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As the issues of global energy crisis and climate change are becoming increasingly prominent in the world, urban microgrids have received widespread attention as an effective way to improve energy utilization efficiency and reduce environmental pollution. Among them, the cogeneration of heat and power (CHP) system is considered as one of the key technologies to improve the energy efficiency of urban microgrids because it can provide both electricity and heat. However, how to optimize the energy flow scheduling for CHP systems, especially in the context of increasing renewable energy sources, has become a hot topic of current research. Existing studies usually rely on the traditional dualtime-scale scheduling strategies, namely day-ahead scheduling and real-time scheduling, but both have obvious limitations in dealing with the uncertainty and volatility of new energy sources. To address the above problems, this paper proposes a thermodynamic analysis-based scheduling method for optimizing the energy flow in the CHP system of urban microgrids. First, this paper introduces the concepts of rolling schedule and real-time schedule to improve the traditional time-scale scheduling method, so as to enhance the system's adaptability to new energy power fluctuations. Second, for the absorption CHP system, this paper proposes a thermal cycle performance optimization strategy, which significantly improves the utilization efficiency of thermal energy through the cascaded recycling of system waste heat. Through these two innovations, this study not only realizes a more accurate and efficient energy management, but also provides a new strategy for the sustainable development of urban microgrids. [ABSTRACT FROM AUTHOR]

Renewable energy consumption has gained growing importance in the world energy consumption portfolio over recent years. One of the reasons is the increasingly negative development of climate change. The research carried out in this paper aims to discern whether the examined economic indicator (GDP per capita) and the environmental indicator (CO2 emissions per capita) affect the renewable energy consumption in the region of the Visegrad Group (V4 - Czech Republic, Hungary, Poland, and Slovak Republic) countries, and to draw implications for public administration in the given issue. The fixed effects panel regression model was used to verify the mentioned relationships between variables from 1990-2020. The results show that the level of the share of renewable energy consumption on the total energy consumption in the region of the V4 countries can be affected by the GDP per capita (positive relationship validated) and the CO2 emissions per capita (negative relationship validated). These results are mostly in line with the findings of other researchers conducted on different samples of countries, although some differences can be noted, especially regarding the direction of the relationship. The implications of the research results are presented on three levels: practical implications for the business sector, emphasis placed on political implications for public administration, and theoretical implications that lay the foundation for further research. The main limitation of the research results comes from the sample used in V4 countries and, thus, from the limited possibilities of generalizing the results. The direction of further research in the addressed issue will include a larger number of countries in the research and the use of various quantitative and qualitative research methods. [ABSTRACT FROM AUTHOR]

Climate change is directly linked to a broad array of changes because of disorganized activities within the economic system and human intervention. Climate change affects the well-being status of both non-living and living things. Relevant policies to mitigate and adapt to climate change conditions concentrate on solutions that intend to use renewable energy instead of fossil fuels or other conventional energy sources. This study aims to process a review focused on how renewables advance environmental quality and create relevant benefits within severe economic activities. This study elaborates on the case of China for two main reasons. First, China has a pivotal role in the economic system worldwide. Second, China is making serious attempts to transition into a low-carbon economy. An integrative review was processed to receive selected publications. The advantage of this process is that it considers empirical and non-empirical studies, policy papers, and conceptual frameworks. Inclusion and exclusion criteria were applied to retrieve the final number of publications. Review results from 39 well-acknowledged Journals provided 180 selected publications categorized into seven study groups: data analyses, model optimization studies, market issues, renewable energy technology publications, nuclear energy publications, ocean energy publications, and policy-related studies. Policy implications concern China's efforts to accelerate the integration of renewables in the energy mix. Hence, the country should increase energy efficiency in consumption and process investment plans based on robust research and development efforts. [ABSTRACT FROM AUTHOR]

Under rapid urbanization-induced global warming and resource depletion, growing interest in zero-energy building (ZEB) and zero-emission building (ZEB) technologies have emerged globally to improve energy performance in homes and shape sustainable cities. Although several countries have released ZEB-enhanced strategies and set national standards and policies to promote ZEBs, construction projects are still limited to demonstration projects. This paper reviews global ZEB activities and state-of-the-art technologies for energy-efficient residential building technologies [based on an evaluation of 40 residential buildings]. Over 40 residential buildings on different continents were reviewed, and their technical details and performance were evaluated. Our results show that 62.5% of the buildings achieved the +ZEB standard, 25% of the buildings were net-zero energy buildings, and only 12.5% of the buildings were near-zero energy buildings. Solar PV is the most widely used renewable energy source in the studied cases, while in warmer climates, advanced cooling technologies and heat pumps are the preferred technologies. A building envelope and thermal ventilation with heat recovery are essential in cold climates. Our systematic analysis reveals that the thermal performance of the building envelope and solar energy are the most effective mechanisms for achieving energy efficiency and shaping sustainable cities. [ABSTRACT FROM AUTHOR]

