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Abstract: This paper investigated the performance, combustion and emission characteristics of diesel engine fueled by biodiesel at partial load conditions. Experiments were conducted on a common-rail fuel injection diesel engine using ultra low sulfur diesel, biodiesel (B100) and their blend fuels of 10%, 20%, 50% (denoted as B10, B20 and B50 respectively) under various loads. The results show that biodiesel/blend fuels have significant impacts on the engine’s brake specific fuel consumption (BSFC) and brake thermal efficiency (BTE) at partial load conditions. The increase in BSFC for B100 is faster than that of pure diesel with the decrease of engine load. A largest increase of 28.1% in BSFC is found at 10% load. Whereas for BTE, the results show that the use of biodiesel results in a reduced thermal efficiency at lower engine loads and improved thermal efficiency at higher engine loads. Furthermore, the characteristics of carbon monoxide (CO) emissions are also changed at partial load conditions. When running at lower engine loads, the CO emission increases with the increase of biodiesel blend ratio and the decrease of engine speed. However, at higher engine loads, an opposite trend is obtained. [Copyright &y& Elsevier]

Abstract: In spite of the rapid development and introduction of renewable and alternative resources, coal still continues to be the most significant fuel to meet the global electricity demand. Emission from existing coal based power plants is, besides others, identified as one of the major sources of anthropogenic carbon dioxide, responsible for climate change. Advanced coal based power plants with acceptable efficiency and low carbon dioxide emission are therefore in sharp focus for current development. The integrated gasification combined cycle (IGCC) power plant with pre-combustion carbon capture is a prospective technology option for this purpose. However, such plants currently have limitations regarding fuel flexibility, performance, etc. In an EU initiative (H2-IGCC project), possible improvements of such plants are being explored. These involve using premix combustion of undiluted hydrogen-rich syngas and improved fuel flexibility without adversely affecting the availability and reliability of the plant and also making minor modifications to existing gas turbines for this purpose. In this paper, detailed thermodynamic models and assumptions of the preliminary configuration of such a plant are reported, with performance analysis based on available practical data and information. The overall efficiency of the IGCC power plant with carbon capture is estimated to 36.3% (LHV). The results confirm the fact that a significant penalty on efficiency is associated with the capture of CO2. This penalty is 21.6% relative to the IGCC without CO2 capture, i.e. 10.0% points. Estimated significant performance indicators as well as comparisons with alternative schemes have been presented. Some possible future developments based on these results and the overall objective of the project are also discussed. [Copyright &y& Elsevier]

Abstract: This paper quantitatively assesses the co-benefits of atmospheric CO2 stabilization at 400ppmv by 2100 on air pollutants emissions from road vehicles using a global energy system model treating the road transport sector in detail. It is estimated that the reduction rate of global cumulative emissions of SO2, NO x , and PM from road vehicles during the period 2020–2100 in the 400ppmv CO2 stabilization scenario compared to the no CO2 constraint scenario is 22.1%, 10.8%, and 14.4%, respectively. Such co-benefits are the largest for SO2 because biomass-derived Fischer–Tropsch products are chosen as a major alternative fuel for road transport in the former scenario and because their SO2 emission factor is zero, whereas their NO x and PM emission factors are lower than those for petroleum products only by 27% and 21%, respectively. This implies that introducing liquid biofuels would not lead to a noticeable reduction in NO x and PM emissions. Such co-benefits are the smallest for NO x . The first reason is that, except for 2100 in the no CO2 constraint scenario, heavy-duty trucks account for the largest share of global road vehicles’ NO x emissions in the two scenarios throughout the time horizon. The second reason is that in each time period, heavy-duty trucks emit almost the same amount of SO2, NO x , and PM between the scenarios because of almost the same technology and fuel choices in this sector. This implies the necessity of promoting R&D for developing cost-effective low-carbon alternatives to diesel heavy-duty trucks to achieve a further reduction in global air pollutants emissions from road vehicles. [Copyright &y& Elsevier]

