Energy Solution

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A Review of the Current Trends in the Production and Consumption of Bioenergy
(Sami Publishing Company(SPC), 2021) Korir, Benjamin K.; Kibet, Joshua; Mosonik, Bornes C.
With the current traditional fossil fuels depleting at an alarming rate coupled with environmental degradation because of toxic emissions, there is a mounting desire in search of renewable and sustainable energy resources. In this regard, bioenergy is considered one of the greatest potential to address the global energy demands in order to foster confidence in energy security, economic sustainability, and environmental protection. Global use of biomass to generate electricity and enhanced green energy transport is expected to increase in the near future. Accordingly, the demand for renewable energy is aimed at minimizing energy poverty and mitigation against climate change. Bioenergy despite bioconversion challenges is one of the key solutions to the world’s current energy demands. Model bioenergy plant sources – Croton megalocarpus, palm oil, Jatropha, and soybeans are briefly discussed in this review as major sources of bioenergy. The increased focus on bioenergy has been necessitated by high oil and gas prices, and the desire for sustainable energy resources. Nonetheless, corrupt practices and lack of political goodwill has hampered efforts towards achieving the full utilization of bioenergy. Corruption has been widely cited as a major setback to bioenergy development in a range of global jurisdictions. In order to minimize environmental damage, carbon trade has been projected as a necessary action by developing countries to reduce carbon emissions. Generally, the analysis of the use of fossil fuels across the world shows a strong interrelationship involving energy utilization, degradation of air quality, and environmental health concerns.
Exhaust Gases Energy Recovered from Internal Combustion Engine for Useful Applications
(IOSR Journal of Mechanical and Civil Engineering, 2017-06-01) Orido, George; Ngunjiri, Prof; Rugiri, Musa
Abstract : The importance of this study is primarily to address the energy problem. The main contribution of this study, in addition to conserving energy through recovery technique, is reduction in the impact of global warming due to exhaust gas emission to the environment. The objective of the research is to recover exhaust gases energy from internal combustion engines for utilization. The experimental set-up consisted of a single cylinder, four-stroke, multi-fuel engine connected to eddy current dynamometer for loading. Thermocouple temperature sensors and transmitters were used to measure exhaust gas to calorimeter inlet temperature and exhaust gas from calorimeter outlet temperature. Exhaust gas mass flow rate and temperature measurements were used to determine the recovered energy. Recovered heat energy was 1.257% of fuel energy when the engine was operated on diesel at 1000 rpm and a torque load of 18 Nm. 3.153% of fuel energy was recovered at 1500 rpm and a torque load of 6 Nm when biodiesel was used. At a speed of 1000 rpm 22.6% and 23.004% of the thermal energy through exhaust was recovered when the engine used diesel and biodiesel at torque loads of 6 Nm and 14 Nm respectively.
Improved short-circuit current density in bulk heterojunction solar cells with reduced graphene oxide-germanium dioxide nanocomposite in the photoactive layer
(Elsevier, 2020) Amollo, Tabitha A.; Mola, Genene T.; Nyamori, Vincent O.
In the quest to improve the optical absorption and electrical transport of poly-3-hexylthiophene (P3HT) and (6-6) phenyl-C61-butyric acid methyl ester (PCBM) blend film, reduced graphene oxide-germanium dioxide nanocomposite (rGO-GeO2) was employed in the photoactive layer of thin film organic solar cells. Bulk heterojunction solar cells (BHJ SCs) with rGO-GeO2 composite in the active layer exhibited an increase in power conversion efficiency (PCE) of up to 53%. Significant improvement in the measured photocurrent is achieved by the incorporation of rGO-GeO2 in the active layer. High short-circuit current density (Jsc) of up to 17 mA/cm2 is attained in the BHJ SCs. The high Jsc shows that the inlay of rGO-GeO2 in the active layer facilitates exciton separation and creates percolation pathways for charge transport to the electrodes. Charge separation is energetically favoured by a built-in potential difference between the donor and acceptor phases of the active layer. Hence, the incorporation of rGO-GeO2 composite in the active layer improves its charge photogeneration, separation and transport to yield high Jsc and enhanced PCE.
Improved short-circuit current density in bulk heterojunction solar cells with reduced graphene oxide-germanium dioxide nanocomposite in the photoactive layer
(Elsevier, 2020-11) Amollo, Tabitha A.; Mola, Genene T.; Nyamori, Vincent O.
