Landfill gas (LFG) is the end product of microbial degradation of organic material under anaerobic conditions i.e. in the absence of oxigen. The degradation process takes place in different steps, in which the raw organic material is degraded to smaller material which, in the course of the processes, will be converted into landfill gas. In undiluted form, landfill gas consists primarily of the greenhouse gasses methane (approximately 60%) and carbon dioxide (approximately 40%). The formation of landfill gas can be influenced by various factors, e.g. composition of the waste, waste pre-treatment, site characteristics, local and regional climatic conditions, etc. These aspects vary greatly from site to site.
When the Drehid Waste Management Facility was originally proposed in 2004, Bord na Móna carried out a feasibility assessment of installing a landfill gas (LFG) utilisation system as soon as the first phase of the landfill was finally capped, and pumping tests had been carried out to determine the quantity and quality of gas being produced.
Co-incidentally, a key element of Bord na Móna’s corporate strategy has been the diversification of its business interests away from reliance on peat related activities. Coupled with this diversification agenda is a strong focus on growth. The existing investment in the waste management sector therefore presented the company with an opportunity to develop landfill gas electricity generation, which is the process of gathering, processing and treating landfill gas to produce electricity.
The landfill gas is collected through a series of pipes which are fitted throughout the landfill. Initially, it was directed to a series of flares which burned the gas to break down the methane, a particularly harmful greenhouse gas. Once the landfill gas could be collected and processed however, it can be used to fuel a combustion engine which drives generators to create electricity.
Today, the landfill gas utilisation facility at Drehid generates enough sustainable and renewable electricity to power 8,500 homes – while at the same time helps to save the environment!