Efficient Utilization Of Renewable Energy Research Articles

Progresses and Challenges of Renewable Energy Development in Northeast China

Renewable energy development in Northeast China has rapidly accelerated over the past decade. The purpose of the paper is to present the status, achievements, and challenges of renewable energy development in Northeast China by conducting a detailed review of relevant studies. The growth in renewable energy, especially wind and biomass power, has contributed to the decarbonization of electric power in the region and enabled the rise of related industries. However, its further development is facing severe challenges in terms of inefficient utilization and low economic return, which has led to energy waste and has created burdens for local economic development. Currently, the biggest barrier to further development of renewable energy in Northeast China is not production capability but rather the efficient utilization of renewable energy. Therefore, achieving a balance between production and consumption and improving economic efficiency are important for the sustainability of renewable energy development in Northeast China.

Room Temperature Synthesized Hybrid Open Frameworks for Li-Ion Battery Cathodes

Li-ion batteries (LIBs) have been the most promising battery technology owing to their large energy density, environmental friendliness and design flexibility. LIBs have been dominating the rechargeable battery market fue to their advantages and they found application in various electonic gadgets. Large scale utilization of LIBs is anticipated in the near future for efficient utilization of renewable energy as there is gap between energy supply and demand. As solar radiation is available during daytime, the peak energy demand is at night. In addition, LIBs are expected to push forward the production of eco-friendly transportation such as electric vehicles (EVs) and hybrid electric vehicles (HEVs). Transformation from conventional vehicles to EVs are mainly hindered by the high upfront price of the EVs which are mainly due to the high cost of the battery packs used to power these vehicles. Hence, cost reduction of LIBs is one of the major strategies to bring forth the EVs to compete in the market with their gasoline counterparts. In our attempt to produce cheaper high-performance cathode materials for LIBs, a Graphene/MOPOF (Metal Organophosphate Open Framework) [1-3] nanocomposite with ~4 V of operation has been developed by a cost effective room temperature synthesis that does not require any expensive post-synthetic treatments at high temperature in inert atmospheres like Ar/Ar-H2. These open frameworks has a layered structure with each layer made of metal phosphate cross-linked by oxalate. Presence of alkali ions in the interlayer space with a redox system helpes in the reversible extraction of them, making it a feasible cathode material. Though the pristine material undergoes reversible lithium storage, there was capacity fading. Enhanced lithium cycling with minimal capacity fading was witnessed with the graphene nanocomposite owing to the increased electronic conductivity and enhanced Li diffusivity. Stable reversible capacity of ~100 mAh g-1 were obtained. Refereces A. Shahul Hameed, M. V. Reddy, M. Nagarathinam, Tomče Runčevski, Robert E Dinnebier, Stefan Adams, B. V. R. Chowdari and Jagadese J. Vittal, Sci. Rep., 2015, 5, 16270. A. Shahul Hameed, M. Nagarathinam, Martin Schreyer, M. V. Reddy, B. V. R. Chowdari and Jagadese J. Vittal, J. Mater. Chem. A, 2013, 1, 5721-5726.M. Nagarathinam, K. Saravanan, E. J. H. Phua, M. V. Reddy,B. V. R. Chowdari and J. J. Vittal, Angew. Chem., Int. Ed., 2012, 51, 5866–5870.

Autonomous Active Power Control for Islanded AC Microgrids With Photovoltaic Generation and Energy Storage System

In an islanded ac microgrid with distributed energy storage system (ESS), photovoltaic (PV) generation, and loads, a coordinated active power regulation is required to ensure efficient utilization of renewable energy, while keeping the ESS from overcharge and overdischarge conditions. In this study, an autonomous active power control strategy is proposed for ac-islanded microgrids in order to achieve power management in a decentralized manner. The proposed control algorithm is based on frequency bus-signaling of ESS and uses only local measurements for power distribution among microgrid elements. Moreover, this study also presents a hierarchical control structure for ac microgrids that is able to integrate the ESS, PV systems, and loads. Hereby, basic power management function is realized locally in primary level, while strict frequency regulation can be achieved by using additional secondary controller. Finally, real-time simulation results under various state of charge (SoC) and irradiance conditions are presented in order to prove the validity of the proposed approach.

