Development of a new solar,gasification and fuel cell based integrated plant

Despite its shortcomings, fossil-based fuels are still utilized as the main energy source, accounting for about 80% of the world's total energy supply with about one-third of which comes from coal. However, conventional coal-fired power plants emit relatively higher amounts of greenhouse gases, and the derivatives of air pollutants, which necessitates the integration of environmentally benign technologies into the conventional power plants. In the current study, a H₂–CO synthesis gas fueled solid oxide fuel cell (SOFC) is integrated to the coal-fired combined cycle along with a concentrated solar energy system for the purpose of promoting the cleaner energy applications in the fossil fuel-based power plants. The underlying motivation of the present study is to propose a novel design for a conventional coal-fired combined cycle without altering its main infrastructure to make its environmentally hazardous nature more ecofriendly. The proposed SOFC integrated coal-fired combined cycle is modeled thermodynamically for different types of coals, namely pet coke, Powder River Basin (PRB) coal, lignite and anthracite using the Engineering Equation Solver (EES) and the Ebsilon software packages. The current results show that the designed hybrid energy system provide higher performance with higher energy and exergy efficiencies ranging from 70.6% to 72.7% energetically and from 35.5% to 43.8% exergetically. In addition, carbon dioxide emissions are reduced varying between 18.31 kg/s and 30.09 kg/s depending on the selected coal type, under the assumption of 10 kg per second fuel inlet.     

Simulation of hydrogen and coal gas fueled flat-tubular solid oxide fuel cell (FT-SOFC)

Solid oxide fuel cells (SOFCs) are considered an important technology in terms of high efficiency and clean energy generation. Flat-tubular solid oxide fuel cell (FT-SOFC) which is a combination of tubular and planar cell geometries stands out with its performance values and low costs. In this study, the performance of an FT-SOFC is analyzed numerically by using finite element method-based design as a result of changing parameters by using different fuels which are pure hydrogen and coal gas with various proportions of CO. In addition, cell performance values for different temperatures were analyzed and interpreted. Analyzes have been performed by using COMSOL Multiphysics software. The rates of CO composition used are 10%, 20%, and 40%, respectively. In addition, the air was used as the oxidizer in all cases. The cell voltage and average cell power of the FT-SOFC were examined under the 800 °C operating condition. The maximum power value and current density value were obtained as 710 W/m² and 1420 A/m² for the flat-tubular cell, respectively. As a result of the study, it was observed that the maximum cell power densities increased with increasing temperature. Analysis results showed that FT-SOFCs have suitable properties for different fuel usage and different operating temperatures. High-performance values and design features in different operating conditions are expected to make FT-SOFC the focus of many studies in the future.     

Development of ceramic fiber reinforced glass ceramic sealants for microtubular solid oxide fuel cells

Ceramic fibers in various forms with different fiber sizes are tested to improve the sealing performance of glass ceramic seals for microtubular solid oxide fuel cell applications. In this regard, several sealing pastes are prepared by mixing each ceramic fibers type with glass ceramics at 1.25 wt %. Five layered microtubular anode supported cells are also fabricated by extrusion and dip coating methods to evaluate the sealing performance of the composite sealants. The pastes are applied between the cells and gas manifolds made of Crofer22 APU. The electrochemical and sealing performances at an operating temperature of 800 °C under hydrogen are investigated after the glass forming process. Microstructures of the sealants are also examined by a scanning electron microscope. Experimental investigations reveal that the cells sealed by the pastes with ceramic bulk fiber and ceramic fiber rope gasket show acceptable open circuit potentials close to the theoretical one. These cells can be also pressurized up to around 150 kPa back pressure in the sealing performance tests. On the other hand, the pastes without any filler, with ceramic rope and with ceramic blanket exhibit poor sealing performance due to gas leakage originated from flowing of the main glass ceramic matrix from the joints. Therefore, ceramic bulk fiber and ceramic fiber rope gasket are found to behave as a stopper and can be used to prevent glass ceramics from flowing for microtubular solid oxide fuel cells or similar applications.     

