Journal of Energy Research and Reviews

Aims: To assess the composition of the Natural Gas (NG) supplied for domestic consumption through the distribution network to correlate the physical properties linked to it were to be determined in order to investigate their fluctuations.

Study Design:  The samples were analyzed in accordance with the method described in the ISO 6974‑4 standard, “Natural Gas. Determination of Composition with Defined Uncertainty by Gas Chromatography”.

Place and Duration of Study: Center of Technology Research, Fuels Laboratory, between January and December 2016.

Methodology: Over the course of the year, a total of eighty-four samples of natural gas for domestic use were analyzed.  These were collected at a rate of one per month in seven cities in the geographical zone under study (Galicia_Spain), in which the number of users is significant.

Results and Conclusion: The protocols for technical management of the Gas System have a section on quality specifications for Natural Gas at entry points to the system.  This sets limits for only three of the physical properties of natural gas: Wobbe index, superior calorific value and relative density.

The figures obtained for Wobbe index, superior calorific value and relative density from the eighty-four samples studied showed that the quality of the Natural Gas distributed remained steadily within the acceptable limits throughout the whole year. The values for standard deviations bore witness to the fact that any variations did not significantly alter the quality of the Natural Gas supplied.

The concentrations of the odorant, THT, were always above the recommended value of 18.0 mg/Nm³, the fluctuations noted over the course of the year were such as to make it possible to see them as excessive. In some instances, a high concentration of odorant may lead users to erroneous impressions, so that they come to think that there are leaks from the gas-pipes or even that the gas is not burning properly.

A stable, reliable and uninterrupted power supply is one of the basic requirement for economic, social and industrial growth of any nation. Electricity generation capacity in Nigeria is grossly insufficient for the growing demand and there is a need to incorporate small hydropower (SHP) schemes which can be installed in some of the available rivers and streams that are scattered around the country to complement the energy shortage and deficiency. This paper investigated the viability of Elemi river, Ado-Ekiti, Nigeria for a small hydropower scheme as a possible source of off-grid electricity generation to solve the incessant power outages in the three major higher institutions within its catchment. The power demand of the three higher institutions was estimated using questionnaires. The hydrological data for the study area for 11 years spanning 2005 to 2015 were collected and analyzed to determine the flow duration curve (FDC). The mean average velocity of the stream was calculated as 1.21m/s, with average annual flow discharge of 45.9 m³/s, and an average minimal flow of 9.1 m³/s. The average mean estimated hydro power potential obtainable using a diversion scheme is 2.21MW. It was discovered that the yield capacity of Elemi river for power generation with a diversion scheme could not provide the power requirement for any of the 3 higher institutions within its course due to its relatively flat terrain with the maximum derivable head of 8 m. A recommendation for the construction of a dam for an impounded scheme with a minimum gross head of 20 m, which adequately serve the needs, of at least one of the Institutions is made.

Based on the results of no-load tests carried out on a simplified Pico hydropower system currently undergoing development, on-load tests were carried out. A turbine of runner diameter 0.40 m, penstock diameters in the range  and nozzle area ratios in the range  were used for the on-load tests. A 2.5 kW alternator was linked to the turbine using a v-belt drive on pulleys of ratio 6:1. The effective vertical height from the outlet of the reservoir to the plane of the turbine shaft was 6.95 m. A 0.74 kW electric pump was used to recycle the water to the overhead reservoir. The rotational speeds of the turbine and alternator shafts, the volume of water displaced and voltage were measured for each penstock diameter and nozzle area ratio. The measured data were used to compute the system volumetric flow rate and to estimate the power output based on the alternator manufacturer’s specifications. The turbine efficiency was also computed. The system developed a maximum voltage of 224 V with  and a minimum voltage of 111 V with  and . The corresponding estimated power outputs were 2.125 kW and 1.545 kW respectively. The mean maximum and minimum efficiencies based on the estimated power output were 0.85 and 0.618 respectively. The overall results indicate very good potential for the system as a clean, decentralized small power generation unit that gives control to the user.

For the dual reasons of energy security and environmental and climate preservation, there has been a global campaign for drastic reduction in the use of fossil fuels and a consequential aggressive pursuit for the development of clean energy systems. Hybrid renewable energy systems, ahead of single source renewable energy systems, promise to be an effective alternative to the use of fossil fuels. However, if hybrid renewable energy systems must effectively and reliably serve as an alternative to fossil fuel use, then improvements in the control and management of energy flow among the renewable energy supplies, energy storage components, and the load is of very vital significance. More intelligent and optimized, and easy-to-develop control techniques need to be introduced to replace already existing conventional techniques. And very importantly, extra measures have to be taken to ensure longer battery life and the overall safety of the system. This work is a design of a fuzzy logic-based control system for managing energy flow in a hybrid renewable energy system. A dedicated output was incorporated in the fuzzy controller for controlling the load connection status. The results showed that the fuzzy logic controller accurately emulated expert decisions in monitoring the battery state-of-charge and renewable energy supply capacities, and effectively determining and controlling the battery charging and discharging functions. The employment of fuzzy logic control in the system eliminated the need for complex and tedious mathematical modelling as required in conventional control methods. Thus the system was easier to develop.

In order to advance the research on using new techniques to produce clean and affordable energy, many gasification experiments have been conducted on different feedstocks and the results have been analyzed. Two promising feedstocks which in the future could help to meet the energy demand are coal and biomass. In this paper, we have collected deep insightful information about the processes of coal and biomass gasification and then compared them. The information contained in this paper cover coal and biomass properties, the devolatization process and the reactions occurring during char gasification. The contrast analysis which has been conducted showed for instance that biomass’ higher atomic ratio (H/C, O/C) was the cause of its lower heating value in comparison to coal; carbon conversion values for biomass was significantly higher compared to coal, and during the gasification process, coal feedstock released significantly higher pollutant gases (like H₂S) than biomass. In the end, we also presented some innovative technologies that are now developed in the gasification field and which have proven to be highly efficient.