Abstract:Tanzania is facing challenges in energy provision with a lot of people leaving in rural areas experiencing energy poverty exhibited by lack of access to electricity, therefore relying on traditional fuels for cooking and lighting. In Tanzania, the electricity access has risen from 18.4% in 2013 to 24% in 2015. Power generation remained generally stable in 2013 which contributed 7.3% to the growth of the National economy. In 2014 the estimates shows that the National economy grew by 7.2%, and is projected to reach 7.4% in 2015. It is reported that, the electricity demand in Tanzania is about 7% per year over the past 10 years. A large proportion of majority of rural population is located far away from the National grid and it is un economical to connect to the grid. The main objective of this paper is to examine renewable energy policies and practices in Tanzania and their contribution to Tanzania economy and poverty alleviation. The study focused on content analysis of projects reports and policy in 10 years. Tanzania has drafted renewable energy policies so as to shift dependence from hydropower which is many times affected by draught and weather patterns and petroleum that have been affected by price fluctuation to solar, wind, biogas and other biomass which are renewable. However, the adoption rate of these renewable energy technologies is low because of financial constraints, lack of awareness, lack of coordination between the Government, non Governmental organizations and private sectors. Existing renewable energy policies should be harmonized and the current practice should be evaluated so as to upgrade the adoption rate of renewable technologies.

Municipal Solid Waste (MSW) generation has been increasing due to population growth, changing life style, technology development and increased consumption of goods. The increase of waste generation combined with the use of waste dumps may lead to environmental and social problems such as water contamination, land and atmospheric pollutions, resulting to breeding grounds for vermin, cause risk of fire, bad smell and potentially are the cause of illness. Energy recovery from municipal solid waste can alleviate these problems while providing a source of energy. The objective of this study is to evaluate the combustion properties and energy potential from municipal solid waste of Arusha, Tanzania. Incineration is among the methods for MSW treatments, and therefore, the data and information provided shows that energy can be recovered from Arusha MSW during incineration process. Energy flow (exothermic and endothermic) and thermal degradation analysis were carried out using Differential Scanning Calorimetry (DSC) and thermo -gravimetric analysis (TGA) respectively. The sample of composition of municipal solid waste examined included paper, cardboard, wood, textile, rubber, polyethylene Teraphthalate (PETE), low density polyethylene (LDPE) and food waste. These materials were heated in a combined DSC and TGA analyser and experiments were performed at heating rate of 10 ○ C/min, in a pure nitrogen atmosphere at temperatures between room temperature and 1100 ○ C. The results observed from TGA and DTG show that the highest reactivity was the samples from Central Market, followed by those from Sakina and Ngarenaro market. It was observed that municipal solid waste is less reactive to combustion compared to dry biomass, thus its reactivity can be improved by removing non-combustible materials such as metals and food scraps or by pre-treating the MSW so as to reduce the amount of oxygen present in it. The final analysis of the municipal solid waste showed that, the average percentage of nitrogen, sulfur, chlorine and phosphorus in the waste were 2.36%, 0.37%, 0.04% and 0.11% respectively, which is low and therefore, emissions released by this MSW during combustion are also low. The energy content of the solid waste tested was about 12MJ/kg on dry basis. The elemental composition shows that municipal solid waste contains 50% and 5% of carbon and hydrogen respectively.

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Mathematical modeling and computer simulation for the municipal solid waste incineration process provides important understanding into the incinerator's performance. The application of mathematical modeling for the incineration process will increase the incinerator operating efficiency. The broad objective of this study was to optimize the design of municipal solid waste incinerators using mathematical modeling and computer simulation. Computation Thermal Predictions (CTP) relations involving different types of incineration parameters such as temperature, density, velocity and species concentration were formulated based on theories of incineration process with various assumptions. The solution of the mathematical model developed was done and accomplished by Computational Fluid Dynamics (CFD). Finite element method of numerical analysis was applied to solve the temperatures in the simulated incinerator model as well as species/flue concentration at the end of its chimney. Dimensions used on the simulated model were applied to construct the physical incinerator for analysis. Tests were performed on the physical model incinerator and data used to validate the results obtained from the simulated model. Both simulated and experimental results showed that it is possible to forecast temperature and flue gases by the application of mathematical expressions. The incinerator CTP model was applied to simulate the incineration process and aid to regulate temperature at different locations and species/flue concentration at the end of incinerator chimney. The CTP results were very close to those obtained from experiment. The t-test method conducted revealed that simulated and experimental results did not differ significantly at 0.05 level of significance. Therefore, there is an agreement between the empirical model and experimental data as they show true trend of the incineration process.