Abstract

Exploring sustainable energy supply and effective solid waste disposal methods is becoming a challenge around the world. Refuse derived fuel (RDF) has been proposed as a potential alternative to coal, natural gas, oil, and coke due to its advantages of higher calorific value than original wastes, uniform composition in both physical and chemical aspects, transportation and storage, simplicity, low emission rate, and less extra air demand during combustion. However, the applicability of RDF in a given region needs to be evaluated by the combination of market analysis and political conditions. Based on the background research of Ningbo, an important industrial city in China, this paper analyzes and evaluates the energy structure, market potential of RDF and its sources in Ningbo, showing that the area has a demand for more than 7 million tons of RDF per year and is suitable for promoting and applying RDF as the alternative to coal.

Abstract

Carbon sequestration — is an important method to achieve carbon neutrality and resist climate change. Burying CO2 in the depth of geological structure and solidifying it into hydrate is a promising carbon sequestration technology. The development of hydrate- based CO2 sequestration requires greater CO2 storage capacity and mild thermodynamics. In this study, 1,3- dioxolane (DIOX) was introduced as the hydrate thermodynamic promoter. The effect of the DIOX-water system lowers than the stoichiometric concentration on the formation of CO2-DIOX mixed hydrate was evaluated by measuring phase equilibrium and formation kinetics. The results show that DIOX shows thermodynamic promotion to CO2 enclathration. Even at the ultra-low concentration (0.15 mol%), the system still maintains a phase equilibrium pressure shift of 0.45 MPa. Compared with the system of 5.56 mol%, the system of 3.00 mol% has better formation kinetics; the 0.15 mol% system still maintains considerable CO2 storage capacity (56.0 mmol/mol). The study of low concentration DIOX not only has a practical significance of the passive decline in promoter concentration on large-scale carbon sequestration but also meets the requirements of environmental protection and economy in the use of the thermodynamic promoter.

Abstract

Carbon capture is gathering the momentum to achieve the target of carbon neutrality. However, common carbon capture technology e.g. absorption technology has a very high regeneration energy which leads to the loss of thermal efficiency when retrofitting for the plant. This paper initially proposes a general concept of sorption carbon capture technology with heat pump and explore the performance of adsorption carbon capture integrated with compression heat pump as a case study. Activated carbon is selected as the adsorbent for temperature swing adsorption (TSA). Results indicates that theoretical exergy efficiency of 4-step TSA cycle ranges from 0.05 to 0.16 at different adsorption and desorption temperatures. Net efficiencies of coal-fired plant using adsorption capture technologies range from 35.1% to 35.4% when desorption temperature rises from 50oC to 70oC. Also levelized cost of electricity of coal-fired plant using activated carbon ranges from 50.5 USD·MWh-1 to 50.9 USD·MWh-1 which has a marginal increase at different desorption temperatures. The result is about 6% lower than that using Monoethanolamine. It is demonstrated that adsorption capture for coal-fired plant may be a promising solution to reduce the energy consumption in the near future.

Abstract

In view of burgeoning carbon dioxide (CO2) emission, adsorption post-combustion capture technology has drawn more attention. As the most critical part of capture technology, the selectivity of adsorbents with superb performance and appropriate economic benefit becomes a study hot button. Therefore, a new commercial biomass-derived activated carbon, i.e. coconut shell (CS), is developed, investigating the effects of adsorption and desorption temperatures for practical applications. Also, a solar-assisted coal-fired power plant integrated with temperature swing adsorption process is initially proposed for techno-economic assessment. Results show that CS has an excellent low-temperature adsorption capacity (1.19 mmol·g-1 at 0 ℃) and a relatively low desorption temperature (1.13 mmol·g-1 at 80 ℃). Compared with the system using monoethanolamine and zeolite 13X, carbon emission intensity, levelized cost of electricity and cost of CO2 removed of the system using CS always show the best performances, corresponding to 93.19 g·kWh-1, 62.32 USD·MWh-1 and 18.67 USD·tonCO2-1, respectively. CS may be a potential solution for carbon capture with low capital costs, low regeneration temperatures and high adsorption capacities.