In the quest to improve the optical absorption and electrical transport of poly-3-hexylthiophene (P3HT) and (6-6) phenyl-C61-butyric acid methyl ester (PCBM) blend film, reduced graphene oxide-germanium dioxide nanocomposite (rGO-GeO2) was employed in the photoactive layer of thin film organic solar cells. Bulk heterojunction solar cells (BHJ SCs) with rGO-GeO2 composite in the active layer exhibited an increase in power conversion efficiency (PCE) of up to 53%. Significant improvement in the measured photocurrent is achieved by the incorporation of rGO-GeO2 in the active layer. High short-circuit current density (Jsc) of up to 17 mA/cm2 is attained in the BHJ SCs. The high Jsc shows that the inlay of rGO-GeO2 in the active layer facilitates exciton separation and creates percolation pathways for charge transport to the electrodes. Charge separation is energetically favoured by a built-in potential difference between the donor and acceptor phases of the active layer. Hence, the incorporation of rGO-GeO2 composite in the active layer improves its charge photogeneration, separation and transport to yield high Jsc and enhanced PCE.
Investigation of magnetic properties of FeMnP1-xAx (A = In, Se and Sn, where x = 0.33) by use of GGA functionals
(Elsevier, 2021-07) Vincent, Otieno; Mulwa, Winfred Mueni; Kirui, M. S. K.
Magnetic properties of stable iron-based compounds (FeMnP1-xAx (A = Si, In, Se and Sn) were investigated by use of Quantum Espresso (QE) within the Density Functional Theory (DFT) formalism as a viable magnetic refrigerant. In this research work, DFT technique was the first principle theoretical approach that was employed along with the planewave pseudopotentials (ultrasoft), and the projected augmented wave (PAW) within the generalized gradient approximation (GGA) to describe the electronic structure and investigation of magnetic properties. Magnetic stability is described as the repeated magnetic performance of a material under specific conditions over the life of a magnet. In this case our reference compound, FeMnP0.67 Si0.33 was optimized and its properties were examined in both ferromagnetic (FM) and antiferromagnetic (AFM) states. Two Si atoms were later substituted with atoms of post-transitional metals in period four and five which has shown first-order magnetic transition at near room temperatures. In, Se and Sn were chosen to replace silicon since they would easily mimic the bond, their availability and nontoxic nature. The results showed that only ferromagnetic states of both host and doped compounds gave promising magnetic properties that can be applied in magnetocaloric effect phenomenon. Their band structure results indicated that they were all metals. Antiferromagnetic states showed no magnetic properties as the spin-polarized graph resulted in perfect symmetry of spin up projected density of states (PDOS) and spin down PDOS. From the thermo_pw calculations, it was realized that FeMnP0.67 In0.33 is the best candidate for near room temperature magnetic refrigeration among the studied compounds.
Reduced graphene oxide-germanium quantum dot nanocomposite: electronic, optical and magnetic properties
(IOP Publishing, 2017-11-13) Amollo, Tabitha A.; Mola, Genene T.; Nyamori, Vincent O.
Graphene provides numerous possibilities for structural modification and functionalization of its carbon backbone. Localized magnetic moments can, as well, be induced in graphene by the formation of structural defects which include vacancies, edges, and adatoms. In this work, graphene was functionalized using germanium atoms, we report the effect of the Ge ad atoms on the structural, electrical, optical and magnetic properties of graphene. Reduced graphene oxide (rGO)-germanium quantum dot nanocomposites of high crystalline quality were synthesized by the microwave-assisted solvothermal reaction. Highly crystalline spherical shaped germanium quantum dots, of diameter ranging between 1.6–9.0 nm, are anchored on the basal planes of rGO. The nanocomposites exhibit high electrical conductivity with a sheet resistance of up to 16 Ω sq−1. The electrical conductivity is observed to increase with the increase in Ge content in the nanocomposites. High defect-induced magnetization is attained in the composites via germanium adatoms. The evolution of the magnetic moments in the nanocomposites and the coercivity showed marked dependence on the Ge quantum dots size and concentration. Quantum confinement effects is evidenced in the UV–vis absorbance spectra and photoluminescence emission spectra of the nanocomposites which show marked size-dependence. The composites manifest strong absorption in the UV region, strong luminescence in the near UV region, and a moderate luminescence in the visible region.
Simulated performance of a novel solid-state dye-sensitized solar cell based on phenyl-C61-butyric acid methyl ester (PC61BM) electron transport layer
(Optical and Quantum Electronics, 2021-07-01) Korir, Benjamin K.; Kibet, Joshua K.; Ngari, Silas M.