Abstract: A large number of research works were undertaken for the planning of sustainable electricity generation and CO2 mitigation (EGCM) infrastructure design under uncertainty. The typical methodologies assessed the performance of the problem under the variability of the uncertain parameters by optimizing the expected value of the objective function. This approach can have large probabilities of the value optimized in unfavorable scenarios. In this paper, we present a mathematical programming model in planning sustainable electricity generation and CO2 mitigation (EGCM) infrastructure design, including financial risk management under uncertainty. The proposed model allows us to determine available technologies to produce electricity and treat CO2 on the purpose of maximizing the expected total profit and minimizing the financial risk of handling uncertain environments (i.e. CO2 mitigation operating costs, carbon credit prices and electricity prices, etc.), while fulfilling electricity demands and CO2 mitigation standards. The multi-objective optimization problem was solved by using the weighted-sum method that imposes a penalty for risk to the objective function. The capability of the proposed modeling framework is illustrated and applied to a real case study based on Korea, for which valuable insights are obtained. [Copyright &y& Elsevier]

Abstract: This paper proposes a new framework for the operation of distribution companies (discos) in the liberalized electricity market environment considering distributed generation (DG) units and carbon dioxide (CO2) emission penalty cost. The proposed short-term framework is a two-stage model. The first stage, namely day-ahead stage, deals with the activities of discos. This stage includes a optimization problem to minimize the costs of distribution company (operational and CO2 emission costs). The first stage is formulated as a mixed integer nonlinear programming (MINLP) framework using the Benders decomposition to determine the decisions of discos to buy power from grid, schedule the DG units and contract with interruptible loads (ILs). The results of the first stage are imposed as the boundary constraints in the second stage which deals with the activities of discos in an hour-ahead period. In the hour-ahead stage, the retailers determine the amount of purchased active and reactive power from the grid and the production of each DG unit in the energy and reserve market keeping in mind its day-ahead decision to maximize the desired short-term profit. Finally, the efficiency of the proposed framework is studied on a case study. [Copyright &y& Elsevier]

Abstract: Recently, oxy-fuel combustion has received increasing attention as one of the short-term solutions for capturing CO2 from power plants. Despite their quick development, there are several issues that need further research. Combustion characteristics, heat transfer, emissions levels, optimum oxygen concentration and flue gas recycle are the main concern of the literature. All these issues may introduce several changes in power plant and boiler configuration that causes uncertainty in the final design of future installations. In this respect, oxy-fuel combustion in fluidized bed seems to present advantages in terms of flexibility, operational adaptability and simplicity of design modifications respect to air combustion. These issues have been though scarcely analysed in open literature. Oxy-fuel combustion in fluidized beds would require the use of additional heat transfer surfaces in order to control the bed temperature and the pollutant formation, minimising the CO emission and taking advantage of the fuel energy in the steam cycle. Moreover, the adaptability to different operational conditions (flue gas recycle, oxygen concentration, boiler load, etc.) inherent to fluidized bed characteristic would require an accurate location of heat transfer surfaces. To achieve this aim, this paper describes and compares the simulation results of a circulating fluidized bed boiler with an external heat exchanger, working under air and oxy-firing conditions. Calculation of fluidization conditions and comparison with different oxy-fuel combustion characteristics are presented. Results show the suitable location of heat transfer equipment in circulating fluidized bed to obtain similar temperature profiles along the boiler. A broad range of conditions have been run for different boiler designs, and several operational limitations have been set for selected boiler geometries. [Copyright &y& Elsevier]

Abstract: The residential sector is recognized as a major energy consumer and thus a significant contributor to climate change. Rather than focus only on current energy consumption and the associated emissions, there is a need to broaden sustainability research to include full life cycle contributions and impacts. This paper looks at houses from the perspective of the ecological footprint (EF), a well-known sustainability indicator. Exemplifying single-detached houses of the early 20th century, the century-old REEP House (downtown Kitchener, Canada), together with its high performance energy retrofits, is examined in detail. This research combines material, energy and carbon emission studies. Its scope covers the life cycle of the house, including the direct and indirect consumption of material and energy, and concomitant carbon emissions during its stages of material extraction, transportation, construction, operation, and demolition. It is revealed that the REEP House had a typical impact on the environment when it was built, and, even though the renovations to improve energy efficiency by 80% introduce additional embodied environmental impacts, they are environmentally sound activities because the environmental payback period is less than 2years. [Copyright &y& Elsevier]

