Nigeria

Integrated photovoltaic‐fuel cell (IPVFC) systems amongst other integrated energy generation methodologies are renewable and clean energy technologies that have received diverse re‐ search and development attentions over the last few decades due to their potential applications in a hydrogen economy. This article systematically updates the state‐of‐the‐art of IPVFC systems and provides critical insights into the research and development gaps needed to be filled/addressed to advance these systems towards full commercialization. Design methodologies renewable energy‐ based microgrid and off‐grid applications energy management strategies optimizations and the prospects as self‐sustaining power sources were covered. IPVFC systems could play an important role in the upcoming hydrogen economy since they depend on solar hydrogen which has almost zero emissions during operation. Highlighted herein are the advances as well as the technical challenges to be surmounted to realize numerous potential applications of IPVFC systems in unmanned aerial vehicles hybrid electric vehicles agricultural applications telecommunications desalination synthesis of ammonia boats buildings and distributed microgrid applications.

As the clamour for a Net Zero carbon energy economy increases it is necessary to harness the potential of renewable energies in powering buildings to lower fossil power plants' contributions to the overall energy mix. This paper aims to present an energy balance load sensitivity analysis and multi-criteria method for sizing a green energy system for powering two office complexes that house space research laboratories. The energy component considered includes battery storage (BAT) captive diesel generator (DG) fuel cell (FC) hydrogen storage (H2T) solar photovoltaic (PV) and wind turbine. Using HOMER the techno-economic features and the hourly operational details of the energy components were obtained. The efficacy of Entropy- Additive Ratio Assessment was deployed on the outputs from HOMER to obtain the most preferred energy system based on more than one criterion. The result of the study indicates that the most preferred energy system for Abuja is a PV WD FC DG and BAT having a total net present cost (TNPC) of $220930. In contrast the most suitable energy system for the energy in the Anyigba office consists of PV FC and BAT with its TNPC at $106955.

One of the many technical benefits of green diesel (GD) is its ability to be oxygenated lubricated and adopted in diesel engines without requiring hardware modifications. The inability of GD to reduce exhaust tail emissions and its poor performance in endurance tests have spurred researchers to look for new clean fuels. Improving gasohol/hydrogen blend (GHB) spark ignition is critical to its long-term viability and accurate demand forecasting. This study employed the Response Surface Methodology (RSM) to identify the appropriate GHB and engine speed (ES) for efficient performance and lower emissions in a GHB engine. The RSM model output variables included brake specific fuel consumption (BSFC) brake thermal efficiency (BTE) hydrocarbon (HC) carbon dioxide (CO2) and carbon monoxide (CO) while the input variables included ES and GHB. The Analysis of Variance-assisted RSM revealed that the most affected responses are BSFC and BTE. Based on the desirability criteria the best values for the GHB and the ES were determined to be 20% and 1500 rpm respectively while the validation between experimental and numerical results was calculated to be 4.82. As a result the RSM is a useful tool for predicting the optimal GHB and ES for optimizing spark-ignition engine characteristics and ensuring benign environment.

Hydrogen is considered the fuel of the future due to its cleaner nature compared to methane and gasoline. Therefore renewable hydrogen production technologies and long-term affordable and safe storage have recently attracted significant research interest. However natural underground hydrogen production and storage have received scant attention in the literature despite its great potential. As such the associated formation mechanisms geological locations and future applications remain relatively under-explored thereby requiring further investigation. In this review the global natural hydrogen formation along with reaction mechanisms (i.e. metamorphic processes pyritization and serpentinization reactions) as well as the suitable geological locations (i.e. ophiolites organic-rich sediments fault zones igneous rocks crystalline basements salt bearing strata and hydrocarbon-bearing basins) are discussed. Moreover the underground hydrogen storage mechanisms are detailed and compared with underground natural gas and CO2 storage. Techno-economic analyses of large-scale underground hydrogen storage are presented along with the current challenges and future directions.

Energy transition is a key driver to combat climate change and achieve zero carbon future. Sustainable and costeffective hydrogen production will provide valuable addition to the renewable energy mix and help minimize greenhouse gas emissions. This study investigates the performance of in-situ hydrogen production (IHP) process using a full-field compositional model as a precursor to experimental validation The reservoir model was simulated as one geological unit with a single point uniform porosity value of 0.13 and a five-point connection type between cell to minimize computational cost. Twenty-one hydrogen forming reactions were modelled based on the reservoir fluid composition selected for this study. The thermodynamic and kinetic parameters for the reactions were obtained from published experiments due to the absence of experimental data specific to the reservoir. A total of fifty-four simulation runs were conducted using CMG STARS software for 5478 days and cumulative hydrogen produced for each run was recorded. Results generated were then used to build a proxy model using Box-Behnken design of experiment method and Support Vector Machine with RBF kernel. To ascertain accuracy of the proxy models analysis of variance (ANOVA) was conducted on the variables. The average absolute percentage error between the proxy model and numerical simulation was calculated to be 10.82%. Optimization of the proxy model was performed using genetic algorithm to maximize cumulative hydrogen produced. Based on this optimized model the influence of porosity permeability well location injection rate and injection pressure were studied. Key results from this study reveals that lower permeability and porosity reservoirs supports more hydrogen yield injection pressure had a negligible effect on hydrogen yield and increase in oxygen injection rate corelated strongly with hydrogen production until a threshold value beyond which hydrogen yield decreased. The framework developed in the study could be used as tool to assess candidate reservoirs for in-situ hydrogen production.