Electrochemical performance and distribution of relaxation times analysis of tungsten stabilized La0·5Sr0·5Fe0·9W0·1O3-δ electrode for symmetric solid oxide fuel cells

W-doped La_0·5Sr_0·5Fe_0·9W_0·1O_3-δ (LSFW) was prepared and evaluated as a symmetric electrode for solid oxide fuel cells (SSOFCs). Phase and structural stability of LSFW under both reducing and oxidizing atmospheres was studied. The oxygen reduction reaction (ORR) and hydrogen oxidation reaction (HOR) mechanisms were investigated by using electrochemical impedance spectra (EIS) and distribution of relaxation times (DRT). Electrode polarization resistance (R_p) of LSFW are 0.08 and 0.16 Ω cm² in air and wet hydrogen at 800 °C, respectively. DRT results indicate that the rate-limiting step of LSFW at 800 °C in cathodic conditions and anodic conditions are related to oxygen diffusion and hydrogen adsorption/diffusion, respectively. A La_0·8Sr_0.2Ga_0.8Mg_0·2O_3-δ (LSGM) electrolyte-supported single cell using LSFW electrodes shows a maximum power density of 617.3 mW cm⁻² at 800 °C with considerable stability and reversibility, which enables LSFW a promising SOFCs symmetric electrode material.     

Energy analysis of the system of two-stage anaerobic processing of liquid organic waste with production of hydrogen- and methane-containing biogases

In recent years, public attention has been increasingly attracted to solving two inextricably linked problems - preventing the depletion of natural resources and protecting the environment from anthropogenic pollution. The annual consumption of livestock waste for biogas production is about 240 thousand m³ per year, which is 0.17% of the total manure produced at Russian agricultural enterprises. At present, the actual use of organic waste potentially suitable for biogas production is 2–3 orders of magnitude lower than the existing potential for organic waste. Currently, hydrogen energy is gaining immense popularity in the world due to the problem of depletion of non-renewable energy sources - hydrocarbons, and environmental pollution caused by their increasing consumption. Of particular interest is the dark process of producing hydrogen-containing biogas in the processing of organic waste under anaerobic conditions, which allows you to take advantage of both energy production and solving the problem of organic waste disposal. An energy analysis of a two-stage anaerobic liquid organic waste processing system with the production of hydrogen- and methane-containing biogases based on experimental data obtained in a laboratory plant with increased volume reactors was performed. The energy efficiency of the system is in the range of 1.91–2.74. Maximum energy efficiency was observed with a hydraulic retention time of 2.5 days in a dark fermentation reactor. The cost of electricity to produce 1 m³ of hydrogen was 1.093 kW·h with a hydraulic retention time of 2.5 days in the dark fermentation reactor. When the hydraulic retention time in the dark fermentation reactor was 1 day, the specific (in ratio to the processing rate of organic waste) energy costs to produce of 1 m³ of hydrogen were minimal in the considered hrt range, and amounted to 26 (W/m³ of hydrogen)/(m³ of waste/day). Thus, the system of two-stage anaerobic processing of liquid organic waste to produce hydrogen and methane-containing biogases is an energy-efficient way to both produce hydrogen and process organic waste.     

Extraction of protein from food waste: An overview of current status and opportunities

The chief intent of this review is to explain the different extraction techniques and efficiencies for the recovery of protein from food waste (FW) sources. Although FW is not a new concept, increasing concerns about chronic hunger, nutritional deficiency, food security, and sustainability have intensified attention on alternative and sustainable sources of protein for food and feed. Initiatives to extract and utilize protein from FW on a commercial scale have been undertaken, mainly in the developed countries, but they remain largely underutilized and generally suited for low-quality products. The current analysis reveals the extraction of protein from FW is a many-sided (complex) issue, and that identifies for a stronger and extensive integration of diverse extraction perspectives, focusing on nutritional quality, yield, and functionality of the isolated protein as a valued recycled ingredient.     

Enhanced and stable strontium and cobalt free A-site deficient La1-xNi0.6Fe0.4O3 (x=0, 0.02, 0.04, 0.06, 0.08) cathodes for intermediate temperature solid oxide fuel cells

