinning and standing reserve with energy payback of thermostatically controlled loads

Thermostatic loads are expected to support the transition to low-carbon systems by providing an array of ancillary services. The delivery of energy-intensive services requires the thermostatic appliances to payback the deployed thermal energy via extra power consumption at a later time. This is made available by conventional generators providing contingency reserve. Previous works acknowledged the interplay between secondary response and contingency reserve. However, the structure of the payback period was fixed and did not fully consider the capabilities of generators providing contingency reserve, e.g., modelling only spinning generators while neglecting standing units. This paper introduces a novel methodology that allows to optimally coordinate the energy recovery of thermostatic loads and the allocation of contingency reserve among spinning and standing units. To do so, the commitment times and structures of secondary response and contingency reserve can be optimally chosen depending on system needs and current availabilities at each time step. The model is applied to the Great Britain network, which is connected to the power system in Continental Europe via a high-voltage direct-current link. Results illustrate the techno-economic advantages stemming from the proposed methodology.

Energy Transitions: The Case of Greece with a Special Focus on the Role of the EU ETS

Major energy transitions are associated not only with fundamental transformations of the energy sector but also with multidimensional changes in societies. Existing energy systems are heavily implicated in climate change. This paper investigates from an ecosocialist perspective the prevalent high-carbon energy systems in capitalism and their ongoing transformations, with a special focus on Greece as an EU member. Furthermore, it explores whether the EU ETS, in comparison to renewable energy sources (RES) support schemes, created considerable incentives for effective and socially fair transitions to low-carbon systems. Empirical data reveals the enduring high-carbon composition of gross inland energy consumption in Greece while evidence on gross electricity generation by fuel discloses the limited penetration of RES since 1990. The neoliberal design of ETS at the EU level and its poor workings did not induce investments in low carbon technologies. RES support policies have been more significant. However, both have adverse distributional effects, especially on working people since the latter bear the cost of transition for the most part. Effective and fair low-carbon energy transitions need radical social transformation — an ecosocialist path out of capitalism.

Key drivers, challenges and strategies towards successful low-carbon campus: the case of UiTM Shah Alam campus

PurposeThere is a growing awareness of the dangers of climate change and global warming due to increasing energy consumption and associated greenhouse gas emissions. Campus universities are critical for implementing low-carbon development efficiently, given the large population and socio-economic activities concentrated on campus. This paper aims to explore the existing campus management initiatives and recommends holistic driving elements towards successful low-carbon campus development.Design/methodology/approachThis study’s triangulation of information was supplemented by contributions from 116 respondents on the UiTM Shah Alam campus and eight professional interviews with stakeholders involved in low-carbon campus projects.FindingsThe study reported that low-carbon strategies had been implemented on the UiTM Shah Alam campus, with most existing programmes and activities focusing on low-hanging fruit initiatives. Moreover, the findings indicate that financial, cultural, behavioural, organisational and physical constraints are critical challenges to effectively implementing low-carbon approaches. The proposed techniques suggest that generating green funding, defining clear targets, developing standard procedures for carbon assessment and monitoring, also boosting education and outreach programmes lead to the improvement of low-carbon campus efforts.Practical implicationsThe outcomes of this paper offer perspective to campus administration and community into an evaluation of current approaches and strategies for merging low-carbon systems. The effectiveness of low-carbon implementation was ensured by addressing issues concerning low-carbon uptake and fostering low-carbon improvement.Originality/valueBesides providing a better understanding of techniques to implementing low-carbon development in Malaysia, the critical hurdles and driving factors, the output from this study adds to the existing knowledge available concerning the campus community’s existing comprehension.

Mat-dp: An open-source Python model for analysing material demand projections and their environmental implications, which result from building low-carbon systems.

