The growing share of renewable energy sources drives the need for increased flexibility in the energy systems. The flexibility provision from thermal plants is limited by the boilerâ€™s thermal inertia as a bottleneck. Advanced controllers, such as model predictive control (MPC), have been identified as potential flexibility enablers. Fuel properties are crucial input for controllers. This work investigated the feasibility of using the properties obtained online by using near infrared spectroscopy based soft sensor to further improve the control performance. The performance of the existing proportional integral (PI) controller is compared with those of 2 feed forward (FF) MPC controllers. Both FF MPCs have significant improvement compared to PI controller and the FF MPC based on the full elemental composition shows the best performance due to more complete fuel information. There is a potential for revenues improvement with advanced control up to 1050 euros for one operation day.
A new solar-wind-fuel complementary distributed energy system (DES) is proposed, which is integrated with solar-fuel thermochemical conversion for efficient utilization of solar and wind energy. To address the source-load mismatch caused by intermittent and unstable solar and wind energy, a new multi-energy system consisting of solar, wind and fuel is proposed to maintain the energy supply, with the consideration of the characteristics of day-night and seasonal complementation of solar and wind energy. Through solar-driven methanol decomposition, solar energy is upgraded to high-quality chemical energy in the form of syngas for storage. The results show that the new DES can promote the integrated use of wind and solar energy, increase the proportion of renewable energy in the system and reduce CO2 emissions. Compared to conventional power grid and fuel direct combustion, the new DES achieves a 42.12% reduction in CO2 emission.
Crude oil is a major source of energy across the globe due to its diverse product derivatives for various industries and applications. However, the high CO2 emissions and energy requirements associated with its refining process threaten the goal of achieving carbon neutrality. The Crude Distillation Unit (CDU) has been identified as a major unit for CO2 emissions. Therefore, it is important to investigate the composition of feedstock (blended crude oil samples) fed to the CDU as a possible alternative to reducing CO2 emissions associated with refining. This study uses Aspen Hysys V12 with Aspen Energy Analyser to analyze different blended feedstock from six (6) different Nigerian crude oil; Brent, Bonga, Erha, Qua-Iboe, Usan, and Yoho. The result showed that Blend 1 had the highest CO2 emission linked to the high conversion of paraffin and naphthene to yield the highest Naphtha yield of 27.12 % compared to other blends. Blend 1 also had the highest CO2 emissions cost of $13.92 million/hr compared to $13.68 million/hr for Blend 7, with the lowest product yield. However, Blend 4 had the maximum heating energy requirement linked to its composition (mixtures of high medium and light crude ) which require more reactions to maximize yield. The result indicated that individual crude’s weight ratio in blended feedstock significantly increased Naphtha yield and affects CO2 emissions. Thus, blended feedstock composition will affect product yield, energy consumption, and CO2 emission due to the different compositions of individual crude. Therefore, to achieve the carbon neutrality goal, CO2 emission from individual crude oil needs to be investigated, develop a new model for optimum blending with fewer emissions and the CO2 emission cost should be added to blended feedstock price or individual crude cost to ensure a balance.
Calcium looping process (CaL) is a promising alternative for realizing low-energy-penalty of post-combustion technologies. This study investigates the CO2 enrichment difference of three types of calcium looping heating supply methods: calcium looping combustion (CaLC), oxy-fuel combustion (CaL-Oxy), and Cu-based chemical looping combustion (CaL-CLC). and the three calcium looping processes are integrated with power plant to evaluate the energy efficiency and energy penalty of the power plants with CO2 capture based on these calcium processes. The results show that the CaL-CLC has the highest energy efficiency (39.4%) and the lowest energy penalty (3.46%), which indicates that reducing the gas separation cost plays important role caused by CO2 enrichment in the heat supplying method of calcium looping process.
In order to reduce the frequency deviation and unit generation cost of an isolated microgrid, an adaptive load frequency control (ALFC) method is proposed in this paper. The method employs an adaptive proportional-integral-derivative (PID) controller to achieve adaptive control by adaptively adjusting the parameters of the controller to output the regulation command. In addition, to achieve adaptive regulation of the control parameters, a deep actor-critic (DAC) algorithm is proposed in this paper, which introduces multiple critics and Gaussian noise exploration techniques to enhance the quality of the ALFC strategy. The performance of the proposed method is tested in the Zhuzhou isolated microgrid of the China Southern Grid(CSG), which can effectively reduce frequency deviation and generation cost.
