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Landfill gas recovery for energy production

Organic matter present in landfill experiences a biological decomposition under anaerobic conditions with an accompanying production of methane (CH4) and carbon dioxide (CO2) which contribute to the greenhouse effect and climate change. Sanitary landfills install a piping system for the removal of the landfill gas generated, thus minimizing combustion and explosion hazards. Even simple flaring of the landfill gas can minimize the climate change impact of waste disposal by converting methane into carbon dioxide, since the global warming potential of the first is over twenty times larger than the latter`s. Going one step further, the landfill gas can be collected and used for heat and/or electricity production, displacing the use of fossil fuels for the production of the same amount of energy.
Since the collection and treatment of municipal solid waste usually lies within the responsibilities of the Local Government, municipalities can have a very direct influence on waste and waste-to-energy strategies, and often play the role of facility owner.

Motivation / Relevance

Landfill CH4 is the largest source of GHG emissions from the waste sector. Global CH4 emissions from landfills are estimated to be 500-800 MtCO2eq/year. [2] While the rate of waste disposal in landfills in the EU is decreasing (waste disposal in EU-27 decreased from 54% in 2004 to 45% in 2010 [11]), rates of landfill CH4 emissions are expected to increase in developing countries due to an increased use of controlled and sanitary landfills for waste disposal to control open dumping. In Brazil, 89% of the waste generated in 2000 was either disposed of on open dumps and in landfills (controlled and sanitary) [8]. 

Improved landfill site management through converting open dumping and burning to engineered landfills using cover material results in higher rates of CH4 generation and therefore it should go hand in hand with making use of the CH4 for energy generation.
CH4 is emitted both during and after the period of activity of landfills: therefore, projected sites and landfills being operated should assess the viability of installing gas recovery systems. Landfill CH4 can be used to fuel industrial boilers, to generate electricity and/or heat, and purified to produce a substitute for natural gas after the removal of CO2 and trace components [2].

In addition, if the gas generated in the waste disposal site is not removed, it raises safety hazards: the gas accumulation leads to deformation which may damage lining, may leak into neighboring buildings and may lead to spontaneous combustion.

Main impacts

  • Production of renewable energy (electricity and/or heat generation);
  • Reduce the consumption of fossil fuels for energy purposes;
  • Reduced risk of aquifer contamination associated with solid waste disposal as a result of the extraction of landfill gas, minimizing pollutants migration in the soil [9];
  • Improvement of the health and environmental quality conditions for the population living close to landfills;
  • Creation of jobs for operation and maintenance;
  • Climate change mitigation.

Benefits and Co-Benefits

  • Landfill gas energy-recovery during and after the landfill lifespan;
  • Reduction of the amount of the fossil fuels used as primary energy source;
  • Revenue for local governments by selling electricity to the national grid;
  • Reduction of the release of GHG gases into the atmosphere.