Cervantes Barron et al., (2022). Mat-dp: An open-source Python model for analysing material demand projections and their environmental implications, which result from building low-carbon systems.. Journal of Open Source Software, 7(76), 4460, https://doi.org/10.21105/joss.04460

A systematic review of municipal smart water for climate adaptation and mitigation

This study examines how research on smart water is contributing to climate-resilient municipal water systems around the globe. We identify smart water research trends over time, relationships with climate adaptation and mitigation goals, and applicability to places with developed or developing water and electrical infrastructure. To do so, we systematically review the literature, identifying research on Information Communication Technology-enabled technologies related to water supply, wastewater, and stormwater management. We assess the relationship between each study and climate adaptation and mitigation objectives: managing greater variation in water quantity, leading to scarcity and increased stormwater; managing declining water quality; and low-carbon water systems. We find 96 relevant studies and identify five major categories of research addressing climate adaptation and mitigation: monitoring, modeling, system design, system feedbacks, and uptake and implementation. We find there is a recent acceleration in smart water research, with a concentration of studies focused on modeling. There is an emphasis on water efficiency using data from Advanced Metering Infrastructure, which is most applicable to cities with developed water grids and consistent electrical supplies. Secondarily, there is a concentration of work using distributed sensors for early detection of water quality degradation, which is being done in all municipal contexts. There is far less research on uptake and implementation of smart approaches, especially at the institutional level. In addition, there is relatively little work that explicitly relates smart water technologies to reducing greenhouse gas emissions. While smart water approaches are applicable everywhere, there is a need to for expanded focus on areas without developed water grids or consistent electricity for smart water to meaningfully contribute to Sustainable Development Goal 6.

Long-Term Hydrogen Storage—A Case Study Exploring Pathways and Investments

Future low-carbon systems with very high shares of variable renewable generation require complex models to optimise investments and operations, which must capture high degrees of sector coupling, contain high levels of operational and temporal detail, and when considering seasonal storage, be able to optimise both investments and operations over long durations. Standard energy system models often do not adequately address all these issues, which are of great importance when considering investments in emerging energy carriers such as Hydrogen. An advanced energy system model of the Irish power system is built in SpineOpt, which considers a number of future scenarios and explores different pathways to the wide-scale adoption of Hydrogen as a low-carbon energy carrier. The model contains a high degree of both temporal and operational detail, sector coupling, via Hydrogen, is captured and the optimisation of both investments in and operation of large-scale underground Hydrogen storage is demonstrated. The results highlight the importance of model detail and demonstrate how over-investment in renewables occur when the flexibility needs of the system are not adequately captured. The case study shows that in 2030, investments in Hydrogen technologies are limited to scenarios with high fuel and carbon costs, high levels of Hydrogen demand (in this case driven by heating demand facilitated by large Hydrogen networks) or when a breakthrough in electrolyser capital costs and efficiencies occurs. However high levels of investments in Hydrogen technologies occur by 2040 across all considered scenarios. As with the 2030 results, the highest level of investments occur when demand for Hydrogen is high, albeit at a significantly higher level than 2030 with increases in investments of large-scale electrolysers of 538%. Hydrogen fuelled compressed air energy storage emerges as a strong investment candidate across all scenarios, facilitating cost effective power-to-Hydrogen-to-power conversions.

Redesigning Kidney Care for the Anthropocene: A New Framework for Planetary Health in Nephrology.

Climate change is one of the greatest threats to human health in the 21st century. The human health impacts of climate change contribute to approximately 1 in 4 deaths worldwide. Health care itself is responsible for approximately 5% of annual global greenhouse gas (GHG) emissions. Canada is a recent signatory of the 26th United Nations Climate Change Conference (COP26) health agreement that is committed to developing low carbon and climate resilient health systems. Kidney care services have a substantial environmental impact and there is opportunity for the kidney care community to climate align clinical care. We introduce a framework of redesigned kidney care and describe examples of low carbon kidney disease management strategies to expand our duty of care to the environment which completes the triple bottom line of optimal patient outcomes and cost effectiveness in the Anthropocene.