Microwave has a significant promotion effect in gas-solid phase catalysis due to its unque advantages of heating process. This study introduces an innovative approach that combines microwave irradiation with a structured foam catalyst, Co3O4@S1/SiC, to enhance the isopropanol-to-propylene (ITP) process. The effectiveness of Co3O4@S1/SiC foam was investigated under various reaction temperatures (50-200 Â°C) and space velocities (1200 h-1), in comparison to Co3O4@S1/SiC pellets. The Co3O4@S1/SiC foam exhibited superior performance, achieving a higher selectivity towards propylene (approximately 99%) compared to Co3O4@S1/SiC pellets (93%). This enhancement can be attributed to improved mass and heat transfers facilitated by the foam structure. Co3O4@S1/SiC foam for ITP process has a milder condition with microwave irradiation (121 Â°C for 90% conversion) than conventional heating (184 Â°C for 90% conversion).
Cu-based materials are effective electrocatalysts for converting carbon dioxide to ethylene. However, the hydrogen evolution reaction (HER) in aqueous solutions competes with the desired carbonaceous product, leading to poor selectivity. To overcome this issue, a PVDC coating was applied to a CuO electrode to regulate surface hydrophobicity, suppressing HER and promoting ethylene production. The influence of the PVDC layer on proton transfer and electrocatalyst stabilization was thoroughly investigated by varying the coating amount and order. The modified CuO electrode with a coating layer of only 50 Âµg/cm2 induced an optimal surface hydrophobicity (WCA=122Â°). It exhibited a highly efficient and selective ethylene production (FEC2H4=41.4%, |j|C2H4=6.8mA/cm2) and suppressed hydrogen evolution (FEH2=22.7%) at a low potential of -0.89V vs. RHE. The spent modified CuO electrode exhibited an increased presence of Cu+, facilitating the C-C coupling process. The stable hydrophobic properties and good electrical conductivity of PVDC-modified electrodes offer a simple and successful approach for advanced electrocatalyst development.
Carbon neutrality roadmaps for cities in developing countries are completely different from those in developed countries due to historical, social, and economic limitations. Taking Shanghai as a case, this study proposes a new framework for sustainable net-zero carbon transition of cities in developing countries by integrating multiple purposes within multiple sectors under carbon budget constraints. The results show that 1) the total carbon emissions of Shanghai decreased from 2010 to 2020 in general, with a historic peak in 2011; 2) under the traditional trajectory, reaching the peak before 2030 is difficult; while under the carbon-neutral scenario, carbon peak will be achieved before 2025, and carbon neutrality can be achieved by 2050; 3) Great efforts are needed even in the process of peaking carbon emissions, especially in industrial sectors; 4) the integration of technology innovation and policy mechanisms is crucial to realizing zero carbon target. 5) This study provides improved understanding of urban carbon peaking and neutrality process from a systematic perspective, which could potentially help accelerate the sustainable transition towards carbon neutrality for cities that face dual challenges of development and decarbonization.
Electric vehicles (EVs) have great impacts on power distribution networks due to their spatio-temporal characteristic, especially in urban areas. This paper proposes a framework for optimal planning of urban distribution network (UDN) and electric vehicle charging stations (EVCSs), in which the geographic information system (GIS) is combined to optimize investment decisions. By using hierarchical clustering and Voronoi diagram, the planning area is divided into several sub-areas. All the sub-area is converted into grid networks based on GIS, on which the EVs’ actual temporal charging demand is analyzed. The proposed mixed integer planning model utilizes the second-order cone programming for UDN and grid-based site selection of EVCS by considering the spatio-temporal characteristic of EVs. Case studies on an urban area in Shanghai, China demonstrate the effectiveness of the proposed method.
The solar thermochemical technology as a promising method can effectively convert concentrated solar thermal energy into the chemical form of syngas, and then realizes efficient renewable energy utilization. In this work, a solar-driven polygeneration system with the methane dry reforming based solar thermochemical process is developed, and the generated syngas is further utilized by the methanol synthesis module and the gas-steam combined power cycle, to achieve diverse energy outputs of methanol and electricity. Meanwhile, within the fluctuating solar irradiation, the fed methane can be flexibly adjusted to promote reasonable solar energy utilization and comprehensive system operation performances. Through the system off-design analysis, the favorable concentrating solar heat to chemical energy conversion effects can be achieved with the optimal system energy efficiency of 63.0%. During the typical day operation process, the solar share can reach to 25.1% with the real-time regulation complementation of solar energy and fossil fuel. While the annual system operation efficiency is up to 54.4% with a solar share of 21.0%, the system surplus solar energy can be readily stored by the liquid methanol fuel, and the system monthly methanol outputs capacity is 6.65-26.88 GWh. With the flexible regulation and combination of solar energy and chemical energy, efficient multi-energy generation can be achieved, which provides an alternative way to optimize solar conversion performances.