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Útdráttur:
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Malawi is endowed with huge potential of low-enthalpy geothermal as manifested by several hot springs in different geothermal fields across the country. None of these fields have been developed into useful economic activities. The main purpose of this study was to come up with potential direct utilization technologies for economic development of Malawi’s geothermal fields. Three geothermal fields of Kasitu, Linga and Benga in Nkhotakota district were considered. Four technologies which included swimming pools and spas, greenhouse tomato production, indoor fish drying and raceway aquaculture of tilapia were analysed. Using the heat loss method for greenhouses, swimming pools and spas and aquaculture raceways, and the mass and energy balance method for the fish dryer, energy and hot water requirements were calculated. In addition, economic feasibility was done on each of the technology by calculating internal rate of return (IRR), payback period and net present value (NPV) discounted at 10% discount rate for a 10-year period
Results indicate a total energy requirement of 5.2 MWth with 4.2 MWth being for aquaculture demanding total hot water requirement of 35 l/s for Linga field and 26 l/s for Kasitu field. Excluding aquaculture, the total energy requirement is 1 MWth with corresponding hot water requirement of 8 l/s for Linga and Benga fields and 6 l/s for Kasitu field. Economic evaluation indicates positive IRR ranging from 17% for aquaculture to 29% for spas and positive NPV for all the technologies with highest being with aquaculture at US$ 2.1 million and the lowest being US$ 0.04 million for greenhouse tomato production. Based on the findings, Malawi can effectively develop greenhouse tomato production, swimming pools and spas, indoor fish drying and intensive aquaculture of tilapia in its geothermal fields dependent on the source temperatures. This would greatly boost the tourism industry and achieve sustained availability of high quality tomato and fish (both fresh and dried) throughout the year, thereby contributing to food security and improved livelihood in the areas of development. However, to achieve and maintain flow rates required for aquaculture, there is need for shallow drilling up to 300 m into deeper aquifers below. The use of greenhouses to produce vegetables and intensive fish farming will bring awareness among policymakers and the general public on the potential of the technologies to improve quality and quantity of yields throughout the year. |