Abstract: The development towards high energy efficiency and low environmental impact from human interactions has led to changes at many levels of society. As a result of the introduction of penalties on carbon dioxide emissions and other economic instruments, the energy industry is striving to improve energy efficiency and climate mitigation by switching from fossil fuels to renewable fuels. Biomass-based combined heat and power (CHP) plants connected to district heating networks have a need to find uses for the excess heat they produce in summer when the heat demand is low. On the other hand, the transport sector makes a substantial contribution to the increasing CO2 emissions, which have to be reduced. One promising alternative to address these challenging issues is the integration of vehicle fuel production with biomass-based CHP plants. This paper presents the configuration and operating profits in terms of electricity, heat and ethanol fuel from cellulosic biomass. A case study of a commercial small scale CHP plant was conducted using simulation and modeling tools. The results clearly show that electricity production can be increased when CHP production is integrated with cellulosic ethanol production. The findings also show that the economic benefits of the energy system can be realized with near-term commercially available technology, and that the benefits do not rely solely on ethanol yields. [Copyright &y& Elsevier]

Abstract: Carbon emission reduction targeting is an important and effective effort for industry to contribute in controlling greenhouse gases concentration in atmosphere. Graphical approach has been proposed for CO2 emissions reduction targeting via HEN retrofit and fuel switching. However, it involves potentially time consuming manual procedures and the quality of solutions produced greatly depends on designer’s experience and judgment. Besides, graphical approach hardly account for the cost factor during the design phase, thus potentially generate complex design. This paper introduces an MINLP model for simultaneous CO2 emissions reduction targeting via fuel switching and HEN retrofit. A sequential model execution was proposed along with the proposed model. The application of the model on a crude preheat train case study has demonstrated its workability to generate optimal solution for targeted CO2 emissions reduction at minimum payback period. [Copyright &y& Elsevier]

Abstract: The better to explore the regional characteristics of inter-provincial CO2 emissions and the rational distribution of the reduction of emission intensity reduction in China, this paper proposes an improved PSO-FCM clustering algorithm. This method can obtain the optimal cluster number and membership grade values by utilizing the global capacity of Particle Swarm Optimization (PSO) on Fuzzy C-means (FCM). The clustering results of CO2 emissions indicate that the 30 provinces of China are divided into five clusters and each has its own significant characteristics. Compared with other clustering methods, the results of PSO-FCM are more explanatory. The most important indicators affecting regional emission characteristics are CO2 emission intensity and per capita emissions, whereas CO2 emission per unit of energy is not obvious in clustering. Furthermore, some policy recommendations on setting emission reduction targets according to the emission characteristics of different clusters are made. [Copyright &y& Elsevier]

Abstract: This paper establishes several efficiency models based on environmental production technology, which are capable of integrating undesirable outputs into efficiency evaluation framework. With the proposed efficiency models, we estimate the environmental efficiency, economic efficiency, economic-environmental efficiency and two-stage efficiency of different provinces in China by considering carbon dioxide (CO2) emissions. Our empirical results show that the environmental and economic efficiency of China are generally low and there exist comparatively large differences in different areas. The average proportion for simultaneously reducing CO2 emissions and increasing GDP is about 36–40%. When desirable outputs are adjusted to the optimal level, some provinces have still the possibility to further reduce CO2 emissions. About half of the provinces is found to be in the status of high incoordination between environment and economy. [Copyright &y& Elsevier]

Abstract: Operation mode of combined cooling heating and power (CCHP) system determines its energetic and environmental performances. This paper analyzes the energy flows of CCHP system and separated production (SP) system. The fuel energy consumptions of CCHP system following electrical demand management (EDM) and thermal demand management (TDM) are deduced respectively. Three indicators: primary energy saving, exergy efficiency and CO2 emission reduction, are employed to evaluate the performances of CCHP system for a commercial building in Beijing, China. The feasibility analysis shows that the performance of CCHP system is strictly dependent upon building energy demands. The selection of CCHP operation modes is systemically based on building loads, CCHP system and local SP system. The calculation results conclude that CCHP system in winter under EDM achieves more benefits than in summer. The sensitivity discussion indicates that the coefficient of performance for cooling and the efficiency of electricity generation are the most sensitive variables to the energetic and environmental performances of CCHP system. [Copyright &y& Elsevier]