Application and Analysis of Multi-Source Hybrid Distributed Energy System

Under the background of the global energy crisis and environmental issues, the efficient utilization of renewable energy as a kind of distributed energy resources, is paid more and more attention. However, the intermittency and unpredictability of the renewable energies limit its development and penetration. To deal with such a big challenge, the multi-source hybrid distributed energy system has been proposed. In this paper, the concept and characteristics of the multi-source hybrid distributed energy system are discussed. In addition, three main forms of the proposed innovation energy system are presents and compared.

The Research on the Influence Law on Thermal Resistance of Borehole

GSHP are of strategic and necessary part for the efficient utilization of renewable energy and energy conservation. Vertical ground heat exchanger system is one form of GSHP and it is a way to solve the problem of the imbalance between cooling load and heating load except for some extreme hot or cold climate areas. In the paper, the study of underground heat exchanger heat transfer mode, and the influence law of the borehole diameter, shank spacing, and grout conductivities on thermal resistance of borehole are discussed systematically.

Adequacy Evaluation of Wind-PV-ES Hybrid Power System

Renewable energy resources such as wind, wave, solar and biomass are becoming more important, and Wind-PV-ES hybrid power system is a promising and efficient utilization of renewable energy. Based on the sequential Monte-Carlo simulation approach, an evaluation model of Wind-PV-ES hybrid generation system is built, and storage time series model is optimized. Lastly, the effectiveness and feasibility of the proposed model is verified by a practical example, and the system impacts of PV penetration level, energy storage capacity and rated output power are illustrated.

Renewable energy utilization evaluation method in green buildings

Utilizing renewable energy (RE) is an important part of the design and development of green buildings. However, it is unreasonable to assess renewable energy utilization (REU) only with the net ratio of end-use energy provided by the renewable energy system to a building's total energy consumption, but ignoring the system efficiency of REU with the necessary extra conventional energy consumption, such as electricity. In this paper, the energy quality coefficient (EQC) is introduced to describe the quality of energy, while the energy conversion coefficient (ECC) is applied to evaluate energy system efficiency. The indexes and their expressions were developed based on exergy analysis. Based on these two indexes, an effective substitution ratio (ESR) was developed for the evaluation of REU. Furthermore, the ESR of utilizing RE to substitute for single type and multiple types of conventional energy is discussed. Finally, case studies were conducted and some conclusions were drawn from the results for application of RE in buildings.

Analyzing the Energy Utilization Efficiency of Renewable Energy Resources. Part 1: Energy Analysis Method

Energy consumption depends mainly on the available amounts of local resources, which are closely connected with the present rural economy and living standards. Recently, there has been increasing interest in using energy and exergy modeling techniques for energy utilization assessments in order to attain energy savings, and hence financial savings. The energy utilization of a country can be evaluated using exergy analysis to gain insights into its efficiency. The present study, consisting of two parts, deals with analyzing the energy utilization efficiency of renewable energy resources (RERs). Part 1 uses energy analysis method, while exergy analysis method is applied to Part 2. In the analysis, Turkey with a projected population of 76,840,418 in 2010, is given as an illustrative example. RERs considered are residential-commercial and industrial subsectors used in the Turkish conversion. The energy efficiency values for Turkey's RERs are projected to be 60.99% in 2010. Besides this, total energy utilization efficiency values for those are expected to be 49.85% in the same year. The present study has clearly indicated the necessity of the planned studies towards increasing renewable energy utilization efficiency in the sub-sectors studied and especially the critical role of policymakers in establishing effective energy-efficiency delivery mechanisms throughout the country. It is also expected that this study will fill a considerably large gap since it is the first attempt towards analyzing Turkey's RERs in 2010 in terms of energy utilization efficiencies.