In Africa, switching to renewable energy sources with low carbon emissions is becoming more popular. In the Economic Community of West African states (ECOWAS), the low-carbon energy transition must overcome significant obstacles, including those posed by policies put in place and their implementation. In order to replace the current fossil fuel-driven economy with low-carbon development that also advances the regional aims and Sustainable Development Goals (SDGs), this paper analyzes the current policy landscape in the region. A total of 75 policies from four categories (energy access, energy efficiency, renewable energy, climate change) were chosen for the policy review. Multicriteria decision analysis and a thorough review of the literature have shed light on how well the policies of the ECOWAS countries could promote low-carbon development and what the main challenges to overcome are. The last step was the comparison of the progress of the two key policies in the region: the National Energy Efficiency Action Plan (NEEAP) and National Renewable Energy Action Plan (NREAP). The results illustrate the amount of work still needing to be done in the region, with only 26 of the 75 policies receiving a score above 50. However, the prospect of a better energy strategy that adequately considers the difficulties of the energy transition is possible, given the progress made by the region's nations since the creation of national action plans for energy efficiency (EE) and renewable energy (RE). Our analysis has also shown that countries like Senegal have obtained quite promising results, as evidenced by the best scores of 76.88 and 73.25, respectively, obtained by its NREAP and NEEAP policies. [ABSTRACT FROM AUTHOR]

Biomass use for energy and materials is, on the one hand, one of the key mitigation options to reach the 1.5 °C GMT target set in the Paris Agreement, as highlighted by the IPCC and many other key analyses. On the other hand, particularly in parts of the EU, a strong negative connotation has emerged in public debate and EC policy, with a particular emphasis on the (presumed) displacement effect in markets and land use. This is a remarkable contrast because the reasons to use sustainable biomass, on the one hand, and the possibilities and synergies for supplying sustainable biomass, on the other, are underpinned with strong evidence, also providing insights on how displacement issues can be avoided. Sustainable biomass supplies can contribute 20–30% of the future global and European energy supply, leading to reduced overall mitigation costs, including realizing the net CO2 removal from the atmosphere using BECCS concepts. This paper highlights which options, pathways and preconditions are key to achieving such a substantial contribution of sustainable biomass in future (2050) energy and material supply (with a focus on the European setting). By pinpointing how "biomass can be done right" and how important synergies can be achieved via better agricultural methods, the restoration of marginal and degraded lands and the adaptation of climate change, a different policy agenda emerges in sharp contrast to how a biobased economy has been framed in recent years. It is recommended that future policy priorities, particularly at the EU level, take a more integral view on the synergy between the role of biomass in the energy transition, climate adaptation and mitigation, better agriculture and the better use of land in general. Strategies to achieve such positive results typically require an alignment between renewable energy, and agricultural, environmental, mitigation and adaptation policies, which is a largely missing nexus in different policy arenas. Resolving this lack of alignment offers a major opportunity, globally, to contribute to the European Green deal and improve energy security. [ABSTRACT FROM AUTHOR]

Given the significant energy consumption and carbon emissions associated with buildings, there is increasing interest in improving sustainability of building operations to reduce impact on climate change. A common goal is to operate buildings as "net-zero" energy users in which all energy consumed by the building is balanced against renewable energy purchased from the grid or produced on site. To achieve net-zero status, many buildings will require significant retrofit so as to both reduce energy consumption in the absolute sense and provide the remainder without consuming fossil fuels. Thus, multi-year planning is required to ensure that goals can be met on time. In addition, due to the inherent uncertainty associated with energy consumption and generation, actually achieving net-zero energy use may require discretionary curtailment actions to be taken, and deciding whether such actions are necessary can be challenging. To address these challenges, we propose in this paper a design optimization and operational planning strategy to make the decisions needed to achieve sustainability goals in buildings. The strategy can be applied to schedule design changes over a long horizon to meet annual targets, and it can also be applied in closed loop on a shorter horizon to determine whether curtailment is needed to stay on track. We discuss the formulation of the optimization problem, solution methods, and modeling approaches for key parameters. Application of the strategy is illustrated via examples. Overall, this approach will help automate planning that is often done manually, allowing buildings to take a significant leap forward toward achieving their sustainability goals. • Achieving sustainability goals in buildings requires multi-year planning. • The required design and operational decisions can be made via optimization. • Key problem parameters can be obtained from data-driven modeling. • The strategy allows sustainability goals to be met at minimum cost. [ABSTRACT FROM AUTHOR]

