P2H Modeling and Operation in the Microgrid Under Coupled Electricity–Hydrogen Markets

The uncertainty and volatility of wind power have led to large-scale wind curtailment during grid connections. The adoption of power-to-hydrogen (P2H) system in a microgrid (MG) can mitigate the renewable curtailment by hydrogen conversion and storage. This paper conducts unified modeling for different types of P2H systems and considers the multi-energy trading in a hydrogen-coupled power market. The proposed bi-level equilibrium model is beneficial to minimize the energy cost of microgrids. Firstly, a microgrid operation model applied to different P2H systems including an alkaline electrolysis cell (AEC), a proton exchange membrane electrolysis cell (PEMEC), or a solid oxide electrolysis cell (SOEC) is proposed at the upper level. Secondly, an electricity market–clearing model and a hydrogen market model are constructed at the lower level. Then, the diagonalization algorithm is adopted to solve the multi-market equilibrium problem. Finally, case studies based on an IEEE 14-bus system are conducted to validate the proposed model, and the results show that the microgrid with a P2H system could gain more profits and help increase the renewable penetration.

CATALYTIC PROPERTIES OF Ni-V COATING IN THE PROCESS OF HYDROGEN RELEASE

Solar and hydrogen energy play an important role in providing a variety of industrial facilities with electricity and heat. One of the priorities of modern industry is to increase the production of environmentally friendly energy source – electrochemical synthesis of hydrogen. Modern methods of electrolysis of water do not meet the need for its use, due to the high cost of electrosynthesis of water-alkaline electrolysis, which depends on the material and energy consumption of electrolysis. The useful energy consumption for the production of energy – hydrogen at the cathode and "unnecessary" costs - for the release of oxygen at the anode, depend on the overvoltage of the respective reactions. Therefore, the most important problem of hydrogen energy is the synthesis of electrode materials with low overvoltage of O2 and H2. Electrode materials with low overvoltage will reduce the specific consumption of electricity in obtaining hydrogen by "classical" electrolysis. The prospects of reducing the cathodic and anodic overvoltage, which is a significant part of the voltage at the terminals of the cell, for the development of highly efficient and competitive technologies for hydrogen production by low-temperature electrolysis of an alkaline solution have been theoretically substantiated and experimentally confirmed. To reduce the overvoltage of the cathodic hydrogen evolution, it is proposed to modify the surface of the cathodes. The application of a small amount of electrolytic alloys of metals of the iron family with molybdenum and tungsten on nickel, cobalt, titanium and steel electrodes significantly (by 40–50 %) reduces the overvoltage of cathodic release of hydrogen from alkali solution. The use of steel electrodes, the surface of which is modified with vanadium and ni-ckel, reduces the voltage drop on the cell during the synthesis of H2 and O2 by 0.2–0.3 V, which creates conditions for reducing energy costs and energy savings.

Multiphysical Models for Hydrogen Production Using NaOH and Stainless Steel Electrodes in Alkaline Electrolysis Cell

The cell voltage in alkaline water electrolysis cells remains high despite the fact that water electrolysis is a cleaner and simpler method of hydrogen production. A multiphysical model for the cell voltage of a single cell electrolyzer was realized based on a combination of current-voltage models, simulation of electrolyzers in intermittent operation (SIMELINT), existing experimental data, and data from the experiment conducted in the course of this work. The equipment used NaOH as supporting electrolyte and stainless steel as electrodes. Different electrolyte concentrations, interelectrode gaps, and electrolyte types were applied and the cell voltages recorded. Concentrations of 60 wt% NaOH produced lowest range of cell voltage (1.15–2.67 V); an interelectrode gap of 0.5 cm also presented the lowest cell voltage (1.14–2.71 V). The distilled water from air conditioning led to a minimum cell voltage (1.18–2.78 V). The water from a factory presented the highest flow rate (12.48 × 10−1cm3/min). It was found that the cell voltage of the alkaline electrolyzer was reduced considerably by reducing the interelectrode gap to 0.5 cm and using electrolytes that produce less bubbles. A maximum error of 1.5% was found between the mathematical model and experimental model, indicating that the model is reliable.