In recent decade's world's energy demands are fulfilled by coal, natural gas as well as petroleum though the price of oil is skyrocketing. Moreover, geopolitical tensions around the world may push it higher and demand also increasing as well. The world is faced two new problems severely like energy crisis and environmental degradation. If this continues, global recession is unavoidable and depletion of world reserve accelerates undoubtedly. To produce more fuels and energy more environmental hamper is done by the world that's why many investigations have been done to find out an environment friendly, economically competitive and technically feasible alternative source of energy. Very recently, Biodiesel is found to be more sustainable, non toxic and energy efficient technology which is biodegradable. Around 350 oil bearing crops rapeseed, soybean, jatropha, sunflower, linseed and coconut are the main sources of Biodiesel. But these edible material sources were proved to be unfeasible where demand is much higher than the production. But non-edible materials like algae is acceptable source of biodiesel not only in research but also many recently developed countries like China, Malaysia and India are accepted this technology in production and export. This paper provides an overview of algal biodiesel production at Bangladesh where fuel (oil, gas, coal) is too expensive day by day and to ensure a degradation free environment, alternative source of fuel (Biodiesel) is the time demanding decision for Bangladesh. Both mechanical and chemical methods of biodiesel production are analysed. In China, fundamental research on microalgae energy has a strong engineering and technological base. Several projects were taken from 2005 and algal biodiesel would be the giant source of energy within few years at China. National Biofuel policy of Malaysia increasing productivity and maximising returns in the sector of second generation biofuel technology like biodiesel from algae. In India, they started with jatropha based biodiesel and finally carried out extensive work to find out hydrocarbon at Indian water from hydrocarbon producing algae. For Bangladesh in fostering the development of biofuels industries, government have to play important role to adapt the technologies for their own condition, which raises issues of technology transfer. For both sustainable development and environmental protection, advanced technologies of biodiesel production is imperative for Bangladesh.
Remote communities that have limited or no access to the power grid commonly employ diesel generators for communal electricity provision. Nearly 65% of the overall thermal energy input of diesel generators is wasted through exhaust and other mechanical components such as water-jackets, intercoolers, aftercoolers, and friction. If recovered, this waste heat could help address the energy demands of such communities. A viable solution would be to recover this heat and use it for direct heating applications, as conversion to mechanical power comes with significant efficiency losses. Despite a few examples of waste heat recovery from water-jackets during winter, this valuable thermal energy is often discarded into the atmosphere during the summer season. However, seasonal thermal energy storage techniques can mitigate this issue with reliable performance. Storing the recovered heat from diesel generators during low heat demand periods and reusing it when the demand peaks can be a promising alternative. At this point, seasonal thermal storage in shallow geothermal reserves can be an economically feasible method. This paper proposes the novel concept of coupling the heat recovery unit of diesel generators to a borehole seasonal thermal storage system to store discarded heat during summer and provide upgraded heat when required during the winter season on a cold, remote Canadian community. The performance of the proposed ground-coupled thermal storage system is investigated by developing a Computational Fluid Dynamics and Heat Transfer model.
Different processes that use energy and machines that do work do not have perfect efficiency. So energy is wasted from these processes in the form of heat. Power generating stations, industrial processes, rice mills, brick fields and other human activities are major sources of waste heat. Mud stoves used in rural areas for cooking purpose produce above 85% of waste heat. This wasted heat can be used to generate electrical power using Stirling engine (SE). Stirling engine is a heat engine that is operated at different temperature levels by cyclic operation of compression and expansion of working gas. A DC generator is coupled with the SE to generate electrical energy. In this research amount of waste heat from significant sources has been presented and theoretical analysis has been made to harvest electrical power using a displacer type SE. Utilizing helium as working fluid and a DC generator having 90% efficiency a SE with displacer swept volume of 7.37 ×10 -4 m 3 can generate 80 watt of electrical power at 115 rpm engine frequency. In this mathematical approach the phase angle is 90 o and the temperature difference is about 150 0 K. The setup discussed is working as a personal power plant for each rural household.
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