Policies targeting energy efficiency and renewable energy are sometimes viewed as more politically feasible than carbon pricing in pursuit of emission reduction goals. This paper assesses underlying drivers of energy policy development. These factors include economic, social, environmental, and institutional variables. The between estimator for panel data is an appropriate method for our focus on some exogenous variables that vary more across countries than over time. We find that larger oil reserves per capita have a negative relationship with renewable energy policy development. Education and political globalisation have strong positive relationships with both energy-efficiency and renewable-energy policy development. These results suggest that greater participation in global political groups can be an indirect approach toward energy policy development, in cases where direct and immediate policies are hard to implement. OECD countries have higher policy scores by 33 and 25 points in energy efficiency and renewable energy respectively. Blinder-Oaxaca decomposition analysis shows that these higher scores are primarily due to social and political institution predictors rather than economics and physical endowments. • Large-n cross country international sample on continuous policy score measurement. • Political globalisation is positively linked with renewables and energy efficiency policies. • Education is positively linked to energy policy development, especially for efficiency. • Higher OECD countries' policy scores are primarily due to social and political predictors. • Higher incomes are unlikely to lead to automatic improvements in energy policies. [ABSTRACT FROM AUTHOR]

Global warming, climate change, and resource depletion have forced us to reconsider energy usage and efficiencies over the last few decades. Residential and commercial buildings are both large energy consumers, so improving energy and material usage efficiency in this sector is a common research topic. According to a recent study, the Building Sector (BS) accounts for 40% of greenhouse gas emissions. The primary objective of this paper is to examine and assess the potential of Renewable Energy Systems (RES) and their combinations for enhancing energy efficiency in the BS. Specifically, the focus will be on converting low energy-efficient buildings into highly efficient ones. The potential of the RES and their combinations for the BS is evaluated based on payback durations, energy generation, and reduction of CO 2 emissions. The optimization flow charts for the RES, feasibility studies, commercialization road maps of energy storage systems and the necessity of control mechanisms for enhancing RES efficiency were discussed. Additionally, the technology drawbacks are discussed, along with various innovative techniques recommended to direct future study in this area. Finally, this article assists the audience clear idea in the selection of the right combination of potential RES based on different conditions to achieve deep decarbonization in BSs. • Buildings sector (BS) responsible for 40% of GHG emissions. • Study assesses potential of Renewable Energy System (RES) in BS. • RES evaluated on payback, energy generation, and CO 2 reduction. • Optimization, feasibility and commercialization studies were discussed. • Article recommends right RES combinations for deep decarbonization in BS. [ABSTRACT FROM AUTHOR]

In order to achieve the targets underlined in the European Strategy for climate change and energy efficiency, the so called 20-20-20 package, the European Commission launched the Covenant of Mayors to endorse and support the efforts deployed by local authorities in the implementation of sustainable energy plans, and at the same time contribute to greenhouse gases emissions mitigation. This paper explores how the Covenant of Mayors (CoM) has been adopted in Portugal, and which type of measures are being defined and implemented by the municipalities. For that, all Sustainable Energy Action Plan (SEAP) submitted by Portuguese municipalities (124) have been examined, for which a detailed analysis was performed, including the Baseline Emission Inventory (70, i.e., around 50%). The municipalities that submitted SEAP cover 60% of the total population of the country because the main urban centres are a part of the 30% that have signed the CoM. Most common measures are related with changes on behaviour and infrastructure related to energy (such as renewable energies, energy efficiency in buildings, public lighting, etc.), waste and transport (for example optimization of: transport infrastructures, used vehicles and road operations). Public lighting is one of the energy measures present in all submitted SEAP, which plays a key role in energy consumption, reaching values of upwards of 12%, particularly in coastal areas due to higher population density and urban residential areas. Besides all efforts there is still a long way to go in terms of energy consumption reduction at local level. [ABSTRACT FROM AUTHOR]