Climate change has approached a major crisis limit worldwide due to exhaust emissions arising from the use of traditional transport fuels. Solar energy, therefore, appears to be the most promising alternative energy that can mitigate air quality and environmental degradation. Herein, we report numerical simulation of a novel model solid-state dye-sensitized solar cell consisting of solid-state layers with the configuration FTO/PC61BM/N719/CuSCN/Au using 1-dimensional solar cell capacitance simulator software (SCAPS-1D). The motivation underpinning the numerical simulation of the solar cell architecture proposed in this study was to optimize phenyl-C61-butyric acid methyl ester (PC61BM) performance as the electron transport layer. In this model, the effects of varying several parameters—temperature, absorber thickness, defect density, and metallic back contact on the overall solar cell performance have been critically examined. After optimizing the input parameters, the optimal conversion efficiency was 5.38% while the optimized open-circuit voltage was 0.885 V. Besides, 70.94% was the optimum fill factor and the peak short-circuit current of 8.563 mA cm−2 was achieved. Built-in voltage of ~ 1.0 V was estimated from the Mott–Schottky curve and the cell band diagram. The power conversion efficiency obtained in this study is robust for this cell configuration, and is toxic-free compared to the lead-based perovskite solar cells. These findings are therefore useful in the advancement and fabrication of high-performance dye-based photovoltaic devices for large-scale industrial production.
Structural, Electronic and Mechanical Properties of Re Doped FeMnP_0.67A_0.33 (A=Ga and Ge): A DFT Study
(International Journal of Physics, 2022-02-14) Chirchir, Gabriel Kipkemei; Mulwa, Winfred Mueni; Adetunji, Bamidele Ibrahim
The structural, electronic and mechanical properties of Re doped FeMnP0.67A0.33 (A= Ga and Ge) were examined by use of density functional theory (DFT) within the generalized gradient approximations as demonstrated in Quantum ESPRESSO code. The optimized structural parameters as well as derived lattice parameters are in consistent with other computational and achievable experimental results. The computed independent elastic constants confirm the mechanical stability of the investigated materials. The computed Poisson’s and Pugh’s ratios as well as Cauchy pressure, verify that FeMn0.67Re0.33P0.67Ga0.33 is the most ductile among the studied compounds. The calculated values of bulk modulus, shear modulus and Young’s modulus confirm high values of bond strength, hardness and stiffness of the investigated materials respectively. Therefore, the four compounds considered may be appropriate for industrial applications. The results report that FeMn0.67Re0.33P0.67Ga0.33 compound is more ductile and mechanically stable compared to other investigated compounds. This is the first qualitative computational prediction of the elastic properties of FeMnP0.67Ge0.33, FeMnP0.67Ga0.33, FeMn0.67Re0.33P0.67Ge0.33 and FeMn0.67Re0.33P0.67Ga0.33 compounds and this awaits experimental ratification. The calculated electronic density of states confirms that the Re_2p states are located in the conduction band (CB) in the unite cell while Re_3d dominate the CB in the supercell. Results from the doped compounds could not be compared with experimental or computational findings because to the best of our knowledge, this has not been done.
Structural, Electronic and Mechanical Properties of Re Doped FeMnP_0.67A_0.33 (A=Ga and Ge): A DFT Study.
(SciEP, 2022) Chirchir, Gabriel Kipkemei; Mulwa, Winfred Mueni; Adetunji, Bamidele Ibrahim
The structural, electronic and mechanical properties of Re doped FeMnP0.67A0.33 (A= Ga and Ge) were examined by use of density functional theory (DFT) within the generalized gradient approximations as demonstrated in Quantum ESPRESSO code. The optimized structural parameters as well as derived lattice parameters are in consistent with other computational and achievable experimental results. The computed independent elastic constants confirm the mechanical stability of the investigated materials. The computed Poisson’s and Pugh’s ratios as well as Cauchy pressure, verify that FeMn0.67Re0.33P0.67Ga0.33 is the most ductile among the studied compounds. The calculated values of bulk modulus, shear modulus and Young’s modulus confirm high values of bond strength, hardness and stiffness of the investigated materials respectively. Therefore, the four compounds considered may be appropriate for industrial applications. The results report that FeMn0.67Re0.33P0.67Ga0.33 compound is more ductile and mechanically stable compared to other investigated compounds. This is the first qualitative computational prediction of the elastic properties of FeMnP0.67Ge0.33, FeMnP0.67Ga0.33, FeMn0.67Re0.33P0.67Ge0.33 and FeMn0.67Re0.33P0.67Ga0.33 compounds and this awaits experimental ratification. The calculated electronic density of states confirms that the Re_2p states are located in the conduction band (CB) in the unite cell while Re_3d dominate the CB in the supercell. Results from the doped compounds could not be compared with experimental or computational findings because to the best of our knowledge, this has not been done.

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