Open Access Minireview Article

Fuels for Automobiles: The Sustainable Future

Olumide A. Towoju

Journal of Energy Research and Reviews, Page 8-13
DOI: 10.9734/jenrr/2021/v7i330191

The future of internal combustion engine-powered automobiles hangs in the balance unless clean fuels are available in commercial quantities. Electricity-powered vehicles will displace the internal combustion engine-powered automobiles. However, electricity-powered vehicles are yet to meet some of the automobile demands. A paradigm shift with attendant infrastructural change is necessary for its adoption. Synthetic fuels promise to be the solution. Their invention dates back to the early twentieth century when the concern was not about climate change. The search for alternative fuels later metamorphosed to when fossil fuels reserve depletion and petroleum derivatives cost became a concern. The alternatives were made available in biofuels. The prevailing challenge is now climate change. It is the consequence of the emission of greenhouse gases from the combustion of petroleum derivatives in automobiles. Synthetic fuels show the potential of coming to the rescue despite the prevailing hurdles. The future holds a potential promise of converting greenhouse gas (CO2) to liquid fuels that will allow little or no disruptions to the current transportation infrastructure network. It is, therefore, necessary to encourage further studies on the production of synthetic fuels. The environmental and economic benefits of commercially available synthetic fuels promise to be enormous.

Open Access Original Research Article

Characterization and Ranking of Various Mix Ratios of Cow, Pig and Sheep Manure

Sheila Chepkirui Matwek, Daudi M. Nyaanga, B. O. Osodo

Journal of Energy Research and Reviews, Page 1-7
DOI: 10.9734/jenrr/2021/v7i330190

This work determined the characteristics of various mix ratios of the cow to pig to sheep manures and ranked them with help of principal component analysis (PCA). Ten mix ratios (by mass) namely 1:1:1, 3:1:1, 1:3:1,1:1:2, 2:1:1, 1:2:1, 1:1:2, 1:3:3, 3:3:1, 3:1:3 of cow, pig and sheep manures respectively were selected. Laboratory analysis was done to determine the total solid (TS) content, carbon to nitrogen ratio, pH, and volatile solid (VS) content using standard procedures. The results obtained (except that of pure feedstocks) were subjected to principal component analysis to determine the principal component scores for the mix ratios to enable ranking. The total solids content of pure cow, pig, and sheep manure were found to be 19.18%, 23.50%, and 30.35% respectively. Corresponding carbon to nitrogen ratios values were 23.68, 13.27 and 29.00, pH values were 6.50, 7.90 and 7.00 and volatile content were 88.37%, 84.57% and 80.00%. Upon mixing the three manures at various mix ratios total solid content varies from 22.28% to 26.75%. Total solids content, carbon to nitrogen ratio, pH and volatile solids content varies from 22.28% to 26.75%, 18.76 to 25.05, 7.13 to 7.56 and 85.94% to 82.59% respectively. Using the first principal component scores mix ratio 1:1:3 of cow dung, pig, and sheep manure was the top-ranked followed by 3:1:3 and the third one was 1:1:2 with scores of 2.540, 1.638, and 1.580 respectively.  The 4th ranked mix ratio was 1:3:3, 5th ranked was1:1:1, 6th ranked was 2:1:1, the 7th one was 3:1:1, 8th one was 1:1:2, then 3:1:1 and lastly 1:3:1 with the scores of 0.191, -0.006, -0.147, -0.259, -1.440, -1.810 and -2.287 respectively. Higher positive scores were associated with a possibility of producing higher biogas yield possibly due to the right combination of the several parameters in the mixture while a lower score might indicate a lower gas yield due to an improper combination of parameters. It was then concluded that principal component analysis is a suitable method for selecting few mix ratios to use in anaerobic digestion among the many. It saves on time and resources due to the reduced number of experiments.