Abstract

Around microgrid with PV and energy storage system, this paper adopts a module-level configuration scheme and proposes coordinated control strategy to further release the potential of PV power generation and promote the efficient operation of energy storage unit. Firstly, aiming at the ‘barrel effect’ caused by PV module mismatch and low efficiency of energy storage converter, the module-level PV power optimizer and the energy storage partial power converter are configured respectively to maximize the utilization of solar energy and electrical energy. Secondly, the multi_x0002_mode switching of PV array and energy storage unit under on/off-grid conditions is discussed, and a coordinated control strategy of microgrid with PV and energy storage system is proposed to realize the smooth switching and power automatic distribution of each unit in different control modes. Finally, a 30kW microgrid with PV and energy storage system simulation platform is built by using Matlab/Simulink to verify the feasibility and effectiveness of the proposed coordinated control strategy.

Abstract

The characteristics of synchronous generator can be emulated by power electronic devices to provide moment of inertia and damping for the power grid. It is considered an effective way to connect sustainable energy generation to the power grid. If the voltage of grid-connection point drops because of power grid failure, it may lead to overcurrent, unbalance and instability for virtual synchronous generator (VSG). Therefore, a low-voltage ride-through (LVRT) control strategy for VSG is proposed in the paper. The power loop of VSG is analyzed based on the small-signal model. When an asymmetric fault occurs in the power grid, the positive and negative sequence current control is performed to achieve output current balance. The transient and steady current can be restrained by extra virtual reactance. At the same time, the reactive power is increased to support power grid voltage and the active power is decreased to restrain the steady current and improve the stability. The simulation and experimental results show that the control strategy is effective.

Abstract

With the development of renewable energy, proton exchange membrane fuel cells (PEMFCs) are considered as a promising candidate of next-generation energy conversion. While the design of proton exchange membranes (PEMs) have been considerably investigated over the last decades, the performance and durability are still issues in PEMFCs. We have synthesized a series of sulfonated poly(arylene perfluoroalkylene)s with well-developed morphology, high proton conductivity, good fuel cell performance and excellent oxidative stability. The relationship among the chemical structures, bulk membrane properties and fuel cell performance is discussed and reviewed. The properties of those membranes are compared with the-state-of-the-art PEM (perfluorosulfonic acid).

Abstract

Paris Agreement has prompted the world for using clean energy. Biomass Solid Recovered Fuel (SRF) has the potential to substitute fossil fuel for supplying energy. However, several problems such as slagging, fouling, abrasion, and corrosion need to be investigated before applying SRF as fuel. This study was conducted to evaluate slagging, fouling, abrasion, and corrosion potential in blending Indonesian coals with SRF by using an initial prediction calculation based on ash characteristics. Indonesian coals (MRC Coal and LRC Coal) and SRF was blended with various composition. 50% MRC Coal and 50% LRC Coal was blended to obtain A Coal. Then, blending 5%-25% SRF with A Coal was conducted to obtain other coals. Then, the risk level of those potentials was classified based on a certain score. High slagging risk and medium fouling risk were obtained in blending Indonesian coal with 25% SRF. However, the use of 20% SRF in a blend of Indonesian coal and SRF is still safe although it could increase the slagging potential to medium risk. Increased risk of abrasion and corrosion was not found in any composition.

Abstract

Using Data from China from 1995 to 2019, a Logarithmic Mean Divisia Index (LMDI) method is used to explore the impact of seven structural factors (including the production scales, energy intensity, industrial structure, income level, urbanization rate, and population size) and six sectors on the energy transition. The following basic conclusions are drawn: (1) The effect of China’s energy transition is significant. During the study period, China’s clean energy consumption continued to grow, with an average annual growth rate of 16.13%. (2) The impact of each driving factor on the energy transition varies. The production scale factor is the most important factor that promotes the energy transition, the energy intensity effect is the main factor that inhibits the energy transition, and the inhibiting effect of the energy intensity on the production sector is significantly higher than that of the residential sector. The influence of industrial structure changed from inhibition to promotion. The income level plays a promoting role, and the contribution value gradually increases. The factors of urbanization level and population size promote the energy transition, but their impact is relatively small. (3) Different driving factors have different impacts on the energy transition in different sectors. The service industry and industry are the sectors with the highest clean energy consumption in China.

Abstract

This study proposes two configurations of deep integrating low-grade thermal energy during the discharge process of the Carnot battery. The thermodynamic and economic models for pump thermal energy storage, which integrates low-grade thermal energy on charge and discharge processes, are established. The genetic algorithm is used to obtain the optimal operating performance of the proposed Carnot battery, and a comparative analysis is carried out under different design conditions. The results show that the deep thermal integration can significantly improve the operating performance of the Carnot battery during the discharge process. The operating performance of different configurations is significantly affected by the design charging load.