The transition towards low-carbon economy requires a number of specific actions by a multiplicity of actors in order to reduce greenhouse gas (GHG) emissions, entailing energy efficiency, production of energy from renewable resources as well as the diffusion of more sustainable production and consumption patterns. Among the actors, local authorities can play a leading role for climate action. However, properly accounting for GHG emissions at local scale and identifying actions for GHG reduction are still an open challenge in many contexts. In this paper, we propose a method for GHG emissions accounting to support the identification of proper actions to achieve GHG reduction targets. The method widens the classical production-based approach to accounting, by proposing an extension of the accounting to three main areas: waste management and recycling, consumption patterns, and local land management. Life cycle thinking is applied as methodological basis for such extension. To illustrate the benefit of the proposed approach, the method has been applied to 16 municipalities (in Northern Italy), which were signatories of the Covenant of Mayors (CoM) initiative. CoM is a European initiative by which local authorities voluntarily commit to reduce their GHG emissions through the implementation of Sustainable Energy Action Plans. A comparison of the emission profile of the different municipalities helps identifying common patterns and local peculiarities to be addressed to achieve the reduction target. For the analysed case studies, the biggest contribution to GHG emissions comes from the consumption of the natural gas and electricity by the household sector. Emissions from waste generation play a minor role in the selected case studies. However, the inclusion of avoided emissions coming from waste recycling highlights the reduction potential if an appropriate waste management system is in place. Consumption patterns, as well, may play a relevant role. For example, assessing GHG emissions related to food consumption on top of those due to other drivers, the total municipal emissions change by increasing for an average of 22.6% for the selected case studies. Moreover, local land use planning and management should be included in the assessment, being crucial not only for the emissions uptake but also for climate mitigation and adaptation. The proposed approach to GHG accounting, including consumption-based aspects, may help identifying a wider set of climate actions to be implemented by local authorities to reduce environmental burdens. [ABSTRACT FROM AUTHOR]

[Display omitted] • A method for spatiotemporal coordination of multienergy systems is proposed. • Virtual energy storage gain is calculated based on spectral analysis. • The hydropower regulation ability affects the virtual energy storage gain. • The optimal coordination range between multiple energy sources is obtained. Utilizing the spatial heterogeneity and climate periodicity of various available renewable energy sources can enhance the multienergy complementarity, which will further reduce the energy storage demand and contributes to the "virtual energy storage gain." In this paper, we propose a spatiotemporal coordination method based on spectral analysis for a wind-PV-hydropower system that targets the maximum virtual energy storage gain. The complementary effect of hydropower on wind and PV power can be seen as changes in the regulation ability resulting from the hydropower construction development as well as a decreased variance in the total system production output. This method is used to determine the optimal coordination distance of multiple energy sources that are matched over different periods representing typical climate variation. A case study in the Yalong River basin in China obtains the best range of hydropower bundling surrounding wind power and PV power stations under different hydropower construction planning scenarios, and it reveals that increased regulation capacity of hydropower will reduce the optimal coordination distance but can achieve more energy balance if both actual storage and virtual storage is accounted for. This approach can realize energy delivery with the optimal coordination distance to meet intensive and efficient development needs, which can provide guidance and support for the planning and construction of wind-PV-hydropower storage systems. [ABSTRACT FROM AUTHOR]

Almost all countries have committed to develop Nationally Determined Contributions (NDC) to reduce GHG emissions. They determine the level of GHG mitigation that, as a nation, they will commit to reducing. Zimbabwe has ambitious and laudable GHG mitigation targets. Compared to a coal-based future, emissions will be reduced by 33% per capita by 2030. If historical climate conditions continue, it can do this at low or negative cost if suitable sources of climate financing are in place. The NDC plots a positive future. However, much of Zimbabwe's NDC mitigation center on hydropower generation and other measures that are dangerously vulnerable to climate change. Should the climate change in accordance with recent projections, these investments will be at risk, severely constraining electricity supply and causing high degrees of economic damage. This paper uses the Open-Source energy Modelling SYStem (OSeMOSYS) to consider two adaptation pathways that address this vulnerability. In the first, the country turns to a historically accessible option, namely the deployment of coal. In so doing, the electrical system is made more resilient, but emissions ramp up. The second pathway 'climate proofs' the power sector by boosting solar and wind capacity, using hydropower to provide balance for these new renewable resources, and introducing significant energy efficiency measures. This second pathway would require a set of extra accompanying investments and changes to the power market rules, but allows for both system resilience and NDC targets to be met. The paper shows that Zimbabwe's low emissions growth can be made resilient, and while this path promises strong benefits, it also requires strong commitment and political will. From this paper insights are drawn and requirements for future analysis are made. Two critical insights are that: (i) NDCs that focus on mitigation should include resilience in their design. If they do not, they can introduce deep vulnerability; (ii) a departure from historical electricity market structures appears to hold potential for strong environmental, cost and reliability gains. [ABSTRACT FROM AUTHOR]

