Hofstetter BV

Utilisation of landfill gas for the generation of energy


Courtesy of Hofstetter BV

The gases in landfill sites that develop during degradation processes, largely contribute to the greenhouse effect and additionally harbour considerable safety and health hazards. However, they are also often rich in methane and therefore a potential energy carrier. In many countries much of this potential for the generation of electricity and heat from landfill gas still exists. Furthermore, through the continual advances in technology, laws and regulations have been passed whereby household refuse landfills – independent of their size – are to be degassed and the landfill gas burned off in a high temperature flare.

Technical solutions

Without technical solutions, landfill gas is a dangerous substance. The methane contained within it can form a combustible mixture with the atmospheric oxygen so that under certain circumstances a danger of explosion exists. If the landfill gas collects in cavities and shafts, people could suffocate there. Furthermore, many trace components such as sulphur, chlorine and fluorine compounds are contained in the landfills which even in low concentrations can have a harmful effect on health.

High climatic relevance

Apart from these characteristics that form a direct danger for people, the gas escaping uncontrolled and untreated from a landfill also has a high climatic relevance. Methane is deemed to be a contributory cause of destroying the ozone layer and contributes to the greenhouse effect being 21 times stronger than carbon dioxide. Through thermal treatment – that means through burning in high temperature flares – the negative effects of the gases can be reduced.

Economic value

Through worldwide emission trading, the greenhouse gas reductions that are achieved through the energetic utilisation of landfill gas, acquire an economic value in so-called emerging countries. Today, this economic added value stands under the international abbreviation CDM. The abbreviation means «Clean Development Mechanism». This instrument agreed upon in 1997 at the international climate conference in Kyoto, enables industrial and developing countries to mutually implement climate protection projects in developing countries. In doing so, it is first calculated how much climatic gas is produced by a power station, a factory, a Landfill. It is then determined how much greenhouse gas can be reduced when the landfill gas is burned in a flare or utilised for the generation of electricity and heat. After that, a company from an industrial country invests in and finances the landfill gas power station in a developing country and receives corresponding certificates for the greenhouse gas reduction thereby achieved. With these certificates, the company can meet the obligations of saving a corresponding amount of climatic gases for their own business at their own location or the investor sells the certificates to other companies within the framework of emission trading. The aim of the investments in such projects is to prevent as many climatedamaging emissions as possible. At the same time how ever, this should help the emerging and developing countries introduce new technologies which they are not normally able to finance themselves.

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