This was a research project into environmental hazards from the biggest dumpsite in Kenya, the Dandora dumpsite. Study included explorations of community based methane gas capture solutions.
Landfill gas energy projects have been implemented in the developed world from as far back as the late 1970s, providing sustainable alternative energy to communities, industries, institutions and businesses. Landfill gas projects have been used in various countries to substitute other forms of energy most of which are more expensive and destructive to the environment with most impacts being felt on air quality.
Emissions from landfills comprised mainly of methane (40-60% of typical landfill gas emissions), carbon-dioxide, and non-methane organic compounds (NMOCs). Methane gas is both a fuel and a pollutant causing global climate change. It is estimated that each ton of methane emitted into the atmosphere has as much global warming effect as 21 tons of carbon-dioxide over a 100 year period. Methane also cycles in the atmosphere 20 times more quickly than carbon-dioxide, meaning that stopping methane promises quick progress in slowing down global climate change. Methane produced on decomposition of organic waste can be captured and processed to generate energy which could be used to supplement other forms of energy.
The amount of gas that can be captured from a landfill depends on:
- The amount of waste-in-place (WIP);
- The age and status of the landfill (a large landfill that is still receiving waste is a good candidate for an energy recovery project-the case for Dandora);
- The amount of rainfall that a landfill receives (Nairobi receives an average of 1000mm per annum of rainfall, making it ideal for bacterial action in landfills and methane production and
- The type of waste: Methane is produced when organic waste, such a paper and food scraps, decomposes, therefore sites for industrial and construction demolition waste are not ideal.
The Dandora landfill is one of the oldest, largest, and most active landfill sites in Kenya. The proposed project at the landfill site is intended not only to bring socio-economic benefits to neighboring communities but also contribute significantly in improving the ambient air quality and the reduction of green house gas emissions that cause global warming, hence climate change. The project was developed by Eco-Build Africa, in collaboration with Climate Network Africa.
Pump tests were done after installing extraction wells within a representative section of the site, and connecting these to an extraction rig. Objectives of the pump tests were:
- To measure sustainable methane levels of the extracted LFG;
- To get the percentage by volume of CH4, CO2, O2;
- To measure average gas temperature at the top, middle and bottom of the well;
- To measure pressure and flow relationships while actively extracting LFG; and
- To use the results of the pump tests to determine the projections of landfill gas recovery.
The findings showed that the highest concentration in of methane in the site is 26% below the level that can be flared. The recommendations were that waste separation be done, and waste dumped systematically so that adequate depth, pressure and temperatures can be achieved for commercially viable methane capture.
The study also included a survey to establish the energy demands for the Dandora community. Over 1000 households were surveyed, with the help of some 35 research assistants, all drawn from the community and trained by the Eco-Build Africa and Climate Network Africa’s team. The parameters explored included: the type, cost and amount of energy consumed annually by the community. Below is a summary of some of the findings of the survey.
Most households in Dandora rely on grid electricity for their lighting and charcoal for their cooking. Grid electricity is expensive in Kenya, i.e. Kshs. 10 per KW. On the other hand poor ventilation in houses in Dandora makes cooking with charcoal precarious, especially with regard to airborne diseases affecting children. Petroleum based gas is also used for cooking in some families, however it is expensive based on the income of people in Dandora.
