Journal of Sustainable Energy

5

Authors: KLADISIOS P., SAGIA A.

Supercritical water gasification is a promising and environmentally friendly biomass conversion method. Compared to conventional gasification, it is capable of handling biomass with high moisture and displays higher conversion efficiency and decreased tar formation. Through supercritical gasification, organic feedstock in the presence of supercritical water is converted into a mixture of H2, CO2, CO, CH4 and traces of other gases over shorts periods of time. The composition and yield of the final gas mixture depends highly on reaction temperature, feed concentration and nature of catalyst in use. Reaction pressure and residence time play a less important role. Despite being appealing for the production of hydrogen from an inexpensive source, hydrothermal gasification suffers from decisive technical challenges, with corrosion and efficiency being the most critical.

6

Authors: EL FARRI. H, BOUACHRI. M, FAHOUME. M

In this paper, the performance of CIS Based solar cells was investigated, using a simulation program named SCAPS-1D Software (Solar Cells Capacitance Simulator). CIS cell structure is based on Cu(In, Ga), (Se,S)2; which is a semiconductor compound as an absorber layer; un-doped Zinc Oxyd (i) ZnO as a window layer, and Sulfide Cadmium as a Buffer layer, with an efficiency of ƞ=17%. We studied the influence of different layers’ thickness and their defect densities, working temperature and absorber carrier density on the CIS based solar cells. The photovoltaic parameters have been calculated, and we have obtained the optimal values of every constraint cited above. As a result, we obtained a new high efficiency value of 19.71%, under air mass (AM) 1.5 and 100 mW/cm2 illumination and the area of this device was 0.15 cm2 [8].

8

Authors: TIRUNEH A.T., DEBESSAI T., NKAMBULE S., BWEMBYA G.

The performance of compound parabolic solar concentrators (CPC) is extended through the provision of additional external reflectors that increased the angle of acceptance and hence achieve concentration for longer part of the day. The modified setup increased the angle of acceptance by over 70% while achieving comparatively close concentration ratio ranging between 90-100% of the maximum attainable. For construction of geometry of the reflector profile, an approach involving coordinate transformation has been used. Satisfactory performance of the solar concentrator has been observed for applications involving grey water treatment, production of struvite and drying of fecal matter from urine diversion dry toilets and compost.

10

Authors: FELEA. I., MOLDOVAN V., BUNDA. S., LIBOR L., ILE I.

Knowing the level of energy efficiency is essential for substantiating investment decisions, operation and maintenance of energy consuming equipment and machines. Urban public transport is an important consumer of energy and, at the same time, an important source of pollution of the urban environment with greenhouse gases and micro particles. The present paper is aimed to identify the level of the energy performance of a public transport car fleet, having buses equipped with Diesel engines. The analysis methodology and the mathematical model used are applicable to other similar structures. The obtained results are valid for the analyzed car fleet, highlighting the values of the energy performance indicators, on the whole, by bus categories and for each bus from the park component. Based on the results obtained within the energy audit, comparisons are made for the level of energy performance with similar consumers, and feasible measures to improve energy efficiency are identified.

3

Authors: OHAJIANYA A. C., MBAMALA E. C., AMAKOM C. M., AKUJOR C. E.

Zinc-Chlorine battery received huge attention from researchers in the 1970s and 1980s due to its simplicity and low cost of basic materials. But the additional materials in the existing designs which are meant to enable the battery to operate with a reasonable level of efficiency; have considerably increased the complexity and cost of the battery. This led to a loss of interest by researchers as literature revealed that there has not been researched work in this battery for many years now. We hereby present a new and simple design for Zinc-Chlorine battery that does not use ion exchange membrane, pump, cooler, and heater. The designed electric cell was constructed and tested. It produced an open-circuit voltage of 2.14 V after charging for 2 hours with a dc source voltage of 5.0 V. A maximum current of about 12 mA/cm2 was realized from the electric cell

5

Authors: NANA TWUM DUAH, PRINCE KOFI ASAMOAH.

The use of electricity and heat are essential in our daily life activities. They areused domestically for heating, lighting, washing, cooling, and cooking. Commercially, it is used in transportation, heating, cooling, manufacturing and processing. In view of this, there is the need to use energy (electricity and heat) efficiently to reduce the waste from energy such as heat and CO2 released into the atmosphere. The efficient use of energy makes the environment safe and maintains a high quality of lives of people. The majority of electricity generated in the world today is from thermal, which has a low efficiency ranging between 30-37% and combines cycle gas turbine (CCGT) having approximately 47%. A high percentage of the primary fuel used to generate power is converted to waste as heat into the environment. Therefore, the need arises to recover the heat and used for another purpose to enhance efficiency. To attain higher efficiency and effective use of primary fuel, Combined Heat and Power (CHP) is employed in recovering of waste heat to be reused, therefore, increasing productivity. This paper highlights the working principles, application, factors influencing the selection of CHP and economic importance of installing CHP. It further uses a Salford hospital as a case study to explain the economic benefits of installing CHP.

7

Authors: MD. ABDULLAH AL ZAMAN, H. M. A. R. MARUF, RIFAT AMIN, M. R. ISLAM, MD. MEHEDY HASAN TANVIR

The growingdisposition of livestock resources as well as the poultry sector with the corroborating weather conditions in Bangladesh encourages an auspicious future of bioenergy. In this paper, existing energy situation of Bangladesh and noteworthy activities associated with renewable energy has been mentioned. After presenting the potential of livestock resources of Bangladesh, the Union based biogas plant model has been explained. The model has been employed to study the potential of generating biogas as well as electricity in Chattogram division of Bangladesh. Under this model, each union can contribute 552 m3 of gas or 0.75 MW of electricity daily and in total 3.2×105 m3 of gas or 435 MW of electricity can be generated in Chattogram division. Union based biogas plants will be beneficial for the rural development but difficult in implementation. Therefore, several issues that required reconciling before installations have been indicated.

7

Authors: FELEA. I., RANCOV N., ALBUT-DANA D.

Knowing energy performance level of an energy consumer is essential for substantiating the decisions for development, operation and maintenance. Energy performance level is highlighted through consecrated indicators which are obtained by means of energy balance. The present paper is a synthesis of electric energy balance that was done within a mixed fodder factory (MFF). In the first part a short presentation of the consumer (MFF) is presented and also analysis methodology. After that we refer to specificities regarding the energy balance model (EB) applied and to characterization elements of typical processes for MFF. An important part of the paper is dedicated to present the obtained results and the energy performance level. In the last part of the paper we present the conclusion of energy audit (EA) and the recommendations to improve the energy performance level.