The scientific evidence of climate change as a result of greenhouse gas emissions which causes ozone layer depletion is becoming increasingly obvious and clear. Findings revealed that energy from the fossil fuel is the major source of greenhouse emission which destroys the environment and makes it unhealthy for living beings. In Nigeria, conventional energy (oil and gas) with gas flaring has the highest percentage of 52% and liquid fuel of 32% of carbon dioxide (CO2) respectively. This sector contributes revenue of over 70% to Nigeria s economy and generates an average total 21.8% of greenhouse gas emission. In Nigeria, there is a much more potential for share renewables with 15.4% of total energy production and 8.6 % of energy consumption. In reality with global environmental concern, Nigeria s carbon dioxide emissions have increased with energy production and consumption. The Integrated Renewable Energy Master Plan of 2008 projects a 26.7% renewable energy contribution to the Nigeria s energy use and this is expected to reduce CO2 and greenhouse gas emissions at 38% by2025. Nigeria has not been playing significant role by reducing emissions of greenhouse gases. This paper highlights Nigeria s climate change situation and penetration requirements for various renewable energy deployments as mitigating instrument for climate change towards healthy and productive environment. [ABSTRACT FROM AUTHOR]

Energy sectors of all the countries around the world are faced with a big challenge: the energy transition under the imperative of continuous reduction of carbon dioxide emissions. The energy transition and the sustainability constraints pose a significant challenge for engineers, researcher and scientists developing new and clean energy-efficient technologies. Energy production and transformations, along with its storage, distribution and consumption, are achieved by utilising new and clean energy technologies, with the goal of the continuous increase of energy efficiency, the growth of renewable energy sources utilisation, the uninterrupted switch from fossil fuels to alternative energy sources, and the continued reduction of CO2 emissions. This editorial paper addresses the latest progress and the findings in research and developments in the sustainable energy technologies, energy and environment systems from selected papers of the conference on Sustainable Development of Energy, Water and Environment Systems held in 2019. [ABSTRACT FROM AUTHOR]

In the context of climate changes and the rapid growth of energy consumption, intermittent renewable energy sources (RES) are being predominantly installed in power systems. It has been largely elucidated that challenges that RES present to the system can be mitigated with energy storage systems (ESS). However, besides providing flexibility to intermittent RES, ESS have other sources of revenue, such as price arbitrage in the markets, balancing services, and reducing the cost of electricity procurement to end consumers. In order to operate the ESS in the most profitable way, it is often necessary to make optimal siting and sizing decisions, and to determine optimal ways for the ESS to participate in a variety of energy and ancillary service markets. As a result, many publications on ESS models with various goals and operating environments are available. This paper aims at presenting the results of these papers in a structured way. A standard ESS model is first outlined, and that is followed by a literature review on operational and investment ESS models at the transmission and distribution levels. Both the price taking and price making models are elaborated on and presented in detail. Based on the examined body of work, the paper is concluded with recommendations for future research paths in the analysis of ESS. [ABSTRACT FROM AUTHOR]

This paper reviews the many criticisms that Integrated Assessment Models (IAMs)—the bedrock of mitigation analysis—have received in recent years. Critics have asserted that there is a lack of transparency around model structures and input assumptions, a lack of credibility in those input assumptions that are made visible, an over-reliance on particular technologies and an inadequate representation of real-world policies and processes such as innovation and behaviour change. The paper then reviews the proposals and actions that follow from these criticisms, which fall into three broad categories: scrap the models and use other techniques to set out low-carbon futures; transform them by improving their representation of real-world processes and their transparency; and supplement them with other models and approaches. The article considers the implications of each proposal, through the particular lens of how it would explore the role of a key low-carbon technology—bioenergy with carbon capture and storage (BECCS), to produce net negative emissions. The paper concludes that IAMs remain critically important in mitigation pathways analysis, because they can encompass a large number of technologies and policies in a consistent framework, but that they should increasingly be supplemented with other models and analytical approaches. [ABSTRACT FROM AUTHOR]