Open Access Original Research Article

Reliability Analysis of a Home-scale Microgrid Based on a Threshold System

Taufal Hidayat, Ali Muhammad Rushdi

Journal of Energy Research and Reviews, Page 14-26
DOI: 10.9734/jenrr/2021/v7i330192

The reliability of a microgrid power system is an important aspect to analyze so as to ascertain that the system can provide electricity reliably over a specified period of time. This paper analyzes a home-scale model of a microgrid system by using the threshold system model (inadvertently labeled as the weighted k-out-of-n:G system model), which is a system whose success is treated as a threshold switching function. To analyze the reliability of the system, we first proved that its success is a coherent threshold function, and then identified possible (non-unique) values for its weights and threshold.  Two methods are employed for this. The first method is called the unity-gap method and the second is called the fair-power method. In the unity-gap method, we utilize certain dominations and symmetries to reduce the number of pertinent inequalities (turned into equations) to be solved. In the fair-power method, the Banzhaf index is calculated to express the weight of each component as its relative power or importance. Finally, a recursive algorithm for computing system reliability is presented. The threshold success function is verified to be shellable, and the non-uniqueness of the set of weights and thresholds is demonstrated to be of no detrimental consequence, as different correct sets of weights and threshold produce equivalent expressions of system reliability.

Open Access Original Research Article

Approaching an Efficient and Feasible Carnot Engine by Carnot Cycle Analysis

Ramon Ferreiro Garcia

Journal of Energy Research and Reviews, Page 27-45
DOI: 10.9734/jenrr/2021/v7i330193

Based on the knowledge exhibited in the literature on the Carnot cycle, a preliminary study is carried out on Carnot machines capable of implementing the Carnot cycle at high thermal efficiency. Therefore, two engine structures are proposed: (i) reciprocating single and double-acting cylinder-based thermal engines implemented under a closed processes-based Carnot thermal cycle characterised by a mechanical structure internally coupled, and (ii) similar engines characterised by a mechanical structure internally decoupled.

In order to perform the cycle analysis, however, observational (experimental) evidence confirms on a daily basis the fact that there are two performance criteria: conventional (output net work/input heat) thermal efficiency and output/input energetic-based first law efficiency. Based on such premises, this study investigates both coupled and decoupled Carnot engine structures.

The results confirm that an important fraction of heat can be converted into useful work by configuring a decoupled structure of the Carnot engine.

Indicative results support the use of internally decoupled thermal machines, especially when the heat source has a low or medium temperature. Even at high temperatures, such machines are advantageous in terms of energy efficiency. Furthermore, avoiding internal coupling allows for power regulation without disturbing interactions due to variations in load, thus enabling robust control.

Open Access Original Research Article

Energy, Exergy and Environmental Compatibility Analyses of LPG and Household Kerosene Utilisations as Domestic Fuels in Nigeria: 1980 – 2019

I. Badmus, A. J. Bakri

Journal of Energy Research and Reviews, Page 46-56
DOI: 10.9734/jenrr/2021/v7i330194

Household kerosene and Liquefied Petroleum Gas form the bulk of domestic fuels, especially in Nigerian urban areas. Data on both fuels, from 1980 to 2019, were collected, mainly from Nigerian National Petroleum Corporation sources. Energy, exergy and environmental compatibility analyses were carried out on the utilisation of LPG for cooking, and household kerosene for both cooking and lighting. Kerosene lighting, with 0.05% energy efficiency and 0.045% exergy efficiency, was extremely poor. Cooking, with different mixes of both fuels, yielded energy efficiencies ranging from 35.04% to 44.54%. Corresponding exergy efficiencies were from 7.75% to 9.98%. Associated environmental compatibility factors were from 0.71749 to 0.73945. Overall process energy efficiencies, involving both cooking and lighting, were from 4.05% to 34.19%. Corresponding exergy efficiencies were from 0.93% to 7.61%. Overall environmental compatibility factors ranged from 0.71746 to 0.73259. Energy and exergy efficiencies, as well as environmental compatibility factors, increased directly with increase in LPG utilisation in the fuel-mix.