Abstract: The increasing pressure resulting from the need for CO2 mitigation is in conflict with the predominance of coal in China’s energy structure. A possible solution to this tension between climate change and fossil fuel consumption fact could be the introduction of the carbon capture and storage (CCS) technology. However, high cost and other problems give rise to great uncertainty in R&D and popularization of carbon capture technology. This paper presents a real options model incorporating policy uncertainty described by carbon price scenarios (including stochasticity), allowing for possible technological change. This model is further used to determine the best strategy for investing in CCS technology in an uncertain environment in China and the effect of climate policy on the decision-making process of investment into carbon-saving technologies. [Copyright &y& Elsevier]

Abstract: This paper investigates thermal performance of an existing eco-friendly and low embodied energy vault roof passive house (or mud-house) located at Solar Energy Park of IIT Delhi, New Delhi (India). Based on embodied energy analysis, the energy payback time for the mud-house was determined as 18 years. The embodied energy per unit floor area of R.C.C. building (3702.3MJ/m2) is quiet high as compared to the mud-house (2298.8MJ/m2). The mud-house has three rooms with inverted U-shape roof and remaining three rooms with dome shape roof. A thermal model of the house consisting of six interconnected rooms was developed based on energy balance equations which were solved by using fourth order Runge Kutta numerical method. The predicted six room air temperatures were found in good agreement with the experimental observed data on hourly basis in each month for one year. The annual heating and cooling energy saving potential of the mud-house was determined as 1481 kWh/year and 1813kWh/year respectively for New Delhi composite climate. The total mitigation of CO2 emissions due to both heating and cooling energy saving potential was determined as 5.2 metric tons/year. The annual carbon credit potential of mud-house was determined as € 52/year. Similar results were obtained for the different climatic locations in India. [Copyright &y& Elsevier]

Abstract: The UK government’s economy-wide 60% carbon dioxide reduction target by 2050 requires a paradigm shift in the whole energy system. Numerous analytical studies have concluded that the power sector is a critical contributor to a low carbon energy system, and electricity generation has dominated the policy discussion on UK decarbonisation scenarios. However, range of technical, social and market challenges, combined with alternate market investment strategies mean that large scale deployment of key classes of low carbon electricity technologies is fraught with uncertainty. The UK MARKAL energy systems model has been used to investigate these long-term uncertainties in key electricity generation options. A range of power sector specific parametric sensitivities have been performed under a ‘what-if’ framework to provide a systematic exploration of least-cost energy system configurations under a broad, integrated set of input assumptions. In this paper results of six sensitivities, via restricted investments in key low carbon technologies to reflect their technical and political uncertainties, and an alternate investment strategies from perceived risk and other barriers, have been presented. [Copyright &y& Elsevier]

Involving residential actors in the energy transition is crucial for its success. Local energy generation, consumption and trading are identified as desirable forms of involvement, especially in energy communities. The potentials for energy communities in the residential building stock are high but are largely untapped in multi-family buildings. In many countries, rapidly evolving legal frameworks aim at overcoming related barriers, e.g. ownership structures, principal–agent problems and system complexity. But academic literature is scarce regarding the techno-economic and environmental implications of such complex frameworks. This paper develops a mixed-integer linear program (MILP) optimisation model for assessing the implementation of multi-energy systems in an energy community in multi-family buildings with a special distinction between investor and user; the model is applied to the German Tenant Electricity Law. Based on hourly demands from appliances, heating and electric vehicles, the optimal energy system layout and dispatch are determined. The results contain a rich set of performance indicators that demonstrate how the legal framework affects the technologies' interdependencies and economic viability of energy communities with multi-energy systems. Certain economic technology combinations may fail to support national emissions mitigation goals and lead to lock-ins in Europe's largest residential building stock. The subsidies do not lead to the utilisation of a battery storage. Despite this, self-sufficiency ratios of more than 90% are observable for systems with combined heat and power plants and heat pumps. Social C O 2 mitigation costs range between 147.5–272.8 € / t CO 2 . Finally, the results show the strong influence of the heat demand on the system layout. • System optimisation of distinct operators and consumers in multi-family buildings. • Inclusion of Tenant Electricity Law leads to complex investment and dispatch decisions. • Highest profitability combining photovoltaic, combined heat and power and heat pump. • Combined heat and power is favoured, but profits depend on building's heating demand. • Legislation incentivises energy communities but may offset national CO 2 mitigation. [ABSTRACT FROM AUTHOR]

