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Off-grid multiple energy system (MES) has been regarded as a promising modality for future energy due to high efficiency, consumer adaptability and system independency. Nevertheless, balancing the supply and demand of multiple energy forms simultaneously raises challenges to the operation control due to the strong interactions, characteristic discrepancies and fluctuations among multiple types of energies. The advantages of off-grid MES may never unfold if the multiple energy conversion processes are not managed in a coordinated manner. To this end, this paper takes a typical off-grid combined heat and power generation MES as example to show the strong coupling and multi-timescale features of the MES. A multi-timescale distributed model predictive control (MDMPC) based coordinated controller is then developed to fully exploit the interactions between power and heat, upgrading the operating performance of the MES. Offset free tracking design is also fused in the MDMPC framework to attain more precise following of the load demands even in the presences of process disturbances. Simulation results show that the MDMPC can achieve superior control performance at electricity side while maintaining a high-standard thermal-side control. Discussions are then carried out to further identify the efficacy of the MDMPC under four representative energy consumption scenarios. This paper points to the new directions of using coordinated control strategies for the stable, efficient and flexible operation of modern multiple energy system towards low-carbon transition. [Display omitted] • MDMPC is proposed for power-heat coordinated control of the off-grid MES. • Dynamic interactions and multi-timescale features of the MES are evaluated. • Offset-free design is fused in the MDMPC to modify the load tracking ability of MES. • 57% decrease of electric side IAE index is achieved by the MDMPC in the base case. • The applicability of MDMPC in low carbon transition of modern MES is demonstrated. [ABSTRACT FROM AUTHOR]

The city of Pécs in Hungary has developed an energy strategy to be implemented in the years to come which proposes structural changes in both the supply and demand sides. This paper offers a model based on the proposed system aimed at providing a basis for comparison for decision-makers. The model has been developed with the help of energy system analysis tool energyPRO, and covers the three basic sectors of heat, electricity and transport. It shows the energy system of Pécs in terms of hourly production and demand levels – and these values enable the model to analyse intermittent energy sources. The model is also validated – to ensure that it is satisfactory for the simulation of future energy systems. It analyses two scenarios – one where the city does not implement the changes proposed in the strategy, and one where it does. The paper compares the two scenarios based on sustainability, energy security and affordability. [ABSTRACT FROM AUTHOR]

A vital first step for regional energy transitions is to develop an understanding of the current energy balance and related carbon dioxide emissions. However, there is a lack of clarity within existing literature on how best to determine a complete regional energy balance including industry, residential, services, agriculture, and transport sectors. This paper identifies four key limitations in the literature: over-reliance on simple population-based proportioning, a narrow focus on building energy, subsequent omission of transport energy in the majority of studies and a lack of transparency in a significant number of studies. This paper proposes a novel conceptual framework to address these gaps using a combination of local energy usage indicators and national unit energy consumption statistics. The authors apply this multi-dimensional approach to a rural case study region, carefully examining the range of energy usage indicators in each sector before selecting the most suitable. The results quantitatively demonstrate the value of this approach, with the final energy demand in some sectors varying by as much as double or threefold compared with a population weighting. Focusing on the socio-economic drivers of energy demand in this manner provides useful insights into the local context that defines the energy system. • Conceptual framework for developing a regional energy balance proposed. • Complete regional energy balance carefully determined. • Value of multi-dimensional approach demonstrated using an isolated rural case study. • Implications for local energy planning discussed. • Decarbonisation challenges for rural communities discussed. [ABSTRACT FROM AUTHOR]

The trigeneration combined the electricity, cooling and heating makes adiabatic compressed air energy storage system (ACAES) popular as an energy storage technology. Based on thermodynamic analysis, this paper studies the influence on the system performance of four variable factors, including compression stages, expansion stages, water (heat storage medium) mass flow rates in charging process and discharging process to provide a guidance for the design of ACAES for different user demand. The results show that changing these four factors can achieve different energy output distributions in a very wide range (power supply ratio is 0.50–0.86, heating output ratio is 0.00–0.39, cooling supply ratio is 0.00–0.41). Simulation results also indicate that fewer compression and expansion stages are suggested for the cases requiring shorter running time. Furthermore, according to this study, less compression stages than expansion is good for electricity generation and more compression stages is good for cooling supply. And for large heating supply demand, less compression is suggest. Besides, the energy efficiencies for different configurations of trigenerative ACAES are also achieved which are changed from 0.62 to 0.87 and the best configurations with highest system efficiency are also presented. Finally, by economic analysis, the most economic condition is achieved. • Single ACAES is used for trigenerative application to meet different energy demands. • Thermodynamic, exergy and economic analysis are used to perform the trigenerative application. • The energy efficiency of trigenerative ACAES is changed from 0.62 to 0.87. • The payback period of trigenerative ACAES is 3.4–6.8 years with different configurations. • The design guidance of compression stage, expansion stage, thermal storage are provided. [ABSTRACT FROM AUTHOR]

