Despite the increasing use of nuclear, biofuels, and renewable energy sources in energy production, the use of fossil fuels in energy production continues widely. Combined cycle power plants are among the best options that enable the more efficient use of fossil fuels. These power plants, which use a combination of the Brayton and Rankine cycles, use fossil fuels more efficiently while also cause less environmental damage. In this study, energy and exergy analysis of a natural gas-fired combined cycle power plant was carried out using the actual operational data of the power plant. The exergy efficiency of the power plant was determined to be 61.2 % as a result of the analyses performed under conditions where the ambient temperature and pressure were 25.4 °C and 98.1 kPa, respectively, while the component with the highest exergy destruction was the combustion chamber with 89 MW. The condenser was determined to be the most exergy efficient component of the power plant, with a 96.4 % efficiency rating. While the total power obtained from the power plant is 205 MW, the power of the Brayton cycle is 134 MW and the power of the Rankine cycle is 71 MW. In this study, the effects of increasing the ambient temperature and the gas turbine inlet temperature were also investigated. Nükleer, biyoyakıtlar ve yenilenebilir enerji kaynaklarının enerji üretimindeki kullanımları gün geçtikçe artsa da enerji üretiminde fosil yakıt kullanımı yaygın olarak devam etmektedir. Fosil yakıtların daha verimli bir şekilde kullanılmasını sağlayan en iyi seçeneklerin başında kombine çevrim santralleri gelmektedir. Brayton ve Rankine çevrimlerinin birleştirilmesinden oluşan bu santraller bir taraftan fosil yakıtları daha verimli kullanırken, diğer yandan çevreye daha az zarar vermektedir. Bu çalışmada doğalgazla çalışan bir kombine çevrim santralinin enerji ve ekserji analizleri, santralin gerçek operasyon verileri kullanılarak gerçekleştirilmiştir. Ortam sıcaklığının ve basıncının sırasıyla 25,4 °C ve 98,1 kPa olduğu şartlarda gerçekleştirilen analizler sonucunda, santralin ekserji verimi % 61,2 olarak bulunurken, en yüksek ekserji kaybına sahip olan bileşen 89 MW ile yanma odası olmuştur. Ekserji verimi en yüksek santral bileşeni ise % 96,4 ile yoğuşturucu olarak tespit edilmiştir. Santralden elde edilen toplam güç 205 MW olarak hesaplanırken Brayton çevriminin gücü 134 MW, Rankine çevriminin gücü 71 MW olarak hesaplanmıştır. Ortam sıcaklığı ile gaz türbini giriş sıcaklığının arttırılmasının etkileri bu çalışmada ayrıca incelenmiştir.

The acceleration of the green energy transition has reinforced the importance of reliable, cost-effective hydrogen production technologies. Alkaline water electrolyzers (AWEs) have become a critical option due to their lack of requirement of platinum group metals, as well as their scalability; however, the materials, geometry, and operating conditions used must be comprehensively evaluated alongside electricity costs. This study presents an approach that directly integrates a COMSOL-based electrochemical polarization model with a techno-economic module and validates the results against published U–J curves and 2024 public LCOH ranges. The scans across the 25 kW–10 MW range show that temperature and separator porosity are the most powerful factors affecting performance; narrow cell gaps significantly reduce ohmic losses, and the electrolyte concentration provides limited additional benefit beyond a certain threshold. KOH outperforms NaOH under most conditions, but the difference between the two electrolytes narrows as temperature increases. Economic analyses confirm that electricity price is the dominant determinant of LCOH; levels of 4–5 $·kg⁻¹ are achievable at the MW scale, while high-cost scenarios reach 7–10 $·kg⁻¹. In conclusion, the study provides a validated and scalable framework for the joint optimization of AWE design and operation.

The flow field design in the bipolar plate, which is a DMFC structure, is extremely important in the mass transfer in the fuel cell and the electrochemical reactions occurring in the cell. One of the main purposes of DMFC is to improve the flow plate in order to provide less pressure drop in all channels. Therefore, different leaf types have been investigated to improve the flow distribution performance of DMFC. Populus, Large-surface Bamboo, Palm, Philodendron, Lotus, Mulberry, Loquat and Fig leaves with similar properties were sized using the COMSOL Multiphysics program and designed by examining their environmental and physical properties. Flow and pressure distributions in accordance with the flow field design similar to leaf dimensions in two dimensions were investigated. The biological and physical properties of each bio-inspired leaf design are described and its compliance with the DMFC is explained. Finally, flow images are presented with a comparison of flow areas. When these studies in the literature are examined; while applying the bio-inspired approach, it was seen that the shape similarity approach was adopted. However, by specifying the leaf, the flow field was not created exactly in the size of the leaf. Although there is a research on the flow design in the PEM fuel cell, it has not been used at the same rate for the DMFC. Considering that it is suitable for the DMFC system with the flow channel designs in the bipolar plate in question, it is expected that the performances that will increase the flow transmission to optimum levels will also increase when used.

Ammonia has become a strategic compound for sustainable energy systems due to its carbon-free structure, high hydrogen density and compatibility with existing infrastructures. In this study, the technical and economic feasibility of green ammonia production based on the electrochemical Haber-Bosch (eHB) process is analysed in detail. Modelling results show that reactor pressure and electrolyser efficiency have decisive effects on the levelized cost of ammonia (LCOA) and operating expenses (OPEX). Under pressures above 9 MPa, the conversion efficiency and the residence time in the reactor decreases, decreasing the conversion efficiency but resulting in a smaller reactor volume, thus reducing reactor costs. Especially at electricity prices as low as 30 USD/MWh, LCOA has been observed to be competitive with conventional methods at scales above 25 tonnes/day. Furthermore, increases in capacity factor and production scale improve economic performance by spreading capital and fixed operating costs over a larger production volume The results demonstrate that high-pressure eHB systems supported by renewable sources offer an industrially viable and competitive option for decentralised green ammonia production across various sectors, from the fertiliser industry to hydrogen carrier applications.