Abstract: In this paper, energy consumption by the mankind is considered as a global process within the system of ‘Sun-Earth-cosmic environment’. The upper limit for the energy consumption rate is estimated, provided that the thermodynamic equilibrium in this system is retained. This viewpoint leads to the following principles of energy consumption: (i) the energy should be consumed from the renewable sources only; (ii) the amount of the consumed energy should not exceed the amount of energy coming to the Earth. Three major sources of the renewable energy are considered: a direct incoming solar irradiation, a chemical energy due to products of photosynthesis and, finally, an outgoing infrared (IR) radiation from the Earth as a heated body. It is shown that only the first source gives the most effective way of energy consumption from the viewpoint of the global energy conversion. The ranges of materials suitable for construction of energy converters from the last source are briefly reviewed. It is discussed that the proper use of the outgoing IR radiation on the large scale can be helpful in controlling the climate changes. It is shown that the energy consumption rate which meets the global thermodynamic balance and expected technical facilities cannot exceed a limit of 10¹⁴W, which is approximately an order higher of the contemporary rate of energy consumption by the mankind. The conclusion is made that we should learn how to restrict the energy consumption rate in the near future.

Abstract: The duck and chicken eggshell wastes were applied as raw materials for the preparation of heterogeneous catalyst in biodiesel production. Prior to use, the calcium carbonate (CaCO₃) content in the waste shell was converted to calcium oxide (CaO) by calcining at 600-900C for 4h. The physicochemical properties of the solid oxide catalyst were characterized by X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscopy (SEM) and the Brunauer-Emmett-Teller (BET) method. The catalytic activity of the catalyst in transesterification of palm oil with methanol was evaluated, and the fuel properties of obtained biodiesel were measured. The effect of reaction time, reaction temperature, methanol/oil molar ratio, catalyst loading, and reusability of catalyst was also investigated. Eggshell waste is a bioresource for the production of heterogeneous base catalyst that can be successfully utilized for the synthesis of biodiesel with high purity.

Abstract: Sustainable energy systems are necessary to save the natural resources avoiding environmental impacts which would compromise the development of future generations. Delivering sustainable energy will require an increased efficiency of the generation process including the demand side. This paper reviews the pattern of energy-use in Nigeria and makes a case for the implementation of an energy efficiency policy as a possible strategy to address the nation’s energy crisis. The study as well explores the role of industrial energy use in sustainable development in Nigeria and the potential sources to increase energy efficiency in industrial sector. The study showed that the pattern of electrical energy consumption in the industries reviewed was majorly from generating set while power supply from national grid compliment generating set if available; this is due to either low voltage or epileptic power supply from national grid. Direct and indirect sources that lead to electrical energy waste and in-efficient energy utilization in the industries were identified such as energy loss as a result of aging electric motor, worn out or slack / misaligned machine parts, excessive heating and cooling, use of low efficient lightings etc. The review paper shows that industrial energy efficiency in Nigeria is a readily achievable, cost effective and has potential of reduction in industrial consumption using good energy management practices and energy efficient equipment. This study will be of help to government, industrialists and industrial policy makers.

Abstract: Renewable energies are playing a fundamental role in supplying energy, as these kinds of energies can be clean, low carbon and sustainable. Solar chimney power plant is a novel technology for electricity production from solar energy. A solar chimney power plant derives its mechanical power from the kinetic power of the hot air which rises through a tall chimney, the air being heated by solar energy through a transparent roof surrounding the chimney base. The performance evaluation of solar chimney power plant was done by FLUENT software by changing three parameters including collector slope, chimney diameter and entrance gap of collector. The results were validated with the solar chimney power plant which was constructed in Zanajn, Iran with 12 m height, 10 m collector radius and 10 degree Collector angle. By simulation and numerical optimization of many cases with dimensional variations, increasing 300 to 500 percent of chimney velocity and eventually increasing output power of system was observed in different cases.