Tuesday, November 29, 2022

The downside to methane extraction

The Director in the Department of Waste Management and Pollution Control, Oarabile Serumola has said that extraction of methane gas from landfills for use as fuel in vehicles and for domestic purposes is a very expensive project to undertake. 

It is said that methane is one of the Green House Gases whose emission into the atmosphere contibute in global warming and as such harvesting it through processes like extraction from landfills for reuse can help address this problem.  Extraction of methane from the landfill is typically through extraction wells strategically placed during the construction of the landfill. Another method that can be used to extract methane is through horizontal trenches. Through both systems, the landfill gas is collected at the collection wells and a blower is required to pull the gas to the collection header for purification. This involves removing traces and other gases such as carbon dioxide.

Serumula said during an interview that there should first be a feasibility study to ascertain whether there is enough methane in the 44 landfills around the country to cover the cost of extraction which will be substantial as the technology to do so will be imported. Furthermore, “for ease of extraction the waste should be well compacted, which is not the case in our country. Extraction is easier if all the waste is biodegradable. But here even rabbles from construction sites are dumped at landfills; which cannot be compacted.” She emphasized the fact that the feasibility study cannot be done any time soon as the country does not have the funds to do so. There are a number of projects, she said, that could be implemented at lesser costs. The government therefore has to prioritize, she advised. 

On whether there are local companies with expertise to carry out the job of harvesting the gas she responded; “indeed there are people locally who are knowledgeable in the extraction process. Their challenge would be the technology to do it.”

A landfill, she said, can take up to 30 years which as a result makes the extraction process a very long one. The process to place the machinery at the landfill and start extracting the gas can take months, she explained. She added that the most important thing is how much methane has accumulated there, for extraction; hence the importance of a feasibility study. 

Botswana as a signatory of the Conference of Parties (COP) 21 has the obligation to reduce its emission of Green House Gases into the atmosphere. Prior to the COP 21, countries had to submit their Intended Nationally Determined Contributions (INDCs) which means action that a country had intended taking to reduce its emission of Green House Gases (GHGs) into the atmosphere as was required by the United Nations Framework Convention on Climate Change (UNFCCC). A number of workshops were held with participating partners where consultants were engaged to help compile the INDCs from which recommendations were made. The construction of a landfill gas facility was one of the recommendations the consultants came up with. Their report motivated that; “assuming that all future landfills will incorporate methane recovery program, it is estimated that approximately 20 Giga grams (Gg) of methane can be extracted which represents approximately 15 per cent of total methane production in the country. Through a methane recovery plant by 2030, total emission in the country would be 10 Gg Carbon Dioxide equivalent (CO2 eq) based on Intergovernmental Panel on Climate Change (IPCC) spreadsheet.”


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