Abstract

A new geospatial multi-criteria decision analysis method with spatial regression was proposed and implemented to identify Japan’s high-quality onshore wind energy potential in 2030. After identifying the economic potential of grid-connected onshore wind with a GIS-based multicriteria method, logistic regression and Conditional Autoregressive (CAR) regression was used to create a predictive model of development probability and evaluated with ROC curve. Other than economic costs, the model showed other physical, environmental, social factors, and spatial heterogeneity are incorporated to rank the overall quality of potential. The results also showed far more high-quality onshore wind potential exists in Japan than the 10 GW target in 2030.

Abstract

We designed, simulated, and analyzed a gas-fired heat-driven duplex Stirling domestic-combined heat and power system in order to alleviate the energy crisis and improve the efficiency of energy utilization. With the hot-end temperature of the Stirling engine fixed at 650℃ and the temperatures of the heat supply and the surroundings fixed at 60 ℃ and 0 ℃ , respectively, the duplex Stirling machine can achieve an output heating power of 5115W and an output electrical power of 79.2W, corresponding to a relative Carnot efficiency of 44.53%. The output characteristics and efficiency of the system are greatly affected by the hot-end temperature, the surrounding temperature and the average pressure. In addition, our calculations show that optimal performance under different working conditions can be obtained by adjusting the electrical resistance.

Abstract

Photovoltaic thermal (PV/T) system is a well-engineered extension of photovoltaic (PV) technology to get both heat and electricity. Heat exchanger (flow channel) extract heat from the PV cells by heat transfer fluid for thermal applications. Material used to fabricate the flow channel has a vital impact on effective heat removal. In the present research, effect of flow channel material on heat transfer rate and PV/T performance has been investigated experimentally for copper and aluminum based PV/T system under the same ambient condition. Maximum PV/T thermal efficiency attained are 71% and 70% for copper and aluminum channel respectively where the aluminum based PV/T is about 2.5 times cheaper than copper based PV/T. It can be concluded that aluminum based PV/T is more cost-effective.

Abstract

The efficiency of high-loaded axial turbines significantly influences the performance of Compressed Air Energy Storage (CAES) system. In present study, the effect of bowed stator on aerodynamic performance of a turbine is investigated by further considering structural strength of rotor. A fluid-structure interaction model is thus proposed, and the variation of isentropic efficiency, mass flow rate, stress and deformation of rotor with bowed parameters of stator are revealed. The bowed stator with bowed angle of 15 and normalized bowed height of 0.3 are suitable in present study, which also increases the isentropic efficiency at variable operation condition without influencing the stress significantly. The obtained results can provide a useful guide for design, optimization and application of the turbine in CAES system.

Abstract

Cities are requiring more energy by increasing the population. Among urban elements, buildings account for about 40% of energy demands and 30% of carbon dioxide emissions globally. To address the increasing energy demands and environmental responsibility from the population growth, existing buildings should be transformed into high energy efficient forms while satisfying human comfort. This research explores a transformative model optimizing energy balance and indoor thermal comfort based on building forms. The transformative model is built based on analyzing 903 buildings in Sumida-ward, Tokyo, Japan. The result enables city planners to predict urban building performance based on planning or designing building typologies. The model can contribute to planning an optimal urban buildings’ retrofitting or redevelopment for future smart and sustainable communities.

Abstract

The surge in atmospheric carbon dioxide has become a major contributor to the global warming effect. Using geology for CO2 capture and storage (CCS) has been identified as a new and highly efficient mitigation measure. Hydrate-based CO2 capture and storage is a promising technology for capturing CO2 from the plants and storageing CO2 as hydrate. The barriers for the new technology is the low formation rate and high energy cost. The purpose of this review is to summarize the influence of various nanoparticles on CO2 hydrate, and to understand the influence mechanism of different nanoparticles on CO2 hydrate, so as to provide a reasonable basis for future research.

Abstract

The implementation of CO2 capture and sequestration (CCS) in deep saline aquifers can reduce greenhouse gas emissions effectively. The diffusion and dissolution of CO2 in heterogeneous shallow aquifer is an important area for mass transfer. In order to investigate the effect of gas-water migration in this layer, we carried out experiments at core-scale by using of Magnetic Resonance Imaging (MRI) and pore-scale by using of microfluidic chip. This study place emphasis on CO2 migration process, including displacement interface change and dissolution regular in several pores. CO2 saturation is quantitative analyzed respectively at two scale. The continuous phenomenon of drainage-dissolution-drainage process at pore scale was found, which cannot observable at pore scale. The dissolution of CO2 in limited number pores is observed with qualitative description. The fact proves that the combination of multiple scales can give more comprehensive analysis. These studies can give some implications for the long-term safety of CCS in some degree.

Abstract

With the development of power system technology, multi-terminal DC transmission based on voltage source converter has gradually become a superior choice for power transmission because of its decoupling control ability. Most studies about AC/DC power flow presented in the literatures use iterative method and nonlinear models. Work on linearization steady state model is still insufficient. An approximate linearized power flow model for VSC based AC/DC grid using logarithmic transform of voltage magnitudes (LTVM) is proposed in this paper. The model of AC/DC system and VSC are established. The logarithm of voltage magnitude is utilized as independent variables of power flow equations. This technique transforms the power flow equations of AC/DC grid from (V, θ, U) space to (v, θ, u) space, which makes power flow equations a set of linear equations. Simulation of the proposed method and classic iterative algorithm is performed in several test systems. The results demonstrate the validity and accuracy of the proposed method.

Abstract

Energy efficiency is deemed to play a crucial role in improving sustainability. Within the current debate on the design of more effective policies to promote energy efficiency in industry and society, the aim of this paper is to carry out an exhaustive evaluation of the Italian tax relief scheme by a specifically developed comprehensive multi-stakeholder cost-benefit evaluation framework. The framework considers the entire set of stakeholders involved in a broad set of cost-benefit items. The application of the evaluation framework in the Italian context shows that tax relief scheme had a positive impact for energy users and players in the energy efficiency value chain, while the State and energy utilities suffered from a negative cost-benefit balance. In particular, results seem to call for a business model transformation for the energy efficiency value chain, where utilities may counterbalance a reduction in their original business (marketed energy) through a greater role in offering energy efficiency value-added services to final users. The findings, beside providing policy-makers with useful insights on the (re)design of energy efficiency incentive mechanisms, also contribute to future academic research on the topic.

Abstract

This paper reviewed seasonal sensible heat storage which is the most mature storage concept from technical and economic points of view. The results showed that tank storage and pit storage have higher storage capacity and less geological requirements, while borehole storage and aquifer storage are more economically effective.