The potential of energy recovery from municipal solid waste in Kampala City, Uganda by incineration

Abstract

• Techno-economic study of energy recovery from MSW in Kampala by incineration was done. • Characterization of the MSW was conducted. • A MSW incineration plant was designed and simulated. • The plant can produce 774 kWh of electricity per ton of MSW. • The NPV was USD 34 million, project IRR of 12.9 %, and a payback period of 6 years. With the increasing urbanization, global generation of Municipal Solid Waste (MSW) is expected to increase to 3.4 billion tons by 2050. Annually, 1.9 billion tons of MSW is generated with each person contributing 218 kg of MSW to this projected grand total. In Kampala, the annual MSW collection exceeds 350,000 tons which is disposed at the city’s landfill which has exceeded its capacity. This has side effects including environmental contamination, methane gas generation promoting global warming, and labour issues. No research has been conducted towards assessing the potential of energy recovery from the city’s MSW by incineration. In this paper, the techno-economic assessment of energy recovery from MSW in Kampala city using incineration was done. Waste data was collected through sampling upon delivery at the landfill. Chemical composition of the waste was determined by proximate analysis and calculation of the elemental composition followed by determination of the calorific value. A MSW incineration plant was designed based on a mass burn incineration. The design parameters were determined using thermodynamic equations and Peng Robison’s equations of state. Simulation was done using Aspen Plus and Aspen Hysys, for a plant combusting 220,000 tons per annum of MSW at a feed rate of 27 tons of MSW per hour. The economic analysis was done assuming that the project was a Public Private Partnership debt financed by 75 % with an interest rate of LIBOR plus 5 % margin over a term of 15 years. Results showed that the composition of the waste was largely organic with an 80% composition. The Lower Heating Value was 6.12 MJ/kg with a moisture content of 25%. The elemental composition was 43.47% Carbon, 5.52% Hydrogen, and 41% Oxygen with absence of Nitrogen and Sulfur. The ash content was reported at 6.65 %. From the simulations, the plant is capable of exporting 774 kWh of electricity per ton of MSW to the national grid, capable of powering 1,062 medium income households in Uganda. A capital investment of USD157 million with the sale of electricity and a gate fee as the sources of revenue for a project running for 25 years was considered. The resulting Net Present Value was USD 30 million with a project Internal Rate of Return of 12.6 % and a payback period of 6 years. Thus, the present study demonstrates the possibilities to increase the adoption and use of renewable and clean energy, prioritise energy efficiency, and biodiversity for a green and sustainable Kampala city. Moreover, the results provide immediate technical information for policy makers and potential investors in the development of waste to energy projects in Uganda.