Nowadays, the integrated energy system (IES) has become a hot topic in the field of energy research. In this paper, a bi-level optimal configuration strategy is proposed for a community integrated energy system (CIES), which is based on energy supply-demand responses and robustness adjustable scenarios. First, from the perspective of energy supply and demand, various energy equipment on the community side and aggregated energy loads on the user side are analysed and qualitatively modeled, and a multi energy supply-demand of CIES is established. Next, according to the robustness requirements of IES planning, the scenario sampling, sorting, screening and reduction are performed subsequently to obtain a typical set of robustness adjustable scenarios. On this basis, a bi-level optimal configuration model that coordinates the aggregated configuration and operation is developed to design the CIES. While the upper-level model takes the lowest total annual cost as the goal to configure the quantity and capacity of energy equipment, the lower-level model optimizes the scheduling scheme with the aim of the best operation economy under typical scenarios. Finally, case studies are carried out based on a practical town area, and simulation results show the effectiveness and advantage of the proposed strategy. • A new energy supply-demand response model is developed. • A typical set of robustness adjustable scenarios is obtained for configuration. • A new bi-level optimal configuration strategy is proposed with coordinated planning and operation. • The economy, robustness, environmental protection and user interests are jointly considered. [ABSTRACT FROM AUTHOR]

Abstract: Since energy consumption in process industries accounts for a great proportion of China''s total energy consumption, energy conservation becomes the practical choice to reduce the conflict between energy demand and energy supply in China, and therefore, promoting energy conservation is the long-term solution to China''s energy and environment problems from the source. In this paper, based on the introduction of the concept of energy consumption status in China''s key energy-consuming process industries, the main technical bottlenecks and resource-environment problems were analyzed with special emphasis on energy utilization efficiency, energy consumption mode, and waste emission. As for the measures to resolve these problems, at the policy level, policies and programs of Chinese government related to energy conservation were introduced in combination with China''s circular economy structure. At the technical level, the key technologies and research progress to improve energy utilization efficiency, reducing energy consumption, as well as utilizing the resource of discharged wastes were reviewed. Finally, three typical cases of the development of circular economy at three levels, namely the chemical industry, metallurgical industry, and electric power industry, were studied for the enforcement of circular economy and energy conservation in China''s process industries. [Copyright &y& Elsevier]

Abstract: China''s total installed electrical power capacity reached 700GW by the end of 2007 and is predicted to surpass 900GW in 2010. The rapid increase in energy demand and increasing global warming have both pushed China to change its current electrical power structure where coal power accounts for nearly 75% of the total electric power generation. China has already become the world''s largest solar water heater producer and user. However, there is still much to be done in the solar thermal power field before its commercialization. Solar thermal power technologies including solar power towers, solar parabolic trough concentrators, solar dish/stirling systems, linear Fresnel reflectors, and solar chimneys have been studied in China since the 1980s. A 10kW dish/stirling project was funded by the Ministry of Science and Technology (MOST) during 2000–2005 with a 1MW solar power tower and research of trough concentrator metal–glass evacuated tubes supported during 2006–2010. This paper describes a continued solar thermal power development roadmap in China in 5-year intervals between 2006 and 2025. [Copyright &y& Elsevier]

Abstract: This paper presents an overview of the initiatives launched in energy supply and consumption and the challenges encountered in sustainable road transportation development in China. It analyzes the main energy challenges related to road transportation development arising in the context of economic development, rapid urbanization, and improvement in living standards. It also discusses technological- and policy initiatives needed to deal with these challenges, drawing comparisons with foreign experience: promoting the development and dissemination of alternative fuels and clean vehicles such as: LPG, CNG, EV, HEV, FCV, ethanol, methanol, DME, bio-diesel, and CTL, strengthening regulations relating to vehicle fuel economy and emission, improving traffic efficiency and facilitating public transport development, and strengthening management of the soaring motor vehicle population. If the current pattern continues, by the year 2030, the vehicle population in China will be 400million and fuel demand will be 350milliontons. The potential energy saving capacity being 60%, the actual oil demand by 2030 from on-road vehicles might technically be kept at the current level by improving fuel economy, propagating use of HEV and diesel vehicles, improving supply of alternative fuels, and developing public transport. Several uncertainties are identified that could greatly influence the effect of the technical proposals: traffic efficiency, central government''s resolve, and consumers'' choice. [Copyright &y& Elsevier]