Saudi Arabia

This study investigates numerically combustion attributes and NOx formation of premixed ammonia-hydrogen/air flames within a swirl burner of a gas turbine considering various conditions of hydrogen fraction (HF: 0 % 5 % 30 % 40 % and 50 %) equivalence ratio (φ: 0.85 1.0 and 1.2) and mixture inlet temperature (Tin: 400–600 K). The results illustrate that flame temperature increases with hydrogen addition from 1958 K for pure ammonia to 2253 K at 50 % HF. Raising the inlet temperature from 400 K to 600 K markedly enhances combustion intensity resulting in an increase of the Damköhler number (Da) from 117 to 287. NOx levels rise from ∼1800 ppm (0 % HF) to ∼7500 ppm (50 % HF) and peak at 8243 ppm under lean conditions (φ = 0.85). Individual NO N2O and NO2 emissions also reach maxima at φ = 0.85 with values of 5870 ppm 2364 ppm and 10 ppm respectively decreasing significantly under richer conditions (2547 ppm 1245 ppm and 5 ppm at φ = 1.2). These results contribute to advancing low-carbon fuel technologies and highlight the viability of ammonia-hydrogen co-firing as a pathway toward sustainable gas turbine operation.

The rock wettability is one of the most critical parameters that influences rock storage potential trapping and H2 withdrawal rate during Underground hydrogen storage (UHS). However the existing review articles on wettability of H2-brine-rock systems do not provide detailed information on complexities introduced by reservoir wettability influencing parameters such as high pressure temperature salinity conditions micro-biotic effects cushion gases and organic acids relevant to subsurface environments. Therefore a comprehensive review of existing research on various parameters influencing rock wettability during UHS and residual trapping of H2 was conducted in this study. Literature that provides insight into molecular-level interaction through machine learning and molecular dynamic (MD) simulations and role of surface-active chemicals such as nanoparticles surfactants and wastewater chemicals were also reviewed. The review suggested that UHS could be feasible in clean geo-storage formations but the presence of rock surface contaminants at higher storage depth and microbial effects should be accounted for to prevent over-estimation of the rock storage potentials. The H2 wettability of storage/caprocks and associated risks of UHS projects could be higher in rocks with high proportion of carbonate minerals organic-rich shale and basalt with high plagioclase minerals content. However treatment of rock surfaces with nanofluids surfactants methylene blue and methyl orange has proven to alter the rock wettability from H2-wet towards water-wet. Research results on effect of rock wettability on residually trapped hydrogen and snap-off effects during UHS are contradictory thus further studies would be required in this area. The review generally concludes that rock wettability plays prominent role on H2 storage due to the frequency and cyclic loading of UHS hence it is vital to evaluate the effects of all possible wettability influencing parameters for successful designs and implementation of UHS projects.

Blue hydrogen technology generated from natural gas through carbon capture and storage (CCS) technology is a promising solution to mitigate greenhouse gas emissions and meet the growing demand for clean energy. To improve the sustainability of blue hydrogen it is crucial to explore alternative feedstocks production methods and improve the efficiency and economics of carbon capture storage and utilization strategies. Two established technologies for hydrogen synthesis are Steam Methane Reforming (SMR) and Autothermal Reforming (ATR). The choice between SMR and ATR depends on project specifics including the infrastructure energy availability environmental goals and economic considerations. ATR-based facilities typically generate hydrogen at a lower cost than SMR-based facilities except in cases where electricity prices are elevated or the facility has reduced capacity. Both SMR and ATR are methods used for hydrogen production from methane but ATR offers an advantage in minimizing CO2 emissions per unit of hydrogen generated due to its enhanced energy efficiency and unique process characteristics. ATR provides enhanced utility and flexibility regarding energy sources due to its autothermal characteristics potentially facilitating integration with renewable energy sources. However SMR is easier to run but may lack flexibility compared to ATR necessitating meticulous management. Capital expenditures for SMR and ATR hydrogen reactors are similar at the lower end of the capacity spectrum but when plant capacity exceeds this threshold the capital costs of SMR-based hydrogen production surpass those of ATR-based facilities. The less profitably scaled-up SMR relative to the ATR reactor contributes to the cost disparity. Additionally individual train capacity constraints for SMR CO2 removal units and PSA units increase the expenses of the SMR-based hydrogen facility significantly.