Perovskite oxides with cobalt and strontium element exhibit severe degradation during the operation for the solid oxide fuel cells (SOFC). Here, we report stable non-cobalt and non-strontium La_1-xNi_0.6Fe_0.4O₃ perovskite cathodes with improved oxygen reduction reaction (ORR) activity. A-site deficient La_1-xNi_0.6Fe_0.4O₃ cathodes within 8 at.% all exhibit the invariable phase structure with LaNi_0.6Fe_0.4O₃ (LNF), and the matched thermal expansion coefficient with that of the (Ce_0.90Gd_0.10)O_1.95 (GDC) electrolyte. The polarization resistance of the La_0.94Ni_0.6Fe_0.4O₃ (LNF94) cathode is 0.61 Ω cm² at 750 °C in air, which is 1/5 of the LaNi_0.6Fe_0.4O₃ (2.78 Ω cm²). The peak power density of the corresponding single cell with LNF94 cathode is 0.37 W cm⁻² at 750 °C, which is 2.36 times higher than that of the single cell with LNF cathode (0.11 W cm⁻²). We further study the long-term stability of LNF and LNF94 cathodes, the polarization resistance of the LNF94 electrode slightly fluctuates around 0.18 Ω cm² during 50 h operation at 800 °C, while the polarization resistance of the LNF increases by about 15%. This work highlights the A-site deficient LNF as an effective and stable non-cobalt and non-strontium cathode for the intermediate temperature solid oxide fuel cells.     

Investigation of surficial and interfacial properties of BaCo0.4Fe0.4Zr0.1Y0.1O3-δ cathode directly on yttria-stabilized zirconia electrolyte for solid oxide fuel cell

The cobalt/iron-containing perovskites are the most promising cathodes for the intermediate-temperature solid oxide fuel cell (IT-SOFC). However, these cathodes are generally not directly applied on the currently available commercial yttria-stabilized zirconia (YSZ) electrolyte due to the issues of over-firing, harmful reaction and thermal incompatibility. BaCo_0.4Fe_0.4Zr_0.1Y_0.1O_3-δ (BCFZY) which contains both zirconium and yttrium ions can theoretically be more compatible with the YSZ electrolyte. This paper focuses on the surficial and interfacial properties of BCFZY directly prepared with YSZ under different conditions. The surface of BCFZY by the glycine-nitrate process (GNP) can form the nanoparticles in contrast to that by solid-state reaction (SSR). The peak power density of the cell with BCFZY-GNP cathode directly on YSZ electrolyte can reach 1250 mW cm⁻² at 750 °C, which is hardly achieved on the reported traditional cobalt/iron-containing cathodes. It is proved that BCFZY-GNP cathode fired at 900 °C can show more distinct nanoparticles with extensive specific surface area and better BCFZY|YSZ interface, which can promote both oxygen exchange and ion incorporation processes.     

Do people put more value on electricity produced using waste-to-hydrogen? Findings from South Korea

South Korea is pushing for the waste-to-hydrogen (W2H) project to reduce greenhouse gases and utilize plastic and vinyl waste (PVW) while reducing environmental pollution from PVW. This research seeks to estimate additional willingness to pay (WTP) for electricity produced using W2H over that produced using traditional power sources, such as coal and nuclear. For the purpose of the estimation, a contingent valuation survey of 1000 people was performed employing the closed-ended one-and-one-half-bound question during November 2020. A spike model is utilized to reflect zero WTP values that a number of interviewees reported in the survey. Several factors affecting the additional WTP were also analyzed to derive implications. The average WTP was computed as KRW 27.7 (USD 0.025) per kWh with statistical significance, which reaches 26.4% of the electricity price. One more point to note is that 54.3% of the respondents stated a zero WTP as they thought that W2H is of no value to them or were worried that the W2H project could increase electricity bills.     

A distributed energy system integrating SOFC-MGT with mid-and-low temperature solar thermochemical hydrogen fuel production

Solar thermochemical hydrogen production with energy level upgraded from solar thermal to chemical energy shows great potential. By integrating mid-and-low temperature solar thermochemistry and solid oxide fuel cells, in this paper, a new distributed energy system combining power, cooling, and heating is proposed and analyzed from thermodynamic, energy and exergy viewpoints. Different from the high temperature solar thermochemistry (above 1073.15 K), the mid-and-low temperature solar thermochemistry utilizes concentrated solar thermal (473.15–573.15 K) to drive methanol decomposition reaction, reducing irreversible heat collection loss. The produced hydrogen-rich fuel is converted into power through solid oxide fuel cells and micro gas turbines successively, realizing the cascaded utilization of fuel and solar energy. Numerical simulation is conducted to investigate the system thermodynamic performances under design and off-design conditions. Promising results reveal that solar-to-hydrogen and net solar-to-electricity efficiencies reach 66.26% and 40.93%, respectively. With the solar thermochemical conversion and hydrogen-rich fuel cascade utilization, the system exergy and overall energy efficiencies reach 59.76% and 80.74%, respectively. This research may provide a pathway for efficient hydrogen-rich fuel production and power generation.