Evaluation of theoretical models to estimate landfill gas(LFG) potential as a renewable energy source: a case study of Chunga landfill

Abstract

According to the World Bank, Zambia generates approximately 0.9 kg of solid waste per person per day. The strategies in place for Municipal solid waste (MSW) management include a combination of three techniques: recycling, combustion, and landfill disposal. In Lusaka, at least 22.5 % of the waste generated is disposed at Chunga landfill. Landfills pose as environmental threats due to uncollected landfill gas (LFG) emissions generated by biochemical processes arising from the disposed waste but if properly managed, methane in LFG can be a valuable energy resource.Currently no landfill gas to energy (LFGTE) project exists in Zambia for utilization of LFG and little information is available on the potential of electricity generation from the gas. With the electricity demand in Lusaka increasing at 10 % per annum coupled with electricity deficits, exploiting LFG will not only provide a segment of the needed energy, but also help curb the environmental problems.The main objective of this study therefore was to, “investigate the energy potential of LFG and the feasibility of LFGTE project at Chunga landfill by applying appropriate LFG estimation models”. A mixed method research approach was used in conducting this study. Secondary data was collected by literature review while primary data through interviews, surveys and manipulation of pre-existing data using analytical and numerical methods was collected. Three LFG estimation models namely, LandGEM, Afvalzorg and IPCC were used to estimate methane generation based on site specific data and waste acceptance history for the landfill considering both conventional and bioreactor operations of the landfill. The electricity generation potential was then estimated based on the results. Peak LFG flows were used to design the gas collection system for the purpose of conducting cost analysis using LFG-Cost WEB model. The study revealed that installation of a microturbine operating as a bioreactor landfill provides an estimated average annual energy of 19.2 million kWh capable of powering at least 3500 residential houses with a consumption band between 100-300 kWh per month. The model estimated a capital cost of US$ 4.71 million (K 45 million) at US$ 0.094 (K 0.89) per kWh to achieve an investment payback period of 5 years.