(a) Historical carbon emission mitigation of the residential building sector and (b) emission benchmarks of the future residential building sector in China. • Carbon mitigation of the residential building sector in 2000–2015 is 1.817 (±0.643) BtCO 2. • Residential building will achieve its emission peak in 2037 (±4) at 1.419 (±0.081) BtCO 2. • Floor space per capita and energy intensity are determining in the uncertainty of emission peak. • Future residential building energy benchmark should be controlled at 0.703 (±0.042) Btce. • A benchmark of 1.258 BtCO 2 can achieve the residential buildings' 2030 emission peak goal. Fast-growing carbon emissions from the residential building sector are a hindrance for China to achieve its 2030 emission peak goal. To identify future low carbon roadmaps of residential buildings, this study is the first to assess the historical carbon mitigation and simulate the energy and emission peaks of China's residential building sector using a dynamic emission scenario. It shows that the emission mitigation of the residential building sector during 2000–2015 is 1.817 (±0.643) billion tons of carbon dioxide (BtCO 2), and the normal distribution-based scenario simulation demonstrates that the residential building sector will achieve its carbon emission peak in 2037 (±4) with a peak value of 1.419 (±0.081) BtCO 2. The sensitivity analysis reveals that the impacts of floor space per capita and energy intensity of urban residential buildings are the most significant for the uncertainty of emission peaks. A strict energy demand benchmark of the residential building sector suggests a control at 0.661 billion tons of standard coal equivalent (Btce), and its peaking time is estimated for 2035, which is 5 years ahead of the business-as-usual scenario, with energy savings of 0.042 Btce. For the earliest peaking time, if the residential building sector aims to achieve its emission peak before 2030, the emission peak should be controlled at 1.258 BtCO 2. Overall, this paper can assist the government in more accurate and feasible building emission mitigation strategies. Moreover, the results provide a more powerful decision-making reference in issuing targeted and feasible strategies for future residential building emission mitigation. [ABSTRACT FROM AUTHOR]

• A realistic post-burn underground coal gasification cavity model is constructed. • Various char walls and rubble floor with different CO2 adsorption capacity. • Coal swelling effect due to CO2 adsorption on the plume confinement is studied. • CO2 transport under various effects is examined. Supplementary to the prospect of carbon storage in the geological formations for carbon emission mitigation, the deep post-burn underground coal gasification (UCG) cavities are proposed to be good venues for carbon dioxide storage, albeit without substantial validation in any form. Using a modelling methodology, this paper intends to bridge that knowledge gap by exploring the feasibility of storing CO2 in the post-UCG venues. A 3D post-burn UCG cavity model was constructed taking into account of the various char walls and rubble floor. To better utilize the subsurface space, the migration of CO2 in a supercritical state was modelled for a span of 10,000 days. The modelling results show that it is possible to inject CO2 into UCG cavities for storage. Insight was achieved concerning the transport pattern of CO2 plume in the UCG cavity under various effects, e.g. CO2 buoyant flow, diffusion and adsorption are coupling behaviours, and coal adsorption and swelling have a complex effect on CO2 transport. [ABSTRACT FROM AUTHOR]

Abstract: This paper explores the cost-effective strategy for introducing modern bioenergy into developing Asia through the 21st century under a 400ppmv CO2 stabilization constraint using a global energy model that treats the bioenergy sector in detail. The major conclusions are the following. First, under the 400ppmv CO2 stabilization constraint, it is cost-effective to use modern bioenergy largely to generate heat and replace direct coal use in developing Asia in the first half of the century, because direct heat generation from modern biomass is efficient and expected to achieve large CO2 reduction. As second-generation bioenergy conversion technologies (mainly gasification-based technologies) become mature in the second half of the century, it becomes cost-effective to introduce biomass-derived hydrogen, electricity, and Fischer–Tropsch synfuels and bioethanol produced using these technologies into developing Asia instead of modern biomass-derived heat. All biomass gasification-based conversion technologies are combined with CO2 capture and storage from 2060, which enables negative CO2 emissions and makes a substantial contribution to achieving the stringent climate stabilization target. Second, due to its small availability of biomass resources, large-scale import of biofuels and wood pellets is inevitable in developing Asia except southeastern Asia under the CO2 constraint used here. It is shown that this contributes to diversifying liquid fuel import sources and improving energy security in developing Asia. Third, sensitivity analysis shows that these findings are robust to bioenergy-related cost parameters. [Copyright &y& Elsevier]